effects of nickel on activated sludge ......activated sludge-sewage mixtures. they found that...
TRANSCRIPT
EFFECTS OF NICKEL ON ACTIVATED SLUDGE PERFORMANCE
AT VARYING COD:TKN RATIOS
by
Patti Gremillion Trahern
Thesis submitted to the Faculty of the
Virginia Polytechnic Institute and State University
in partial fulfillment of the requirements of the degree of
MASTER OF SCIENCE
APPROVED:
W. R. Knocke
in
Sanitary Engineering
J. H. Sherrard
December, 1982
Blacksburg, Virginia
C. W. Randall
ACKNOWLEDGMENTS
Sincere thanks to:
Dr. Joseph H. Sherrard, Dr. William R. Knocke and
Dr. Clifford W. Randall, Advisors and Committee Members, for
their advice, guidance and patience during the course of this
study.
Mr. Glenn Willard, Mr. Richard Mines, Mrs. Marilyn Grender,
and Mr. Victor Gulas for their technical assistance;
Ms. Ann Crate and Ms. Cathy Cook for manuscript preparation.
Special thanks to Bruce, Gordon, and Lynn, for their
unwavering and enthusiastic support.
This research was funded by a grant from the National
Science Foundation.
ii
TABLE OF CONTENTS
ACKNOWLEDGMENTS .
LIST OF TABLES
LIST OF FIGURES
INTRODUCTION
LITERATURE REVIEW .
TREATMENT EFFICIENCY • BOD and COD Removal . Turbidity . . Nitrification . . .
METAL UPTAKE . . . . . . . MECHANISMS OF METAL TOXICITY . SUMMARY ....
MATERIALS AND METHODS .
LABORATORY APPARATUS STARTUP . . . . . . . DAILY PROTOCOL . . . TECHNIQUES OF ANALYSIS
Solids . . . . . . Chemical Oxygen Demand, COD Ammonia Nitrogen, NH3-N Total Kjeldahl Nitrogen, TKN Nitrate Nitrogen, N03-N pH . . . . . . . . . . Alkalinity as Caco3 Nickel, Ni(II) ..
DATA ANALYSIS
RESULTS . . . • . .
TREATMENT EFFICIENCY . COD Removal . . . Reactor Solids, Effluent Suspended Solids, and
Biokinetic Coefficients . . . . • Nitrification .
NICKEL REMOVAL . . . . . . • .
iii
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v
vi
1
5
6 6
12 13 14 20 23
24
25 27 29 34 35 35 35 35 36 36 36 36 37
41
49 49
50 51 52
TABLE OF CONTENTS (continued)
DISCUSSION
TREATMENT EFFICIENCY • COD Removal Efficiency . . • . Reactor Solids Effluent Suspended Solids, and
Biokinetic Coefficients • • • . . • • • • . Nitrification
NICKEL REMOVAL . .
SUMMARY AND CONCLUSIONS
BIBLIOGRAPHY
APPENDIX A
APPENDIX B
VITA
ABSTRACT
iv
S3
S3 S3
SS 63 70
73
7S
79
83
102
LIST OF TABLES
TABLE
I U.S. Consumption of Nickel in 1980 ... 3
II Composition of Wastewater Feed Solution 30
III Parameters Monitored During Steady State Periods . • • • • • 32
IV COD:TKN Ratios and Nickel Doses 42
v Sunnnary of Steady State Data - Reactor I 44
VI Summary of Steady State Data - Reactor II 45
VII Summary of Steady State Data - Reactor III 46
VIII Summary of Steady State Data - Reactor IV 47
IX Summary of Steady State Data - Reactor V 48
x Biokinetic Coefficients 6;
v
LIST OF FIGURES
FIGURE
1 Theoretical Solubility of Nickel Hydroxide 16
2 Speciation Diagram for Nickel-Amine Complexes . • • • • . • 17
3 Experimental Completely Mixed Activated Sludge Unit • . . . . • • • • 26
4 COD Removal Efficiency vs. Mean Cell Residence Time • • • . • • • . • • • . • • . 5 4
5 Total Mixed Liquor Suspended Solids vs. Mean Cell Residence Time 56
6 Specific Utilization Rate vs. Mean Cell Residence Time . . . . . . . 59
7 Specific Growth Rate vs. Specific Utilization Rate • . . • . . 60
8 Observed Yield vs. Mean Cell Residence Time 64
9 Percent Nitrification vs. Mean Cell Residence Time . • • • . . . • . . . . • • . • . • . 65
10 Measured Change in Alkalinity vs. Predicted Change in Alkalinity . . . . • . . • • 68
11 Effluent pH vs. Mean Cell Residence Time 69
12 Nickel Removal vs. Mean Cell Residence Time 71
13 Percent Effluent Soluble Nickel vs. Mean Cell Residence Time 72
vi
INTRODUCTION
As the activated sludge process became an increasingly
popular method of wastewater treatment in the fifties and
sixties, more attention was devoted to specific problems
encountered in the optimization of secondary treatment plant
performance. The purpose of secondary wastewater treatment is
to reduce the amount of unstabilized organic material in the
wastewater by biological processes. In the activated sludge
process, this reduction is achieved by the natural respiratory
and oxidative functions of a diverse community of bacteria and
other heteotrophic microorganisms suspended in the wastewater
being treated.
The activated sludge process can also be operated to provide
nitrification. Nitrification, the oxidation of ammonia to
nitrate, is required of wastewater treatment systems discharging
into receiving waters which could be harmed by an ammonia-bearing
effluent. Two types of autotrophic bacteria, Nitrosomonas and
Nitrobacter, are responsible for nitrification. Nitrosomonas
oxidizes ammonia to nitrite:
2 + Nitrosomonas NH4 + 3 o2 [ lj
and then Nitrobacter oxidizes nitrite to nitrate:
2 - Nitrobacter N02 + o2 [ 2]
1
2
Performance of the activated sludge process, capable of very
high organic material removal, is dependent on many factors.
These include plant operating parameters, such as mean cell
residence time, suspended solids concentration, and dissolved
oxygen concentration, and physical factors, such as temperature,
pH and the presence of toxic materials, such as heavy metals.
The impact of heavy metals on human health has been recog-
nized since the 1800's. Adverse effects caused by inhalation of
heavy metal dust and vapor by workers in mining, smelting, and
other metal operations led to the development of metal toxi-
cology. The scope of this field was considerably broadened when
it became apparent that exposure to heavy metals and their toxic
effects was not limited to the industrial workplace. Incidents
such as the occurrence of itai-itai disease and methylMercury
poisoning, which affected many Japanese in the 1970's, piqued
interest in the fate of heavy metals in the environment (1).
In many of these cases, water, and specifically wastewater,
had introduced heavy metals into the environment. Nickel is
contributed to treatment plant influent almost exclusively by
industrial sources (2). A tough, silvery metal, nickel is used
in producing metal alloys, especially stainless steel. In 1970,
600 U.S. companies used nickel, a~d of those 600, 150 users manu-
factured alloys (3). Table 1 presents a breakdown of U.S.
consumption of nickel by use and form in 1980 (4). Nickel may be
released to the environment in smelting, refining, forming and
3
TABLE I
U.S. CONS!JMPTION OF NICKEL IN 1980
Use
Steel: Stainless- and heat-resisting Alloys (excluding stainless)
Super alloys
Ni-Cu and Cu-Ni alloys
Permanent magnetic alloys
Other nickel and nickel alloys
Cast irons
Electroplating
Chemicals and other chemical uses
Other uses
TOTAL
Short Tons
54,738 16,936
19,153
8, 775
538
27,444
4,074
18,751
1,475
4,442
156,299
4
fabrication operations. Most of these operations are more likely
to release nickel to the atmosphere than directly to wastewater
streams; however, electroplating rinses and any type of operation
which uses water to wash down nickel-bearing dust may contaminate
wastewater streams.
The purpose of this investigation was to determine the
effects of a small dose of nickel on activated sludge performance
by evaluating organic removal efficiency, degree of nitrifi-
cation, and biokinetic coefficients. Nitrification being of
particular interest, nitrogen loading rates were varied to assess
the effect of nitrogen concentration on nickel toxicity to
nitrification.
LITERATURE REVIEW
Much of the early work on metal toxicity to activated
sludge, co11ducted in the 1960's, concentrated on the effect of
heavy metals on treatment efficiency. Later studies, using
analytic techniques developed in the field of physical and
chemical kinetics, investigated the effects of heavy metals at
different stages of growth and substrate utilization by the
biomass responsible for organic degradation. These studies used
the concept of mean cell residence time as elucidated initially
by Jenkin (5) and expanded by others (6,7,8) as the primary
operating variable for the activated sludge process.
The effects of heavy metals on nitrification were briefly
noted in some of the early work, but interest in this particular
area was stimulated by the increasing number of activated sludge
plants required to provide nitrification as effluent standards
became more stringent.
Heavy metal doses used in these studies ranged from less
than 1 mg/1 to 100 mg/l. The effects of lesser doses are of
greater relevance to actual plant performance, as average heavy
metal concentrations in the influent to wastewater treatment
plants are generally low. For example, Hannah and others (2)
found an average of 0.2 mg/l nickel reaching 157 wastewater
plants, with individual plants receiving between 0.04 and 3 m.g/l
nickel average. A similar range was reported by Barth (9) in his
survey of four municipal plants.
5
6
Other researchers were interested in the phenomenon of metal
removal or uptake by activated sludge. Information as to how
metals actually bonded to the sludge led to hypotheses about the
mechanisms of toxicity.
The purpose of this chapter is to review and discuss re-
search conducted in these areas: (1) effects of heavy metals on
treatment efficiency, including nitrification, (2) heavy metal
uptake, and (3) mechanisms of heavy metal toxicity.
TREATMENT EFFICIENCY
Treatment efficiency for secondary wastewater treatment
systems is usually defined in terms of the effluent BOD and
suspended solids limitations placed upon them by regulatory
agencies. Researchers have used BOD removal rates, COD removal
rates, effluent turbidity and degree of nitrification to evaluate
the relative performance of metal-fed systems. Copper, chromium,
nickel and zinc have been of primary interest. Researchers have
observed the effects of shock loading and continuous dosing of
these metals on bench-scale and full-scale activated sludge
systems. Early research focused on copper, and these studies set
the protocol for the following investigations of nickel and other
heavy metals.
BOD and COD Removal
Heukelekian and Gellman (10) tested the effect of several
heavy metals, including nickel, on the oxidation of sewage and
7
activated sludge-sewage mixtures. They found that concentrations
of heavy metals from 5 to 100 mg/l depressed oxidation by both
sewage and activated sludge-sewage mixtures. Metals had a toxic
effect within a characteristic pH range, which, for copper,
corresponded to its solubility. The ratio of organic material to
metal concentration influenced toxicity. The activated sludge-
sewage mixtures were less susceptible to the toxic effects of
metals and exhibited an "increased tolerance" to metals upon
repeated exposures. Appearance of toxic effects tended to be
delayed for these mixtures when compared to sewage mixtures.
In 1963, McDermott (11) reported the effects of copper on
"replicate" activated sludge pilot plants. The pilot plants,
which were used in concurrent and later studies (12,13,14),
included units for primary settling, "spiral flow" aeration,
final settling, and anaerobic sludge digestion. The plants were
fed undiluted domestic sewage, supplemented synthetically if
necessary to approximate the characteristics of strong sewage.
The concept of mean cell residence time had not then been fully
developed. Researchers instead attempted to approach steady
state conditions by maintaining constant mixed liquor suspended
solids concentrations and detention times similar to those
encountered in the field.
McDermott dosed the pilot plants with up to 25 mg/l copper.
The metal-fed units experienced drops in COD removal efficiency
8
which ranged from insignificant to seven percent, with doses
under 1 mg/l having no apparent effect on removal efficiency.
That same year, Moulton (15) found that continuous doses up
to 45 mg/l of copper reduced but did not totally inhibit COD
removal by activated sludge. A year later, Salotto (12) epplied
continuous 1 and 5 mg/l doses of copper to pilot plants similar
to those used by McDermott. He discovered that the toxicity of
copper was not greatly affected by variations in organic loading.
COD removal efficiency was reduced by the addition of 5 mg/l of
copper, however.
In 1965, McDermott and others (13) turned their attention to
nickel toxicity. They conducted a pilot study to assess the
effect of continuous doses of nickel ranging from 1 to 10 mg/l
on replicate activated sludge pilot plants. BOD removal was
slightly depressed by nickel concentrations between 2.5 and 10
mg/l. Decrease in treatment efficiency was not proportional to
nickel dose. Treatment efficiency was about the same for the
unit fed 1 mg/l nickel and for the control unit run simulta-
neously. The researchers concluded that 1 mg/l produced no
significant toxic effects. The control unit used for comparison,
however, was about eight percent less efficient than the control
units run simultaneously with the reactors dosed between 2.5 and
10 mg/l. The possibility exists, therefore, that toxic effects
did occur at 1 mg/l.
9
Summarizing the results of these and other pilot studies on
the effects of copper, chromium, nickel, and zinc at doses
varying from 0.4 to 50 mg/l on replicate activated sludge plants,
Barth (14) noted that treatment efficiency was reduced by small
doses of each metal. Based on loss of treatment efficiency, a
threshold concentration for continuous doses of each metal was
set. The threshold concentration for nickel was estimated to be
between 1 and 2.5 mg/l.
Concurrently, Barth and others (16) studied the effects of
mixtures of copper, chromium, nickel and zinc, totaling 8.9, 4.9,
and 2.0 mg/l on pilot plants. The two higher concentrations
caused five percent decreases in COD removal efficiencies,
whereas the effect of the third, lower concentration was slight.
The results of a field survey of four municipal wastewater
treatment plants receiving wastes bearing copper, chromium,
nickel, and zinc, conducted by Barth and others (9), indicated
that treatment efficiency measured in the field was not notice-
ably impaired by similar concentrations of heavy metals. Of the
three activated sludge plants studied, treatment efficiency at
two was evaluated as excellent, with BOD removal averaging 92
percent at both plants, and COD removal averaging 85 and 87
percent. The third plant achieved only 75 percent BOD and 67
percent COD removals, but this lower efficiency was attributed to
process design limitations rather than to the presence of metals.
10
The development of the concept of mean cell residence tine
(MCRT), a parameter based on kinetically derived equations, but
easily determined from field measurements, led to a reawakening
of interest in the area of metal toxicity. Derived from kinetic
relationships for substrate utilization, mean cell residence time
offered activated sludge treatment plant operators a tool for
process optimization, and researchers a tool for further explor-
ation of the effects of metals on the activated sludge process.
Mean cell residence time, a measure of the time an individual
cell remains in the activated sludge system, depends upon a
number of practical values, including detention time, mixed
liquor suspended solids concentration, and degree of treatment.
It also depends upon the growth and decay rates of the micro-
organisms composing the biomass. Evaluation of certain para-
meters at known mean cell residence times allows calculation of
these kinetic rates.
Bagby (17), Weber (18), Sujarittanonta (19), and DiSalvo
(20) operated bench-scale, continuous flow activated sludge units
fed continuous doses of heavy metals at different MCRT's.
Organic removal efficiency was measured and changes in biokinetic
growth and utilization coefficients evaluated. Changes in treat-
ment efficiency were related to metal concentration and to metal
concentration-to-total system solids and organic load-to-metal
concentration ratios.
11
In Bagby's (17) study of cadmium and nickel, one reactor was
fed 5 mg/l cadmium and 1 mg/l nickel; the other, 10 rng/l cadmium
and 5 mg/l nickel, over a range of mean cell residence times. A
follow-up study was conducted at one MCRT with 5 mg/l cadmium and
1 mg/l nickel, and synthetic feed components doubled. At both
combined metal concentrations, COD removal efficiency was reduced
for all MCRT's. Increase in organic loading to the metal-fed
unit resulted in good COD removal, while increase in the ratio
of total influent metal concentration to total system solids de-
creased removal efficiency.
Weber (18) found that cadmium concentrations of 5 and 10
mg/l caused a slight drop in COD removal efficiencies for similar
units. Biokinetic coefficients were not affected. Sujarittanonta
(19) observed that nickel concentrations of 1 and 5 mg/l also did
not significantly alter treatment efficiency. Nickel toxicity
depended upon the COD-to-nickel ratio, the mixed liquor suspended
solids-to-nickel ratio, and the operating MCRT. Biokinetic
coefficients varied with COD-to-nickel ratios.
DiSalvo (20) dosed similar units with 0.5 mg/l nickel at
different organic loadings. COD removal efficiency was not
significantly impaired by the addition of this small concen-
tration of nickel over a range of MCRT's, although slight
inhibition was apparent at lower MCRT's. For both organic
loadings, removal efficiency increased with MCRT. Maximum
yield coefficient was greater for the metal-fed reactor than
12
for the control fed the same organic loading, and comparable
for the metal-fed reactor fed half the organic loading. (Control
data was collected, however, during a separnte, earlier study
(19); thus differences in yield coefficient between control and
metal-fed reactors cannot be attributed definitely to the
presence or absence of nickel.)
