CHAPTER 2 CHAPTER 2 INDUSTRIAL WASTEINDUSTRIAL WASTE

by:by:Dr. N AbdullahDr. N Abdullah

ENVIRONMENTAL HEALTH ENGINEERING ENVIRONMENTAL HEALTH ENGINEERING ECH 4102ECH 4102

LEARNING OBJECTIVES

1.1. Identify different sources and the major types Identify different sources and the major types industrial toxic & hazardous wasteindustrial toxic & hazardous waste

2.2. Distinguish treatment technologies for different type of Distinguish treatment technologies for different type of industrial wasteindustrial waste

3.3. Describe Hazardous waste management and controlDescribe Hazardous waste management and control

WasteWaste

The Universe of WasteThe Universe of Waste

Sources & composition of solid wastesSources & composition of solid wastes

What is industrial waste?What is industrial waste?

TYPES OF INDUSTRIAL TYPES OF INDUSTRIAL WASTEWASTE

Toxic substances are Toxic substances are primarily associated with primarily associated with industrial wastesindustrial wastes

Range of toxic substances Range of toxic substances present in industrial present in industrial wastes is too broad to wastes is too broad to cataloguecatalogue

Source of Industrial Source of Industrial WasteWaste

Hazardous waste sources

INDUSTRY HAZARDOUS WASTE

Valley of Drums

Q: How to classify and assess the hazard?

HAZARDOUS WASTE Classification

Definition:

Listed in EPA regulations

Ignitable, corrosive, reactive, or toxic

Declared by the generator

HAZARDOUS WASTE CHARACTERISTIC

HAZARDOUS WASTE ASSESSMENT CRITERIA

Bioconcentration Ability of material to be

retained in animal tissue Many pesticides will reside in

fatty tissue of animals Most concern – aquatic

animals (seals & penguins) & birds ( pelicans, eagles, falcons, condors) that feed on fish

LD50 amount of chemical that is

needed to kill half of a group of test specimens e.g mice

Animals in a toxicity study are fed progressively higher doses of chemical until half of them die, & this dose is known as median lethal dose (50%)

The lower amount of toxin used to kill 50% of specimens, higher toxic value of chemical

HAZARDOUS WASTELC50 Concentration at which

some chemical is toxic used where the amount

ingested cannot be measured, such as in aquatic environment or in evaluating quality of air

Specimens such as goldfish, are placed in a series of aquariums, & increasingly higher concentrations of toxin are administered

Fraction of fish dying within a given time is recorded

Phytotoxicity Chemical is considered

toxic if it exhibits toxicity to plants

All herbicides are toxic materials & when they must be disposed of, they must be treated as hazardous waste

ROUGH GUIDELINE : A WASTE IS CONSIDERED TOXIC IF IT IS FOUND TO HAVE LD50 OF < 50 mg/kg body weight OR IF THE LC50 <

2mg/kg

Toxicity assessmentToxicity assessment

CDI C(CR)(EDF)

BW

1

AT

CDI = chronic daily intake (mg/kg body weight. day)CDI = chronic daily intake (mg/kg body weight. day) C = chemical concentration (mg/L)C = chemical concentration (mg/L) CR = contact rate (L/day)CR = contact rate (L/day) EDF = exposure duration (yr) & frequency (day/yr)EDF = exposure duration (yr) & frequency (day/yr) BW = body weight (kg)BW = body weight (kg) AT = average time (d)AT = average time (d)

CDI equation for CDI equation for different exposure different exposure

pathwaypathway

CDI (CW )(IR)(EF)(ED)

(BW )(AT )

CDI (CR)(IR)(FI)(EF)(ED)

(BW )(AT )

CDI (CW )(CR)(ET)(EF )(ED)

(BW )(AT)

AD(CW )(SA)(PC)(ET)(EF)(ED)(CF )

(BW )(AT )

AD(CS)(CF )(SA)(AF)(ABS)(EF)(ED)

(BW )(AT )

CDI (CA)(IR)(ET)(EF)(ED)

(BW )(AT )

INGESTION IN DRINKING WATER INGESTION WHILE SWIMMING

INGESTION OF CONTAMINATED FOOD INHALE AIRBORN

DERMAL CONTACT WITH SOIL DERMAL CONTACT WITH WATER

CDI (CS)(IR)(CF)(FI)(EF )(ED)

(BW )(AT)

INGESTION OF CONTAMINATED SOIL

Types of Industrial WasteTypes of Industrial Waste

TOXIC WASTE SOURCESTOXIC WASTE SOURCESTOXINTOXIN SOURCESSOURCES

ACIDS ACIDS – mainly inorganic but some organic – mainly inorganic but some organic causing; pH < 6causing; pH < 6

ACID MANUFACTURE, BATTERY MANUFACTURE, ACID MANUFACTURE, BATTERY MANUFACTURE, CHEMICAL INDUSTRY, STEEL INDUSTRYCHEMICAL INDUSTRY, STEEL INDUSTRY

ALKALISALKALIS – causing pH > 9 – causing pH > 9 BREWERY WASTES, FOOD INDUSTRY, CHEMICAL BREWERY WASTES, FOOD INDUSTRY, CHEMICAL INDUSTRY, TEXTILE MANUFACTUREINDUSTRY, TEXTILE MANUFACTURE

