[Evaluation of phosphorus removal from filtered effluent of activated sludge using the electrochemical process]

ABSTRACT

Phosphorus [in a concentration range of 0.005-0.05 mg/L-P] is enough for eutrophication of water bodies; therefore, phosphorus removal from effluents is necessary. The electrochemical process is one of the methods used for phosphorus removal. Thus, this study aimed to examine the effect of the electrochemical process on phosphorus removal from filtered effluent of activated sludge. This bench-scale experimental study was carried out on the samples of filtered effluent of activated sludge in a batch system. Phosphorus concentrations for 210 samples were measured through stannous-chloride method [The Standard Method, 4500 P-D.]. Data were analyzed using Green house Geisser, one-way ANOVA and the Tukey's post- hoc tests. The average phosphorus concentration before the electrochemical process in the filtered samples and the maximum efficiency of phosphorus removal were 1.93 +/- 0.86 mg/L-P and 98%, respectively. The residual phosphorus concentrations [electrical current >/= 0.3A, reaction time >/= 10min] in all samples were decreased to less than 1mg/L-P. Results showed that the electrochemical process can decrease the residual phosphorus to less than the standard limit [1mg/L-P] in Iran. The plot for the average residual phosphorus concentrations versus reaction time is a straight line [R[2]=0.837]. Phosphorus removal from the samples of filtered effluent of activated sludge is considered as a second-order reaction and the fitted model can be formulated as y= -0.001x[2] + 0.133x + 0.875 [R[2]=0.925]