Turbidity
At low doses, heavy metals appear to improve settling by
changing floe characteristics, and effluent suspended solids
may be measurably reduced. Barth (16) found that both BOD and
suspended solids in the effluent from a reactor fed a low con-
centration of a mixture of heavy metals (2 mg/l) were less than
for his control, and surmised that the metal-fed sludge, being
more dense, settled more effeciently. McDermott (11) also
noted improved settling, despite increased effluent solids, for
reactors fed 1 mg/l copper. In most of the heavy metal studies
(11,13,15,16,21), however, effluent turbidity and suspended
solids increased in proportion to metal concentration. Moulton
(15), applying continuous doses of copper up to 45 mg/l, attri-
buted increased effluent suspended solids to the escape of
bacterial cells. Neufeld (22), primarily interested in the
phenomenon of heavy metals-induced deflocculation, found in-
creased suspended solids in the effluent of reactors shock-dosed
with mercury. While the increase in effluent suspended solids
could, in the case of non-soluble or partially soluble feed,
13
result from decreased organic removal efficiency, it seems
reasonable to speculate, as Moulton did, that higher doses of
heavy metals may cause an increase in the concentration of
bacterial cells in the effluent.
Nitrification
From the results of pilot studies, Barth (14) observed that,
for metal-fed reactors, effluent ammonia and dissolved oxygen
concentrations were higher, effluent nitrate much lower, and
effluent nitrite erratic.
Tomlinson (23) conducted a fill-and-draw batch activated
sludge reactor study, and concluded that heavy metals (copper,
mercury, and chrome) have a diminished effect on Nitrosomonas
when it is in mixtures of activated sludge and sewage than when
in pure cultures. Because sludge can accumulate metals, he
suggested that long-term effects might be more severe than
short-term effects.
In Weber's (18) study, nitrification was inhibited by
cadmium at concentrations of 5 and 10 mg/l applied to bench-
scale, continuous flow activated sludge reactors. Bagby (17)
found nitrification greatly reduced for a mixture of 5 mg/l
cadmium and 1 mg/l nickel applied to similar units, and almost
completely inhibited for a mixture of 10 mg/l cadmium and 5 mg/l
nickel. When substrate strength was doubled, some nitrification
was achieved at the lower combined metal concentration.
14
Sujarittanonta (19) showed that l and 5 mg/l of nickel also
effected an almost complete inhibition of nitrification. As for
COD removal, the COD-to-nickel ratio influenced the toxicity of
nickel on nitrification. In contrast, DiSalvo (20) discovered
substantial nitrificationin reactors fed 0.5 mg/l nickel; in
fact, nitrate production was higher for the nickel-fed reactors
than for the control. (As noted above, the control data used for
comparison was collected during another study (19).) Low pH's
did not hinder nitrification.
METAL UPTAKE
Nickel's behavior in aqueous systems is characteristic of
the heavy metals. These transition elements have unfilled inner
electron shells which make them amenable to coordination with
molecules and anions. In coordinative relationships, the type
and number of coordinative partners may change without change in
the oxidation state of either the metal cation or other species
involved (24).
Formation of a coordinative relationship between a metal
cation and either a molecule or an anion is known as com-
plexation. The participating nolecule or anion is a ligand.
Chelation is a form of complexation where the ligand (or
chelating agent) has multiple bonding sites and forms, with
the cation, a ring structure.
Metal and ligand solubility, pH, and the type and concen-
tration of metals and ligands present determine the distribution
15
of metal species in an aqueous system. The effect of pH on the
theoretical solubility of nickel hydroxide is shown in Figure 1.
A speciation diagram for nickel-amine complexes is shown in
Figure 2. (Calculations for these figures are presented in
Appendix A.)
In activated sludge, the potential for formation of coordi-
native relationships with metals is high. Heavy metals tend to
form stable compounds with carboxyl, hydroxyl, carbonyl, amino,
and sulfur groups. These groups are found in the cells and
cellular products---polysaccharides, lipids, and nucleic acids,
which constitute the biomass of activated sludge. Other che-
lating agents present in wastewater may include NTA (nitrilo-
triacetate); EDTA (ethylenediamine tetraacetate); sodium citrate;
linear chain polyphosphates used for detergent manufacture, water
treatment, metal cleaning, and food processing; humic material,
and amino acids (25).
Many researchers have observed the rate at which heavy
metals were taken up or removed by activated sludge. McDermott
(13) noted that approximately 30 percent of influent nickel was
removed by a complete activated sludge unit. This included a
small amount removed in primary settling. Salotto (12) found
that more copper remained soluble at higher organic loadings. He
suggested that more soluble metal complexes were formed at these
higher loadings.
0
2
4 • N z a.
~
6
7
8
16
Ni(0Hl2a41
0 2 4 6 8 10 12
pH
FIGURE I. THEORETICAL SOLUBILITY OF NICKEL HYDROXIDE.
14
~
z 0
I-<..> ex a: LL.
17
1.0
0.90
0.80
0.70
Ni(NH3)4•2 Ni++
060
0.50
~
0.30
0.20
0.10
0 -2.0 -1.0 0 1.0 2.0 3.0 4.0 5.0 6.0
FIGURE 2. SPECIATION DIAGRAM FOR NICKEL -AMINE COMPLEXES.
7.0
18
Esmond and Petrasek (26) discovered that, regardless of
influent concentration, nickel removal at a 2-MGD pilot plant
operated at a mean cell residence time of 13 days was approxi-
mately 15 parts per billion. This was in contrast to the
removals of other metals, which were removed at a greater rate
as their influent concentrations increased. They inferred that
the sludge had a "fixed demand" for nickel.
In a field study of a 6.5-MGD conventional activated sludge
plant, Oliver and Cosgrove (27) determined that only one percent
of the total nickel and less than one percent of the dissolved
nickel was removed. Removals of most other metals was sub-
stantially higher.
Chen and others (28) reported that secondary treatment at
a 340-MGD activated sludge plant achieved less than 30 to 60
percent removal of total nickel and less than 40 percent of
soluble nickel. Nickel remained in soluble form through the
activated sludge process and was more likely to be associated
with smaller particulates. In this respect, nickel behaved like
lead and manganese, in contrast to other metals studied.
Neufeld and Hermann (29) used sewage cultures acclimated to
sewage feed to assess the effects of shock doses of mercury,
cadmium, and zinc. ~ found that uptake was not dependent on
metal concentration or on organism viability. Some metals seemed
to reach a saturation value, such that the percentage of metal on
the floe at the higher doses was lower than for smaller doses.
19
Cheng and others (30) conducted heavy metals uptake studies
on batch-operated, laboratory-scale activated sludge reactors,
using nickel doses ranging from 2 to 25 mg/l. Results indicated
that uptake of heavy metals took place in two phases. The first
phase was very rapid (3 to 10 minutes); the second, slow and
long-term. Addition of soluble ligands such as ETDA and NTA
interfered with metal uptake by the sludge. Order of uptake
efficiency corresponded to metal solubility, with nickel being
less easily removed than other metals. Uptake of metals was
greater at higher initial concentrations, but the percentage of
uptake was less. Contrary to results for other metals, nickel
uptake in relationship to unit weight of volatile suspended
solids decreased as the volatile suspended solids increased, with
a maximum nickel removal per unit volatile suspended solids of
two percent.
Uptake increased with increasing pH until precipitation
began to occur. Cheng speculated that a high pH environment
favors uptake by reducing the competition between metal cations
and hydrogen ions for binding sites in the biofloc.
Jenkins (31) found that samples of domestic sewage dosed
with 1 to 100 mg/l of nickel precipitated approximately fifty to
sixty percent of the nickel. In contrast to copper, precipi-
tation of nickel was only slightly affected by pH.
Friedman and Dugan (32) studied the uptake of copper and
cobalt by Zoogloea in both growth and non-growth situations,
20
using batch cultures. They found that both cell and surrounding
matrix took up metals which accounted for as much as 34 percent
of total cell weight. Growth or physiological state of the
organism affected the rate of accumulation of metal ions by
cells. Affinity was greater between older cells and metals than
between actively growing cells and metals. The investigators
suggested that this was the result of increased synthesis of
zoogleal material by mature cells and subsequent uptake of ions
by this material.
MECHANISMS OF METAL TOXICITY
It is the coordinative aspects of the physico-chemical
behavior of heavy metals, described above, which are thought to
cause their toxicity. It has been hypothesized that the toxic
effects of heavy metals on activated sludge are caused by form-
ation of complexes between metal cations and enzymes crucial to
respiration in the microorganisms constituting the biomass. Two
types of inhibition are considered relevant: competitive in-
hibition and noncompetitive inhibition.
Competitive inhibition occurs when a compound structurally
similar to the substrate binds to the active site of an enzyme,
thereby preventing substrate utilization. The degree of in-
hibition depends upon the relative concentrations of the sub-
strate and the competing compound. Competitive inhibition is
reversible (33). Increases in organic loading or the addition of
21
preferred ligands or other cations may facilitate the release of
metal cations (25,30,34).
Noncompetitive inhibition occurs when strong covalent bonds
form between an enzyme and a substance, which either block the
active site or contort the physical configuration of the enzyme.
Noncompetitive inhibition is not reversible (33). Heavy metals
may also combine with amino acids and precipitate them as metal-
protein salts.
Poon and Bhayani (35) studied the effects of copper,
chromium, nickel, silver, and zinc on pure cultures of typical
"sewage bacteria," Zoogloea ramigera, and of a poorly settling
fungus, Geotrichium candidum, by measuring oxygen uptake rates
of cultures dosed with from 1 to 100 mg/l heavy metal. Results
were interpreted using the Michaelis-Menten model of enzyme
inhibition. Nickel and silver were found to be most toxic to the
sewage bacteria. Nickel and the other metals produced linear
noncompetitive inhibition in sewage bacteria, and linear com-
petitive inhibition in the fungus. The authors suggested that
this difference in reaction might explain patterns of mixed
inhibition in mixed cultures such as activated sludge.
Adjustments in cell metabolism may account for the ability
of biological systems to acclimate to the presence of heavy
metals. Toxic effects may be mitigated by the replacement of
damaged enzymes, the use of alternate metabolic pathways, or the
development of new pathways (36).
22
The flocculating characteristics of activated sludge also
seem to influence metal toxicity. Pavoni and others (37) found
that bioflocculation occurred in the endogenous growth phase of
microorganisms and proceeded similarly in cultures with different
predominant organisms. Bioflocculation depends upon the accumu-
lation and bonding of exocellular polymers, which consist of
polysaccharide, protein, RNA, and DNA, and have functional
surface groups that are anionic or nonionic at neutral pH's.
These characteristics make them prime coordinative partners for
metal cations.
In a study conducted by Bitton and Freihofer (38), both
cadmium and copper were toxic to both capsulated and non-
capsulated bacteria. But the extracellular polysaccharides
produced by the capsulated bacteria evidently chelated the metal
ions and reduced their toxicity. Dugan and Feister (39) noted,
in a comparison of aerobic waste treatment systems and the
characteristics of lake eutrophication, that the extracellular
polymer fibrils produced by floe-forming bacteria have the
ability to concentrate and accumulate transition metal cations.
When separated, the polymer flocculates the metal and settles
out.
Brown and Lester (40), summarizing work related to the
mechanisms of flocculation with respect to metal removal effic-
iency in activated sludge, reported that the major mechanism of
uptake appears to be physico-chemical interaction or absorption
23
by negatively charged groups present on extracellular polymers.
Absorption depends upon the quantity of polymer, which in turn
depends upon the nutrients available, sludge age, and polymer
oxidation; on the type of polymer (gels absorbing better than
soluble polymers); on the presence of other cations such as
calcium and magnesium, which may be replaced by heavy metals,
and by the possibility of formation of cation-anion matrices in
the floe. Metals may also adsorb to cell walls or accumulate in
cytoplasm.
SUMMARY
With few exceptions (17,18,19,20), metal toxicity studies
have concentrated on evaluating the effects of relatively high
doses of heavy metals, not usually encountered in the field, on
the activated sludge process. At these doses, nitrification has
been severely inhibited. The purpose of the current study was to
continue earlier studies conducted at VPI&SU (19,20), in which
bench-scale reactors were dosed 0.5 and 1 mg/l nickel, in order
to assess the effects on nitrification of varying the COD:TKN
ratio on reactors fed relatively low concentrations of nickel.
liATERIALS AND METHODS
The purpose of this study was to determine the effects of
continuously fed doses of nickel of approximately 0.5 mg/l on the
performance of bench-scale, completely mixed, continuous flow
activated sludge reactors. This study utilized similar operating
parameters, including nickel dose, as earlier work (20) conducted
at VPI&SU, which compared the effects of COD:Ni ratio on perfor-
mance of similar units. This previous study found an apparent
increase in nitrification for metal-fed reactors operated at
COD:TKN ratios of 3.7:1 when compared to a control unit operated
under similar conditions (19). The current study held nickel and
COD concentrations constant, and varied influent nitrogen concen-
trations in order to assess the effect of the COD:TKN ratio on
performance. Of particular interest were the effects of nickel
on the process of nitrification.
In this study, three bench-scale, completely mixed, con-
tinuous flow activated sludge reactors were operated over a
period of eight months, from March to November, 1980. Two
reactors received 0.5 mg/l concentrations of nickel as Ni(II),
while the third reactor received no nickel and served as a
control unit. All reactors were fed a soluble, synthetic waste-
water with 400 mg/l influent COD. One nickel-fed reactor and the
control reactor were operated at an influent COD:TKN ratio of
2.4:1, while the other nickel-fed reactor was operated at an
influent COD:TKN ratio of 7.3:1.
24
25
As in previous studies of the effects of nickel on activated
sludge conducted at VPI&SU, mean cell residence time was varied
to produce comparable sets of data. All reactors were operated
at a hydraulic detention time of 14 hours, at an ambient temper-
ature of 20° ± 1° C.
LABORATORY APPARATUS
A schematic diagram of the laboratory apparatus used in this
study is shown in Figure 3. Each plexiglass unit consisted of a
6.0-liter aeration tank and a 2.5-liter settling tank, separated
by a sliding baffle. Compressed air, filtered through glass
wool, was released into the aeration tank through two porous
diffuser stones. Sufficient air was introduced into the reactor
to maintain a dissolved oxygen concentration above 2.0 mg/l.
Adjustment of the baffle height, the flow of compressed air,
and the position of the diffuser stones was made to provide the
following:
a. continuous and thorough mixing of the contents of
the aeration tank,
b. quiescent conditions for optimum settling in the
settling tank, and
c. constant exchange of solids beneath the baffle
between tanks.
In practice, these conditions were achieved by adjusting the
baffle between tanks so that it imparted a rolling motion to the
contents of the aeration tank, and by raising or lowering the
ADJUSTABLE BAFFLE
CALIBRATED
EFFLUENT eOLLECTION
~ ~ TANK
26
p
FEED PUMP
CALIBRATED FEED TANK
COTTON AIR Fil TER
2 DIFFUSER STONES
AERATION TANK
SETTLING TANK
FIGURE 3. EXPERIMENTAL COMPLETELY MIXED
ACTIVATED SLU OGE UNIT.
27
baffle to obtain a well-mixed, aerated sludge blanket with a
well-defined interface in the settling tank.
Each reactor received 14.5 liters of feed solution per day,
pumped continuously from a 19-liter Nalgene carboy through Tygon
tubing to the reactor by a Durrum Instrument Corporation positive
displacement pump (Model 12AP Dial-a-Pump). Feed carboys and
feed lines were rinsed daily with a mild chlorine solution to rid
them of any microorganisms which might consume feed nutrients
before they reached the reactor, thereby reducing the strength
of the feed.
Effluent from each reactor was collected in a 19-liter
Nalgene carboy.
STARTUP
During the course of this study, three bench-scale, com-
pletely mixed, continuous flow activated sludge reactors were
operated over a period of eight months. The study began in
December, 1979, when the initial activated sludge culture was
obtained from a continuous flow reactor operated by another
student. Two liters of sludge was transferred to an aerated
2-gallon glass jar, which served as a batch reactor unit, and
diluted with tap water to 5 liters. The sludge had been
acclimated to a feed similar in composition to the feed used in
this study, except that bacto-peptone was to replace jack bean
meal as the organic nutrient source. After transfer, the sludge
in the batch reactor was fed a mixture of jack bean meal and the
28
bacto-peptone. The proportion of bacto-peptone to jack bean meal
was gradually increased until the organic feed consisted entirely
of bacto-peptone.
At the end of December, the batch culture was seeded with
500 mls of settled solids from activated sludge obtained from
the nitrification basin sludge return lines at the Roanoke Water
Pollution Control Facility, Roanoke, Virginia.
Attempts to start continuous flow reactors in January and
February, 1980, were hindered by faulty pump operation. In
March, the first continuous flow reactor was started up with 2.5
liters of sludge transferred from the batch reactor and diluted
with tap water to 8.5 liters. The reactor was operated at a
COD:TKN ratio of 3.7:1, with no supplemental ammonia being added.
