Effects of nutrient addition on phenol biodegradation rate in biofilm reactors for hypersaline wastewater treatment

Hypersaline wastewater, generated by many industrial activities, is difficult to treat through conventional biological processes. In this kind of hypersaline environment, complex nutrients are needed for the normal growth of many microorganisms. For this paper, the organisms were taken from a municipal wastewater treatment plant and acclimated to 15% salinity in a biofilm treatment process (Sequencing Batch Biofilm Reactor) during the treatment of phenol-containing synthetic wastewater. They are used to evaluate the effects of nutrient addition on the phenol biodegradation rate. Adding yeast extract, glucose, KCl and four mineral nutrients into the shaking flasks containing wastewater and cultivating organisms, revealed phosphate as the crucial nutrient stimulating phenol biodegradation at 15% salinity. The operation results of the sequencing batch biofilm reactor indicates that phosphate content increased up to five times the original level can increase the phenol removal rate by 150%. A 99% phenol removal efficiency could be achieved by shortening the reaction time in the biofilm reactor from 40 h to 16 h, compared with basic nutrients added. In this article we applied an applicable and effective shaking-culture method to determine nutrient requirements in biotreatment processes without stopping the running reactors.