ANTIBIOTICSANTIBIOTICS PHARMACEUTICAL INDUSTRYPHARMACEUTICAL INDUSTRY

AMMONIACAL NITROGENAMMONIACAL NITROGEN COKE PRODUCTION, FERTILIZER MANUFACTURE, COKE PRODUCTION, FERTILIZER MANUFACTURE, RUBBER INDUSTRYRUBBER INDUSTRY

CHROMIUMCHROMIUM – mainly hexavalent but also less – mainly hexavalent but also less toxic trivalent formtoxic trivalent form

METAL PROCESSING, TANNERIESMETAL PROCESSING, TANNERIES

CYANIDECYANIDE COKE PRODUCTION, METAL PLATINGCOKE PRODUCTION, METAL PLATING

DETERGENTSDETERGENTS – mainly anionic but some – mainly anionic but some cationiccationic

DETERGENT MANUFACTURE, TEXTILE DETERGENT MANUFACTURE, TEXTILE MANUFACTURE, LAUNDRIES, FOOD INDUSTRYMANUFACTURE, LAUNDRIES, FOOD INDUSTRY

HERBICIDES & PESTICIDES HERBICIDES & PESTICIDES – mostly – mostly chlorinated hydrocarbonschlorinated hydrocarbons

CHEMICAL INDUSTRYCHEMICAL INDUSTRY

METALS METALS – mainly Cu, Cd, Co, Pb, Ni, & Zn– mainly Cu, Cd, Co, Pb, Ni, & Zn METAL PROCESSING & PLATING, CHEMICAL METAL PROCESSING & PLATING, CHEMICAL INDUSTRYINDUSTRY

PHENOLSPHENOLS COKE PRODUCTION, OIL, REFINING, WOOD COKE PRODUCTION, OIL, REFINING, WOOD PRESERVINGPRESERVING

SOLVENTS SOLVENTS – mostly benzene, acetone, carbon – mostly benzene, acetone, carbon tetrachloride & alcoholstetrachloride & alcohols

CHEMICAL INDUSTRY, PHARMACEUTICALSCHEMICAL INDUSTRY, PHARMACEUTICALS

WASTE GENERATOR WASTE TYPES

Chemical Manufacturers Acids and Bases, Spent Solvents, Reactive Waste, Wastewater Containing Organic Constituents

Printing Industry Heavy Metal Solutions, Waste Inks Solvents, Ink Sludges Containing Heavy Metals

Petroleum Refining Industry Wastewater Containing Benzene & other Hydrocarbons Sludge from Refining Process

Leather Products Manufacturing Toluene and Benzene

Paper Industry Paint Waste Containing Heavy Metals, Ignitable Solvents

Construction Industry Ignitable Paint Waste, Spent Solvents, Strong Acids and Bases

Metal Manufacturing Sludges containing Heavy Metals, Cyanide waste, paint waste

EXAMPLES OF HAZARDOUS WASTE EXAMPLES OF HAZARDOUS WASTE GENERATED BY INDUSTRIESGENERATED BY INDUSTRIES

INDUSTRY HAZARDOUS WASTE

METAL PROCESSING WASTES Metal Finishing: involves stripping, removal of undesirable oxides, cleaning

and plating.

The most ubiquitous contaminants are chromium, zinc, copper, nickel, tin and cyanides. Alkaline cleaners, grease and oils are universally present.

Two major sources of waste:

1. Concentrated solutions

2. Rinse waters

Sources of wastes –numerous & extremely variable in quantity & quality

Metals forms:

large particles of pure metal in suspension

metallic ions & complexes in solution

Wastes can be classified as follows:

a) MINING – ore production & washing (also contains inert SS)

b) ORE PROCESSING – smelting, refining, quenching, gas, scrubbing (also contains sulfides, ammonia & organics)

c) MACHINING – metal particles usually mixed with lubricants

d) DEGREASING – metals mostly in solution with cyanides, alkalis & solvents

e) PICKLING – acids with metals & metallic oxides in solution

f) DIPPING – alkalis with sodium carbonate, dichromate, plus metals

METAL PROCESSING WASTES

g) POLISHING – particles of metals & abrasives together

h) ELECTROCHEMICAL OR CHEMICAL BRIGHTENING & SMOOTHING – acids, mainly sulfuric, phosphoric, chromic & nitric with metals in solution

i) CLEANING – hot alkalis with detergents, cyanides & dilute acids plus metals in solution

j) PLATING – acids, cyanides, chromium salts, pyrophosphates, sulfamates & fluoroborates plus metals in solution

k) ANODIZING – chromium, cobalt, nickel & manganese in solution

METAL PROCESSING WASTES

BathBathformulaformula

Metallic +Metallic +cyanide (ppm)cyanide (ppm)

Rinse Conc,Rinse Conc,ppmppm

0.5gph drag-out0.5gph drag-out

Rinse Conc,Rinse Conc,ppmppm

2.5gph drag-2.5gph drag-outout

Nickel,Nickel, 40oz/gal nickel sulfate40oz/gal nickel sulfate8oz/gal nickel chloride8oz/gal nickel chloride

6oz/gal boric acid6oz/gal boric acid

82,000 Ni82,000 Ni 171 Ni171 Ni 855 Ni855 Ni

Chromium,Chromium,53 oz/gal chromic acid53 oz/gal chromic acid.53 oz/gal sulfuric acid.53 oz/gal sulfuric acid

