Nitrate and pesticide removal by a combined bioelectrochemical/adsorption process

Biological denitrification and trace pesticide removal in a combined biofilm-electrode reactor/adsorption process has been investigated. In long-term (more than 260 days) continuous experiments, influent and effluent concentrations of nitrate, nitrite, isoprothiolane and gas composition were measured at different electric current and pesticide loading conditions. Experimental results showed that complete and stable denitrification was achieved in BER without accumulation of nitrite and nitrous oxide. Isoprothiolane (IPT) was removed by adsorption onto either granular activated carbon or silicone resin. Removal efficiency of IPT exceeding 97% was achieved and effluent concentration was below the guideline value (40 micrograms/l). Theoretically predicted effluent concentrations were in good agreement with the observed results. From these results, it is concluded that the combined process is applicable to treat nitrate and pesticide contaminated drinking water. Moreover, from comparison with former studies, different possible options to further enhance the decomposition of pesticide were suggested.