Use of DiaCell modules for the electro-disinfection of secondary-treated wastewater with diamond anodes

Abstract

In this work, the disinfection of the effluent of the secondary treatment of a municipal wastewater treatment plant is studied using two stacks of commercial electrochemical cells powered with very low current densities (0.14-10 A m-2), in order to prevent the formation of chlorates and perchlorates during the electrolysis. Results demonstrate that this technology is robust and efficient and it can attain the complete disinfection of wastewater even at very low current densities. These low current densities are high enough to produce hypochlorite and chloramines (when ammonium is present in solution), being the disinfection process more efficient when the concentration of chloramines is higher. Therefore, the presence of hypochlorite together with higher concentrations of chloramines significantly improve the removal of microorganisms. In comparing the two stacks studied in this work, it was obtained that commercial DiaCell stacks containing bipolar connected electrodes are more efficient than those containing monopolar-connected electrodes for the disinfection. Differences are explained in terms of the higher cell voltage applied in that stack (higher current density in bipolar stack) that results in (1) an improved reduction of nitrates to ammonium (BDD cathode in bipolar stack) with the latter formation of chloramines as the main positive effect and (2) in the increase in the power consumed as the primary negative consequence.

Electrochemical Disinfection in Water and Wastewater Treatment: Identifying Impacts of Water Quality and Operating Conditions on Performance

“… 78 Due to the relative abundance of ammonia in electrochemical wastewater treatment contexts, chloramine should be present in any system generating free chlorine. 12 , 64 , 71 , 75 , 79 …”

Efficient electrochemical degradation of poly- and perfluoroalkyl substances (PFASs) from the effluents of an industrial wastewater treatment plant

“…Furthermore, the efficiency of this process has already been assessed for landfill leachates [26], recalcitrant compounds in industrial wastewater [27], pharmaceuticals in reverse osmosis concentrates [28], and other emerging contaminants contained in the secondary effluents of wastewater treatment plants (WWTP) [29][30][31].…”

Disinfection of urine by conductive-diamond electrochemical oxidation

“…The second mechanism, indirect disinfection, consists of the attack of disinfectant species (usually chlorine derivatives) to microorganisms contained in wastewater. These species can be directly added to the effluent or be generated in situ during the treatment [28][29][30]. In this context, the composition of the synthetic urine used in this work presents large amounts of chlorides which can be electrooxidized, favoring the production of chlorine and…”