Abstract
Fortysix processing industry plants of wastewater treatment that utilize only secondary activated sludge were checked on concentrations of phosphorus in their influents and effluents to estimate the environmental (BOD, COD, T-N and P) loading form this source. While influent levels of 17.7 mg/l were reduced to 6.2 mg/l (as P) in the effluent, an overall removal of about 65%. The remainder is still high enough to contribute significantly to the accelerated eutrophication of freshwater stream, lakes and marshes as well as the marine waters in some coastal areas of Japan.
Therfore, a pilot plant study was initiated to investigate the further removal of phosphorus from these processing industry wastewaters though the use of chemical coagulants such as aluminum sulfate, ferric chloride, and calcium hydroxide. The pilot plant data showed increases in efficiency of phosphorus removal to more than 90%. Moreover phosphorus contents in the sludge and weight of sludge were measured.