207,000 Cr207,000 Cr 431 Cr431 Cr 2155 Cr2155 Cr

CadmiumCadmium3.5 oz/gal cadmium oxide3.5 oz/gal cadmium oxide

14.5 oz/gal sodium cyanide14.5 oz/gal sodium cyanide

23,000 Cd23,000 Cd57,700 CN57,700 CN

48 Cd48 Cd120 CN120 CN

240 Cd240 Cd600 CN600 CN

Characteristics of Metal-Plating Wastes

Most stripping baths - acidic contain HMost stripping baths - acidic contain H22SOSO44, HNO, HNO33 and HCl and HCl Alkaline baths - sodium sulfide cyanide and hydroxide are Alkaline baths - sodium sulfide cyanide and hydroxide are

also used. also used. [chemicals] are usually less than 10%, 100,000 mg/l.[chemicals] are usually less than 10%, 100,000 mg/l. Common plating baths are as follows:Common plating baths are as follows:

Metal Processing Waste method of treatment – depends on form of metal, Conc., pH, method of treatment – depends on form of metal, Conc., pH,

other constituents, & desired effluent standardother constituents, & desired effluent standard Treatment are Treatment are ::

1.1. Modifications in design and/or operation- to minimize or Modifications in design and/or operation- to minimize or eliminate the waste.eliminate the waste.

2.2. installation a P-Chemical treatment plant installation a P-Chemical treatment plant

3.3. Modifications include:Modifications include:

- eliminating breakable containers- eliminating breakable containers

- drip pans, rinses- drip pans, rinses

- reducing spillage- reducing spillage

- fog rinses- fog rinses

- reclaiming metals- reclaiming metals

LAUNDRY WASTES 4 gallons of waste per pound of clothes.4 gallons of waste per pound of clothes. Waste originates from dye, grease, starch, scouring, dirtWaste originates from dye, grease, starch, scouring, dirt Most installations contain 25-35 machines and use 25-30 gal. of water per Most installations contain 25-35 machines and use 25-30 gal. of water per

washing cycle.washing cycle.22 gal. are cold and 8 hot 22 gal. are cold and 8 hot resulting in an average dischargeresulting in an average discharge water at 100F.water at 100F.50,000 gal/wk installation 50,000 gal/wk installation can be expected.can be expected.

100 lbs of detergent are used 100 lbs of detergent are used per weekper week

Analysis Commercial Domestic

pH 10.3 8.1

Alkalinity, ppm 511 678

TDS, ppm 2114 3314

BOD5,ppm 1860 3813

Grease, ppm 554 1406

Treatment of Laundry WastesTreatment of Laundry Wastes Acidification with HAcidification with H22SOSO44, CO, CO22 or SO or SO22 followed by coagulation with alum or followed by coagulation with alum or

ferric sulfate.ferric sulfate. After chemical coagulation, trickling filtration and activated sludge processes are After chemical coagulation, trickling filtration and activated sludge processes are

effective.effective.

CANNED FOOD WASTE

Require great deal of water as wash water from cleaning vegetable, sorting, peeling and coring, spillage from filling and sealing machines, wash water from cleaning floors, tables, belts.

Product Volume, per case,

gal

BOD5ppm

SSppm

Asparagus 70 110 30

Carrots 23 520-3030 1830

Spinach 3 6300 630

Apricots 57-80 200-1020 260

Tomatoes, whole

3-15 570-4000 190-2000

MEDICAL WASTE 1987-88: New York and New Jersey beach closures due to washed-up 1987-88: New York and New Jersey beach closures due to washed-up

medical wastesmedical wastes November 1988 – Medical Waste Tracking Act (November 1988 – Medical Waste Tracking Act (MWTAMWTA) added medical ) added medical

waste to RCRAwaste to RCRA Types of medical waste:Types of medical waste:

Cultures and stocksCultures and stocks Pathological wastesPathological wastes Human blood and blood productsHuman blood and blood products Used sharpsUsed sharps Animal wasteAnimal waste Isolation wasteIsolation waste Unused sharpsUnused sharps

MEDICAL WASTE

Method of Disposal:Method of Disposal: Favored treatment option is Favored treatment option is

incinerationincineration Required for “Red Bag” (or Yellow Required for “Red Bag” (or Yellow

bag in some countries )(potentially bag in some countries )(potentially infectious) wasteinfectious) waste

Used for most waste for extra safety Used for most waste for extra safety and “aesthetics” (incinerated waste is and “aesthetics” (incinerated waste is not recognizable as medical waste)not recognizable as medical waste)

RADIOACTIVE WASTE High-level waste :High-level waste :

1.1. spent nuclear fuelspent nuclear fuel

2.2. Transuranic waste – defense-Transuranic waste – defense-related wasterelated waste

3.3. Uranium mill tailingsUranium mill tailings Low-level wasteLow-level waste

1.1. Natural occurring radioactive Natural occurring radioactive materials (NORM)materials (NORM)

2.2. accelerator-produced radioactive accelerator-produced radioactive wastewaste