Beginning at this time, the sludge was fed continuous doses of
nickel. The dosage was increased over a period of two weeks
until the desired Ni(II) concentration of 0.5 mg/l was reached.
Two weeks after startup of the first unit, 4 liters of
completely mixed sludge was transferred from the first continuous
flow reactor to a second. Tap water was added to each reactor to
bring the total volume of each to 8.5 liters. The second con-
tinuous flow reactor was operated at a COD:TKN ratio of 2.4:1.
It continued to receive 0.5 mg/l nickel. On the same ~ 2.5
liters of completely mixed activated sludge were transferred from
the batch reactor to another 2-gallon aerated glass jar. Tap
29
water was added to each to bring the total volume of each to 5
liters.
A week later, the entire contents of one of these batch
reactors were transferred to a third continuous flow reactor.
Tap water was added to bring the total volume of the reactor to
8.5 liters. The third continuous flow reactor was operated at a
COD:TKN ratio of 2.4:1 and received no nickel, as it was to serve
as the control.
Within a week, the contents of the control reactor turned
bright pink. Microscopic examination of the culture revealed
that it was infested with small worms. The contents of the
reactor were disposed and 2.5 liters of mixed liquor transferred
from the batch reactor to the continuous reactor. The contents
of the reactor were again diluted with tap water to a volume of
8.5 liters, and feeding and wasting resumed.
For the last run of the control reactor, the culture was
seeded with an additional 2 liters of settled solids from the
nitrification basin sludge return lines at the Roanoke Water
Pollution Control Facility. The purpose of reseeding was to
increase the solids concentration of the reactor in order to
achieve a relatively high mean cell residence time in a short
period of time.
DAILY PROTOCOL
Each day, a 16-liter feed solution was prepared from the
components listed in Table II for each reactor, and a calculated
30
TABLE II
COMPOSITION OF WASTEWATER FEED SOLUTION
Stock Quantity Concentration Used Per Final Per 2 Liters 16 Liters Concentration
Constituent (gm) (ml) (mg/1)
Bacto-Peptone (nutrient broth) 64.5* 87.5 353
MgS04 7H20 20.0 80.0 50.0
MnS04 H20 2.00 80.0 5.00
FeC13 6H 20 0.25 80.0 0.63
CaC12 1.50 80.0 3.75
(NH4) 2so4 200 85.4 variable **
KH 2Po4 *** 105 107.0 349
K2HP04 *** 214 107.0 716
NiC12 6H 2) 8.10 8.00 2.03 [Ni(II)] = 0.50
* Prepared in one liter stock solutions (Nominal COD of waste 400 mg/1)
**One nickel-fed reactor received no (NH4) 2so4 . The other nickel-fed reactor and the control received 534 mg/l (NH4) 2so4 for an [NH4-N] = 56 mg/l
*** Phosphate buffer solution
31
amount of completely mixed solids wasted from the reactor. When
a reactor reached steady state at the desired mean cell residence
time, the parameters listed in Table III were monitored daily.
Daily protocol proceeded as follows:
a. The feed pump was stopped and the feed line removed from
the reactor and from the feed carboy. The effluent port of the
settling tank was plugged, and the baffle separating the aeration
tank and the settling tank removed, allowing the contents of the
reactor to mix completely. The feed carboy was rinsed once with
a mild chlorine solution (15 mls bleach in 8 liters tap water)
and then four times with tap water.
b. The correct amounts of stock feed solutions listed in
Table II were added to the feed carboy, and diluted with tap
water to 16 liters in order to achieve the concentrations listed
in Table II. The feed carboy was vigorously shaken to ensure
complete mixing of the feed components and tap water, and thus
the homogeneity of the feed solution.
c. While the feed solution was allowed to equilibrate,
samples of the effluent were taken. The effluent carboy was
first capped and vigorously shaken to completely nix its con-
tents. Then 50 mls of sample, pipetted from the carboy, were
transferred to an acid-washed Nnlgene bottle and acidified with
concentrated nitric acid to a pH below 2.0, and reserved for
Ni(II) analysis. Another 450 mls were filtered through a
Millipore filter apparatus. Of this filtered sample, 200 mls
32
TABLE III
PARAMETERS MONITORED DURING STEADY STATE PERIODS
Sample
Influent Feed
Unfiltered Effluent
Filtered Effluent
Reactor
Parameters Monitored
Chemical Oxygen Demand Ammonia Nitrogen Concentration Total Kjeldahl Nitrogen Concentration Nickel Concentration pH Alkalinity as Caco3 Nitrate Nitrogen Concentration
Nickel Concentration Suspended Solids Concentration
Chemical Oxygen Demand Ammonia Nitrogen Concentration Total Kjeldahl Nitrogen Concentration Nickel Concentration Nitrate Nitrogen Concentration pH Alkalinity as Caco3
Mixed Liquor Suspended Solids
33
were used for immediate pH and alkalinity measurements; 50 mls
were transferred to an acid-washed Nalgene bottle and acidified
as described above, and 300 mls were transferred to another
acid-washed Nalgene bottle, acidifed with concentrated sulfuric
acid to a pH below 2.0, and stored at 4°C for subsequent
analyses.
d. After effluent sampling was completed, wasting was
accomplished by pumping from the reactor a calculated amount of
completely mixed sludge with a Fisher Scientific Manostat Vari-
staltic pump (Solid State Model). The sludge was then poured
from the graduated cylinder in which it was collected into a
beaker, whose contents were kept completely mixed by a magnetic
stir bar. A sample was withdrawn, filtered through a Millipore
filter apparatus, and the Reeve-Angel 0.45-µ filter retrieved and
analyzed for suspended solids.
e. Samples of the feed solution were then taken. The feed
carboy was capped and vigorously shaken to completely mix its
contents. Filtration was not necessary, as all feed components
were soluble. Therefore, only one sample was taken for Ni(II)
analysis. Otherwise, influent sampling proceeded exactly as
effluent sampling.
f. Following sampling, the feed lines were returned to the
reactor and the feed carboy, and the feed pump was started.
34
Daily wasting rates were initially based on the previous
day's solids concentrations in the reactor and in the effluent
and calculated to achieve the desired mean cell residence time
a~ d to the equation:
where
8 c
e c
vx Q X+(Q-0 )X w 'w e
mean cell residence time, days
V volume of reactor, liters
X mixed liquor suspended solids, mg/l
Qw wasting rate, liters/day
Q flow rate, liters/day
X suspended solids in the effluent, mg/l. e
[ 3]
The results obtained by this method, however, were erratic.
Starting in May, wasting rates were calculated using the esti-
mation of mean cell residence time:
[4]
where the parameters are as described above (Equation 3).
TECHNIQUES OF ANALYSIS
Parameters listed in Table III were tested according to the
following procedures.
35
Solids
Mixed liquor suspended solids taken from the completely
mixed contents of the aeration and settling tanks and effluent
suspended solids were measured according to the procedures for
determining "Total Filtrable Residue Dried at 103-105°C", as
described in Standard Methods for the Examination of Water and
Wastewater (Standard Methods) (41), Test 208B. Reeve-Angel
5.5-cm glass-fiber filters (0.45 micron pore size) were used in
filtering solids through a Millipore filter apparatus. Solids
were weighed on a Mettler Instrument Corporation balance
(Model HlO).
Chemical Oxygen Demand, COD
The soluble COD concentration of the influent and the
filtered effluent was determined by analyzing preserved samples
as described in Standard Methods (41), Test 508.
Ammonia Nitrogen, NH3-N
The NH3-N concentration of the influent and the filtered
effluent was determined by distilling preserved samples and then
analyzing the samples according to the procedure for the "Acidi-
metric Titration Technique," as described in Standard Methods
(41), Test 418D.
Total Kjehdahl Nitrogen, TKN
The TKN concentration of the influent and the filtered
effluent was determined by first digesting and distilling
36
preserved samples according to the procedure for determining
organic nitrogen, and then analyzing samples using the
"Acidimetric Titration Technique," as described in Standard
Methods (41), Test 421.
Nitrate Nitrogen, N03-N
The N03-N concentration of the influent and the filtered
effluent was determined using the "Brucine Method" as described
in Standard Methods (41), Test 4190. Prepared samples were
analyzed on a Bausch & Lomb Spectronic 100 spectrophotometer.
The pH of the influent and the unfiltered effluent was taken
immediately upon sample collection with a Fischer Accumet pH
meter (Model 120).
Alkalinity as Caco3
Alkalinity of the influent and the unfiltered effluent was
determined immediately upon sample collection according to the
procedure outlined in Standard Methods (41), Test 403. The end
point pH during titration was taken as 5.1.
Nickel, Ni(II)
Ni(II) concentration of the influent and both filtered and
unfiltered effluent was determined by atomic absorption spectro-
photometry, using a Perkin Elmer 403 atomic absorption
37
spectrophotometer. Unfiltered samples were first digested
according to the instructions for "Sample Pretreatment of Total
Metal Analysis" set forth in Standard Methods (41), Method 301C.
DATA ANALYSIS
The following equations were used to evaluate degree of
treatment efficiency and nitrification, and to determine specific
growth and utilization rates and the biokinetic yield and decay
coefficients over a range of mean cell residence times.
where
The soluble removal efficiency is:
E s
s -s o e s
0
(100)
E soluble COD removal efficiency, percent s S influent soluble COD, mg/l
0
S = effluent soluble COD, mg/l e
To calculate percentage effluent ammonia:
where
100(NH3-Neff) TKN
[ s]
[6]
percentage of influent nitrogen exiting as
ammonia nitrogen, percent
NH3-Neff = effluent ammonia concentration, mg/l
38
TKN influent total Kjeldahl nitrogen concentration,
mg/l
To calculate percentage synthesized nitrogen:
where
% Synthesized Nitrogen lOO(TKN-(TKNeff+N03-Neff))
TKN
% Synthesized Nitrogen = percentage of influent total
kjeldahl nitrogen synthesized, percent
TKN influent total Kjeldahl nitrogen, mg/l
TKNeff effluent total kjeldahl nitrogen, mg/l
N03-Neff effluent nitrate nitrogen, mg/l
To calculate percentage nitrate:
where
100(N03-Neff) TKN [8]
percentage of influent nitrogen exiting as
nitrate nitrogen, mg/l
N0 3-Neff = effluent nitrate nitrogen, mg/l
and TKN is as defined above (Equation 7).
[ 7]
The specific growth rate was calculated by inverting the
mean cell residence time:
µ [ 9]
where
39
-1 µ specific growth rate, days
8 = mean cell residence time, days c
The specific utilization a ~ was calculated by:
where
u
G
u s -s o e
X8
-1 specific utilization rate, days
hydraulic detention time, days
X = mixed liquor suspended solids, mg/l
and S and S are defined above (Equation 5). o e
[ 10]
Biokinetic coefficients were determined from correlation
of specific utilization and specific growth rate, as shown in
Figure 7. This relationship is:
where
1 =
9 c
y max
1 Y U-k max d e
c
-1 specific growth rate, days
-1 maximum cell yield, days
-1 decay coefficient, days
and U is as defined above (Equation 8).
The observed yield coefficient is calculated by:
y obs
[11]
[12]
where
40
Yobs observed yield coefficient, days-l
Sc mean cell residence time, days
and other parameters are as defined above (Equation 12).
RESULTS
The purpose of this study was to determine the effects of
a small soluble dose of nickel on bench-scale, continuous flow
activated sludge units operated at various mean cell residence
times (MCRT's). The effects of nickel on nitrification were of
particular interest. Influent ammonia concentration was varied
to assess the influence of nitrogen concentration on the degree
of nitrification in the presence of nickel. Pertinent data were
collected to determine the degree of nitrification at each MCRT,
as well as to permit evaluation of organic removal rates, bio-
kinetic coefficients, and nickel removal.
The COD:TKN ratios and nickel doses for the five reactors
discussed in this study are given in Table IV. Raw data for all
reactors are presented in Appendix B.
Three of these reactors (Reactors I, II, and IV) were
operated during the course of the study, each brought to steady
state at four mean cell residence times. All reactors received
a synthetic, soluble feed with a COD of approximately 400 mg/l.
Data from two separate, earlier studies have been included
for comparison. These studies used sinilar bench-scale units
and amassed the same types of data. These reactors (Reactors II
and V) also received 400 mg/l influent COD.
Reactor I was operated at a COD:TKN ratio of 2.4:1 and
served as the control unit. It was operated at four mean cell
residence times from 5.6 to 18.1 days. Total influent nitrogen
41
42
TABLE IV
COD:TKN RATIOS AND NICKEL DOSES
Influent Influent Reactor COD:TKN Ratio Nickel Dose, mg/1
I 2.4:1
II 2.4:1 0.56
III 3.7:1 0.58
IV 7.3:1 0.54
v 3.7:1 0.97
43
was 166 mg/l, with approximately 61 mg/l organic nitrogen and
the remainder ammonia nitrogen. Control data are presented in
Table V.
Reactor II was fed 0.56 mg/l total nickel and a total
nitrogen concentration of 166 mg/l, constituted by about 60 mg/l
organic nitrogen and 106 mg/l ammonia nitrogen, for a COD:TKN
ratio of 2.4:1, identical to the control. It was operated at
four mean cell residence times, from 4.2 to 14.0 days. Data
collected from this reactor are presented in Table VI.
Reactor III received 0.58 mg/l nickel and 110 mg/l total
influent nitrogen for a COD:TKN ratio of 3.7:1. Approximately
half the influent nitrogen was contributed by ammonia and half
by organic sources. Reactor III was operated at three mean cell
residence times, from 6.0 to 12.0 days. Data for this reactor
are presented in Table VII (20).
Reactor IV received 0.54 mg/l nickel and 55 mg/l total
influent nitrogen, all of it organic, for a COD:TKN ratio of
7.3:1. Mean cell residence times varied from 5.2 to 15.0 days.
Data for this reactor are presented in Table VIII.
Reactor V was fed 0.97 mg/l nickel and, as Reactor III, half
ammonia nitrogen and half organic nitrogen, for a total influent
nitrogen concentration of 106 mg/l. COD:TKN ratio was 3.7:1.
Mean cell residence times varied from 5.2 to 14.5 days. Data
from this reactor are presented in Table IX (19).
