Isolation and Characterization of Useful Microorganisms for Efficient Biological Treatment of Wastewaters and Their Application to Upscaled Processes

Abstract

With the population increase and industrial development, lots of industrial wastewater were generated. They were physically, chemically or biologically treated. Biological treatment of wastewater by microorganisms are less dangerous, and simpler than physicochemical reaction. In this study, we demonstrated characteristics of biological treatment of dyeing, leather and fish industry wastewater by newly isolated microorganisms in lab scale and pilot scale. Dyeing industry wastewater (DIW) has non-degradable high-colored compounds which was not able to be treated by conventional methods. In this study, 2 fungi (Ascomyteces and Basidiomycetes) newly isolated from influent and recycled water were used in the treatment of dyeing industry wastewater. Approximately 80% of chromaticity removal was shown in the dye-contained tube and flask scale experiment. In the affinity test between photosynthetic bacteria and fungi, the 1:1 mixed culture of them exhibited 88% of color removal in the dye mixture. Also the microorganisms degraded the dyes when cultured in ME medium better than BSM medium. In the 70 days operation of 200 m3/d pilot scale DIW treatment plant, the fungi were seeded into the aeration tank in a daily basis (0.2%, v/v). the chromaticity was well removed, it reached approximately 230 and it met the required standard. Leather industry wastewater (LIW) was containing high nitrogen concentration which was effectively removed by 8 isolated bacteria. Among them, one strain named as KH8 had showed the great ability in denitrification under an aerobic condition, and it was identified as Pseudomonas aeruginosa R12. From the nitrogen balance at the cell-combining ratio of 10:1 (KH8 isolate to the other seven isolates) within the seeded cells, the percentage of nitrogen lost during the aerobic denitrification process was estimated to be 58.4, which was presumed to be converted to N2 gas. When these seed cells with lactose we are applied to plant-scale aeration tank for 56 d to treat high-strength N in LIW, the removal efficiencies of CODCr and TN we are achieved to be 97.0 and 89.8%, respectively. Under this treatment, the final water quality of the effluent leaving the treatment plant was below the water-quality standard concentrations. High salinity fishery wastewater (HFW) was treated by NaCl-tolerant bacterium. For reutilization of fisheries waste, a strain was isolated from a coastal area in Busan. It was identified as Bacillus licheniformis TK3-Y. From plate assay and 500-mL flask experiments, it was revealed that the isolate simultaneously possessed cellulolytic, proteolytic and lipolytic activities with salt-tolerance (survivability at 17.5% NaCl concentration). And the TK3-Y strain showed 1.07-U/mL cellulolytic, 1426-U/mL proteolytic and 6.45-U/mL lipolytic activities. Each enzyme activity could be stable within a range of 17.5-35%. And in 150-L pilot scale bioreactor, TK3-Y strain degraded the mixture of anchovy and green seaweed wastes and the enzyme activities were shown 0.45-U/mL of cellulase, 1014-U/mL of protease and 5.8-U/mL of lipase. The results of DIW, LIW and HFW treatments indicated that the importance of using suitable microorganisms according to the characteristics of wastewaters and proved the possibility to apply to biological treatment of large-scale industrial wastewater by microorganisms.