Mixed waste – radioactive and Mixed waste – radioactive and hazardoushazardous

Livestock & Animal Livestock & Animal WasteWaste

EXAMPLE: Hog industryEXAMPLE: Hog industry

TOXICITY FROM THE COLLECTION TOXICITY FROM THE COLLECTION SYSTEMSYSTEM

Uncontrolled discharge – lead to poisonous gases

Health of sewer workers – damage

Levels of HCN & H2S of 0.03% in atmosphere are toxic

H2S –problem of anesthesia – difficult detection

Some organic solvents may cause similar difficulties

High cost of constructing a waste collection system

70% of the total cost for treatment & disposal

Strict control on discharge of toxic substances eg. HCN, H2S

Some organic solvents may cause similar difficulties

Tend to be immiscible with water, volatile & intoxicating

Also may form explosive mixtures

TOXICITY FROM THE COLLECTION TOXICITY FROM THE COLLECTION SYSTEMSYSTEM

TYPICAL CONSENT CONDITIONS FOR DISCHARGE TO SEWERS

PARAMETERPARAMETER CONSENT CONDITIONCONSENT CONDITION

MAXIMUM TEMPERATUREMAXIMUM TEMPERATURE 40-5040-50OOCC

pHpH 6-106-10

SUBSTANCES PRODUCING INFLAMMABLE VAPOURSSUBSTANCES PRODUCING INFLAMMABLE VAPOURS NILNIL

CYANIDE CYANIDE CONCENTRATIONCONCENTRATION 5-10 mg/L5-10 mg/L

SULFIDESULFIDE CONCENTRATION CONCENTRATION 1 mg/L1 mg/L

SOLUBLE SULFATESSOLUBLE SULFATES 1250 mg/L1250 mg/L

SYNTHETIC DETERGENTSSYNTHETIC DETERGENTS 30 mg/L30 mg/L

FREE CHLORINEFREE CHLORINE 100 mg/L100 mg/L

MERCURYMERCURY 0.1 mg/L0.1 mg/L

CADMIUMCADMIUM 2 mg/L2 mg/L

CHROMIUMCHROMIUM 5 mg/L5 mg/L

LEADLEAD 5 mg/L5 mg/L

ZINCZINC 10 mg/L10 mg/L

COPPERCOPPER 5 mg/L5 mg/L

ZINC EQUIVALENT (Zn + Cd + 2Cu + 8Ni)ZINC EQUIVALENT (Zn + Cd + 2Cu + 8Ni) 35 mg/L35 mg/L

TOTAL NON-FERROUS METALTOTAL NON-FERROUS METAL 30 mg/L30 mg/L

TOTAL SOLUBLE NON-FERROUS METALTOTAL SOLUBLE NON-FERROUS METAL 10 mg/L10 mg/L

Industrial Waste Industrial Waste TreatmentTreatment

SUMMARY OF ALTERNATIVE SUMMARY OF ALTERNATIVE TREATMENT TECHNOLOGIES (1992)TREATMENT TECHNOLOGIES (1992)

Solidification/stabilization (28%)

Soil vaporextraction

(18%)

On-siteincineration

(11%)

Off-siteincineration

(15%)

Ex situbioremediation

(6%)

In situbioremediation

(4%)

In situflushing

(3%)

Soilwashing

(3%)

Thermaldesorption

(5%)

Soil aeration,in situ flaming &

chemical neutralization (2%)

In situ vitrification(<1%)

Dechlorination(<1%)

Solvent extraction(<1%)

Other innovative(<1%)

Application of Innovative Treatment Technologies

Soil vaporextraction

Thermaldesorption

Bioreme-diation

In situ flushing Solventextraction

Soil washing0

10

20

30

40

50

60

70

80

90

100

VOCs

SVOCs

Metals

Nu

mb

er

of

ap

plicati

on

s

PRE-TREATMENT

Pretreatment is on-site, advantages:

recovering specific substances in an uncontaminated condition

avoidance of contamination of a much larger wastewater stream

In some cases, dilution of the wastes by admixture with sewage reduces the toxic inhibition

many industrial wastes are deficient in some nutrient (N or P)

PRE-TREATMENT

Key factors in deciding for or against pre-treatment:

Availability of space

Availability of expertise

Sludge and/or odor production may create a nuisance

Possibility for the introduction of clean technologies

PHYSICAL METHODS PROCESSPROCESS AIMAIM EXAMPLESEXAMPLES

SCREENINGSCREENING REMOVAL OF COARSE SOLIDSREMOVAL OF COARSE SOLIDS Vegetable canneries, paper millsVegetable canneries, paper mills

CENTRIFUGINGCENTRIFUGING CONCENTRATION OF SOLIDSCONCENTRATION OF SOLIDS Sludge dewatering in chemical industrySludge dewatering in chemical industry

FILTRATIONFILTRATION CONCENTRATION OF FINE CONCENTRATION OF FINE SOLIDSSOLIDS

Final polishing & sludge dewatering in Final polishing & sludge dewatering in chemical & metal processingchemical & metal processing

SEDIMENTATIONSEDIMENTATION REMOVAL OF SETTEABLE SOLIDSREMOVAL OF SETTEABLE SOLIDS Separation of inorganic solids in ore Separation of inorganic solids in ore extraction, coal & clay productionextraction, coal & clay production