44
TABLE V SUMMARY OF STEADY STATE DATA - REACTOR I
COD:TKN = 2.4:1, Ni(II) = 0.02 mg/l
Mean Cell Residence Time, days Parameter
COD Feed, mg/l Effluent, mg/l (1) Net Change, %
Reactor Solids Reactor, mg/l Effluent, mg/l
Ammonia Nitrogen, Feed, mg/l Effluent, mg/l Net Change %
Organic Nitrogen, Feed, mg/1 Effluent, mg/1 Net Change, %
NH -N r-::-(1)
Org-N
(1)
Nitrate Nitrogen, N03-N Feed, mg/l Effluent, mg/l (1)
£!! Feed Effluent
Alkalinity as Caco3 Feed, mg/l Effluent, mg/1 Net Change, %
Nickel, Ni (II) Feed, mg/l Effluent, total, mg/l Effluent, soluble, mg/l
-1 Observed Yield, day -1 Specific Growth Rate, day
-1 Specific Utilization Rate, day
Wasting Rate, l/day
(l)filtered
5.6 8.1 9.7 18.1
377 26
93.1
1427 87
103 87
-15.1
63 2
97.6
0.50 86
7.1 6.3
428 125
-70.9
0.02 0.04 0.02
0.334
0.179
0.420
o. 710
396 38
90.3
1304 64
112 85
-23.9
56 3
94.0
a.so 77
7.0 6.0
440 104
-76.3
0.02 0.04 0.03
0.323
0.124
0.468
0.530
401 37
90.7
1634 49
95 77
-14.5
63 5
92.0
0.90 82
7.1 5.7
428 35
-91.8
0.02 0.04 0.03
0.316
0.104
0.380
0.475
358 28
92.2
2650 71
111 107
-3.7
61 3
95.8
0.40 56
7.1 6.6
474 267
-43.8
0.03 0.14 0.01
0.285
0.055
0.212
0.100
45
TABLE VI SUM¥.ARY OF STEADY STATE DATA - REACTOR II
COD:TKN = 2.4:1, Ni(II) = 0.56 mg/l Mean Cell Residence Time, days
Parameter COD --Feed, mg/l
Effluent, mg/l (1) Net Change, %
Reactor Solids Reactor, mg/l Effluent, mg/l
Ammonia Nitrogen, Feed, mg/l Effluent, mg/l Net Change %
Organic Nitrogen, Feed, mg/l Effluent, mg/l Net Change, %
NH -N 3-
(1)
Org-N
( 1)
Nitrate Nitrogen, N03-N Feed, mg/l Effluent, mg/l (1)
£!! Feed Effluent
Alkalinity as Caco3 Feed, mg/l Effluent, mg/l Net Change, %
Nickel, Ni (II) Feed, mg/l Effluent, total, mg/l Effluent, soluble, mg/l Removal, %
-1 Observed Yield, day -1 Specific Growth Rate, day
-1 Specific Utilization Rate, day
Wasting Rate, l/day (l)filtered
4.2 7.8 11.9 14.0
368 34
90.5
728 52
91 151
+70.2
51 2
95.7
0.50 5
7.0 7.2
397 566
+43.3
0.62 0.49 0.47 20.6
0.305
0.239
0.783
1.075
401 31
92.2
1596 46
105 84
-20.6
58 4
94.1
0.60 76
7.1 6.0
429 77
-82.0
0.55 a.so 0.28 27.8
0.305
0.128
0.395
o. 710
410 41
89.3
2405 33
109 73
-34.0
64 2
96. 9
0.70 89
7.2 4.9
461 1
-99.8
0.55 0.48 0.48 11.3
0.305
0.084
0.262
0.530
411 28
93.2
2625 25
119 76
-36.6
59 1
99.2
0.60 97
7.2 5.1
462 0
-100
0.53
0.51
0.305
0.071
0.249
0.475
46
TABLE VII SUMMARY OF STEADY STATE DATA -REACTOR III COD:TKN = 3.7:1, Ni(II) = 0.58 mg/l
Mean Cell Residence Time, days Parameter
COD Feed, mg/l Effluent, mg/l (1) Net Change, %
Reactor Solids Reactor, mg/l Effluent, mg/l
Ammonia Nitrogen, Feed, mg/l Effluent, mg/l Net Change %
Organic Nitrogen, Feed, mg/l Effluent, mg/l Net Change, %
NH -N r-::-
(1)
Org-N
(1)
Nitrate Nitrogen, N03-N Feed, mg/l Effluent, mg/l (1)
.E!! Feed Effluent
Alkalinity as Caco3 Feed, mg/l Effluent, mg/l Net Change, %
Nickel, Ni (II) Feed, mg/l Effluent, total, mg/l Effluent, soluble, mg/l Removal, %
-1 Observed Yield, day
-1 Specific Growth Rate, day
-1 Specific Utilization Rate, day
~a Rate, l/day
(l)filtered
6. 0 8. 9 12. 0
412 57
86.2
1258 39
55 61
+9.9
55 4
92.4
36
7.0 6.6
254 145 -42. 9
0.59 0.56 0.55 6.8
0.34
0.167
0.486
1.000
401 36
90.9
1721 30
56 45
-18.7
57 5
91. 7
57
7.0 5.6
255 23
-91.0
0.55 0.50 0.48 12.7
0.31
0.112
0.365
o. 725
418 37 91.2
2158 26
56 43
-23.5
54 4
92.0
61
7.0 5.3
250 10
-96.0
0.60 0.60 0.60 0
0.27
0.083
0.304
0.540
47
TABLE VIII SUMMARY OF STEADY STATE DATA - REACTOR IV
COD:TKN = 7.3:1, Ni(II) = 0.54 mg/l Mean Cell Residence Time, days
Parameter COD --Feed, mg/l
Effluent, mg/l (1) Net Change, %
Reactor Solids Reactor, mg/l Effluent, mg/l
Ammonia Nitrogen, Feed, mg/l Effluent, mg/l Net Change %
Organic Nitrogen, Feed, mg/l Effluent, mg/l Net Change, %
NH -N ~
(1)
Org-N
( 1)
Nitrate Nitrogen, N0 3-N Feed, mg/l Effluent, mg/l (1)
E!! Feed Effluent
Alkalinity as Caco3 Feed, mg/l Effluent, mg/l Net Change, %
Nickel, Ni (II) Feed, mg/l Effluent, total, mg/l Effluent, soluble, mg/l Removal, %
-1 Observed Yield, day -1 Specific Growth Rate, day
-1 Specific Utilization Rate, day
Wasting Rate, l/day (l)filtered
5.2 7.2 13.5 15.0
396 35
91.2
994 43
0.1 35
+100
54 4
91. 9
0.60 2
7.0 7.6
241 378
+57.9
0.55 0.51 0.44 10.9
0.291
0.193
0.620
1.075
411 57
84.0
1086 36
0.3 30
+100
55 10
81.0
0.60 17
7.0 7.3
247 328
+32.5
0.53 0.40 0.34 24.9
0.273
0.139
0.556
o. 710
423 29
93.0
1942 15
0 0 0
57 2
95.8
0.60 53
7.1 6.4
242 84
-65.4
0.54 0.36 0.32 34.8
0.227
0.074
0.346
0.530
400 9
97.6
2363 16
0 0.3
60 3
95.4
0.50 53
7.2 6.6
253 112
-55.6
0.53 o.so 0.46 6.9
0.218
0.067
0.282
0.475
48
TABLE IX SUMMARY OF STEADY STATE DATA - REACTOR V
COD:TKN = 3.7:1, Ni(II) = 0.97 mg/l
Parameter COD Feed, mg/l
Effluent, mg/l (1) Net Change, %
Reactor Solids Reactor, mg/l Effluent, mg/l
Ammonia Nitrogen, Feed, mg/l Effluent, mg/l Net Change %
Organic Nitrogen, Feed, mg/l Effluent, mg/l Net Change, %
NH -N r-:: (1)
Org-N
(1)
Nitrate Nitrogen, N03-N Feed, mg/l Effluent, mg/l (1)
~ Feed Effluent
Alkalinity as Caco3 Feed, mg/l Effluent, mg/l Net Change, %
Nickel, Ni (II) Feed, mg/l Effluent, total, ng/l Effluent, soluble, mg/l Removal, %
-1 Observed Yield, day -1 Specific Growth Rate, day
-1 Specific Utilization Rate, day
Wasting Rate, l/day (l)filtered
Mean Cell Residence Time, days 5.2 10.6 14.5
394 25
93.7
1106 29
56 86
+53.6
53 3
94.1
1.4
7.2 7.7
241 337
+40.1
0.99
0.92 7.1
0.334
0.192
0.572
1. 250
396 29
92.7
1475 11
57 89
+56.1
51 4
91.9
1. 7
7.1 7.6
232 354
+52.7
1.0
0.86 14.0
0.227
0.094
0.427
0.700
399 33
91. 7
1716 11
49 85
+73.5
53 8
84.6
1.6
7.0 7.6
233 360
+51.8
0.93
0.85 8.6
0.184
0.069
0.366
0.500
49
TREATMENT EFFICIENCY
Influent and effluent COD, influent and effluent ammonia,
TKN, and organic nitrogen, and other parameters were analyzed so
that common expressions of treatment efficiency could be calcu-
lated. These included COD removal efficiency, ·degree of nitrifi-
cation, and the biokinetic growth and utilization rates. Effluent
suspended solids were also measured as an indication of treatment
efficiency.
COD Removal
Reactor I. For all HCRT's, COD removal exceeded 90 percent,
for influent COD's averaging 383 mg/l. Small changes in removal
efficiency were not related to mean cell residence time. Average
effluent COD levels were maintained between 26 and 38 mg/l.
Reactor II. COD·removal efficiency varied from 89 to 93 percent
for influent COD's averaging 398 mg/l. Average effluent COD's
ranged from 31 to 41 mg/l.
Reactor III. An average of 86 to 91 percent of the influent COD
of 407 mg/l was removed. Average effluent COD values ranged from
36 to 57 mg/l.
Reactor IV. Net change in COD varied from 84 to 98 percent, for
an average influent COD of 408 mg/l. Effluent COD's ranged from
9 to 57 mg/l.
Reactor V. Influent COD, which averaged 396 mg/l, was reduced to
25 to 33 mg/l, with all MCRT's showing good removals.
50
Reactor Solids, Effluent Suspended Solids, and Biokinetic Coefficients
Reactor I. Reactor solids were maintained at 1427, 1304, 1634,
and 2650 mg/l for MCRT's of 5.6, 8.1, 9.7, and 18.1 days, re-
spectively. Effluent suspended solids ranged from 49 to 87 mg/l
on the average, with daily values rising as high as 204 mg/l.
The observed yield and the specific growth rate declined with
increasing MCRT. Specific utilization rate was erratic.
Reactor II. Reactor solids were held at 728, 1596, 2405, and
2625 mg/l to achieve MCRT's of 4.2, 7.8, 11.9, and 14.0 days.
Effluent solids ranged from 25 to 52 mg/l. Observed yield was
maintained at a relatively constant level throughout the study.
The specific growth rate and the specific utilization rate
declined as MCRT increased.
Reactor III. MCRT's of 6.0, 8.9, and 12.0 days were maintained,
with average reactor solids of 1258, 1721, and 2158 mg/l,
respectively. Effluent suspended solids measured from 26 to
39 mg/l.
Reactor IV. Reactor solids were 994, 1086, 1942, and 2363 mg/l
for MCRT's of 5.2, 7.2, 13.5, and 15.0 days, respectively.
Average removal of suspended d~ was quite high at higher
MCRT's, with effluent suspended solids averaging 15 to 16 mg/l.
At lower MCRT's, effluent suspended solids varied from 36 to
43 mg/l. Observed yield, specific growth rate, and specific
utilization rate declined as MCRT increased.
51
Reactor V. Reactor suspended solids were 1106, 1475, and
1716 mg/l for MCRT's of 5.2, 10.6, and 14.5 days, respectively.
Effluent suspended solids were low, ranging from 11 to 29 mg/l.
Observed yield, specific growth rate, and specific utilization
rate declined with increasing MCRT.
Nitrification
Reactor I. Net changes in ammonia concentration varied from a
3.7 to 23.9 percent decrease, while organic nitrogen was almost
completely destroyed at each MCRT. Nitrate was produced at each
MCRT, with effluent nitrate concentration varying from 56 to
86 mg/l. Effluent ammonia and nitrate concentrations were
erratic.
The pH of the reactor dropped at all MCRT's, as alkalinity
was destroyed. Changes in alkalinity did not correspond well to
either ammonia and organic nitrogen destruction or to nitrate
production.
Reactor II. Disappearance of organic nitrogen was virtually
total at all MCRT's. Nitrate production increased with in-
creasing MCRT to a maximum of 97 mg/l.
Alkalinity was produced at a MCRT of 4.2 days, but at all
other times, alkalinity was destroyed. Alkalinity destruction
was complete at 13.1 days. The pH correspondingly rose at 4.2
days from 7.0 to 7.2, and dropped at other MCRT's to a low of 5.1
at 14.0 days.
52
Reactor Ill. As for Reactor II, ammonia concentration increased
at the low MCRT, and then decreased with increasing MCRT. Organic
nitrogen removals were about 92 percent throughout the study.
Effluent nitrate increased from 36 to 61 mg/l.
Alkalinity destruction was evident at all MCRT's. As
alkalinity decreased, so did pH, to a low of 5.3 at a MCRT of
12.0 days.
Reactor IV. Ammonia was produced at the two lower MCRT's,and
destroyed at the two higher. Organic nitrogen was reduced at
all MCRT's, from 81 to 96 percent. Effluent nitrate production
occurred at all MCRT's, increasing from a minimum of 2 mg/l
at the lowest MCRT of 5.2 days to SJ mg/l at the two higher.
Reactor V. Organic nitrogen was destroyed and ammonia produced
at each MCRT. Nitrate production was practically absent, with
effluent nitrate concentration averaging 1.6 mg/l.
Alkalinity was produced at all MCRT's, and pH of the
effluent rose to 7.6 and 7.7.
Nickel Removal
For Reactors 11 and IV, nickel was removed at all MCRT's,
but at varying levels. Nickel removal for Reactor Ill was
slight, with no nickel removal occurring at 12.0 days. Nickel
removal for Reactor V averaged 10 percent over the course of the
study.
DISCUSSION
TREATMENT EFFICIENCY
As in previous studies (19,20), the effect of nickel on
degree of treatment efficiency, as measured by COD removal,
effluent suspended solids concentration, and, in particular,
nitrate production, of the activated sludge process was of
primary interest. Evaluation of common parameters, such as
influent and effluent COD, reactor suspended solids concen-
tration, and hydraulic detention and mean cell residence times
(MCRT), also permitted determination of specific growth and
substrate utilization rates, which, in turn, were used to cal-
culate biokinetic yield and decay coefficients for each reactor.
COD Removal Efficiency
COD removal efficiency was good to excellent for all five
reactors, as can be seen from Figure 4, which shows COD removal
efficiency vs. mean cell residence time. Efficiency was not
impaired even at the highest nickel dose of 0.97 mg/l. Differ-
ences in efficiency did not relate to COD:TKN ratio or to nickel
dose. Nor did they relate to MCRT, although the two lowest
removal rates occurred at MCRT's less than 8 days, and the
highest at 15.0 days.
These results support earlier findings (13), which
also showed little or no change in removal efficiencies for
reactors dosed at similar nickel concentrations. They tend
53
54
FIGURE 4. COD REiwlOVAL EFFICIENCY vs. MEAN CELL RESIDENCE.
SS
to substantiate the hypothesis that the threshold concentration
for nickel toxicity, as judged by COD removal efficiency, is
equal to, or greater than, 1 mg/l.
Reactor Solids, Effluent Suspended Solids, and Biokinetic Coefficients
Total mixed liquor suspended solids increased with mean cell
residence time for all reactors, as shown in Figure S. Reactor
solids concentrations were consistently lower for Reactor V, with
a 0.97 mg/l nickel dose, than for Reactor III, fed the same
COD:TKN ratio, but half the nickel concentration. As discussed
above, both these reactors showed good to excellent COD removal.
Toxic effects on the heterotrophic community are thus apparent at
nickel doses below those necessary to affect degree of treatment.
Reactor solids concentrations were also dependent on COD:TKN
ratio at moderate to high MCRT's, as evidenced by Reactors II,
III, and IV. Fed approximately the same nickel dose as Reactor
IV, but two and three times the influent nitrogen concentration,
respectively, Reactors II and III carried proportionately greater
solids concentrations. At low MCRT's, influent nitrogen concen-
tration for Reactor IV was sufficient to support solids concen-
trations similar to those of the other reactors, fed greater
influent nitrogen.
At moderate to high MCRT's, Reactors II and III carried
higher solids concentrations than Reactor I, the control, which
was fed equal and greater influent nitrogen. This reactor showed
(/) 0 ...J 0
5000
2500
(/) 2000 0 UJ 0 z ~ 1500 (/) ::> (/)
~ 1000 ::> 0 ...J
~ 500 x :i;:
0 0 2
56
4 6 8 10 12
0 REACTOR I /;:, REACTOR lI. 0 REACTOR m 0 REACTOR N 0 REACTOR 1L
14 16
ec, MEAN CELL RESIDENCE TIME I DAYS
FIGURE 5. TOTAL MIXED LIQUOR SUSPENDED SOLIDS vs. MEAN CELL RESIDENCE TIME.
18
57
erratic increase in reactor solids over the range of MCRT's. In
part, this departure from the ordered relationship among Reactors
II, III, and IV was caused by the loss of solids over Reactor I's
weir, as the sludge tended to bulk at higher MCRT's. It is also
possible that the solids in Reactors II and III had accumulated
nickel to the degree that reactor solids were measurably in-
creased, as compared to Reactor I, by the added weight of the
nickel. Given the small quantities of nickel applied to the
reactor, removal rates, and the relatively short duration of the
study, this could account for only a very small increase (<40
mg/l, had removal been complete.)
All reactors, except Reactor I, produced a fairly clear
effluent over the range of MCRT's. Effluent suspended solids
decreased as MCRT increased. Nickel visibly improved settling,
with nickel-fed Reactors II and IV having fine, dense, rapidly
settling sludge in the settling tank of the bench-scale unit.
The control, on the other hand, frequently spilled large masses
of floating solids, driving daily average suspended solids above
200 mg/l. Effluent suspended solids for this reactor were higher
at all MCRT's than for any other reactor. From this evidence, as
well as from the lower-than-expected reactor solids found in this
unit, it is surmised that the control may have been infested with
~ type of Microorganisms, inhibited by even low doses of
nickel, which adversely affected process performance.
58
Alternatively, poor settling may have been caused by inefficient
reactor design (42).
Figure 6 shows the specific substrate utilization rate vs.
mean cell residence time for all reactors. The specific sub-
strate utilization rate, which is a measure of the amount of COD
removed per day per unit weight of microbial mass, decreased with
MCRT for all reactors. This is an obvious result of the main-
tenance of consistent COD removal rates, while reactor solids
increased with MCRT. At higher mean cell residence times and
reactor solids concentrations, each microorganism consumes less
organic matter, as there is proportionately less available. The
relative specific utilization rates of the five reactors differed
simply with reactor solids concentrations, as discussed above.
Figure 7 shows specific growth rate as a function of
specific utilization rate for all reactors. The biokinetic yield
coefficient, Y , and decay coefficient, kd, were determined max
from the coordinates plotted on this graph by linear regression,
and these values are presented in Table X. The yield coefficient
is the maximum microbial mass produced per day per unit mass of
substrate used, while the decay coefficient is a measure of
endogenous decay. The decay coefficient is used to account for
the fact that not all cells are dividing at a maximum rate,
dependent only on generation time and maximum utilization rate
(42). Endogenous decay is the metabolism of protoplasm by
microbial cells when substrate availability is limited.
