Recovery of phosphorus resource from a new bidogical wastewater treatment process with on-site reduction of excess sludge

With the decrease of the global phosphorus resource and increase of phosphorus in waste water, development of technology for the removal and recovery of the phosphorus resource from waters is becoming urgent. We have developed a bioreactor capable of removal of COD, nitrogen and achieving the no production of excess sludge by repeatedly coupling the aerobic and anaerobic microbes (rCAA) along the reactor. In this system, the phosphorus is present in the form of inorganic phosphate in the effluent due to the on-site degradation of grown microbes, which enables the recovery of the phosphor from wastewater as a resource to be feasible. In the present study, in order to develop an effective phosphorus recovering process from the treated water by chemical flocculation with the emphasis on the reuse of the recovered phosphorus as a controlled-release phosphorus fertilizer, a natural polymer, tannic acid was selected as the coagulant aid. The features of the phosphorus removal from various kinds of water were examined by the coagulation with FeCl3 and tannic acid. The structure of the precipitates by the coagulation and its mechanism were examined further by Raman spectroscope.