Influence of Electrode Material on the Electroflocculation Treatment Efficiency of Swine Wastewater

Swine wastewater, composed of farm effluents, poses significant risks to the environment and public health due to its pollutant loads. This wastewater is frequently applied as fertilizer, but repeated use can lead to soil and water eutrophication and contamination. Various pre-treatment techniques have been explored to mitigate these impacts. Electroflocculation has emerged as a promising technique to reduce the pollution load before soil application. This process involves the controlled release of metal ions, which destabilize colloidal particles in the mixture, resulting in an effluent with substantially lower contaminant levels. Electrode material is a critical parameter in the electroflocculation process. Aluminum and iron are the most commonly used electrodes; however, the required exposure time to the electric current is usually long, making the process costly in terms of both time and financial resources. This study investigated the electroflocculation of swine manure using various alternative electrodes (aluminum, stainless steel, carbon, copper, and zinc) to assess the efficiency of contaminant removal under short exposure times and low voltage conditions, aiming to optimize the process. Manure collected from a farm in Palencia (Spain) was treated at 12 volts for 3, 6, and 9 minutes. After the treatments, both treated and control samples were analyzed in the laboratory for pollutants including turbidity, organic matter, phosphorus and other minerals. The results showed that stainless steel and zinc electrodes were particularly effective reducing turbidity (47% - 67%), organic matter (23%), phosphorus (34% -62%), and calcium (27% - 54%) in the effluent after 9 minutes of current exposure. The average energy consumption was 0.36 W/L which was considerably lower than previous studies. However, these electrodes released some heavy metals into the solution, which could be further reduced through a complementary treatment. Overall, electroflocculation using alternative electrode materials with short treatment times appears to be a suitable pre-treatment strategy for swine manure, reducing pollutant loads while maintaining low energy consumption.