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

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.