Enhanced removal of organics and ammonia from municipal wastewater using an activated carbon/zeolite coupled atmospheric plasma system

Abstract

This study evaluates the feasibility of a dual plasma discharge (DPD) system integrated with activated carbon (AC) and zeolite (Ze) for comprehensive municipal wastewater treatment. The DPD system, combining a multipin corona discharge (MCD) and a pulsating liquid-contact discharge (PLCD), enhanced the production of reactive species such as ozone (O3) and hydroxyl radicals (•OH). Compared to individual plasma discharges PLCD or MCD, the DPD system achieved an increase in O3 and •OH production of 1.7 and 3 times, respectively. Optimal dosages of 30 g/L of AC and 100 g/L of Ze resulted in the removal of up to 70 % total organic carbon (TOC) and 90 % ammonia, respectively. Continuous operation at low hydraulic retention time of 1 h demonstrated sustained efficiency, with AC and Ze maintaining high removal rates over multiple cycles with energy efficiency as high as 3.8 gTOC/kWh. Statistical analyses indicated significant improvements in removal efficiencies with p-values of 0.03 for AC and 0.02 for Ze. Additionally, the calculated specific energy consumption (SEC) value of 24 kWh/m3 favourably compares with the atmospheric plasma systems applied at the tertiary stage of wastewater treatment, further underscoring AC/Ze-coupled DPD system's potential as standalone, cost-effective and environmentally friendly wastewater treatment with sustainable adsorbent regeneration.