Biological nitrogen removal from plating wastewater by submerged membrane bioreactor packed with granular sulfur

Recent toughened water quality standards have necessitated improvements for existing sewer treatment facilities through advanced treatment processes. Therefore, an advanced treatment process that can be installed through simple modification of existing sewer treatment facilities needs to be developed. In this study, a new submerged membrane bioreactor process packed with granular sulfur (MBR-GS) was developed and operated to determine the biological nitrogen removal behaviors of plating wastewater containing a high concentration of NO₃⁻. Continuous denitrification was carried out at various nitrogen loading rates at 20 °C using synthetic wastewater, which was comprised of NO₃⁻ and HCO₃⁻, and actual plating wastewater, which was collected from the effluent water of a plating company called ‘H Metals’. High-rate denitrification in synthetic plating wastewater was accomplished at 0.8 kg NO₃⁻-N/m³·day at a nitrogen loading rate of 0.9 kg NO₃⁻-N/m³·day. The denitrification rate further increased in actual plating wastewater to 0.91 kg NO₃⁻-N/m³·day at a nitrogen loading rate of 1.11 kg NO₃⁻-N/m³·day. Continuous filtration was maintained for up to 30 days without chemical cleaning with a transmembrane pressure in the range of 20 cmHg. Based on stoichiometry, SO₄²⁻ production and alkalinity consumption could be calculated theoretically. Experimental alkalinity consumption was lower than the theoretical value. This newly proposed MBR-GS process, capable of high-rate nitrogen removal by compulsive flux, is expected to be applicable as an alternative renovation technique for nitrogen treatment of plating wastewater as well as municipal wastewater with a low C/N ratio.