Effluent treatment…….

Effluent treatment…… The household sewage and the industrial waste contains organic and inorganic impurities, which can cause potential threat (POT) to plants, animals, or human beings. Generally effluent is discharged into the following water bodies which causes contamination . Can make groundwater unfit and soil infertile. Treatments aim to reduce BOD and COD.

Primary treatment…….. Aims at sedimentation of suspended organic particles. Sewage flows through large tanks(PRE- SETTLING BASINS OR PRIMARY CLARIFIERS). Here heavy solids settle to bottom while oil and grease and lighter solids float to surface. Settled and floating materials are removed Remaining liquid may be discharged or subjected to secondary treatment.

SECONDARY TREATMENT…. Removes dissolved and suspended biological matter. Relies upon m/o M/o mineralizes suspended organic matter and converts dissolved matter into suspended form. M/o used in form of biofilm or homogenously suspended .

Tertiary treatment…… provide a final treatment stage improve effluent quality before discharging to receiving environment. Treated water if disinfected called as EFFLUENT POLISHING. Waste water contains high levels of nutrients(N,P). Excessive release to environment lead to EUTROPHICATION (overgrowth of weeds, algae and cyanobacteria).

Nutrient = plants require them for growth Potential problems from nutrients: water quality aquatic ecosystem human & animal health

NITROGEN…… Biochemically inter convertable forms : organic N (proteins, urea) ammonia gas (NH3) ammonium ion (NH4+) nitrate (NO3) nitrite (NO2) elemental N2 gas (78% of air) Mobile (esp. nitrate) Limiting nutrient in salt waters

NITROGEN REMOVAL…… Two-step biological method Step 1: Aerobic Nitrification Ammonia to nitrate conversion m.o: Nitrosomonas Step 2: Anoxic-anaerobic De nitrification nitrate to N2 conversion requires carbon source m.o.: Pseudomonas Nitrogen gas is released to atmosphere and thus removed form water. Sludge is mixed by using SUBMERSIBLE MIXERS

PHOSPHORUS REMOVAL…… Forms: organic phosphorus orthophosphate (PO4) polyphosphates phosphorus-containing rocks Binds to soils and sediments Limiting nutrient in fresh waters

PHYSICAL-CHEMICAL REMOVAL.. Chemical precipitation (3 options) add alum (Al2SO4) to form aluminum phosphate add ferric chloride (FeCl3) add lime (CaO) Coagulation / flocculation Clarifier/settler

BIOLOGICAL REMOVAL…… Called as ENHANCED BOLOGICAL PHOSPHORUS REMOVAL. Poly phoshphate -accumulating organism(PAO) are used Enriched selectively Accumulate large quantities of P within their cells Biomass enriched with this has a fertilizer value.

Thanking you……….