Modified electrochemical processes for industrial-scale treatment of wastewater having high TKN content

Abstract Electrochemical phenomena were implemented to treatment of industrial wastewater containing high nitrogen concentrations. Organic nitrogen and ammonia, measured by Total Kjeldahl Nitrogen (TKN), raise concerns for most conventional wastewater treatment plants having limited capability of their removal. To avoid contamination of ecosystems with an excessive nitrogen discharge, environmental regulations do not permit for dilution of effluent containing nitrogenous compounds but rather require their adequate removal. This is a challenge for many industrial facilities producing wastewater containing TKN at the level of thousands milligrams per liter. The studied wastewater comprised such TKN along with a significant concentration of ferrous ions in a dissolved form. It was found that ferrous ions in so high concentrations could be advantageous as they provide a platform for designing a sustainable process. In this study, combined electrochemical advanced oxidation and modified electro-Fenton like process was designed and validated at three distinct scales with the goal of finding a scalable solution for TKN removal. An Electro-Fenton Sequential Batch Reactor (EF-SBR) was developed to facilitate the removal efficiency of ammonia and TKN, by more than 99% and 98%, respectively. The reproducibility of the process was validated through several SBR cycles. Moreover, the implementation of EF-SBR permitted to optimize the specific energy consumption and resulted in a pronounced decrease in sludge production.