FLOTATIONFLOTATION REMOVAL OF LOW SPECIFIC REMOVAL OF LOW SPECIFIC GRAVITY SOLIDS & LIQUIDSGRAVITY SOLIDS & LIQUIDS

Separation of oil, grease & solids in Separation of oil, grease & solids in chemical & food industrychemical & food industry

FREEZINGFREEZING CONCENTRATION OF LIQUIDS & CONCENTRATION OF LIQUIDS & SLUDGESSLUDGES

Recovery of pickle liquor & non-Recovery of pickle liquor & non-ferrous metalsferrous metals

SOLVENT SOLVENT EXTRACTIONEXTRACTION

RECOVERY OF VALUABLE RECOVERY OF VALUABLE MATERIALSMATERIALS

Coal carbonizing, plastics manufactureCoal carbonizing, plastics manufacture

ION EXCHANGEION EXCHANGE SEPARATION & CONCENTRATIONSEPARATION & CONCENTRATION Metal processingMetal processing

REVERSE REVERSE OSMOSISOSMOSIS

SEPARATION OF DISSOLVED SEPARATION OF DISSOLVED SOLIDSSOLIDS

Desalination of process & wash waterDesalination of process & wash water

ADSORPTIONADSORPTION CONCENTRATION & REMOVALCONCENTRATION & REMOVAL Pesticide manufacture, dyestuffs Pesticide manufacture, dyestuffs removalremoval

PHYSICAL PRE-TREATMENT METHODS

Devices to improve effluent quality

eg. screening, filtration, coarse or fine, to reduce solids, grease trap, grit arrestors, sedimentation etc.

The effluent from high-rate filters often has a BOD & COD similar to settled sewage & is suitable either for discharge to a sewer or for further biological treatment on site

CHEMICAL METHODS may be used in addition to biological treatment

Aims- to convert waste into a settleable formFor oxidizing particular compounds (eg. Cyanide) since it is

expensive & liable to lead to the production of undesirable chlorinated organics

For pH correction & improving solid removal

COMMON PRE-TREATMENT METHODS

COMMON CHEMICALS USED:CHEMICALCHEMICAL PURPOSEPURPOSE

CALCIUM HYDROXIDECALCIUM HYDROXIDE pH adjustment, precipitation of metals & assisting pH adjustment, precipitation of metals & assisting sedimentationsedimentation

SODIUM HYDROXIDESODIUM HYDROXIDE Used mainly for pH adjustment in place of limeUsed mainly for pH adjustment in place of lime

SODIUM CARBONATESODIUM CARBONATE pH adjustment & precipitation of metals with soluble pH adjustment & precipitation of metals with soluble hydroxidehydroxide

CARBON DIOXIDECARBON DIOXIDE pH adjustmentpH adjustment

ALUMINIUM SULFATEALUMINIUM SULFATE Solids separationSolids separation

FERROUS SULFATEFERROUS SULFATE Solids separationSolids separation

CHLORINECHLORINE OxidationOxidation

ANIONIC ANIONIC POLYELECTROLYTESPOLYELECTROLYTES

Enhance coagulation & flocculationEnhance coagulation & flocculation

PRIMARY SEDIMENTATION TREATMENT

Wastewater treatment :

preliminary, primary & secondary (+tertiary if necessary)

Preliminary – usually screening & grit removal;

- have little effect on toxic materials

- (But Effect primary sedimentation to toxic wastes –important)

- Toxic materials in suspension (e.g., Particulate metals) – effectively removed

Good flocculant - has great capacity for adsorption & removes majority of dissolved metals, pesticides & other toxic organics

PRIMARY SEDIMENTATION TREATMENT

Chemicals addition – enhance the effectiveness of primary sedimentation; also, assist the precipitation process

ADVANTAGES: enables industry to avoid secondary biological

treatmentEnables waste to be discharged to a sewer, estuary or sea

DISADVANTAGES:

can be expensive, often requires pH correction, & may produce large quantities of sludge with a disposal problem

PRIMARY SEDIMENTATION TREATMENT

Chemically enhanced sedimentation

main aim: increase removal of solids

But since many toxins (metals & chlorinated organics) adsorb strongly, their removal also increase to levels similar to combined primary & secondary treatment

PRIMARY & SECONDARY TREATMENT

TYPICAL FOR ENHANCEMENT: LIME

METALMETALCONC. IN CONC. IN

WASTEWATER WASTEWATER (mg/L)(mg/L)

% REMOVAL BY % REMOVAL BY SEDIMENTATIONSEDIMENTATION

% REMOVAL (WITH % REMOVAL (WITH LIME) BY LIME) BY

SEDIMENTATIONSEDIMENTATION

IRONIRON 6.36.3 4848 8080

COPPERCOPPER 0.60.6 2828 6060

CHROMIUMCHROMIUM 0.340.34 4040 5858

LEADLEAD 0.120.12 3333 5555

MERCURYMERCURY 0.0280.028 1515 5050

NICKELNICKEL 0.080.08 1515 1515

ZINCZINC 0.70.7 3838 7070

Technique most commonly employed to precipitate metal

Optimum pH – varies depend on metal

Typical value – 8.0 – 9.0

Zinc – avoid high pH to prevent formation of zincates

Other constituents of waste (e.g., Ammonia) – can affect solubility of metal hydroxide; thus, impossible to predict accurately level of residual metal in treated effluent

