An introduction to Pollution control

WATER POLLUTION CONTROL CIVL270-Maraqa Wells Water distribution system Industry Stream Lake or Sea WTP Storage Tank Characteristics Treatment processes Drinking water Standards Sanitary sewer Pretreatment Characteristics Homes WWTP Treatment processes Reuse or discharge Standards Fujairah WTP CIVL270-Maraqa Al Owair WWTP US Primary Drinking Water MCL in mg/L (partial list) Inorganic Chemicals Arsenic 0.05 Mercury 0.002 Barium Nickel 0.1 Cadmium 0.005 Nitrate (as N) 10 Chromium (total) 0.1 Nitrite (as N) Copper TT Nitrate + nitrite 10 Fluoride Selenium 0.05 Lead TT Thallium 0.002 Asbestos 7×106 fiber /L VOCs Benzene 0.005 Ethylbenzene 0.7 Vinyl chloride 0.002 Carbon tetrachloride 0.005 CIVL270-Maraqa Bacteriological limits US EPA states that “bacterial quality criteria for drinking water from public supplies require not more than total-coliform/100 ml as the arithmetic mean of all water samples examined per month, with no more than coliforms/100 ml in any sample if the number of samples is ≤ 20/month, or no more than per 100 ml in 5% of the samples if the number of samples exceeds 20 per month Bouwer, Groundwater Hydrology, McGraw-Hill, 1978 Number of samples taken for coliform testing depends on the population served by the treatment facility CIVL270-Maraqa Population served Number of samples/month [...]... blockages and abrasive, wear on machinery and pipe works CIVL270-Maraqa Aeration Tanks Incoming sewage, “seeded” with active organisms, passed through tanks with surface aerators to provide oxygen for the degradation process and to ensure mixing that would maintain sewage and organisms in suspension Settling Tanks After the aeration process the activated sludge is allowed to settle, leaving an effluent... than 30 PPM of suspended solids CIVL270-Maraqa Return Activated Sludge: Some of the sludge from the settling tanks is returned to be mixed with incoming sewage to the aeration tanks, in order to seed active organisms into the process Aeration tank Settling tank To further processes Return sludge Sludge to digesters Filtration: After secondary settling, treated wastewater passes through sand filters to. .. BOD and 90% SS CIVL270-Maraqa Advanced Treatment May include: Activated carbon to remove organic contaminants Filter to capture suspended solids Nitrate removal CIVL270-Maraqa Zakher Wastewater Treatment Plant CIVL270-Maraqa Design capacity 54,000 m3/day CIVL270-Maraqa Screening Remove large solids and rags that cause problems if passed through the plant Grit Removal Remove 95% of grit and stones,... Chamber Screens Disinfectant Primary Settling tank Contact tank Effluent Primary treatment removes about 35% BOD and 60% SS CIVL270-Maraqa Secondary Treatment Disinfectant Secondary Wastewater after primary settling Biological treatment Settling tank Contact tank Effluent Biological treatment can be done by one of the following methods: Activated sludge Rotating biological contactors Trickling filters... suspended solids to about 10 ppm CIVL270-Maraqa Disinfection Chlorine gas is injected into the final effluent before the effluent is being reused Residual chlorine content of 1 ppm is the desired final concentration Overall treatment efficiency  BOD removal =98%  TSS removal =99% Treated effluent is pumped into an elevated tower about 12 km away from the works The tower supplies the roundabout and roadside...Disinfection Objective: To inactivate pathogens Methods Chlorine Chloromines Ozone UV CIVL270-Maraqa Common worldwide Common in Europe Wastewater Treatment System Treated Raw wastewater wastewater CIVL270-Maraqa Characteristics of Domestic Wastewater Constituent Concentration, mg/L BOD5 100-300 COD 250-1000 TDS 200-1000 Suspended solids 100-350 Total nitrogen 20-80 Total phophorous 5-20 CIVL270-Maraqa... treatment efficiency  BOD removal =98%  TSS removal =99% Treated effluent is pumped into an elevated tower about 12 km away from the works The tower supplies the roundabout and roadside irrigation networks and is also used for irrigation of parks CIVL270-Maraqa