6种常见湿地植物生物质用作污水反硝化碳源的脱氮效果及出水残留有机组分

Nitrogen removal effect of six common wetland plant biomass as denitrification carbon source and residual organic components in effluent

湿地植物生物质是处理低碳氮比尾水的潜在反硝化外碳源,但使用过程中会受到植物种类、投加量和有机物组分过度释放的限制。本研究选取6种常见湿地植物生物质,利用序批式实验,研究分析了各植物生物质不同投加量作为反硝化碳源的脱氮性能,并对高效脱氮处理组出水中残留的有机组分特性深入探究。结果表明,经1%Na OH处理的香蒲、风车草和芦竹的液固比降低至50:1及以下的处理系统才能持续高效脱氮,香蒲、风车草、芦竹和菹草的高效脱氮期最长的系统液固比分别为33:1、25:1、25:1和100:1。持续高效脱氮处理的系统均需经过1~5批次脱氮启动期(脱氮效果较差甚至去除率为负值),才能进入高效脱氮阶段,并且前1~2批次出水中存在高COD(1000~7000mg·L^(-1))残留。对4种植物的高COD出水有机组分特性分析的结果表明,香蒲、风车草和菹草的有机组分以腐殖酸类腐殖质为主,芦竹则是以含苯环蛋白质、溶解性微生物代谢产物为主;香蒲、风车草、菹草出水中,≥1 k Da的大分子有机组分为主,占比达到60%以上,而芦竹出水中则是<1 k Da的小分子有机组分为主,占比60%以上;菹草和芦竹出水中芳香性组分具有较好的光解特性,紫外光光解效果优于可见光光解,其他2种植物的则较差。从脱氮效果和生长周期来看,香蒲和菹草2种植物生物质更适宜作为尾水反硝化外碳源,其生物质投加量分别在液固比33:1和100:1时具有最优的持续高效脱氮效果,实际应用时应通过预处理或出水深度处理等措施去除启动期出水中大量难降解有机组分。以上研究结果可为植物生物质作为低碳氮比尾水反硝化碳源的可行性提供参考。

Wetland plant biomass is a potential denitrification external carbon source for treating tail water with low carbon-nitrogen ratio,but it is limited by plant species,dosage and excessive release of organic components during use.In this study,six kinds of common wetland plant biomass were selected,and the nitrogen removal performance of each plant biomass with different dosages as denitrification carbon source was studied and analyzed by batch experiments,and the characteristics of residual organic components in the effluent of highefficiency denitrification treatment group were deeply explored.The results showed that the liquid-solid ratio of Typha orientalis,Cyperus involucratus and Arundo donax treated with 1%NaOH could be reduced to 50:1 and below,and the longest periods of efficient denitrification for Typha orientalis,Cyperus involucratus,Arundo donax,and Potamogeton crispus were achieved at solid-liquid ratios of 33:1,25:1,25:1,and 100:1,respectively.The continuous high-efficiency denitrification treatment system needs to go through 1~5 batches of denitrification start-up period(the denitrification effect was poor or even the removal rate was negative)before entering the high-efficiency denitrification stage,and the first 1~2 batches effluents had ultra-high COD(1000~7000 mg·L^(-1))residuals.The analysis of the characteristics of organic components in the ultra-high COD effluent of four plants showed that the organic components of Typha orientalis,Cyperus involucratus and Potamogeton crispus were mainly humic acid humus,while Arundo donax was mainly benzene ring protein and soluble microbial metabolites.In the effluent of Typha orientalis,Cyperus involucratus and Potamogeton crispus,the macromolecular organic components of≥1 kDa were dominant,accounting for more than 60%,while the small molecular organic components of<1 kDa were dominant in the effluent of Arundo donax,accounting for more than 60%.The aromatic components in the effluent of Potamogeton crispus and Arundo donax had better photodegradation characteristics,and the photodegradation effect of ultraviolet light was better than that of photodegradation,while that of the other two plants was poor.From the perspective of denitrification effect and growth cycle,Typha orientalis and Potamogeton crispus are more suitable as external carbon sources for denitrification of tail water.Their biomass dosages have the best continuous and efficient denitrification effect in the range of liquid-solid ratio of 33:1 and 100:1,respectively.In practical application,a large number of refractory organic components in the effluent during the start-up period should be removed by pretreatment or advanced treatment of effluent.This study provides a scientific basis for the feasibility of using plant biomass as a carbon source for denitrification in effluents with low carbon-to-nitrogen ratios.