Sanitary Sewage Flashcards
Sanitary Sewage
wastewater from households, institute and commercial establishment
threat to human health
E.Coli-> monitored for using fecal coliform tests
A. Problems ass w Direct Release of Sanitary Sewage
1) Release of Disease-Causing Agents (virus…)
2) Eutrophication: +N, P in water -> increase in V of aquatic plants
D. I & II sludge
- Dewatering to decrease V
- Anaerobic digester to generate heat + kill bac
- Digested sludge to go Sheppard LF
- go to CALGRO to further process
- applied to agriculture land
CALGRO
- Biosolid-to-land Program started 1983 btw the city and province
- Beneficiaries: provides Local farmers w fertilizers from biosolids
- I & II sludge taken from WWTP converted to biosolids, taken to Shepard Lagoons and Sheppard landfill
Rules and Regs for biosolids
crop restrictions minimum N/P/ metal ratios max application rates agricultural Land pH requirements (6.5) seasonal restrictions on land application
septic tank & tile beds
h2o well shouid be upgradient
min distance 25-35m
design of septic tank
2 basic layers
- septic tank
- drainage field (Absorption field)
septic tank
undergrd tank, used to separate liquids from solids
anaerobic digestion
drainage field
consists of a series of perforated pipes located below the soil surface
release the WW contains Suspended organic, mineral matter
soil type for DF
k soil
good percolation of the ww thru soil
depth to water table
in unsaturated zone
lots of O2 available for digestion of WW
5m below the base of DF
Depth of the Bed rx
> 1.2 m below drainage field
topography
surface slope <150
shallow enough so WW doesn’t run quickly off-site
anaerobic digestion of the organics
produces CO2, CH4, NH4
tank leaks can release large V of pathogens into the soil
be careful of bleaches + drainage cleaners - destroy the anaerobic system
evolution of the waste stream
- anaerobic digestion of the organics
- aerobic oxidation of the organic matter and NH4
- anaerobic denitrification
aerobic oxidation of the OM and amonia
OM -> CO2(g) (oxidation)
NH4 -> NO3- + H+ -> by product + CaCO3 -> buffer the acids
anaerobic denitrification
rare
NO3 -> N2 (reduction)
contaminant Ass w Septic tank
CH4, NH4, CO2, trace meals
contaminant ass w DF
NO3-, Ca2+, CO2
aerobic spray system
3 tank system
- tank1: solids settle out
- tank2: air pumping to promote the aerobic digestion
- tank3: the water treated with chlorine
tank4: sprinkler system: discharge water onto surface
Sewage disposal options
Ocean dumping Landfilling Land application Incineration WWT facility
Municipal WWT facilities
Purpose: removal of SS & pathogens from water
Accomplished by: primary, secondary & tertiary treatments
Primary
Physical Remove Large particles Screen &gravitational settling tech Solid from screen -> LF Solid is primary sludge
Secondary
Biological
Remove suspended OM
Accomplished: trickling filter, activated sludge processes & BPNR bioreactors
Trickling filters
WW + aerated Rx bed + aerobic microbes = consumed OM
Activated Sludge Processes
Digested particles settle down @ bottom
Remove OM but dissolved contaminants N,P + Pathogens
BPNR bioreactor
3 steps process that utilizes anaerobic, anoxic & aerobic
Remove soluble N, P, OM
BPNR pros
Green solutions that used natural bacteria
Less sludge produced
BPNR cons
High skill level-worker
Expensive labs to monitor & analysis
Need a standby chem facility
Tertiary
Chemical
Removal of Dissolved minerals, heavy metals, pathogens
Accomplished: Cl2, UV disinfection, BPNR, chem removal of P