1.0
090
0.80
-I (/) >- 0.70 <t 0 -w .....
0.60 <t a:: z 0 ..... 0.50 <t N ..J ..... 0.40 :::> (.)
LL (.) 0.30 w a.. VI -:::> 0.20
0.10
0 0
0 REACTOR I t:::. REACTOR n 0 REACTOR m 0 REACTOR DZ 0 REACTOR 1Z:
2 4 6
59
8 10 12
9c, MEAN CELL RESIDENCE TIME 1 DAYS
14 16
FIGURE 6. SPECIFIC UTILIZATION RATE vs. MEAN CELL RESIDENCE TIME.
18
0.35
- 0.30 I
en >-<t 0 0.25 w I-<t a:: 0.20 :E: I-3:: 0 0.15 a: c:> (.)
LL.
u 0.10 w Cl. en . u 0.05 g_
0
60
0 REACTOR I
6 REACTOR 1I
0 REACTOR m 0 REACTOR Ill
0 REACTOR 1Z
0 0.10 020 0.30 040 0.50 0.60 0.70 0.80 0.90
U, SPECIFIC UTILIZATION RATE, DAYS- 1
FIGURE 7. SPECIFIC GROWTH RATE vs. SPECIFIC UTILIZATION RATE.
1.00
61
TABLE X
BIOKINETIC COEFFICIENTS
Correlation Reactor COD:TKN kd y Coefficient max
I 2.4:1 0.018 0.362 0.62
II 2.4:1 0.000 0.305 0.99
III 3.7:1 0.057 0.461 1.00
IV 7.3:1 0.042 0.355 0.94
v 3.7:1 0.160 0.611 0.99
62
Y varied among the reactors, with Reactor II showing the max
lowest value, and Reactor V, dosed at 1.0 mg/l nickel, showing
the highest value. For the reactors dosed at approximately 0.5
mg/l, Y did not depend upon the COD:TKN ratio. Y 's for max max
Reactors I, II, and IV were in the typical range of 0.25 to 0.40
(43), with Reactors III and V slightly greater.
The decay coefficient, kd, also varied among the reactors.
As for Y , kd for the reactors dosed at 0.5 mg/l was in-max
dependent of the COD:TKN ratio. The kd's for Reactors III and IV
fell into the typical range of 0.04 to 0.075 (43), with Reactors
I and II having relatively small kd's, and Reactor V, relatively
large.
The biokinetic coefficients were noticeably different for
Reactors II and V, Reactor II being distinguished by a very low
decay coefficient (essentially zero), and Reactor V having high
decay and growth coefficients. It appears that the low decay
rate for Reactor II resulted from the relatively large amount of
influent nitrogen available, which may have permitted enhanced
growth of both heterotrophs and autotrophs. This interpretation
is not conclusively supported, however, by the results for
Reactor I, fed the same COD:TKN ratio.
The marked differences in the biokinetic coefficients for
Reactor V, when compared to the other reactors, are attributed to
the nickel dose, which, as noted above, depressed reactor solids
concentration, while having no observable effects on COD removal.
63
The high Y reflects the greater-than-90-percent COD removal max
efficiencies for all reactors achieved over the range of mean
cell residence times for all reactor solids concentrations, and
should not connote stimulation.
The observed yield, shown in Figure 8, decreased with MCRT,
except ·for Reactor II, which had a fairly constant Y b , due to 0 s
the fact that the decay coefficient for this reactor was very
close to zero. The relative observed yields among reactors
at most MCRT's corresponded to relative reactor solids concen-
tration, again excepting the control, which showed a higher
observed yield than suggested by comparison.
Nitrification
As shown in Figure 9, which presents percentage nitrifi-
cation as a function of MCRT, production and destruction of
ammonia followed two distinct patterns. For Reactors I, II,
III, and IV, effluent ammonia nitrogen was produced at low
MCRT's. As MCRT increased, effluent ammonia nitrogen was
reduced increasingly below influent levels, until, at the
highest MCRT, destruction either remained fairly constant,
or fell off slightly to markedly. For Reactor V, effluent
ammonia was produced at all MCRT's, with effluent ammonia
concentration increasing with MCRT.
Net ammonia production at low MCRT's results from the
breakdown of organic nitrogen by microorganisms during synthesis,
in the absence of a well-established nitrifying population.
0.45
040
64
FIGURE 8. OBSERVED YIELD vs. MEAN CELL RESIDENCE TIME.
,oo
,0
10
10 z ... .. eo " .. ~
i !,Cl .. z •o ... V .. ... )0 ..
zo
,o
0 0
,oo
10
,o
z 10 ... .. " "' ,o .. i ~
~o z ... 40 u "' ... .. so
zo
,o
0 0
NH4 •-N
~ o:
' IZ •• 9c, M [ AN C[LL ~[SID[IIC[ TIM[
. . . "
~········
SYNTHlStZ NITIID11£N
' • IZ II
1k, M[AII C[LL flUIO[NCE TIM[
II
II
100
90
ID
70 z ... i '° .. i $0 .. z 401 ... u "' : JO
zo
10
0 o·
100
90
,o
z 70 ... .. ~ '° .. i $0 .. : 40 u "' r )o
zo
10
0 0
NH4 t •N
IYTH£SIZ[D NITIIOG[N
4 I II .. lie, M[AN C[LL IICSIOENCE TIM[
I I
NH4• •N
~ SYN!"ft[AIJ!ED ~N NITROGEN
4 I II II le, MEAN CELL RESIDENCE TIME
II
II
100.----,-------..----.--- ..
90
10
z 70 .. g,o ~ i IC) .. z .,,o u "' f JO
NN4• •N
NITIIOG[~ I • • • 1 0 0 4 I 12 16
lie, M[AN CfLL RUIO[NC[ TIM£
0 REACTOR I 6 REACTOR n 0 REACTOR m 0 REACTOR nr 0 REACTOR JZ'
II
FIGURE 9. PERCENT NITRIFICATION vs. MEAN CELL RESIDENCE TIME.
a, VI
66
As MCRT increases, the number of nitrifiers increases as well.
This is evidenced by Figure 9, which shows the percentage
nitrate-nitrogen rising with MCRT. Little organic nitrogen
appeared in the effluent of any reactor at any mean cell resi-
dence time, indicating that utilization of organic nitrogen was
not inhibited by these nickel concentrations.
Reactors I, II, III, and IV had good to excellent nitrifi-
cation, while Reactor V had almost none. Reactor IV, with no
annnonia-nitrogen in the influent, and the lowest COD:TKN ratio,
achieved 96 percent nitrification at a MCRT of 13.5 days.
Reactors I, II, and III, with close or equal COD:TKN ratios, had
similar degrees of nitrification at moderate MCRT's. The nickel-
fed reactors (Reactors II and IV) were less efficient than the
control (Reactor I) at lower MCRT's. At high MCRT's, however,
nitrate production for the control dropped significantly. This
decrease was unexpected, and probably resulted from insufficient
stabilization of the reactor following reseeding, as described in
"Materials and Methods".
The stabilization of nitrification at similar levels for
Reactors II and III at moderate MCRT's suggests that the frac-
tion of nitrifiers in the biomass increases with MCRT until a
maximum relative concentration is reached. Excess nitrogen exits
the reactor as ammonia-nitrogen. The influent nitrogen concen-
tration for the reactor with the lowest COD:TKN ratio (Reactor
.IV) was such that total consumption by the nitrifying population
67
was achieved. The nickel dose of 0.5 mg/l appeared to have no
effect on nitrification, except, as noted above, at low MCRT's.
In contrast, the nickel dose of 0.97 mg/l resulted in sharp
inhibition of nitrification. This is consistent with other
reported findings (14).
For all reactors, measured alkalinity corresponded closely
to predicted alkalinity, as calculated by the equation:
..:.Alk 3.57 [(6 Org-N) -(Synthesized N)]
-7.14(6NO; -N)
where
6Alk
60rg-N
Synthesized N
~ ~
change in alkalinity, mg/l
change in organic nitrogen, mg/l
synthesized nitrogen, mg/l
change in nitrate nitrogen, mg/l
and shown in Figure 10.
This relationship, developed by Scearce and others (44),
accounts not only for alkalinity destroyed during nitrification,
but also for alkalinity produced when organic nitrogen is miner-
alized to ammonia, and destroyed if the ammonia is synthesized by
the microorganisms in the biomass.
Figure 11 presents effluent pH vs. MCRT. Effluent pH
decreased, as expected, with the mineralization of ammonia,
which liberates hydrogen ions. A comparison of Figures 9 and
11 shows that substantial nitrification is possible at pH's down
' 0 E -.., 0 u a u (/) c(
~ .... z :J c( :Ill: ..J c(
z
68
200
100
0
-100
-200
0 0 REACTOR I -300
~ REACTORU 0 REACTOR m
-400 0 REACTOR llr 0 REACTOR 7
-500 -500 -400 -300 -200 -ioo 0 100 200
PREDICTED CHANGE IN ALKALINITY AS caco,,mg/I
FIGURE 10. MEASURED CHANGE IN ALKALINITY vs. PREDICTED CHANGE IN ALKALI NI TY.
8.0
7.5
7.0
6.5
6.0 x Q.
I-z 5.5 w :l ...I u. u. w 5.0
4.5
0 0 2
0 REACTOR l Cl REACTOR lI 0 REACTOR m 0 REACTOR DZ 0 REACTOR Y
4 6 8
69
10 12 14
ec, MEAN CELL RESIDENCE TIME, DAYS
16
FIGURE 11. EFFLUENT pH vs. MEAN CELL RESIDENCE TIME.
18
70
to 4.9. These results contradict the widely held belief that
nitrification rates are critically reduced at low pH's. Although
nitrification rate may indeed be slowed at low pH's, the decrease
is insufficient to reduce ultimate nitrate production.
NICKEL REMOVAL
Figure 12 shows nickel removal for nickel-fed reactors over
the range of MCRT's, on a total nickel basis. Nickel removal,
while not related to COD:TKN ratio, followed a similar pattern
for all reactors, peaking at moderate to high MCRT's. This
pattern of uptake may be related to the typical growth stages for
the microorganisms constituting the biomass at different MCRT's,
to exocellular polymer production, or to the types of
microorganisms prevalent at different MCRT's. Reactor II, which
showed the greatest single nickel removal at a moderate MCRT,
also had the highest reactor solids at that MCRT. The
relationship does not bear out at other MCRT's or among the other
reactors.
The percentage of total nickel in soluble form for Reactors
II, III, and IV is present in Figure 13. (Total nickel concen-
tration was not measured for Reactor V.) Almost all nickel
remained soluble for these reactors, except at moderate MCRT's,
where the soluble portion dropped to as low as 56 percent.
Moderate MCRT's seemed to favor uptake of the nickel by the
sludge, perhaps by exocellular polymers or by individual cells.
100
90
80
10 ~ 0
....J <l > 60 0 ~ w a:: ....J 50 w ~ (J
z I- 40 z w (J a:: w 30 (l.
20
10
0
71
6 REACTOR n 0 REACTOR lII.
0 REACTOR DZ'
0 REACTOR Y
0 2 4 6 8 10 12 14 16
ec, MEAN CELL RESIDENCE TIME' DAYS
FIGURE 12. NICKEL REMOVAL vs. MEAN CELL RESIDENCE TIME.
18
72
~ 0 0 0 ~
§ 90 0 z 0 _J 0 w ~ 80 u z w _J 10 CD :) _J 0 (/)
(/) 60 <l
_J w ~ 50 u z _J <l ~ 40 0 ~
~ z w 30 :) 6 REACTOR II _J u... u... 0 REACTOR m w
20 ~ 0 REACTOR Ill z w u a:: 10 w a..
0 0 2 4 6 8 10 12 14 16 18
ac, MEAN CELL RESIDENCE TIME, DAYS
FIGURE 13. PERCENT EFFLUENT SOLUBLE NICKEL vs. MEAN CELL RESIDENCE TIME.
SUNMARY AND CONCLUSIONS
In this study, data were collected from three bench-scale,
continuous flow activated sludge reactors and compared to the
data collected from two similar units in earlier studies (19,20).
The reactors were fed nickel doses up to 0.97 mg/1 and at dif-
ferent COD:TKN ratios. From the results of this study, the
following conclusions can be drawn:
1. COD removal efficiency is not impaired by nickel doses
up to 1 mg/1, nor is there an increase in effluent suspended
solids for these doses. The threshold concentration for nickel
toxicity to the activated sludge process, as measured by common
parameters of process performance, is thus greater than 1 mg/1.
2. Reactor solids concentration depends upon the COD:TKN
ratio, with higher concentrations carried at low COD:TKN ratios
at moderate to high mean cell residence times. One mg/1 nickel
depresses reactor solids concentration.
3. One mg/1 nickel causes an apparent increase in cell
yield and in endogenous decay, as measured by the biokinetic
yield and decay coefficients. A 0.5 mg/1 dose of nickel has a
varying effect on these parameters at different COD:TKN ratios.
4. One mg/l nickel inhibits nitrification almost com-
pletely, while a 0.5 mg/l dose has no adverse effect on degree
of nitrification, except at low mean cell residence times.
5. Nickel generally remains soluble through the activated
sludge process. Nickel removal is erratic over a range of mean
73
74
cell residence times, with moderate mean cell residence times
favoring uptake of the nickel by the sludge.
6. At high COD:TKN ratios, complete nitrification is
possible, while lower COD:TKN ratios tend to result in incomplete
but stable nitrification.
7. Degree of alkalinity destruction can be accurately
predicted over a range of COD:TKN ratios.
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1. Friburg, Lars, et al., Handbook on the Toxicology of Metals. Elsevier/North Holland Biomedical Press, Amsterdam (1979).
2. Hannah, Sidney A., et al., Metals in Municipal Sludge and Industrial Pretreatment as a Control Option. United States Environmental Protection AGency, Cincinnati (1977).
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Basis for Journal (1970).
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d a ~ 1968 (1977).
8. Stall, T. R., and J. H. Sherrard, "Evaluation of Control Parameters for the Activated Sludge Process.'' Journal Water Pollution Control Federation, 2.Q_, 450 (1978).
9. Barth, E. F., et al., "Field Survey of Four Municipal Wastewater Treatment Plants Receiving Metallic Wastes." Journal Water Pollution Control Federation, l]__, 1101 (1965).
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11. McDermott, G. N., et al., "Effects of Copper on Aerobic Biological Sewage Treatment." Journal Water Pollution Control Federation, 1.2_, 227 (1963).
75
76
12. Salotto, B. V., "Organic Load and the Toxicity of Copper to the Activated Sludge Process." Proceedings of the 19th Industrial Waste Conference, No. 117, Purdue University (1964).
13. McDermott, J. N., et al., "Nickel in Relation to Activated Sludge and Anaerobic Digestion Processes." Journal Water Pollution Control d a ~ 163 (1965).
14. Barth, E. F., et al., "Summary Report on the Effects of Heavy Metals inthe Biological Treatment Processes." Journal Water Pollution Control d a ~ 86 (1965).
15. Moulton, E. Q., and K. S. Shumate, "The Physical and Bio-logical Effects of Copper on Aerobic Biological Waste Treatment Processes." Proceedings of the 18th Industrial Waste Conference, Purdue University (1963).
16. Barth, E. F. et al., "Effects of a Mixture of Heavy Metals on Sewage Treatment Processes," Proceedings of the 18th Industrial Waste Conference, Purdue University, 1963.
17. Bagby, M. M., "The Effects of Cadmium and Nickel, In Combi-nation, on the Completely Mixed Activated Sludge Process." Master's Thesis, Virginia Polytechnic Institute and State University (1979).
18. Weber, A. S. and J. H. Sherrard, "Effects of Cadmium on the Completely Mixed Activated Sludge Process." Journal Water Pollution Control Federation, _2l, 2378 (1980).
19. Sujarittanonba, S., "The Effects of Nickel on the Completely Mixed Activated Sludge Process." Ph.D. Dissertation, Virginia Polytechnic Institute and State University (1979).
20. DiSalvo, R., and J. H. Sherrard, "The Stimulation of Nitri-fication at Low Nickel Concentrations." Proceedings, 12th Annual Middle Atlantic Industrial Waste Conference (1980).
21. Adams, C. E. ~a "The Effects and Removal of Heavy Metals in Biological Treatment." Heavy Metals in the Aquatic Environment, ed. P. A. Krenkel, Pergamon Press, Oxford (1975).
22. Neufeld, R. D., "Heavy Metals-Induced Deflocculation of Activated Sludge." Journal Water Pollution Control Feder-a ~ 1940 (1976).
77
23. Tomlinson, T. G., et al., "Inhibition of Nitrification in the Activated Sludge Process of Sewage Disposal." Journal of Applied Bacteriology, 29, No. 2, 266 (1966).
24. Stumm, W. and J. J. Morgan, Aquatic Chemistry-An Intro-duction Emphasizing Chemical Equilibria in Natural Waters. Wiley Interscience, New York (1970).
