牛粪液作用下的三种碳源反硝化试验研究

Comparing Three Carbon Substrates with Cow Dung Liquid for the Denitrification of Agricultural Drainage Water

农业排水中的硝酸盐为地表水氮素污染的最主要来源之一,反硝化生物脱氮是一种具有应用前景的削减农业排水中硝酸盐浓度的技术手段,它需要外加碳源来维持持续的反硝化反应。本研究选用了易于获取的农业废弃物玉米芯、麦秸、木屑作为碳源。在反硝化体系中加入不同体积的牛粪液,利用牛粪液所含的木质纤维素降解菌群,促进3种碳源释放小分子有机物。结果表明,在不添加牛粪液的情况下,使用麦秸的反应体系具有最高的累积硝酸盐去除量,其余依次为使用玉米芯和木屑,牛粪液的加入能加强使用3种碳源的各反应体系对硝酸盐的去除。对固相物质分析表明,使用玉米芯和麦秸的反应体系虽然能去除更多的硝酸盐,但两碳源所含易降解成分较多,自身的降解程度也更高,对长期反硝化而言不利。

Nitrate in agricultural drainage water has been one of the most contributing sources of nitrate contamination of surface water in China.Denitrifying bioreactors belong to a promising technology of reducing the amount of nitrate,in which an external carbon is necessary to the maintenance of continuous denitrification.Corn cob,wheat straw and woodchips are chosen as carbon substrates for denitrifying bioreactors in this study,for they are easily available at farmland.Cow dung liquid can accelerate the degradation of lignocellulose materials and the stimulation of three carbon substrates is evaluated.Without mixing with cow dung liquid,all the three substrates stimulates NO3-N removal and the cumulative NO3-N removed at 30 th day from highest to lowest was：wheat straw,corn cob and woodchips.The addition of cow dung liquid stimulates more NO3-N removal.An analysis of weights of solid？phase shows that corn cob and wheat straw lead to higher NO3-N removal rates than woodchips,but these two substrates degrades more rapidly,which can not maintain long-term denitrification.The addition of cow dung liquid to woodchips increases significantly NO3-N removal rates over woodchips alone,but the rates are still much less than that of corn cob and wheat straw.