Removal of organic carbon, nitrogen and phosphorus in sequential batch reactors integrating the aerobic/anaerobic processes

Abstract

The performance of a bench-scale apparatus composed of two sequential batch reactors (SBR), forming an anaerobic/aerobic treatment system, was evaluated as to its potential use for biological removal of organic matter and nutrients. Both the reactors with 12.5 L of useful volume each were operated for the batch cycles of 12 hours receiving 8.0 L of substrate in each cycle. The first reactor (SBRAn) fed with synthetic substrate simulating domestic sewage was meant to remove the largest fraction of carbonic matter and to promote the substrate ammonification. The second reactor (SBRAe) was operated under alternating aerobic and anoxic conditions to establish conditions for achieving nitrification; denitrification and biological phosphate removal in the same batch cycle. Sodium acetate was used as an external carbon source for phosphate removal. Processes monitoring included the analyses of: COD, NTK-N, NH4(+)-N, NO2(-)-N, NO3(-)-N, PO4(3-)-P, alkalinity, volatile acids, pH, redox potential total, fixed and volatile solids. Under the operating conditions imposed, the system exhibited high performance in removing organic matter (COD), nitrogen and phosphorus, producing effluent with COD, NTK-N and PO4(3-)-P concentrations lower than 50.0 mg/L, 4.0 mg/L and 1.0 mg/L, respectively.

Post-Treatment Options for the Anaerobic Treatment of Domestic Wastewater

“…In studies developed by Callado and Foresti (2001), almost complete removal of COD, nitrogen and phosphorus were accomplished in anaerobic-aerobic systems composed of SBRs in series. Nitrification, denitrification and biological phosphorus removal may occur in the second SBR treating the effluent of the first anaerobic SBR supplemented with acetate, operating under aerobic-anoxic cycles.…”

Study of the aerobic biodegradation of coke wastewater in a two and three-step activated sludge process

“…Autotrophic 267 nitrifying microorganisms need to have a certain available alka-268 linity. With an average alkalinity value in the wastewater of 269 0.25 gCaCO 3 /L and for an initial NH 4 + -N concentration of 270 around 200 mg/L, the ratio kgCaCO 3 /kgNH 4 + -N is 1.25, a 271 clearly low value [10,17]. In a previous study, a value of 272 6.5 kgCaCO 3 /kgNH 4 + -N was found to be the optimum for 273 NH 4 + -N removal in this coke wastewater [9].…”

Evaluation of the microbial diversity of denitrifying bacteria in batch reactor

“…Callado & Foresti (2001) operated anaerobic reactors fed with synthetic substrate simulating domestic sewage to remove the largest fraction of carbonic matter and to promote the substrate nitrification, denitrification and biological phosphate removal in the same batch cycle, in a sequential anaerobic/aerobic/anaerobic batch reactor. The system was operated for 41 days with 84 cycles of 12 hours, at the temperature of 28±1 °C.…”

“…Etchebehere et al (2001) enumerated denitrifying cells by the most probable number (MPN) in a basal medium supplemented with yeast extract (0.5 g/L), potassium acetate (1.84 g/ L) and potassium nitrate (0.72 g/ L) and obtained 9,6 x 10 6 MPN/mL with sludge from the anoxic reactor of a leachate treating system. Callado and Foresti (2001) used sodium acetate as carbon source in a sequential anaerobic/ aerobic/anaerobic batch reactor and found more MPN denitrifying bacteria at the beginning of the operation (2.5 x 10 6 MPN/mL) than at the end (3.5 x 10 5 MPN/mL). The authors (op.cit.)…”