Bioremediation of wastewater from automobile service station in anoxic-aerobic sequential reactors and microbial analysis

Abstract

Wastewater released from automobile service station was treated in anoxic (A1)-aerobic (A2) sequential reactor system to facilitate potential reuse of the treated wastewater. The collected wastewater consisted of phenol (37 ± 3 mg/L), hydrocarbons (475 ± 11 mg/L), COD (506 ± 12 mg/L), NH4+-N (170 ± 7 mg/L), NO3−-N (135 ± 6 mg/L), phosphate (20 ± 2 mg/L) and metals. Removals of phenol and hydrocarbons was more than 99% in A1 at 18 h HRT. Residual NH4+-N was oxidised in A2 with more than 99% efficiency at 6 h HRT. Effluent COD was within permissible limits and overall COD removal by the system was 94% at combined hydraulic retention time (HRT) of 24 h. Pseudomonas aeruginosaSKM2013 and Pseudomonas aeruginosaSC2013 were identified in anoxic biomass and were capable of degrading phenol and hydrocarbons by utilizing NO3−-N as electron acceptor. Lysinibacillus sp. H200-510, Stenotrophomonas sp. LW-34, Pseudomonas aeruginosaLZS8436 and Pseudomonas aeruginosaISB4 were identified in the aerobic biomass and the first three showed potential NH4+-N utilization.