ce3503 environmental engineering
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CE3503 Environmental Engineering. Wastewater Treatment. Dr. Martin T. Auer MTU Department of Civil & Environmental Engineering. The Clean Water Act. ‘fishable-swimmable’. yes. Technology-Based Standards. no. yes. Water Quality-Based Standards. T otal M aximum D aily L oads. - PowerPoint PPT PresentationTRANSCRIPT
Dr. Martin T. AuerMTU Department of Civil & Environmental Engineering
Wastewater Treatment
The Clean Water ActThe Clean Water Act
‘fishable-swimmable’
Total Maximum Daily Loads
Technology-Based Standards
Water Quality-Based Standards
Discharge Permits (NPDES)
yes
noyes
POTW DesignPOTW Design
Federal Water Pollution Control Act Amendments of 1972 (The Clean Water Act)
• Technology-based effluent limits
• Water quality-based effluent limits
• Total Maximum Daily Loads (TMDLs)
• National Pollutant Discharge Elimination System (NPDES)
Add Clark
In A Watershed – Everyone Lives Downstream
ReceivingWaterImpacts
River DO ModelQ = 8C = 0, 250, 100
MichiganNPDESPermit
TreatmentPlantDesign
Design ModelCin = 250
k = 0.1V = 0, 250, 750
Aluminum Forming Battery Manufacturing;Cement Manufacturing; Coil Coating & Can Making;Copper Forming; Dairy Products Processing; Electrical & Electronic Component Manufacturing;Electroplating & Metal Finishing; Explosives Manufacturing; Fruit & Vegetable Processing; Ferroalloy Manufacturing; Fertilizer Manufacturing; Glass Manufacturing; Gum & Wood Chemicals Manufacturing;Ink Formulating; Inorganic Chemical Manufacturing;Iron & Steel Manufacturing; Leather Tanning & Finishing; Meat Products Processing; Metal Molding & Casting; Mining Operations; Nonferrous Metals Processing; Organic Chemicals, Plastic & Synthetic Fibers Manufacturing;Paving & Roofing Materials Manufacturing;Soap & Detergent Manufacturing; Petroleum Refining; Pesticide Manufacturing; Porcelain Enameling; Pharmaceutical Manufacturing; Plastic Molding & Forming; Pulp, Paper and Paperboard ManufacturingTimber Products Processing; Textile Mills
Federally-Regulated Non-Domestic Sources
http://www.socwa.com/indwaste.htm
Chemicals Designated as Priority Pollutants (126)
• AROCLOR 1254 (industrial product; banned)• BENZENE (industrial product)• BENZO(A)PYRENE (asphalt roofing manufacture)• CADMIUM (heavy metal; electric/gas industries)• CHLORDANE (pesticide; banned or restricted)• CHROMIUM (heavy metal; widely used in industry)• DDT (pesticide; banned or restricted)• ENDRIN (pesticide; banned or restricted)• MERCURY (heavy metal; electric/gas and chemical industries)• PENTACHLOROPHENOL (industrial chemical – wood products)• TOLUENE (widely used industrial chemical)• TRICHLOROETHYLENE (industrial solvent, degreaser)
http://www.scorecard.org/chemical-groups/one-list.tcl?short_list_name=pp
What’s in wastewater?
Waste
human feces and urine food from sinks soaps and other cleaning agents runoff from streets and lawns industrial discharges
What’s in wastewater?
Water
lots of it! Urinal - 1 gallon per flush Toilet - 4 gallons per flush Shower - 20 gallons per use Overall - 55 gal/person/day
It’s mostly water!
There are about 500 parts of waste in every 1 million parts of wastewater; that’s500 ppm.
It’s like trying to find this class at a sold out Packers game!
H2O
So what’s the problem?
P SNOT: it’s not a pretty picture!
Pollutant Problem Pathogens Disease Solids Aesthetics Nutrients Algae Organics Oxygen Toxics Wildlife
Solids
Composition of Domestic Wastewater
Constituent Influent Effluent
Suspended Solids 200-300 30
BOD5 200-400 30
Ammonia Nitrogen 20-40 1-2
Phosphorus 7-10 1
Fecal Coliforms 104-106 200
All concentrations are mg/L, except fecal coliformswhich are colony forming units (cfu) per 100 mL.
Where does it go when you flush the toilet?
This is really not something I’ve given a lot of thought to.
Collection Systems
Portage Lake Sewer System
HancockHoughton
Franklin Sq.
Super 8
MTU
M&M Bldg.
