A new strategy for obtaining highly concentrated phosphorus recovery solution in biofilm phosphorus recovery process

Recovery of phosphorus (P) from wastewater is of great significance for alleviating the shortage of P resources. At present, the P recovery process is faced with the problem of excessive organic carbon consumption when obtaining a P-concentrated recovery solution. This study proposed a new strategy to obtain a more highly concentrated P recovery solution with minimal carbon consumption by strengthening the P storage capacity of the biofilm. A biofilm sequencing batch reactor (BSBR) process was modified to treat synthetic wastewater. The effect of the dissolved oxygen (DO) concentration on the P storage capacity of the biofilm was investigated at DO concentrations of DO 3.5 mg/L (P_L) and DO 6.5 mg/L (P_H). The results showed a maximum P storage of 101.2 and 149.6 mg-P/g-mixed liquid suspended solids under the two conditions. Strengthening the P storage capacity of the biofilm resulted in a net increase in the P recovery rate, which was as high as 66.96% in a harvesting cycle, and total soluble P>220 mg/L in the P recovery solution was successfully achieved. Meanwhile, the carbon cost of P recovery in the BSBR was reduced to 41.57 g-chemical oxygen demand/g-P, and the carbon utilization efficiency was enhanced. To highlight the new strategy, the P recovery performance of the BSBR was given and the relationship between P content and anaerobic P release was discussed. In addition, the changes in the microbial communities under P_L and P_H conditions were analyzed.