25. Manahan, S. E. and M. J. Smith, "The Importance of Chelating Agents." Water and Sewage Works, 2_, Vol. 120, 120 (1973).
26. Esmond, S. E., and A. C. Petrasek, "Trace Metal Removal." Industrial Water Engineering, l!_, 14-17 (1974).
27. Oliver, B. G. and E. G. Cosgrove, "The Efficiency of Heavy Metal Removal by a Conventional Activated Sludge Treatment Plant." Water Research, ~ 869 (1974).
28. Chen, K. Y. et al., "Trace Metals in Wastewater Effluents." Journal a ~ Control d a ~ 2663 (1974).
29. Neufeld, R. D., and E. R. Hermann, "Heavy Metal Removal by Acclimated Activated Sludge." Journal Water Pollution Control Federation,!!}__, 310 (1975).
30. Cheng, M. H. et al., "Heavy Metal Uptake by Activated Sludge." JournalWater Pollution Control Federation, !!}__, 362 (1975).
31. Jenkins, S. H., et al., "The Solubility of Heavy Metal Hydroxides in Water-,-Sewage,and Sewage Sludge II: The Precipitation of Metals in Sewage." International Journal Air and Water ~ 679 (1964).
32. Friedman, B. A., and R. R. Dugan, "Concentration and accumu-lation of metallic ions by the bacterium Zoogloea." Develop-ments in Industrial Microbiology, 2_, 381 (1968).
33. Baum, S. J., Introduction to Organic & Biological Chemistry, Second Edition. Macmillan Publishing Co., Inc., New York (1978).
34. Kugelman, I. J. and P. L. McCarty, "Cation Toxicity and Stimulation in Anaerobic Waste Treatment, II: Daily Feed Studies." Proceedings of the 19th Industrial Waste Con-ference, Purdue University (1964).
35. Poon, P. C. and K. H. Bhayani, "Metal Toxicity to Sewage Organisms." Journal Sanitary Engineering Division -ASCE, 2!_, 161 (1971).
78
36. Kugelman, S. J., and McCarty, P. L., "Cation Toxicity and Stimulation in Anaerobic Waste Treatment, II: Daily Feed Studies." Proc., 19th Industrial Waste Conference, Purdue University (1964).
37. Pavoni, J. L. et al., "Bacterial Exocellular Polymers and Biological Flocculation." Journal Water Pollution Control Federation, 44, 414 (1972).
38. Bitton, G., and V. Freihofer, "Influence of Extracellular Polysaccharides on the Toxicity of Copper and Cadmium towards Klebsilla aerogenes." Microbial Ecology, ~ 119 (1978).
39. Dugan, P. and P. Fister, "Implications of Microbial Polymer Synthesis in Waste Treatment and Lake Eutrophication," in Advances in Water Pollution Research, ed. S. H. Jenkins, Proceedings of the 5th Int'l. Conf. Water Poll. Res. Pergamon Press, Ltd., London (1971).
40. Brown, M. J. and J. N. Lester, "Metal Removal in Activated Sludge: The Role of Bacterial Exocellular Polymers." Water Research, ll• 817 (1979).
41. Standard Methods for the Examination of Water and Waste-water, 14th Edition. American Public Health Assoc., Washington, D.C. (1976).
42. Knocke, W.R., Personal Communication, Blacksburg, Virginia (1982).
43. MetCalf & Eddy, Inc., Wastewater Engineering, Treatment, Disposal, Reuse, Second Edition. McGraw-Hill Book Company, New York (1979).
44. Scearce, S. N. et al., "Prediction of Alkalinity Changes in the Activated Sludge Process." Journal Water Pollution Control Federation, -2l• No. 2, 399 (1980).
APPENDIX A
79
APPENDIX A-I
EQUILIBRIUM REACTIONS AND CONSTANTS FOR NICKEL HYDROXIDE
++ - + Ni + OH ~ Ni(OH)
+ [Ni(OH) ]
103.4 ++ -
[Ni ][OH]
+ -Ni(OH) +OH ~
[Ni(OH)2] 6 8 ------= 10.
+ -[Ni(OH) ] [OH ]
Ni(OH) J 102.8
Ni(OH)2 aq ~ Ni(OH)z s
80
APPENDIX A-II
EQUILIBRIUM REACTIONS AND CONSTANTS
FOR NICKEL-AMINE COMPLEXES
++ --- +2 Ni + NH3 - Ni (NH3)
N1.(NH3)+ 2 NH --- .( )+2 + 3 -Ni NH 3 2
Kl [Ni(NH3)+2]
103 ++ [Ni ] [NH3]
+2
K2 [Ni(NH3) 2 ]
102.18 +2 [Ni (NH3) ] [NH3]
+2
K3 [Ni(NH3) 3 ]
101. 64 . +2 [Ni(NH3) 2 ][NH3]
K4 [Ni(NH3):2]
101.16 = [Ni(NH3);2][NH3 ]
81
3 {31 = Kl = 10
82
APPENDIX A-II (continued)
1
1
APPENDIX B
83
TABLE B-1 RAW DATA FOR REACTOR I AT 0 • 5.59 DAYS c
COD MLSS Ni(Il} Ccncentration pH Date Feed Effluent Removal Reactor Effluent e Feed Effluent Effluent Feed Effluent
Filtered Efficiency Solids Solids c Unfiltered Filtered Filtered (1980} (mg/l} (mg/l} (%} (mg/l} (mg/l} (days} (mg/l} (mg/l} (mg/l}
8/23 382 26 93.2 1496 90 5.52 0.022 0.044 0.024 7.1 6.3 8/24 386 26 93.3 1$84 70 6.25 0.018 0.042 0.021 7.1 6.3 8/25 394 26 93.4 1380 136 4.11 0.018 0.040 0.017 7.1 6.2 8/26 378 30 92.1 1312 70 5.88 0.016 0.037 0.024 7.0 6.2 8/27 302 22 92.7 1376 74 5.86 0.020 0.034 0.019 7.1 6.4 8/28 422 26 93.8 1516 80 5.91 0.025 0.032 0.025 7.1 6.4 AVG 377 26 93.1' 14"27 87 5.59 0.020 0.038 0.022 7.1 6.3 00
.po
Alkalinity as Caco3 NH3-N Concentration Org-N Concentration N03-N Concentration Uate Feed Effluent Net Feed Effluent Net Feed Effluent Net Feed Effluent
Filtered Change Filtered Change Filtered Change Filtered (1980} (mg/l} (mg/l} (%} (mg/I} (mg/l} (%} (mg/l} (mg/l} (t} (mg/l) (mg/l)
8/23 456 168 -63.2 113 106 6.2 53.7 0 100 0.60 73.3 8/24 446 118 -73.5 9.9. 7 80.6 19.2 63.8 7.9 87.6 0.60 75.6 8/25 378 110 -70.9 96.3 89.6 7.0 56.0 0 100 0.50 80.6 8/26 434 109 -74.9 89.6 86.2 3.8 57.1 0 100 0.40 98.0 8/27 441 123 -72.1 106 77.3 27.1 59.4 0 100 0.40 107 8/28 412 120 -70.9 112 81.8 27.0 87.4 1.6 98.2 0.60 78.2 AVG 428 125 -70.9 103 86.9 15.1 62.9 1.6 97.6 0.50 85.5
TABLE 8-11 RAW DATA FOR REACTOR I AT 6 c • B.06 DAYS
COD .MLSS Ni(II) Concentration pH Date Feed Effluent Removal Reactor Effluent ec Feed Effluent Effluent Feed Effluent
Filtered Efficiency Solids Solids Unfiltered Filtered Filtered (1980) (mg/l) (mg/l) (%) (mg/l) (mg/l) (days) (mg/l) (mg/l) (mg/l)
8/11 397 43.2 89.1 996 30 8.94 0.035 0.039 0.021 7 .o 6.2 8/12 364 35.0 90.4 1400 54 7.95 0.015 0.039 0.040 7.0 6.1 8/13 405 35.0 91.4 1492 44 9.02 0.019 0.042 0.019 7.0 6. (I 8/14 392 35.0 91.1 688 204 1.82 0.014 0.051 0.026 7.0 6.0 8/15 389 35.0 91.0 1568 38 9.79 0.018 0.044 0.027 7.1 6.0 8/16 405 26.0 93.6 1484 46 8.83 0.025 0.040 0.037 7.0 6.0 8/17 418 59.7 85.7 1500 34 10.04 0.033 0.044 0.023 7.0 6.0 AVG 396 38.4 90.3 1304 64 8.06 0.023 0.043 0.028 7.0 6.0 CXl
V1
Alkalinity as Caco3 NH3-N Concentration Org-N Concentration N03-N Concentration Date ·Feed Effluent Net Feed Effluent Net Feed Effluent Net Feed Effluent
Filtered Change Filtered Change Filtered Change Filtered (1980) (mg/l) (mg/l) (%) (mg/l) (mg/l) (%) (mg/l) (mg/l) (%) (mgil) (mg/l)
8/11 431 137 -68.2 114 94.6 17 .o 57.7 0 100 0.50 72.3 8/12 4ll 93 -77.4 104 85.1 18.2 49.8 2.8 94.4 0.50 69.9 8/13 430 83 -80.7 111 81.2 26.8 59.9 5.0 91. 7 0.60 62.1 8/14 457 81 -82.3 117 90.2 22.9 57.7 1.1 98.1 0.50 80.7 8/15 446 176 -60.5 112 81.2 27.5 56.0 5.0 91.1 0.40 85.9 8/16 448 82 -81. 7 110 80.6 26.7 57.1 1.2 97.9 0.40 87.7 8/17 456 77 -83.1 115 82.9 27.9 56.0 8.4 85.0 0.40 77.0 AVG 440 104 -76.3 ll2 85.1 23.9 56.3 3.4 94.0 0.50 76.5
TABLE B-III RAW DATA FOR REACTOR I AT 0 c • 9.66 DAYS
COD HLSS Ni(II) Concentration pH Date Feed Effluent Removal Reactor Effluent ec Feed Effluent Effluent Feed Effluent
Filtered Efficiency Solids Solids Unfiltered Filtered Filtered ( 1980) (mg/l) (mg/l) (%) (mg/l) (mg/l) (days) (mg/l) (mg/l) (mg/l)
7/24 376 35 90.7 1880 42 10.78 0.018 0.079 0.018 7.0 6.0 7/25 418 30 92.8 1736 50 9.67 0.009 0.032 0.035 7.0 5.7 7/26 408 33 91.9 1644 36 10.87 0.013 0.036 0.023 7.1 5.5 7/27 401 38 90.5 1804 48 10.02 0.014 0.041 0.038 7.0 5.7 7/28 410 33 92.0 1524 44 9.66 0.009 0.027 0.023 7.1 5.6 7/29 385 45 88.3 1468 38 10.14 0.026 0.032 0.031 7.1 5.6 7/30 406 45 88.9 1380 82 6.50 0.020 0.044 0.018 7.1 5.5
AVG 401 37 90.7 1634 49 9.66 0.016 0.042 0.027 7.1 5.6 00 (J\
Alkalinity as Caco3 NH 3-N Concentration Org-N Concentration N03-N Concentration Date Feed Effluent Net Feed Effluent Net Feed Effluent Net Feed Effluent
Filtered Change Filtered Change Filtered Change Filtered (1980) (mg/l) (mg/l) (%) (mg/I) (mg/l) (%) (mg/l) (mg/l) (%) (mg/ 1) (mg/l)
7/24 428 82 -80.8 91.3 86.8 -4.9 67.7 0 100 0.90 71.6 7/25 438 37 -91.6 95.8 73.9 -22.9 57.6 2.3 96.1 0.90 74.9 7/26 424 24 -94.3 110 72.8 -33.8 54.9 18.5 66.3 1.00 87 .0 7/27 394 35 -91.1 102 77.3 -24.2 86.8 8.9 89.8 0.90 85.3 7/28 446 23 -94.8 54.9 76.7 +39.7 64.9 1.1 98.3 0.90 89.3 7/29 416 24 -94.2 102 77.8 -23.7 49.9 0 100 0.90 89.9 7/30 447 19 -95.8 110 75.0 -31.8 62.2 4.0 93.6 0.90 75.4
AVG 428 35 -91.8 95.1 77 .2 -14.5 63.4 5.0 92.0 0.90 81.9
TABLE B-IV RAW DATA FOR REACTOR I AT e • 18.08 DAYS c
COD HLSS Ni(II) Concentration pH Date Feed Effluent Removal Reactor Effluent e Feed Effluent Effluent Feed Effluent
Filtered Efficiency Solids Solids c Unfiltered Filtered Filtered (1980) (mg/ l) (mg/ l) (%) (mg/l) (mg/l) (days) (mg/l) (mg/l) (mg/l)
10/19 339 32 90.6 2440 66 17.36 0.058 0.234 0.170 7.0 6.5 10/20 371 32 91.4 2450 54 20.37 0.034 0.170 0.146 7.1 6.5 10/21 371 28 92.S 2640 56 20.96 0.034 0.118 0.107 7.2 6.7 10/22 315 20 93.7 2570 56 20.54 0.020 0.133 0.066 7.1 6.7 10/23 363 28 92.3 2960 94 15.25 0.027 0.116 0.062 7.2 6.7 10/24 390 28 92.8 2840 100 14.00 0.028 0.062 0.036 7.2 6.7 AVG 358 28 92.2 2650 71 18.08 0.034 0.139 0.098 7.1 6.6 CXl ......
