Orthophosphates removal from synthetic sewage with low pH using the electrocoagulation and the metal digestion method

Unquestionably, effective methods of phosphorus compound removal include precipitation methods. These methods include: electrocoagulation and the experimental metal digestion method. Metal solution and electrocoagulation in this paper use corrosion effect of steel plates to couse iron ions to get through into the synthetic wastewater. Iron ions that are present in solution induct deposition and sorption of phosphate compounds, which subsequently are removed. The real mechanism is quite complicated and consists of transforming phosphorus compounds into insoluble forms, and then separating them from the sewage by flotation, sedimentation, filtration. Electrocoagulation requires the electrical current to be connected with electrodes. The research was conducted with usage of steel electrodes with 1414 cm2 contact surface, which were corroding and releasing iron ions responsible for orthophosphate deposition. The electrocoagulation process was using a direct electrical current with intensity of 0.1 A. Synthetic wastewater containing 10.5 mg P/dm3 ortophosphorus and 3 pH was used. The main object of this paper was to compare electrocoagulation and metal solution as methods of phosphate removal from synthetic wastewater with usage of reactors containing steel electrodes. The analysis were conducted in acidic environment. Additionally there was examined content of the iron and pH in the solution. The article presents a study into comparative tests were conducted on a laboratory scale. The research indicates, that electrocoagulation is a method of wastewater treatment that takes less time than metal solution. Complete phosphate removal in the environment at pH 3 with electrocoagulation was achieved after 240 minutes, whereas with metal solution method it took 420 minutes. The downside of both methods is the secondary contamination of wastewater with iron ions