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-parts 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 qual-ity. 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.

Automated summary

A novel combined system of heterotrophic and bio-electrochemical hydrogen autotrophic (CHBHA) was developed for efficient removal of perchlorate using low chemical dosages and energy consumption. The system showed high perchlorate removal efficiency at different operational stages, with the heterotrophic part (H-part) playing a major role at optimal hydraulic retention times (HRTs) and acetate dosage. The system also demonstrated synergistic removal of perchlorate by the H-part and electrochemical hydrogen autotrophic part (E-part). The combined system significantly reduced energy costs compared to the single E-part system and improved effluent quality by converting perchlorate into active chlorine.