Alkalinity as Caco3 NH3-N Concentration Org-N Concentration N03-N Concentration Date Feed Effluent Net Feed Effluent Net Feed Effluent Net Feed Effluent
Filtered Change Filtered Change Filtered Change Filtered (1980) (mg/l) (mg/l) (%) (mg/l) (mg/l) (%) (mg/l) (mg/l) (%) (mg/ 1) (mg/ 1)
10/19 454 226 -50.2 106 98.6 -7.0 62.1 3.9 -93.7 0.30 45.7 10/20 468 289 -38.3 107 113 +5.6 65.5 0 100 0.40 60.5 10/21 485 276 -43.1 105 114 +8.6 67.2 0 100 a.so 58.2 10/22 482 280 -41.9 122 102 -16.4 51.5 0 100 0.40 51.9 10/23 464 275 -40.7 112 106 -5.4 58.8 3.9 -93.4 0.30 56.7 10/24 490 253 -48.4 116 107 -7.8 59.4 7.2 -87.9 0.40 62.8 AVG 474 267 -43.8 111 107 -3.7 60.8 2.5 -95.8 0.40 56.0
TABLE B-V RAW DATA FOR REACTOR II AT 6 • 4.18 DAYS c
COD MLSS Ni(II) Concentration pH Date Feed Effluent Removal Reactor Effluent 6 Feed Effluent Effluent Removal Feed Effluent
Filtered Efficiency Solids Solids c Unfiltered Filtered Efficiency Filtered (1980) (mg/l) (mg/l) (%) (mg/l) (mg/l) (days) (mg/l) (mg/l) (mg/l) (%)
8/18 356 30 91.6 636 52 3.91 0.670 0.411 0.397 38.7 7.0 7.2 8/19 383 37 90.3 692 62 3. 73 0.573 0.529 0.490 7.7 7.0 7.3 8/20 415 34 91.8 908 64 4.21 0.618 0.531 0.508 14.1 7.0 7.2 8/21 290 34 88.3 712 42 4.55 0.678 0.494 0.473 27.1 7.0 7.2 8/22 396 37 90.7 692 42 4.50 0.574 0.485 0.460 15.5 7 .1 7.2 A\IG 368 34 90.5 728 52 4.18 0.623 0.490 0.466 20.6 7.0 7.2
00 00
Alkalinity as Caco3 NH3-N Concentration Org-N Concentration N03-N Concentration Date Feed Effluent Net Feed Effluent Net Feed Effluent Net Feed Effluent
Filtered Change Filtered Change Filtered Change Filtered (1980) (mg/l) (mg/l) co (mg/l) (mg/l) (%) (mg/l) (mg/l) (%) (mg/l) (mg/l)
8/18 389 610 +56.8 89.l 162 +81.8 47.3 0 100 0.50 6.3 8/19 424 535 +26.2 104 143 +37.5 54. 2 5.0 90.8 0.50 6.0 8/20 392 546 +39.3 98.0 144 +46.9 53.2 1.1 97.9 0.50 5.0 8/21 355 562 +58.3 63.8 148 +132 43.7 4.5 89.7 0.50 4.9 8/22 424 576 +35.9 102 156 +52.9 53.8 0 100 0.50 4.9 AVG 397 566 +43.3 91.4 151 +70.2 50.4 2.1 95.7 0.50 5.4
TABLE B-VI RAW DATA FOR REACTOR II AT ec • 7.80 DAYS
COD MLSS Ni(II) Concentration pH Date Feed Effluent Removal Reactor Effluent e Feed Effluent Effluent Removal Feed Effluer.t
Filtered Efficiency Solids Solids c Unfiltered Filtered Efficiency Filtered (1980) (mg/ 1) (mg/l) (%) (mg/l) (mg/l) (days) (mg/l) (mg/l) (mg/l) (%)
7/17 409 32 92.2 1648 60 7.01 o.530 0.290 0.220 45.3 7.1 5.9 7/18 405 28 93.1 1700 80 6.26 0.518 0.401 0.251 22.6 7.1 6.1 7/19 402 32 92.0 1592 54 7.22 0.516 0.658 0.255 27.5 7.1 6.3 7/20 409 63 84.6 1572 30 8. 73 0.529 0.397 0.259 25.0 7.1 6.1 7/21 417 24 94.2 1564 40 8.00 0.530 0.380 0.295 28.3 7.1 6.0 7/22 405 28 93.l 1640 68 6.63 0.532 0.366 0.310 31.2 7.1 6.0 7/23 380 24 93.7 1536 12 10.40 0.648 0.398 0.302 36.7 7.1 5.9 7/24 394 24 93.9 1624 38 8.23 0.559 0.410 0.313 26.7 7.0 5.8 7/25 364 28 92.3 1532 60 6.80 0.578 1.492 0.302 40.1 7.0 5.8 7/26 402 28 93.0 1624 32 8.66 0.528 0.346 0.285 34.5 7.1 5.9 7/27 421 35 91. 7 1524 30 8.66 0.606 0.345 0.239 43.l 7.0 6.2 CX>
\0 AVG 401 31 92.2 1596 46 7.80 0.552 0.498 0.276 27.8 7. 1 6.0
Alkalinity as Caco3 NH3-N Concentration Org-N Concentration N03-N Concentration Date Feed Effluent Net Feed Effluent Net Feed Effluent Net Feed Effluent
Filtered Change Filtered Change Filtered Change Filtered (1980) (mg/l) (mg/l) (%) (mg/l) (mg/l) (%) (mg/l) (mg/l) (%) (mg/l) (mg/1)
7/17 439 54 -87.7 115 91.0 20.9 55.4 0.8 98.6 0.50 81.3 7/18 436 94 -78.4 110 84.3 23.4 54.8 4.7 91.4 0.60 68.9 7/19 436 117 -73.2 109 88.2 19.1 74.5 3.1 95.8 0.60 73.3 7/20 442 97 -78.1 111 89.9 19.0 51.8 0 100 0.60 74.3 7/21 435 76 -82.5 110 87.1 20.8 54.8 0 100 0.60 81. 3 7/22 424 64 -84.9 108 82.9 23.2 63.6 3.9 93.9 0.60 69.0 7/23 427 55 -87.1 96.4 76.2 21.0 58.2 8.4 85.6 0.50 84.3 7/24 435 45 -89.7 95.2 75.6 20.6 54.3 5.0 90.8 0.50 71.6 7/25 389 53 -86.4 93.5 77.3 17.3 55.0 5.0 90.9 0.50 96.1 7/26 443 61 -86.2 -- 78.4 -- -- 8.4 -- .,0. 70 79.3 7/27 416 135 -67.6 -- 89.6 -- -- 3.9 -- o. 70 69.2 AVG 429 77 -82.0 105 83.7 20.6 58.0 3.9 94.l 0.60 76.3
TABLE B-VII RAW DATA FOR REACTOR II AT 6 • 11.88 DAYS c
COD HLSS Ni(ll) Concentration pH
Date Feed Effluent Removal Reactor Effluent a Feed Effluent Effluent Removal Feed Effluent Filtered Efficiency Solids Solids c Unfiltered Filtered Efficiency Filtered
(1980) (mg/l) (mg/l) (%) (mg/l) (mg/l) (days) (mg/l) (mg/l) (mg/l) (%)
6/24 412 28 93.2 2556 38 11. 52 0.543 0.475 0.468 12.5 7.2 4.9 6/25 408 46 88.7 2432 34 11. 72 0.535 0.512 0.467 4.3 7.2 4.9 6/26 408 42 89.7 2448 22 12.97 0.550 0.486 0.477 12.4 7.2 4.9 6/27 -- 28 -- 2468 30 12.15 0.548 0.487 0.491 11.1 7.2 4.9 6/28 419 50 88.1 2368 50 10.30 0.541 0.498 0.503 8.0 7.2 4.9 6/29 405 57 85.9 2232 24 12.50 0.545 0.480 0.490 11.9 7.2 4.9 6/30 408 39 90.4 2328 30 11. 97 0.554 0.450 0.479 18.8 7.2 5.2 AVG 410 41 89.3 2405 33 11.88 0.545 0.484 0.482 11. 3 7.2 4.9
\0 0
Alkalinity as Caco3 NH3-N Concentration Org-N Concentration N03-N Concentration Date Feed Effluent Net Feed Effluent Het Feed Effluent Net Feed Effluent
Filtered Change Filtered Change Filtered Change Filtered (1980) (mg/l) (mg/l) (%) (mg/l) (mg/l) (%) (mg/l) (mg/l) (%) (mg/l) (mg/l)
6/24 465 0 -100 109 76.2 -30.1 76.7 0 100 0.60 89.1 6/25 462 0 -100 111 74.8 -32.6 57.9 0 100 0.70 97.0 6/26 462 0 -100 112 75.3 -32.8 80.4 0 100 o. 70 94.3 6/27 460 0 -100 -- 74.2 -- -- 0 -- --0 84.4 6/28 460 0 -100 108 65.5 -39.4 57.1 6.2 89.1 0.80 87.2 6/29 455 0 -100 108 71.1 -34.2 56.6 1.1 98.1 o. 70 82.0 6/30 462 6 -98.7 108 70.6 -34.6 57.7 3.3 94.3 0.70 85.7 AVG 461 1 99.8 109 72.5 -34.0 64.4 1. 5 96.9 0.70 88.5
TABLE B-VIII RAW DATA FOR REACTOR II AT 6 • 14.00 DAYS c
COD MLSS Hi(II) Concentration pH Date Feed Effluent Removal Reactor Effluent e Feed Effluent Effluent Removal Feed Effluent
1''iltered Efficiency Solids Solids c Unfiltered Filtered Efficiency Filtered (1980) (mg/l) (mg/l) (%) (mg/l) (mg/l) (days) (mg/l) (mg/l) (mg/l) (%)
6/12 407 27 93.4 2564 26 13. 77 0.541 0.507 0.501 6.3 7.2 5.0 6/13 411 27 93.4 2560 28 13.53 0.532 0.534 0.510 -- 7.2 5.0 6/14 407 27 93.4 2528 30 13.25 0.555 0.589 0.510 -- 7.2 5.1 6/15 415 27 93.5 2624 24 14.09 0.528 0.667 0.516 -- 7.2 5.0 6/16 415 31 92.5 2600 22 14. 32 0.523 0.589 0.513 -- 7.2 5.1 6/17 415 27 93.5 2716 16 15.24 0.526 4 .137 0.512 -- 7.2 5.1 6/18 407 31 92.4 2780 28 13. 79 0.524 54.0 0.493 -- 7.2 5.1 AVG 411 28 93.2 2625 24.9 14.00 0.533 8.718 0.508 7.2 5.1 \0 -- I-'
Alkalinity as Caco3 NH3-N Concentration Org-N Concentration N03-N Concentration Date Feed Effluent Net Feed Effluent Net Feed Effluent Net Feed Effluent
Filtered Change Filtered Change Filtered Change Filtered (1980) (mg/l) (mg/l) (%) (mg/l) (mg/l) (%) (mg/l) (mg/l) (%) (mg/l) (mg/l)
6/12 462 0 -100 119 72.8 38.8 59.9 1. 7 97.2 0.90 99.1 6/13 463 0 -100 120 75.0 37.5 57.4 1. 7 97 .0 0.40 84.9 6/14 463 0 -100 116 75.3 35.1 55.2 0 100 0.40 101 6/15 462 0 -100 122 75.9 37.8 52.3 0 100 0.40 99.5 6/16 465 0 -100 121 76.2 37.0 55.8 0 100 0.40 99.3 6/17 458 0 -100 118 78.9 33.1 65.5 0 100 0.60 98.3 6/18 461 0 -100 120 75.6 37.0 60.2 0 100 0.80 97.3 AVG 462 0 -100 119 75.7 36.6 59.0 0.5 99.2 0.60 97.1
TABLE B-IX RAW DATA FOR REACTOR Ill AT 6 • 5.99 DAYS c
COD HLSS Ni(ll) Concentration pH Date Feed Effluent Removal Reactor Effluent 6 Feed Effluent Effluent Feed Effluent
Filtered Efficiency Solids Solids c Unfiltered Filtered Filtered (1979) (mg/l) (mg/l) (%) (mg/l) (mg/l) (days) (mg/l) (mg/l) (mg/l)
8/3 408.7 66.0 83.8 1292 38 5.92 .58 .55 .54 7.0 6.7 8/4 414.7 68.3 83.5 1232 46 5.69 .57 .56 .55 7 .o 6.7 8/5 412. 7 58.l 85.9 1292 54 5.33 .59 .56 .56 7.1 6.6 8/6 408.7 53.l 87.0 1216 44 5.64 .60 .55 .55 7.0 6.6 8/7 412.7 38.2 90.7 1256 16 7.36 .59 .57 .56 7.1 6.5
AVG 411.5 56.7 96.2 1258 39 5.99 .59 .56 .55 7.0 6.6 \0 N
Alkalinity as Caco3 NH3-N Concentration Org-N Concentration N03-N Concentration Date Feed Effluent Net Feed Effluent Net Feed Effluent Net Feed Effluent
Filtered Change Filtered Change Filtered Change Filtered (1979) (mg/l) (mg/l) (%) (mg/l) (mg/l) (%) (mg/l) (mg/l) (%) (mg/l) (mg/l)
8/3 252 173 -31.3 55.2 62.4 +13.0 55.4 6.0 -89.2 0.50 29.0 8/4 256 171 -33.2 55.7 63.2 +13.5 56.0 6.0 -89.3 0.50 39.8 8/5 254 154 -39.4 54.6 61.3 +12.3 55.4 4.2 -92.4 0.50 33.6 8/6 255 150 -41.2 55.2 60.0 +8.7 55.4 3.0 -94.6 0.50 37.5 8/7 254 133 -47.6 55.7 57.0 +2.3 54.9 1.8 -96.7 0.50 43.9
AVG 254 156 -38.6 55.3 60.8 +9.9 55.4 4.2 -92.4 0.50 36.8
TABLE B-X RAW DATA FOR REACTOR III AT 0
c • 8.86 DAYS
COD MLSS Ni(II) Concentration pH
Date Feed Effluent Removal Reactor Effluent 0 Feed Effluent Effluent Feed Effluent Filtered Efficiency Solids Solids
c Unfiltered Filtered Filtered
(1979) (mg/l) (mg/l) (%) (mg/l) (mg/l) (days) (mg/l) (mg/l) (mg/l)
8/8 397.3 41.l 89.6 1712 20 9. 73 .56 .51 .49 7.0 5.4 8/9 403.l 32.7 91.9 1724 28 8.96 .53 .50 .46 7 .o 5.5 8/10 403.l 36.6 90.9 1712 42 7.90 .54 .47 .47 7.0 5.7 8/11 399.2 32.7 91.8 1756 38 8.17 .56 .51 .50 7.0 5.7 8/12 403.l 38.7 90.4 1700 20 9.54 .54 .52 .50 7.0 5.7
AVG 401.2 36.4 90.9 1721 30 8.86 .55 .50 .48 7.0 5.6 \0 VJ
Alkalinity as Caco3 NH3-N Concentration Org-N Concentration N03-N Concentration
Date Feed Effluent Net Feed Effluent Net Feed Effluent Net Feed Effluent Filtered Change Filtered Change Filtered Change Filtered
(1980) (mg/l) (mg/l) (%) (mg/l) (mg/l) (%) (l!lg/l) (mg/l) (%) (mg/l) (mg/l)
8/8 252 15 -94.0 53.8 49.5 -8.0 58.5 4.6 -92.l 0.50 49.8 8/9 257 17 -93.4 56.3 44.6 -20.8 54.6 4.1 -92.5 0.50 61.2 8/10 255 25 -90.2 56.0 44.l -21.2 55.7 4.4 -92.l 0.50 63.0 8/11 254 28 -89.0 54.9 43.7 -20.4 56.3 5.4 -90.4 0.50 63.3 ~ 259 28 -89.2 57.4 44.5 -22.5 57.7 4.9 -91.5 0.50 51.5
AVG 255 23 -91.0 55.7 45.3 -18.7 56.6 4.7 -91. 7 0.50 57.8
TABLE B-XI RAW DATA FOR REACTOR III A1' 6 • 12.04 DAYS c
COD MLSS Ni(II) Concentration pH Date Feed Effluent Removal Reactor Effluent e Feed Effluent Effluent Feed Effluent
Filtered Efficiency Solids Solids c Unfiltered Filtered Filtered (1979) (mg/l) (mg/l) (%) (mg/l) (mg/l) (days) \ (mg/l) (mg/l) (mg/l)
7/29 427.4 51.8 87.9 2164 34 11.10 .59 .60 .60 7.0 5.3 7/30 403.2 43.6 89.2 2160 12 13. 71 .58 .61 .61 7.0 5.2 7 /31 423.4 37.2 91.2 2152 30 11.60 .59 .59 .59 7.0 5.2 8/1 417.3 24.7 94.1 2160 30 11.55 .62 .59 .58 7.1 5.3 8/2 416.7 26.9 93.5 2156 24 12.24 .60 .60 .60 7.0 5.3
AVG 417 .6 36.8 91.2 2158 26 12.04 .6 .6 .6 7.0 5.3 \0 ~
Alkalinity as Caco3 NH3-N Concentration Org-N Concentration N03-N Concentration Date Feed Effluent Net Feed Effluent Net Feed Effluent Net Feed Effluent
Filtered Change Filtered Change Filtered Change Filtered (1979) (mg/l) (mg/l) (%) (mg/l) (mg/l) (%) (mg/l) (mg/l) (%) (mg/l) (mg/l)
7/29 238 10 -95.8 56.0 41.8 -25.3 54.3 6.5 -88.0 0.5 54.4 7 /30 250 9 -96.4 55.4 43.6 -21.3 51.0 4.4 -91.4 0.5 70.0 7/31 257 9 -96.5 56.0 43.0 -23.2 56.0 4.4 -92.1 0.5 60.5 8/1 251 11 -95.6 55.4 42.l -24.0 54.4 3.7 -93.2 0.5 67.5 8/2 253 11 -95.6 55.7 42.3 -24.0 54.9 2.9 -94.7 0.5 54.l
AVG 250 10 -96.0 55.7 42.6 -23.5 54.1 4.4 -92.0 0.5 61.3
TABLE B-XII RAW DATA FOR REACTOR IV AT a
c • 5.17 DAYS
COD HLSS Ni(II) Concentration pH
Date Feed Effluent Removal Reactor Effluent ec Feed ~ Effluent Removal Feed Effluent Filtered Efficiency Solids Solids Unfiltered Filtered Efficiency Filtered
(1980) (mg/l) (mg/l) (%) (mg/l) (mg/l) (days) (mg/l) (mg/l) (mg/l) (%)
