基于化学与生物膜耦合深度脱除地下水中硝酸盐氮

Currently, there is over 80% contaminated groundwater in north China. Among various pollutants, nitrate has become more and more serious and threatened human health. Usually, the nitrate was removed by zero-valent iron reduction method with ammonia production, which could not be efficiently removed by the biological denitrification method due to insufficient carbon sources in groundwater. Thus, in this study, a novel self-made biofilm carrier, which combined micro-electrolysis chemistry-catalyzed granule with natural biomass loofah, was developed for deep N removal in groundwater through autotrophic and heterotrophic denitrification coupling process. Then a new process for deep N removal was put forward for ex-situ aerobic or anaerobic denitrification, and the corresponding mechanism was discussed. The results showed that the average nitrate removal rate was higher than 91.24% in aerobic reactor at hydraulic retention time (HRT) of 12 hours and dissolved oxygen (DO) of 2.0 to 3.0 mg•L ^-1 . Then the average nitrate removal rate reached above 96.32% in anaerobic reactor at the HRT of 14 hours. Moreover, the coupling functions of micro-electrolysis chemistry-catalyzed granule and biofilm contributed to nitrate removal in groundwater. Micro-electrolysis chemistry-catalyzed granule provided electrons for autotrophic denitrifying bacteria in biofilm, and natural loofah provided necessary carbon source for microorganism. Miseq high-throughput also revealed the dominant genus related to denitrifying. In addition, the effluent of the treatment process had no nitrite and ammonia accumulation. This new technology may provide theoretical basis for contaminated groundwater restoration.