POTW
PP
G
G
G
G
P
Surface; 30”
10’;36”
Lake; 48”
20’; 48”
Near Surface; 30”
Metcalf & Eddy
Diurnal Variation in Wastewater Flow
Metcalf & Eddy
Wet-Dry Variation in Wastewater Flow
Preliminary Treatment Overview(plant protection)
Bar Rack or Screen or Comminutor
Grit Chamber
Flow Equalization
from pumps or wet well
to primary treatment
Preliminary Treatment: Bar Rack
Preliminary Treatment: Screen
ComminutorPreliminary Treatment: C
Preliminary Treatment: Grit Chamber
Preliminary Treatment: Flow Equalization
The Henry Fork Wastewater Treatment Facility, Hickory, NChttp://www.hickorync.gov/egov/docs/1222790452442.htm
Bar Rack or Screen or Comminutor
Grit Chamber
Flow Equalization
from pumps or wet well
to primary treatment
Preliminary Treatment Overview(plant protection)
(Kiely, 1997)
Primary Treatment(solids, sedimentation)
Primary Treatment – Design
In Out
vp
The critical particle is defined as that particle will be captured prior to exiting the sedimentation tank. This particle, and all particles which settle more rapidly, will be retained.
The critical settling velocity, vc, is that of the critical particle.
0c
hv
Primary Treatment – Design
The design parameter for primary treatment is the surface overflow rate,
which can be shown to be equivalent to the critical settling velocity,
0c
hv
QSORA
3
3
22
md
mm m
m d d
In Out
0 0 0
0c
h h Q h Q Qv SORV h A A
Primary Treatment – Design
In Out
Vc, SOR
vp1
The design objective then is to reduce vc (SOR) in order to capture the target particle.
vp2
The steeper the slope,the higher the settling velocity
0 0 0
0c Sh h Q hv Q
VOQ
h A AR
Primary Treatment – Design
In Out
vc
vp2
vp1
This is accomplished by manipulating the tank residence time () by changing the surface area (A),
0 0 0
0c
h h Q h Q Qv SOV A A
Rh
The steeper the slope,the higher the settling velocity
(Kiely, 1997)
Primary Treatment – Design
Primary Treatment: Rectangular Clarifier
Primary Treatment – Circular Clarifier
Secondary Treatment(biological)
Simple carbohydrates (a form of organic matter) are produced by plants through the process of photosynthesis. These are then converted to more complex carbohydrates and other forms of organic matter such as starches, fats and proteins.
The sun’s energy, captured during photosynthesis, is stored in the chemical bonds of this organic matter.
2 2 22( )CO H O OC H O
Organisms (from bacteria to humans) take up and metabolize organic matter to obtain the energy required to support life.
In secondary or biological treatment, we utilize microorganisms to remove the dissolved and small particulate organic matter which would exert an oxygen demand if it were released to the environment. The waste (actually organic matter) is simply converted into another form (microorganisms) which can then be separated from the waste stream by settling yielding a clean effluent.
microbe2
s2 2 2( )C OO O OH C H
The Microbial Loop in Nature
Microorganisms in Secondary or Biological Treatment
Source: http://www.college.ucla.edu/webproject/micro7/studentprojects7/Rader/asludge2.htm
The Microbial Loop in Secondary Treatment
Secondary Treatment: Trickling Filter
Secondary Treatment: Trickling Filter Media
Image Source: Wastewater Engineering, Metcalf & Eddy
Secondary Treatment: Trickling Filter Design
Hydraulic Load (Wh)4-10 m3m-2d-1
Organic Load240-480 gBODm3d-1
hydhyd
AQ QWWA
0 0org
org
Q S Q S VW VV W
AH
Secondary Treatment: Rotating Biological Disks
Secondary Treatment: Activated Sludge
Activated Sludge: aeration (mechanical)
Activated Sludge: aeration (diffuser)
Activated Sludge Design: microorganism growth rate
In the aeration tank, microorganisms take up food (soluble and particulate BOD) and grow, converting waste to microorganisms.
Since the concentration of microorganisms in the aeration take is held constant, the ‘growth’ must be removed or wasted.
The rate of sludge wasting (dX/dt) divided by the mass of sludge in the aeration tank is equal to the microorganism growth rate,
/wdX dtX
Activated Sludge Design: relation to BOD concentration
Gro
wth
Rat
e (
)
Food (BOD)
As the steady state food concentration in the aeration tank increases, the growth rate increases.
High Low
Activated Sludge Design: growth phases
High BODPoor settling
Low BODGood settling
Activated Sludge Design: solids retention time
/wdX dtX
The solids retention time (SRT) or sludge age is defined as the average time that a microorganism spends in the aeration tank and is equal to the inverse of the growth rate,
1/w
XSRTdX dt
Thus, the longer the SRT, the lower the growth rate, the lower the effluent BOD and the better the settling characteristics of the sludge.
The design should seek to operate toward the upper end of the range of SRT values (2-20 days) to achieve the best removal.