PROCESSING WASTES-Precipitation by pH Adjustment-

not all hydroxide precipitation – satisfied with pH adjustment

Example : Cr6+

present in wastes from metal plating

Must reduce to Cr3+ form before treatment with lime or caustic soda

Reducing agents – sodium bisulfate, sulfur dioxide & ferrous sulfate

Reduction process – carried out under acid conditions & subsequent addition of alkali precipitates trivalent chromium hydroxide

PROCESSING WASTES-Precipitation by Reducing Agent-

Particular type of precipitation system used in metal plating industry

Principal feature – rinsing stage immediately after metal plating stage – chemical rinse which precipitates metal from liquid around the article being plated

Further water rinse is required to wash off treatment chemical

PROCESSING WASTES-Precipitation by Integrated treatment-

Advantages :

Water can practically reused

Metals are not precipitated in a mixture – can be recovered

However, sometimes difficult to adapt system to existing plating lines – require extra tank in line

PROCESSING WASTES-Precipitation by Integrated treatment-

Once metals precipitated from solution – liquid & solid phases must be separated

2 Methods of settlement:

1. Small installation

circulate or rectangular tank installation

effluent flow <25 m3/day

convenient to carry on batch basis

settlement can take place in same tanks as that used for reaction (e.g., SBR)

PROCESSING WASTES-Settlement for Solid Liquid separation-

2. Larger installation

–continuous flow system

Size of tanks – depend on maximum effluent flow rate & configuration adopted for tank

Common type – vertical upward flow pattern having a central feed well, peripheral collection launder, & sludge cone at the bottom

Clarification – enhanced by flocculating agents\

Size & mode of operation of precipitation system – affects quality of effluent - But, typical figures for well-designed, efficiently operated, settlement system for metal hydroxide precipitates – range 10 – 30 mg/l ss

PROCESSING WASTES-Settlement for Solid Liquid separation-

alternative to settlement

Process - consists in the carrying of metal hydroxides & other particles in suspension to surface of liquid in flotation vessel by increasing particles buoyancy using bubbles which adhere to the particles

Scum containing gas – bubbles

Separated solids – skimmed off

PROCESSING WASTES-Flotation for Solid Liquid separation-

Variations in process – in method of producing carrier gas bubbles

May be done by :

a) Injecting a super-saturated solution of air in water under pressure into tank (dissolved air flotation) or

b) By injecting air through diffuser (dispersed air flotation) or

c) By electrolysis of water to yield fine bubbles of H2 & O2 (electrolytic

flotation)

gas bubbles produced – extremely small (70-150 m)

PROCESSING WASTES-Flotation for Solid Liquid separation-

Use of direct filtration – for phase separation

Seldom appropriate – filter media tends to blind (e.g. clog) rapidly – due to gelatinous nature of metal hydroxide precipitates

Where more granular precipitate is obtained – direct filtration satisfied & high quality effluent can be obtained

PROCESSING WASTES-Filtration for Solid Liquid separation-

OTHER SEPARATION TECHNIQUESOTHER SEPARATION TECHNIQUES1.1. Ion ExchangeIon Exchange

2.2. EvaporationEvaporation

3.3. Molecular filtrationMolecular filtration

4.4. Solvent ExtractionSolvent Extraction

5.5. ElectrodialysisElectrodialysis

Flash mixingFlocculation

Sedimentation Filtration

Carbontreatedwater

GACadsorbers

Sump

Sludge

Rawwater

to remove dissolved ionic species from contaminated aqueous streams

Treatment for both anionic & cationic contaminants

Ion exchangers – insoluble high-molecular weight polyelectrolytes that have fixed ionic groups attached to a solid matrix

Types of ion exchangers:

1. Natural

2. Synthetics- widely used due to greater stability, higher exchange capacity & greater homogeneity

Resins used: polymeric materials that have chemically treated to render them insoluble, & to exhibit ion exchange capacity

ION EXCHANGE SEPARATION

Often in form of spherical resin beads; membranes also available

Most common synthetic ion-exchange materials:

1. copolymers of styrene

2. divinylbenzene (dvb)

ION EXCHANGE SEPARATION

Treatedwater

Influent Influent

InfluentTreatedwater

Treatedwater

Carbon out

Carbon in

Paralleloperation

Seriesoperation

Moving(pulsed)

bed

High contaminant removalLong column runsSmall systems

Moderate removalsLarge systems

To concentration of aqueous solution

use only where effluent contains high concentration of valuable material

One application – on concentration of static rinses (drag out) from electroplating operations, especially chromium plating

Method: rinse liquor is evaporated to metal concentration which makes concentrate suitable for direct reuse in plating bath

EVAPORATION

MOLECULAR FILTRATION

2 categories:

1. ultrafiltration (UF)

2. reverse osmosis (RO)

Differentiating characteristic – molecular weight cutoff of membrane & corresponding pressure differentials required to achieve a given membrane flux

MOLECULAR FILTRATION

DifferencesDifferences RORO UFUF

1. Molecular cutoff limit1. Molecular cutoff limit 100-200 Da100-200 Da 2000-1000000 Da2000-1000000 Da

RO membranes will retain most organic materials as well as many of inorganic RO membranes will retain most organic materials as well as many of inorganic solutessolutes

