Bioremediation of wastewater from automobile service station in anoxicaerobic sequential reactors and microbial analysis

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 aeruginosa SKM2013 and Pseudomonas aeruginosa SC2013 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 aeruginosa LZS8436 and Pseudomonas aeruginosa ISB4 were identified in the aerobic biomass and the first three showed potential NH4+-N utilization.