School of Sustainable Engineering and the Built Environment, Arizona State University, Biodesign Institute, Tempe, Arizona.
Present address: Escuela de Ingenieria y Ciencias, Tecnologico de Monterrey, Campus Puebla, Puebla, Pue, Mexico.
Biotechnol Bioeng. 2019 Jun;116(6):1439-1448. doi: 10.1002/bit.26945. Epub 2019 Mar 1.
Chloroform (CF) can undergo reductive dechlorination to dichloromethane, chloromethane, and methane. However, competition for hydrogen (H ), the electron-donor substrate, may cause poor dechlorination when multiple electron acceptors are present. Common acceptors in anaerobic environments are nitrate (NO ), sulfate (SO ), and bicarbonate (HCO ). We evaluated CF dechlorination in the presence of HCO at 1.56 e Eq/m -day, then NO at 0.04-0.15 e Eq/m -day, and finally NO (0.04 e Eq/m -day) along with SO at 0.33 e Eq/m -day in an H -based membrane biofilm reactor (MBfR). When the biofilm was initiated with CF-dechlorination conditions (no NO or SO ), it yielded a CF flux of 0.14 e Eq/m -day and acetate production via homoacetogenesis up to 0.26 e eq/m -day. Subsequent addition of NO at 0.05 e Eq/m -day maintained full CF dechlorination and homoacetogenesis, but NO input at 0.15 e Eq/m -day caused CF to remain in the reactor's effluent and led to negligible acetate production. The addition of SO did not affect CF reduction, but SO reduction significantly altered the microbial community by introducing sulfate-reducing Desulfovibrio and more sulfur-oxidizing Arcobacter. Dechloromonas appeared to carry out CF dechlorination and denitrification, whereas Acetobacterium (homoacetogen) may have been involved with hydrolytic dechlorination. Modifications to the electron acceptors fed to the MBfR caused the microbial community to undergo changes in structure that reflected changes in the removal fluxes.
氯仿 (CF) 可还原脱氯生成二氯甲烷、氯甲烷和甲烷。然而，当存在多个电子供体时，对氢 (H) 的竞争可能导致脱氯效果不佳，H 是电子供体底物。在厌氧环境中，常见的电子受体是硝酸盐 (NO )、硫酸盐 (SO ) 和碳酸氢盐 (HCO )。我们在 1.56 eEq/m -day 的 HCO 存在下评估了 CF 的脱氯作用，然后在 0.04-0.15 eEq/m -day 的 NO 存在下，最后在 0.04 eEq/m -day 的 NO 和 0.33 eEq/m -day 的 SO 存在下，在基于 H 的膜生物膜反应器 (MBfR) 中进行了实验。当生物膜以 CF 脱氯条件（无 NO 或 SO ）启动时，CF 通量为 0.14 eEq/m -day，通过同型产乙酸作用生成乙酸的量高达 0.26 eeq/m -day。随后以 0.05 eEq/m -day 的速率添加 NO 可维持完全的 CF 脱氯和同型产乙酸作用，但以 0.15 eEq/m -day 的速率添加 NO 会导致 CF 仍残留在反应器的流出物中，并导致乙酸的生成量可忽略不计。添加 SO 不会影响 CF 的还原，但 SO 的还原会通过引入硫酸盐还原菌脱硫弧菌和更多的硫氧化菌食酸菌显著改变微生物群落。Dechloromonas 似乎进行 CF 脱氯和反硝化作用，而 Acetobacterium（同型产乙酸菌）可能参与水解脱氯作用。MBfR 中添加的电子受体的变化导致微生物群落的结构发生变化，这反映了去除通量的变化。