8/11 419 35 91. 7 1388 40 5.81 0.522 0.465 0.444 10.9 7.0 7.6 8/12 335 31 90.8 728 58 3.96 0.518 0.514 0.456 0.8 7.0 7.6 8/13 418 35 91.6 1040 80 4.03 0.594 0.557 0.427 6.2 7.0 7.6 8/14 405 34 91.6 1384 20 6.70 0.509 0.590 0.440 15.9 7 .o 7.6 8/15 403 30 92.6 800 32 5.27 0.520 0.484 0.435 6.9 7.0 7.6 8/16 407 34 91. 7 780 30 5.34 0.595 0.491 0.456 17.5 7.0 7.6 8/17 388 45 88.4 840 38 5.05 0.608 0.499 0.434 17.9 7.0 7.6
\0
AVG 396 35 91.2 994 43 5.17 0.552 0.514 0.442 10.9 7.0 7.6 V1
Alkalinity as Caco3 NH3-N Concentration Org-N Concentration N03-N Concentration
Uate Feed Effluent Net Feed Effluent Net Feed Effluent Net Feed Effluent Filtered Change Filtered Change Filtered Change Filtered
(1980) (mg/l) (mg/l) (%) (mg/l) (mg/l) (%) (mg/l) (mg/l) (%) (mg/l) (mg/l)
8/11 265 303 +44.5 0 34.7 -- 59.4 7.3 87.7 0.6 3.3 8/12 243 361 +48.6 0 33.0 -- 46.5 6.2 86.7 0. 7 1.0 8/13 204 363 +77.9 0 34.2 -- 52.1 3.3 93.7 0.6 1.6 8/14 250 377 +50.8 0 35.3 -- 54.9 3.9 92.9 0.6 1.0 8/15 251 378 +50.6 0 34.2 -- 56.0 3.3 94.1 0.7 1.3 8/16 250 390 +56.0 0 35.8 -- 56.6 4.0 92.9 0.6 1.1 8/17 221 391 +76.9 0.6 37.0 -- 54.8 2.7 95.1 0.5 1.0
AVG 241 378 +57.9 0.1 34.9 -- 54.3 4.4 91.9 0.6 1.5
TABLE B-XllI RAW DATA FOR REACTOR IV AT 8 • 7.19 DAYS c
COD HLSS Ni(II) Concentration pH Date Feed Effluent Removal Reactor Effluent e Feed Effluent Effluent Removal Feed Effluent
Filtered Efficiency Solids Solids c Unfiltered Filtered Efficiency Filtered (1980) (l!lg/l) (mg/l) (%) (mg/l) (mg/l) (days) (mg/l) (mg/l) (mg/l) (%)
7/29 410 61 85.l 1416 48 7.22 0.548 0.353 0.300 35.6 7.0 7.2 7/30 410 57 86.1 1294 32 8.09 0.529 0.320 0.246 39.5 7.0 7.3 7/31 414 45 89.l 1280 48 6.93 0.531 0.317 0.236 40.3 7.1 7.2 8/1 410 45 89.0 1068 18 9.02 0.532 0.352 0.266 33.8 7.0 7.2 8/2 410 123 70.0 468 34 4.97 0.517 0.418 0.393 19.2 7.1 7.2 8/3 410 66 83.9 708 42 5.56 0.525 0.532 0.484 -- 7.1 7.3 8/4 414 62 85.0 1368 28 8.57 0.532 0.501 0.459 5.8 7.0 7.5 '° AVG 411 57 84.0 1086 36 7.19 0.531 0.399 0.341 24.9 7.0 7.3 (1\
Alkalinity as Caco3 NH3-N Concentration Org-N Concentration N03-N Concentration Date Feed Effluent Net Feed Effluent Net Feed Effluent Net Feed Effluent
Filtered Change Filtered Change Filtered Change Filtered (1980) (mg/l) (mg/l) (%) (mg/l) (mg/l) (%) (mg/l) Cmg/l) (%) (mg/l) (mg/l)
7/29 244 350 +43.4 0 34.7 -- 54.9 5.1 90.7 o. 7 26.3 7/30 247 325 +31.6 0 33.0 -- 54.9 4.0 92.7 0.7 22.7 7/31 248 286 +15.3 0 26.9 -- 54.9 11. 7 78.7 0.6 24.4 8/1 248 296 +19.3 0 27.4 -- 56.6 8.4 85.2 0.7 20.2 8/2 247 306 +23.9 0.6 22.4 -- 54.3 25.2 53.6 0.6 10.7 8/3 248 368 +48.4 0.6 34.2 -- 54.3 5.6 89.7 0.6 6.4 8/4 249 363 +45.8 0.6 30.8 -- 54.8 12.9 76.5 0.6 5.0 AVG 247 328 32.5 0.3 29.9 -- 55.0 10.4 81.0 0.6 16.5
TABLE B-XIV RAW DATA FOR REACTOR IV AT 6 • 13.45 DAYS c
COD HLSS Ni(II) Concentration pH Date Feed Effluent Removal Reactor Effluent e Feed f;ffluent Effluent Removal Feed Effluent
Filtered Efficiency Solids Solids c Unfiltered Filtered . Efficiency Filtered (1980) (mg/l) (mg/l) (%) (mg/l) (mg/l) (days) (mg/l) (mg/l) (mg/l) (%)
7/17 433 10 97.7 2000 18 12.96 0.535 0.365 0.310 31.8 7.1 6.4 7/18 432 28 93.5 2l12 34 11.26 0.535 0.351 0.297 34.4 7.1 6.4 7 /19 412 60 85.4 1968 16 13.21 0.517 0.365 0.327 29.4 7.1 6.4 i/20 439 32 92.7 1916 12 13. 77 0.554 0.339 0.331 38.8 7.1 6.3 7/21 4ll 32 92.2 1960 6 14.84 0.538 0.325 0.310 39.6 7.1 6.3 7/22 424 10 97.6 1948 14 13.48 -- 0.376 0.352 -- 7.0 6.3 7/23 412 32 92.2 1688 6 14.66 -- 0.349 0.337 -- 7.0 6.4
AVG 423 29 93.0 1942 15 13.45 0.536 0.353 0.323 34.8 7.1 6.4 '° -...J
Alkalinity as Caco3 NH3-N Concentration Org-N Concentration N03-N Concentration Date Feed Effluent Net Feed Effluent Net Feed Effluent Net Feed Effluent
Filtered Change Filtered Change Filtered Change Filtered (1980) (mg/l) (mg/l) (%) (mg/l) (mg/l) (%) (mg/l) (mg/l) (%) (mg/l) (mg/l)
7/17 243 80 -67.l 0 0 0 53.8 1.1 98.0 0.7 47.8 7/18 243 85 -65.0 0 0 0 50.4 2.8. 94.4 0.5 60.8 7/19 239 87 -63.6 0 0 0 47.0 2.8 94.0 0.5 61.2 7 /20 248 85 -65.7 0 0 0 79.8 0 100 0.6 45.3 7/21 246 83 -66.3 0 0 0 59.4 l. 7 97.1 0.6 48.8 7/22 237 83 -65.0 0 0 0 53.2 4.5 91.5 0.8 50.6 7/23 237 83 -65.0 0 0 0 53.8 2.2 95.9 0.6 58.3
AVG 242 84 -65.4 0 0 0 56.8 2.2 95.8 0.6 53.3
TABLE B-XV RAW DATA FOR REACTOR IV AT 6 • 15.0 DAYS c
COD HLSS Ni(ll) Concentration pH Date Feed Effluent Removal Reactor Effluent e Feed Effluent Effluent Removal Feed Effluent
Filtered Efficiency Solids Solids c Unfiltered Filtered Efficiency Filtered (1980) (mg/l) (mg/l) (%) (mg/l) (mg/l) (days) (mg/l) (mg/l) (mg/l) (%)
5/26 403 4 99.0 2290 20 14.23 0.516 0.542 0.475 -- 7.2 6.7 5/27 411 11 97.3 2230 12 15.44 0.524 0.514 0.490 1.9 7.2 6.6 5/28 403 11 97.3 2280 12 15.49 0.524 0.487 0.468 7.1 7.2 6.6 5/29 373 11 97.l 2410 8 16.30 0.529 0.488 0.442 7.8 7.2 6.6 5/30 411 8 98.l 2460 16 15.01 0.533 0.478 0.452 10.3 7.2 6.6 5/31 399 15 96.2 2440 14 15.30 0.529 0.489 0.442 7.6 7.2 6.6 6/1 403 6 98.5 2430 30 13.11 0.567 0.488 0.445 13.9 7.2 6.6 AVG 400 9 97.6 2363 16 15.00 0.532 0.498 0.459 6.9 7.2 6.6 \0
00
Alkalinity as Caco3 NH3-N Concentration Org-N Concentration N03-N Concentration Date Feed Effluent Net Feed Effluent Net Feed Effluent Net Feed Effluent
Filtered Change Filtered Change Filtered Change Filtered (1980) (mg/l) (mg/l) (%) (mg/l) (mg/l) (%) (mg/l) (mg/l) (%) (mg/l) (mg/l)
5/26 255 127 -50.2 0 0.6 -- 61.3 3.9 93.6 0.6 54.6 5/27 256 109 -57.4 0 0 -- 62.4 2.8 95.5 0.6 57.8 5/28 253 115 -54.6 0 0.8 -- 58.5 1. 7 97.l 0.5 50.6 5/29 249 113 -54.6 0 0.6 -- 59.0 2.8 95.3 0.4 47.9 5/30 254 109 -57.l 0 0 -- 55.2 2.5 95.5 0.4 46.l 5/31 252 106 -57.9 0 0 -- 59.0 2.8 95.3 0.4 58.5 6/1 252 107 -57.5 0 0 -- 62.2 2.8 95.5 0.5 56.8 AVG 253 112 -55.6 0 0.3 -- 59.7 2.8 95.4 0.5 53.2
TABLE B-XVI RAW DATA FOR REACTOR V AT 8 • 5.2 DAYS c
COD MLSS Ni(II) Concentration pH Date Feed Effluent Removal Reactor Effluent e Feed Effluent Removal Feed Effluent
Fil tend Efficiency Solids Solids c Filtered Efficiency Filtered (1978) (mg/l) (mg/l) (%) (mg/l) (mg/l) (days) (mg/l) c.ngt1> (%)
5/2 410 24 94.2 1124 20 5.5 1.00 0.92 8.0 7.1 7.7 5/3 396 28 92.9 1120 30 5.1 0.96 0.80 16.7 7.1 7.7 5/4 383 32 91.6 1116 27 5.3 0.98 0.91 7.1 7.2 7.6 5/5 396 20 95.0 1120 36 4.9 1.00 1.03 -3.0 7.0 7.6 5/6 400 24 94.0 1036 32 5.0 1.01 1.05 -4.0 7.3 7.7 5/7 389 24 93.8 1112 28 5.2 0.97 0.89 8.2 7.2 7.7 5/8 387 20 94.8 1112 29 5.2 1.00 0.84 16.0 7.2 7.7 AVG 394 25 93.8 1106 29 5.2 0.99 0.92 7.0 7.2 7.7 '° '°
Alkalinity as Caco3 NH3-N Concentration Org-N Concentration N03-N Concentration Date Feed Effluent Net Feed Effluent Net Feed Effluent Net Effluent
Filtered Change Filtered Change Filtered Change Filtered (1978) (mg/l) (mg/l) (%) (mg/l) (mg/l) (%) (mg/l) (mg/l) (%) (mg/l)
5/2 238 330 38.7 58.2 87.9 51.0 54.3 3.4 -93.7 1.3 5/3 244 338 38.5 52.6 86.2 63.9 52.6 2.2 -95.8 0.7 5/4 246 326 32.5 60.5 96.2 42.5 52.1 2.8 -94.6 2.0 5/5 236 336 42.4 60.5 90.7 49.9 52.1 1. 7 -96.7 1.5 5/6 237 344 45.1 53.8 87.4 62.5 53.2 2.2 -95.9 1.6 5/7 239 340 42.3 50.4 82.9 64.5 53.2 3.4 -93.6 1.1 5/8 244 344 41.0 53.8 80.6 49.8 52.6 6.2 -88.2 1.3 AVG 241 337 40.1 55.7 86.0 54.9 52.9 3.1 -94.1 1.4
TABLE B-XVII RAW DATA FOR REACTOR V AT 6 • 10.6 DAYS c
COD MLSS Ni(ll) Concentration pH Date Feed Effluent Removal Reactor Effluent e Feed Effluent Removal Feed Effluent
Filtered Efficiency Solids Solids c Filtered Efficiency Filtered (1978) (mg/l) (mg/l) (%) (mg/l) (mg/l) (days) (mg/l) (mg/l) (%)
3/10 406 36 91.l 1480 12 10.5 1.01 0.85 15.8 7.1 7.6 3/11 414 28 93.2 1512 4 11.5 1.03 o. 70 32.0 7.1 7.8 3/12 398 28 93.0 1564 6 11.3 1.00 0.95 5.0 7.2 7.7 3/13 387 32 91.7 1488 14 10.2 1.02 0.90 11.8 7.1 7.6 3/14 387 28 92.8 1488 5 11.4 0.99 0.77 22.2 7.0 7.6 3/15 375 28 92.5 1396 24 9.1 0.96 1.00 -4.2 7.1 7.6 3/16 402 24 94.0 1436 12 10.4 0.98 0.84 14.3 7.1 7.5 ..... AVG 396 29 92.6 1475 11 10.6 1.00 0.86 13.8 7.1 7.6 0
0
Alkalinity as Caco3 NH3-N Concentration Org-N Concentration N03-N Concentration Date Feed Effluent Net Feed Effluent Net Feed Effluent Net Effluent
Filtered Change Filtered Change Filtered Change Filtered (1978) (mg/l) (mg/ 1) (%) (mg/l) (mg/l) (%) (mg/l) (mg/ l) (%) (mg/l)
3/10 236 356 50.8 56.0 82.9 48.0 48.7 5.3 -89.1 1.9 3/11 229 362 58.1 52.6 85.7 62.9 53.2 3.3 -93.8 1. 7 3/12 224 352 57.l 56.0 89.0 58.9 53.8 4.0 -92.6 1.8 3/13 229 356 55.5 57.1 92.4 61.8 51.5 4.2 -91.8 1.8 3/14 230 354 53.9 57.l 95.2 66.7 52.l 5.6 -89.3 1.9 3/15 236 361 53.0 52.7 94.1 50.1 45.9 3.3 -92.8 1.5 3/16 242 340 40.5 56.0 85.2 52.1 51.5 3.3 -93.6 1.6 AVG 232 354 52.7 56.8 89.2 57.2 50.6 4.1 -91.9 1. 7
TABLE B-XVIII RAW DATA FOR REACTOR V AT 6 • 14.5 DAYS c
COD MLSS Ni(II) Concentration pH Date Feed Effluent Removal Reactor Effluent e Feed Effluent Effluent Removal Feed Effluent
Filtered Efficiency Solids Solids c Unfiltered Filtered Efficiency Filtered (1978) (mg/l) (mg/l) (%) (mg/l) (mg/l) (days) (mg/l) (mg/l) (mg/l) (%)
2/22 402 34 91.5 1736 6 15.5 0.85 -- o. 79 7.1 7.1 7.7 2/23 412 46 88.8 1704 12 14.2 1.00 -- 0.90 10.0 6.9 7.7 2/24 410 38 90.7 1684 8 15.0 0.95 -- 0.83 12.6 7.1 7.5 2/25 402 42 89.6 1648 17 13.2 0.86 -- 0.81 5.8 7.1 7.7 2/26 395 30 92.4 1704 4 16.0 0.98 -- 0.79 19.4 7.1 7.5 2/27 )85 34 91.2 1732 8 15.1 0.94 -- 0.87 7.5 7.1 7.7 2/28 370 27 92.7 1768 16 13.6 0.88 -- 0.90 -2.3 7.0 7.5 3/1 393 23 94.2 1672 14 13.8 0.93 -- 0.87 6.5 7.0 7.6 3/2 431 27 93.7 1808 20 13.0 1.00 -- 0.90 10.0 7 .0 7.6 3/3 )93 31 92.1 1702 6 15.5 0.89 -- 0.88 1.1 7.0 7.6 ...... AVG )99 3) 91. 7 1716 11 14. 5 0.93 -- 0.85 7.8 7.0 7.6 0 ......
Alkalinity as Caco3 NH3-N Concentration Org-N Concentration N03-N Concentration Date Feed Effluent Net Feed Effluent Net Feed Effluent Net Effluent
Filtered Change Filtered Change Filtered Change Filtered (1978) (mg/l) (mg/l) (%) (mg/l) (mg/l) (%) (mg/l) (mg/l) (%) (mg/l)
2/22 222 352 58.6 47.0 84.0 78.7 44.8 10.0 -77.7 1.4 2/23 218 344 57.8 47.0 86.2 83.4 53.8 6.8 -87.4 1.6 2/24 230 346 50.4 52.1 84.0 61.2 49.8 9.0 -81.9 1.4 2/25 222 352 58.6 38.l 84.0 120.5 61.6 9.0 -85.4 1.4 2/26 274 350 27.7 53.8 84.0 56.1 61.6 6.7 -89.1 1. 6 2/27 232 356 53.4 52.1 85.1 63.3 49.8 7.9 -84.1 1. 5 2/28 246 354 43.9 53.8 84.0 56.1 48.1 6.7 -86.1 1.6 3/1 272 388 42 .6 49.3 81.8 65.9 52.6 10.0 -81.0 1.6 3/2 240 384 60.0 51.0 90.7 77.8 57.6 7.9 -86.3 2.2 3/3 225 371 64.9 49.8 88.4 77.5 54.4 7.9 -85.5 1. 7 AVG 233 360 51.8 49.4 85.2 74.1 53.4 8.2 -84.5 1.6
The vita has been removed from the scanned document
EFFECTS OF NICKEL ON ACTIVATED SLUDGE PERFORMANCE
AT VARYING TKN:COD RATIOS
by
Patti G. Trahern
(ABSTRACT)
The effects of a continuous dose of 0.5 mg/l nickel on
activated sludge performance at varying COD:TKN ratios were
investigated. Continuous flow, complete mix, bench-scale
reactors were operated over a range of mean cell residence times,
and COD removal efficiency, biokinetic coefficients, extent of
nitrification, and nickel removal evaluated at each. Data from
two earlier studies, in which 0.5 and 1 mg/l nickel doses were
applied to similar units, were included for comparison.
Organic removal efficiency was not impaired for the nickel
doses considered. Biokinetic coefficients and nitrate production
were also unaffected by 0.5 mg/l nickel. In contrast, one mg/l
nickel sharply inhibited nitrification, caused an apparent
decrease in reactor solids concentration, and related biokinetic
changes in coefficients. Nickel removal was erratic.