Effect of biofilm media application on biomass characteristics and membrane permeability in the biological spatiotemporal phase-separation process

In this study, the effect of moving-bed biofilm carrier, a membrane, and simultaneous employment to solve the settleability problem derived from readily biodegradable organics application in the biological spatiotemporal phase separation and variation of biomass characteristics by biofilm media application were investigated. No significant differences of the treatability among each case were observed. Although the moving-bed biofilm process is commonly used for the treatment of organics and nitrogen in wastewater, phosphorus was also removed perfectly owing to the detached biomass containing orthophosphate was discarded sufficiently. Additionally, the concentration of the suspended biomass decreased significantly, and the settled volume index was improved dramatically from 700 to 100 mL/g after the addition of the biofilm carrier. Although the extracellular polymeric substance (EPS) concentration increased with media addition, the back-flushing interval of the membrane was lengthened. The increment of polysaccharide in the EPS and the non-existence of protein in the soluble EPS were clearly observed. Thus, the suspended-biomass decrement due to media addition and the protein concentration in the EPS played important roles for fouling control. This study provides valuable information on state alternation of biomass by biofilm media application on biological suspended growth wastewater treatment process.