title: Treatment of high-strength pet food wastewater using two-stage membrane bioreactors.
abstract: A two-stage membrane bioreactor was used to treat dissolved-air-flotation pretreated, high-strength pet food wastewater characterized by oil and grease concentrations of 50 000 to 82 000 mg/L and total chemical oxygen demand (COD) and five-day biochemical oxygen demand (BOD5) concentrations of 100 000 and 80 000 mg/L, respectively, to meet stringent surface discharge criteria (i.e., BOD5, total suspended solids [TSS], and ammonium-nitrogen [NH4(+)-N] of < 10 mg/L at an overall hydraulic retention time of 6.3 days). Organic contaminants were removed primarily in the first stage, followed by almost complete removal of ammonia in the second stage. Despite a rise in poorly biodegradable COD in the second stage, overall removal of TSS, BOD5, COD, and ammonia was 100, 99.9, 95.2, and 99.7%, respectively, thus readily achieving the required criteria. Consistent nitrite accumulation over a period of more than 100 days, even at dissolved oxygen concentrations of more than 2.5 mg/L, was remarkable. A residual alkalinity requirement for nitrification was quantified. Membrane performance was extensively studied in this work.
authors.affiliation: Department of Chemical and Biochemical Engineering, University of Western Ontario, London, Canada.
authors.forename: C
authors.initials: C
authors.lastname: Acharya
authors.forename: G
authors.initials: G
authors.lastname: Nakhla
authors.forename: A
authors.initials: A
authors.lastname: Bassi
authors.forename: R
authors.initials: R
authors.lastname: Kurian
mesh_terms: D000821:Animal Feed; D000818:Animals; D000829:Animals, Domestic; D019149:Bioreactors; D008567:Membranes, Artificial; D009573:Nitrites / Q000378:metabolism; D010100:Oxygen / Q000378:metabolism; D014865:Waste Disposal, Fluid / Q000379:methods*; D018508:Water Purification
chemical_list: D008567:Membranes, Artificial; D009573:Nitrites; D010100:Oxygen