Activated Sludge Design: food:microorganism ratio
0 0/ S QF M
X V
The solids retention time or sludge age varies with the rate at which the microorganisms are fed, i.e. the food:microorganism ratio,
Low F/M ratios equate to high SRTs and generate the desired effluent characteristics (low BOD, good settling).
Since S0 and Q0 are fixed and X must be maintained between some bounds, the design parameter becomes V, the volume of the aeration tank.
Note, however, that there are practical limits on the volume of the aeration tank, requiring consideration of less ‘optimal’ treatment.
3
3
33
gBOD mgBODm d
gMLSS gMLSS dmm
(From Kiely, 1997)
EndogenousGrowth
LogGrowth
DecliningGrowth
/wd tXS
XRT
d
Activated Sludge: design and operation
0 0/ SX V
QF M
Design Operation
Activated Sludge: Plug Flow Configurations
(From M&E)
Plug Flow (Conventional)
Activated Sludge: Plug Flow Configurations
(From M&E)
Activated Sludge: Plug Flow Configurations
(From M&E)
Activated Sludge: Completely Mixed Flow Configurations
(From M&E)
Activated Sludge: Completely Mixed Flow Configurations
(From M&E)
Secondary Clarifier
Disinfection (UV light)
Portage Lake Wastewater Treatment Plant
LiftStation
BarScreens
GritChamber
FlowEqualization
1°Clarifier
1°Clarifier
2°Clarifier
2°Clarifier
AerationTank
UVDisinfection
1st StageAnaerobicDigester
2nd StageAnaerobicDigester
LandApplication
SludgeStorage
FilterPress
Recycle
Supernatant
RAS
RAS
WAS
1°S
Polymer A
dded
Feadded
Feadded
Portage Lake Wastewater Treatment Plant
LiftStation
BarScreens
GritChamber
FlowEqualization
1°Clarifier
1°Clarifier
2°Clarifier
2°Clarifier
AerationTank
UVDisinfection
1st StageAnaerobicDigester
2nd StageAnaerobicDigester
LandApplication
SludgeStorage
FilterPress
Recycle
Supernatant
RAS
RAS
WAS
1°S
Polymer A
dded
Feadded
Feadded
putrid: in a state of foul decay, as animal or vegetable matter
putrescible: liable to become putrid
Putrescible
Anaerobic Digestion: Biochemistry
Anaerobic Digestion: Reactors
Sludge Drying Beds
Belt Filter
Centrifuge
Multiple Hearth Furnace
Land Application
The Madison Metropolitan Sewerage District provides wastewater treatment to villages towns and cities surrounding the Madison area lakes. Biosolids produced at the MMSD Nine Springs Wastewater Treatment Plant are recycled to agricultural land as a fertilizer and soil conditioner. Biosolids recycling practices are regulated by both USEPA and Wisconsin DNR to ensure that human and animal health are protected.
http://www.madsewer.org/EMS-start-3.htmhttp://www.stdnet.com/company/?category_number=4&subcategory_number=3
Recycling
The Milwaukee Metropolitan Sewerage District has been marketing its biosolids as Milorganite, a fertilizer and soil conditioner, for over 80 years. Today, 55,000 tons of Milorganite are sold annually. Milorganite is produced by place dewatered sludge cake in massive dryers with a temperature gradient of 800-1200 °F at the inlet and 180-210 °F at the outlet. This effectively inactivates viral and bacterial pathogens.
http://members.cox.net/matthewhill_agrilawn/agrilawn1.htmhttp://www.lowes.com/lowes/lkn?action=productDetail&productId=97821-1321-97821&lpage=none
http://www.biosolids.org/docs/source/MilWI.pdf
Portage Lake Wastewater Treatment Plant
LiftStation
BarScreens
GritChamber
FlowEqualization
1°Clarifier
1°Clarifier
2°Clarifier
2°Clarifier
AerationTank
UVDisinfection
1st StageAnaerobicDigester
2nd StageAnaerobicDigester
LandApplication
SludgeStorage
FilterPress
Recycle
Supernatant
RAS
RAS
WAS
1°S
Polymer A
dded
Feadded
Feadded
Portage Lake Wastewater Treatment Plant
LiftStation
BarScreens
GritChamber
FlowEqualization
1°Clarifier
1°Clarifier
2°Clarifier
2°Clarifier
AerationTank
UVDisinfection
1st StageAnaerobicDigester
2nd StageAnaerobicDigester
LandApplication
SludgeStorage
FilterPress
Recycle
Supernatant
RAS
RAS
WAS
1°S
Polymer A
dded
Feadded
Feadded
Lagoons or Oxidation Ponds
Septic Tanks
Septic Tanks