Livestock wastewater treatment by an advanced electrochemical reactor: Nitrogen compound and total organic carbon removal

This study focuses on the removal of nitrogen compounds (total nitrogen – TN and ammonium – NH 4 + ) and total organic carbon (TOC) from livestock wastewater through electrochemical oxidation (EO). The present study highlights the application of a technology already known for solving a complex problem: water pollution caused by excess nitrates. The reduction of nitrogen content in livestock wastewater can allow farms to increase the spreading of livestock manure onto the soil (according to the Nitrates Directive 91/676/EEC in NVZ), thereby increasing the number of cattle heads. Livestock wastewater was sampled at a farm in San Tammaro (Campania, Italy), an area with high nitrate concentrations designated as Nitrate Vulnerable Zones (NVZ) under the Nitrates Directive 91/676/EEC. Investigations were carried out using an innovative plate reactor. The effects of the current density (J = 1.1-3.3 mA cm -2 ), livestock wastewater flow rate (q = 36.2-68.7 ml min -1 ), initial total nitrogen (36.0-92.8 mg L -1 ), ammonium (12.7-32.6 mg L -1 ), TOC (339.0-920.9 mg L -1 ) and NaCl addition (250 mg L -1 ) on process performance were investigated. The results indicated that, at a current density of 3.3 mA cm -2 , without adding NaCl, removals of 27.5%, 58.9%, and 35.1% for TN, NH 4 + , and TOC were achieved, respectively. The proposed technology is a promising approach for removing nitrogen from livestock wastewaters. • Total Nitrogen and Total Organic Carbon removal using an advanced electrochemical reactor was investigated • Tests were conducted with livestock wastewater • Livestock wastewater was sampled in an area with high nitrate concentration belonging to the Nitrate Vulnerable Zones (NVZ) • Low concentrations of NO 3 - were produced