基于底泥基生物炭介导强化河流底质中硝态氮生物还原作用机制的研究

The accumulation of nitrate nitrogen in river sediment could bring ecological and health risks. Sediment dredging is an important way to control internal pollution, however, producing a great amount of dredging sediment needing to be treated. This project aims at water pollution treatment caused by excessive accumulation of nitrate in river sediment using sediment-based biochar. This project will be conducted by using surface sediment in rivers with different degrees of pollution as raw material for biochar preparation. We plan to establish river sediment-biochar-microorganism microsystem by addition of sediment-based biochar into rivers. The function and activity of nitrogen-transforming microorganisms on surface of sediment-based biochar will be studied to clarify the mechanism of surface characteristics of biochar on the formation of nitrogen-reducing biofilms. The multi-factor mechanism of enhanced nitrate reduction performance will also be clarified by exploring the possible ways of nitrate nitrogen reduction in microsystem. Based on these results, the nitrate reduction performance under hydrodynamic conditions will be investigated to elucidate the effect of various media on nitrate reduction. This project will provide scientific basis for using sediment-based biochar for nitrate nitrogen removal in rivers, as well as utilization of dredging sediment.

硝态氮在河流底质中过量累积会给水环境带来一定的生态健康风险。底质清淤是污染河流内源治理的重要手段，在此过程中产生大量富含有机质的底泥亟待处置。本项目将清淤底泥的资源化利用与底质硝态氮还原脱除过程相耦合，采用底泥基生物炭强化河流底质中硝态氮的脱除。研究拟选取太湖流域典型重污染河流表层底泥为原材料，使用限氧控温热解法制备底泥基生物炭。通过向底质投加所制备的生物炭材料建立河流底质-生物炭-微生物的微体系，分析所制备底泥基生物炭材料特性对其表面生物膜中硝态氮还原微生物活性的影响；研究硝态氮在底泥基生物炭表面生物膜作用下发生还原的可能途径，探索微体系内硝态氮生物还原的促进机制；在此基础上，模拟河流动水条件，考察不同水力参数对所构建微体系内硝态氮还原的影响，阐明多介质耦合作用对微体系内硝态氮还原的影响机制，为清淤底泥的资源化利用和河流底质硝态氮脱除提供科学依据。

硝酸盐是河流中最常见的水污染物之一，已成为严重的全球环境问题。沉积物由长期投入的生活垃圾和农业废物中积累的有机化合物，微生物和养分组成的，典型的受污染沉积物中具有较高的碳含量，这使其具有巨大的生物炭潜力。研究以提高清淤底泥资源化为目标，将其与底质硝态氮还原脱除过程相耦合，具体解析利用限氧控温法制备底泥基生物炭材料主要特征参数，探究河流底质-底泥基生物炭-微生物构成的微体系促进水体硝酸盐还原过程，并通过分批试验探索了其潜在的促进机制。重点分析所制备底泥基生物炭材料特性对其表面生物膜中硝态氮还原微生物活性的影响；研究硝态氮在底泥基生物炭表面生物膜作用下发生还原的可能途径，阐明多介质耦合作用对微体系内硝态氮还原的影响机制，为清淤底泥的资源化利用和河流底质硝态氮脱除提供科学依据。