2. Pressure differential2. Pressure differentialwith trans-membranes with trans-membranes

up to 500 psiup to 500 psias high as 50 psias high as 50 psi

Significant economic implicationSignificant economic implication

MOLECULAR FILTRATION Often when RO is used, upstream UF is provided as pre-treatment

Main operational problem – chemical & biological fouling of membrane (particularly with RO – membrane deterioration)

RO process – used on effluents from electroplating in electronic components industry

Continuous development of process & improved mechanical strength of membranes – increase range of applications

SOLVENT EXTRACTION In general, solvents used are too expensive to be used just once, & contaminants

are highly concentrated in the extract

Thus, spent solvent from liquid-liquid extraction operations needs further treatment – to reclaim solvent for reuse & to reduce further volume containing contaminants

Some solvent re-purification sequences include the use of distillation or adsorption

ELECTRODIALYSIS

Can remove dissolved inorganics (mineral content of wastewater)

When inorganic salt dissolved in water solution, it ionizes to produce positive charge cations & negative charge anions

When electrical potential passed through solution, cations migrate to negative electrode & anions to positive electrode

Commercial semi-permeable membranes – allow passage of ions of only one charge:

1. Cation-exchange membranes – permeable only to positive ions

2. Anion-exchange membranes – permeable only to negative ions

Different Types of Innovative Remediation Technologies

BIOLOGICAL METHODS

For organic waste

Most popular

Either aerobic or anaerobic

Anaerobic - popular for treating high strength industrial wastes

BIOLOGICAL TREATMENT

Further treatment : biological

Key to successful – adaptation of microbes to the presence of toxin

Bacteria & protozoa – can acclimatize & great adaptability in degrading new synthetic organic & toxic compounds

BIOLOGICAL TREATMENT BIOLOGICAL PROCESSES FOR TREATING

TOXIC WASTEWATERS

PROCESSESPROCESSESREACTOR REACTOR

TYPETYPEADVANTAGES & DISADVANTAGESADVANTAGES & DISADVANTAGES

AEROBICAEROBICDISPERSED DISPERSED GROWTHGROWTH

Tend to be completely mixed, therefore dilutes toxin but affects Tend to be completely mixed, therefore dilutes toxin but affects whole biomass. Liable to cause settling problems as well as whole biomass. Liable to cause settling problems as well as interfere with oxidationinterfere with oxidation

AEROBICAEROBIC FIXED FILMFIXED FILMTend to be plug flow so no dilution unless recirculation is used. Tend to be plug flow so no dilution unless recirculation is used. Biomass more robust for shock loads but metazoa more sensitiveBiomass more robust for shock loads but metazoa more sensitive

ANAEROBICANAEROBICDISPERSED DISPERSED GROWTHGROWTH

Tend to be completely mixed and suffer from washout of Tend to be completely mixed and suffer from washout of methanogens. The latter are also more sensitive than acidogens to methanogens. The latter are also more sensitive than acidogens to toxic effects and have a low growth ratetoxic effects and have a low growth rate

ANAEROBICANAEROBIC FIXED FILMFIXED FILMTend to be plug flow but level of attachment not as good as Tend to be plug flow but level of attachment not as good as aerobic filters. Need recirculation to dilute toxinsaerobic filters. Need recirculation to dilute toxins

BIOLOGICAL TREATMENT

TOXIC LEVELS IN AEROBIC BIOLOGICAL TREATMENT

TOXINTOXIN SIGNIFICANT LEVELSIGNIFICANT LEVEL

HYDROGEN IONSHYDROGEN IONS pH < 6 or > 9pH < 6 or > 9

PHENOLSPHENOLS 50 – 100 mg/L50 – 100 mg/L

AMMONICAL-NAMMONICAL-N 500 – 1000 mg/L500 – 1000 mg/L

ZINCZINC 10 – 50 mg/L10 – 50 mg/L

CHROMIUMCHROMIUM 5 – 20 mg/L5 – 20 mg/L

LEADLEAD 5 – 30 mg/L5 – 30 mg/L

ALKYL BENZENE SULFONATESALKYL BENZENE SULFONATES 3 – 20 mg/L3 – 20 mg/L

SULFIDESSULFIDES 5 – 50 mg/L5 – 50 mg/L

BIOLOGICAL TREATMENT TOXIC EFFECTS IN ANAEROBIC TREATMENT

TOXINTOXIN INHIBITORY CONCENTRATION (mg/L)INHIBITORY CONCENTRATION (mg/L)

IN SEWAGEIN SEWAGE IN SLUDGEIN SLUDGE

CHROMIUMCHROMIUM -- 22

CADMIUMCADMIUM 22 22

COPPERCOPPER 1.51.5 --

IRONIRON 10 10 --

LEADLEAD 100100 --

NICKELNICKEL 80 80 --

ZINCZINC 5050 --

DETERGENTDETERGENT -- 2% OF SS2% OF SS

BENZENEBENZENE -- 50 – 20050 – 200

CARBON TETRACHLORIDECARBON TETRACHLORIDE -- 1010

CHLOROFORMCHLOROFORM -- 0.10.1

DICHLOROPHENDICHLOROPHEN 11 --

γγ-BHC-BHC -- 4848

TOLUENETOLUENE -- 430 - 860430 - 860

Industrial Waste Industrial Waste Disposal Disposal

DISPOSAL OF TOXIC WASTES

Proper disposal to prevent any short or long term hazard to man & environment

Some require treatment prior to disposal (e.g., hazardous)

