Phosphorus recovery from beef slaughterhouse wastewater by electrocoagulation process

Abstract

Nitrogen to phosphorus ratio imbalance in natural fertilizer are gaining more and more interest both in science and industry due to eutrophication caused by phosphorus excess. The goal of this study was the phosphorus recovery from Adamawa slaughterhouse wastewater by electrocoagulation (EC) process using iron and aluminum electrodes separately. To achieve this objective, screening and optimization experimental designs were used to determine the optimum conditions of phosphorus recovery from slaughterhouse wastewater by EC process. The results showed that, the order of importance of the parameters that influence the EC process differed depending on the iron and aluminum electrodes. For the iron electrodes, the order of importance in descending order was pH, stirring speed, inter-electrode distance, effluent volume, current intensity, N 2 sparging time, retention time while, for the aluminum electrodes, the order was effluent volume, retention time, pH, inter-electrode distance, current intensity, N 2 sparging time and stirring speed. Optimization of the EC process with iron electrodes revealed that recovery of 100% of phosphorus was observed under optimal operating conditions: pH=3, stirring speed=600 rpm, inter-electrode distance=1.5 cm, effluent volume= 0.5 L, current intensity= 100 mA/cm 2 , retention time= 2h15 min while, with aluminum electrodes, a P recovery of 100% was observed at optimum conditions effluent volume=1 L, retention time=30 min, pH=14, inter-electrode distance=1 cm, current intensity=300 mA/cm 2 , and stirring speed=900 rpm. In view of the obtained results, the recovery of P in slaughterhouse effluent by EC process would be a local solution to face the high cost of fertilizers and by then to sustain environment.