Environmental Advances (Apr 2022)
Bacterial consortium based petrochemical wastewater treatment: from strain isolation to industrial effluent treatment
Abstract
Petrochemical wastewater poses environmental challenge globally due to the presence of multi-pollutants which are predominantly refractory in nature. Thirty-one indigenous bacterial strains belonging to Firmicutes and Proteobacteria were isolated from the wastewater of an effluent treatment plant (ETP) of a large liquid petrochemical cargo terminal located in Vishakhapatnam, India. Based on polyphasic taxonomy, 16S rDNA sequencing and phylogeny, it was found that many of the isolates were represented by petroleum hydrocarbon degrading taxa including Vibrio, Staphylococcus, Aerococcus, Acinetobacter and Exiguobacterium and some of them are potentially new species. Besides, majority of them exhibited metabolic ability to produce key enzymes linked to hydrocarbon degradation such as amylase, protease and lipase producers. Out of 31 isolates, 14 isolates showed growth in presence of toluene as the sole carbon source and most of these isolates were represented by the genus Bacillus. The bacterial isolates formed the basis of a consortium represented by 1:1 proportion and exhibited ability to reduce biological oxygen demand of the petrochemical wastewater by 88% under immobilized condition in laboratory. Response surface methodology-based optimization revealed a reduction of 93.33% biological oxygen demand within 12 h from simulated wastewater at 37°C which had a starting concentration of 400 mg L−1 of toluene. Upon scale-up from 5 L to 12 m3 per day processing capacity, approximately 92% removal of biological oxygen demand could be achieved within 18 to 20 h at the ambient condition in two moving bed biofilm reactors combined in series. The treated water attained discharge level as per the norms of Environmental Protection Agency. The bacterial biofilm that made up the consortium was found to be robust for all the pollutants handled at the ETP and also performed efficiently over the years. The technology could be developed into a sludge free system and thus can produce clear and dischargeable- grade treated water. The treated water could be recovered for reuse in land irrigation and firefighting and overall can lead to significant improvement of ecosystems.