Methods:

1. Incineration

2. To land

3. To Sea

4. Solidification (radioactive waste)

IncineratorIncinerator

-Incineration- Reduces waste to solid residues, gases, and water vapor Process reduces waste volume by 80–90% Solid residues need further disposal (landfilling) Emissions have to be closely monitored and controlled Economic considerations

Incineration costs about $125,000 per ton (cost is affected by plant capacity)

Typical plant capacity is about 1,000 tons per day

Disadvantages:

Require ‘care’ when deal with halogenated materials – irritant corrosive gases may produce

Also a danger to treatment plant – become too complex

Serious problem on toxic wastewater – metallic wastes & radioactive wastes due to characteristics of:

Contain hazardous elements that cannot be broken down

Appear to be less toxic substances that can replace them

DISPOSAL OF TOXIC WASTES-Incineration-

Where wastewaters contain human toxins – require great care to avoid contaminate groundwater

DISPOSAL OF TOXIC WASTES-To Land-

For less hazardous wastes – lagoon; may have connection with watercourse but also permits infiltration (+ some evaporation & possibly some degradation)

Long term – swelling & blinding of soil may reduce infiltration capacity

More hazardous – land disposal policy : segregation followed by long term containment of hazardous material in impervious disposal sites

TREATMENT OF HAZARDOUS WASTESTREATMENT OF HAZARDOUS WASTES

Secure landfill – instead of one impervious liner, require multiple liners & must be stabilized or in containers

Similar to sanitary landfill – leachate is collected & a cap is placed on landfill once completed

Require continued care; EPA require 30 years monitoring

unlimited capacity for dilution & infinite retention time

Capable of diluting acute toxins below toxic threshold but problems may arise with substances that accumulate due to geochemical or biochemical mechanisms

Further complication – international aspect; may transport around the world

DISPOSAL OF TOXIC WASTES-To Sea-

Common practice:

I. Discharge by pipeline to inshore waters

o Dispersion in buoyant jet can give adequate initial dilution

o But, inshore areas sensitive to pollution; being used as shellfisheries & recreational zones

DISPOSAL OF TOXIC WASTES-To Sea-

II. Deep sea disposal

o Several international agreements - volume of hazardous disposal has declined & nature of waste has changed

o Organohalogens, carcinogenic substances, Hg & Cd compounds, & plastics – banned

o Less hazardous material – still takes place but in packaged form & only in deep sea

DISPOSAL OF TOXIC WASTES-To Sea-

DISPOSAL OF TOXIC WASTES -Solidification-

make some hazardous wastes suitable for disposal (e.g., oily wastes, sludges contaminated with pcbs & fly ash contaminated with heavy metals)

reduce mobility of hazardous constituents by binding them into solid matrix (low permeability – leach resistance)

Binding mechanisms – depend on agent employed (typical: cement based, possolanic or silicate based, thermoplastic based or organic polymer based

Cheaper agents widely used – cement, asphalt & pozzolanic-based

Promising result in short term tests

Longer term – less certain except for vitrification

Technique – only financially possible for nuclear waste

Disadvantages are cost and irreversible

DISPOSAL OF TOXIC WASTES -Solidification-

Industrial waste Industrial waste ManagementManagement

HAZARDOUS WASTE HAZARDOUS WASTE MANAGEMENTMANAGEMENT

50%Hazardous waste

7%Solid waste

7%Air quality

36%Water quality

(wastewater/water supply) 1998

Share of Environmental ConsultingShare of Environmental Consulting

Industrial Waste Industrial Waste Management HierarchyManagement Hierarchy

1.1. Waste minimizationWaste minimization Waste auditWaste audit Waste reductionWaste reduction

2.2. Waste ExchangeWaste Exchange

3.3. RecyclingRecycling

Source reductionSource reduction

Waste audit (after step 4.)Waste audit (after step 4.)

Waste exchangeWaste exchange

RecyclingRecycling

TreatmentTreatment

1. Waste minimization1. Waste minimization

11stst strategy is to perform waste audit strategy is to perform waste audit Waste audit steps:Waste audit steps:

1.1. Identify waste streamIdentify waste stream

2.2. Identify sourcesIdentify sources

3.3. Establish priority of waste streams for Establish priority of waste streams for minimizationminimization

4.4. ImplementImplement

5.5. TrackTrack

6.6. Evaluate progress Evaluate progress

1. WASTE MINIMISATION

Strategies to minimize as far as possible the types, quantities & concentration of any toxic wastes discharged through good housekeeping:

extending the life of process solutions by filtration, topping up, adsorption

Altering the production process to use less toxic compounds, e.g. Substituting copper pyrophosphate for copper cyanide in electroplating solutions

Dry cleaning prior to wash-down, which remove a large proportion of the pollutant in solid form

1. WASTE MINIMISATIONAttempt to minimize (cont.):

Evaporation of strong organic liquors, which can often produce a burnable product

Minimizing & segregating any flows which contain toxic material.

separate wastes for safety reasons, e.g. Cyanides or sulfides & acid wastes, trichloroethylene (TCE) & alkaline wastes

to segregate for treatment reasons, but segregation can be very expensive

Options of Industrial Options of Industrial waste Managementwaste Management

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