Cow manure anaerobic fermentation effluent treatment by oxygen-based membrane aerated biofilm reactor

Abstract

After cow manure undergoes anaerobic fermentation process, it still contains several pollutants such as nitrogen, phosphorus, and organic matter. If not treated properly, these pollutants would cause secondary pollution. Membrane-aerated biofilm reactor (MABR) has been widely used to handle the wastewater with high concentration contaminants. In this study, MABR was utilized to treat the cow manure anaerobic fermentation effluence (CMAFE). In order to avoid incomplete biofilm being affected by high concentration of CMAFE, a gradient dilution of CMAFE was employed. The removal rates of NH4+-N and COD were achieved up to 90% and 85%, respectively, in different dilution ratios. RDA demonstrated that NH4+-N removal was in a full-nitrification process in higher dilution ratio (Stage 1 and 2) but in short-nitrification in lower dilution ratio (Stage 4). The gradient dilution did not affect the biofilm growth. The Inner biofilm contained higher amounts of extracellular polymeric substance (EPS) than the Outer biofilm, which reduced the impact of high-concentration CMAFE on the internal aerobic bacteria, especially nitrifying bacteria. Concerning bacteria abundance, a significant modification occurred in the biofilm compared to raw sludge, demonstrating that MABR had a great potential in CMAFE treatment.