Perchlorate removal by a combined heterotrophic and bio-electrochemical hydrogen autotrophic system.

Here, a novel combined heterotrophic and bio-electrochemical hydrogen autotrophic (CHBHA) system was developed to remove perchlorate under low chemical dosages and energy consumption. The perchlorate removal performance at various hydraulic retention times (HRTs) and acetate dosages was investigated. For influent containing 10 ± 0.10 mg/L perchlorate, the optimal removal efficiency by the CHBHA system was 98.96 ± 1.62 %, 92.99 ± 2.99 %, 97.85 ± 0.41 %, and 98.24 ± 1.56 % at different operating stages. Perchlorate was mainly removed in the heterotrophic part (H-part) at a sufficient HRT (6 h) and acetate dosage (14.75 mg/L). At other stages, perchlorate was synergistically removed by the H-part and electrochemical hydrogen autotrophic part (E-part). Since the H-part removed some perchlorate, the E-part's applied current decreased, thus reducing energy costs. The maximum current efficiency of CHBHA system was 22.09 %. Compared with the single E-part system, the combined system used 65 % less energy. Perchlorate was converted into active chlorine in the E-part, which improved the effluent quality. The bacterial community structures of the two parts were significantly different. Comamonas, Dechloromonas, Acinetobacter, and Chryseobacterium were enriched in the H-part, and the dominant genera in the E-part were Thauera, Azonexus, Hydrogenophaga, and Tissierella.