Development of Phosphorus Removal Process of On-site Domestic Wastewater Treatment Systems Using Dripping Method of Thick Iron Solution.

Abstract

An advanced technique of dripping the thick iron solution was developed and applied to on-site domestic wastewater treatment systems. The thick iron solution was obtained by heating and melting FeCl3⋅6H2O crystals.By using the new technique, the T-P concentration of the treated water decreased to less than 1mg·l-1 when the thick iron solution was added at an Fe/P molar ratio of 1.75. The addition of thick iron solution did not affect the removal of BOD, COD, SS and T-N.The T-P concentration of the treated water increased when coagulated sludge containing ferric phosphate was in contact with the anaerobic sludge in the tank for along time. This problem could be solved by improving the process to prevent such contact. It was also shown that the addition of thick iron solution increased the volume of sludge by about 30%.