title: Effect of organic shock loads on a two-stage activated sludge-biofilm reactor.
abstract: The effects of short-term organic shock loads on the performance of a laboratory scale two-stage activated sludge (AS)-biofilm reactor working at 6 h HRT and treating medium strength domestic wastewater was studied by increasing the influent chemical oxygen demand (COD) to 2-4 times the normal values. Each shock load was applied for a period of 6 h, after which normal loading conditions were resumed. The maximum effluent COD concentration obtained was 169, 169, 250 and 617 mg/L under the shock loads of 808, 1170, 1358 and 1900 mg COD/L, respectively. The COD removal rate increased with increasing effective OLR. The system recovered quickly from shock loads; recovery time proportional to the magnitude of shock loads. The optimum loading rate of the reactor was found at effective OLR of 170 mg COD/m(3)/h. Shock loads changed the dominant bacterial type in the reactor from Gram-positive rods to Gram-negative oval shaped bacteria.
authors.affiliation: Department of Civil Engineering, Indian Institute of Technology Roorkee, Roorkee 247 667, India. seetha_183@yahoo.co.in
authors.forename: N
authors.initials: N
authors.lastname: Seetha
authors.forename: Renu
authors.initials: R
authors.lastname: Bhargava
authors.forename: Pramod
authors.initials: P
authors.lastname: Kumar
mesh_terms: D001419:Bacteria / Q000187:drug effects / Q000378:metabolism; D001673:Biodegradation, Environmental / Q000187:drug effects; D018441:Biofilms / Q000187:drug effects*; D018533:Biomass; D019149:Bioreactors / Q000382:microbiology*; D007700:Kinetics; D009930:Organic Chemicals / Q000494:pharmacology*; D010100:Oxygen / Q000032:analysis; D012722:Sewage / Q000382:microbiology*; D013997:Time Factors; D014865:Waste Disposal, Fluid
chemical_list: D009930:Organic Chemicals; D012722:Sewage; D010100:Oxygen