垂直流人工湿地耗氧有机物（COD）的去除机理与迁移转化规律及调控机制

Vertical-flow constructed wetland, as an efficient ecological system of sewage treatment, had wide application prospects in advanced treatment of domestic sewage, agriculture nonpoint and wastewater from sewage treatment plant. Although there were numerous research achievements on vertical-flow constructed wetland in domestic and overseas, including purification mechanism of COD, influence factors, optimization and control of operation parameters, it was not further enough to maximize its treatment effectiveness. This application intended to adopt such methods as artificial soil column, microcosm combined with small-scale constructed wetland, based on matrix, plants and microbes, which could be used to weigh the contribution of vertical-flow constructed wetland in COD removal, especially in physical, chemical and microbes effects of matrix, as well as combined effects of plants and microbes. The objectives we need to make clear respectively are revealing the effectiveness mechanism of matrix, plants and microbes in COD removal; discussing the effectiveness discipline of single-factor and multi-factor(HRT, hydraulic or pollution load, the water level)and obtaining the optimized single-factor parameters and operation parameters with combination scheme in COD removal; optimizing metabolism of microbes and ensure the microbial community structure of wetlands in the best condition; making it clear that the connection between COD removal and soil organic matter accumulation and ecological dynamic model of them, so that we could provide theoretical basis for how to improve COD removal effects of vertical-flow constructed wetland.

垂直流人工湿地是一种高效的污水生态处理系统，它在生活污水、农业面源以及污水厂尾水深度处理中都具有广阔的应用前景。但是目前国内外对其净化COD的机理与影响因素及运行参数调控优化等缺乏深入研究，从而影响了其处理效能的发挥。本申请从基质、植物、微生物和运行参数出发，拟采用人工土柱、微宇宙和小型人工湿地相结合的研究方法，弄清垂直流湿地基质的物理、化学和微生物作用以及植物、微生物及其联合作用在COD去除中的贡献大小，揭示基质、植物、微生物三因素在COD去除中的作用机理；探讨单因素和多因素（HRT、水力或污染负荷、水位）组合方案对COD去除效果的影响规律，获得COD去除效果最佳的单因素参数值和运行参数组合方案等调控措施；优化微生物的代谢作用，确定最优条件下湿地微生物群落结构；弄清COD去除与土壤有机质积累的关系，建立COD去除与有机质积累的生态动力学模型，为提高垂直流人工湿地COD去除效果提供理论依据

人工湿地是通过基质-植物-微生物协同作用去除污水中的有机污染物。基质的物理、化学、微生物学性质、植物种类和运行参数均影响人工湿地有机物的去除。本项目在各个因素单独作用及联合作用条件下研究垂直流人工湿地有机物去除与迁移转化规律，试验结果如下：.（1）复合基质2（河砂+泥炭+红壤）物理作用在COD去除率中占47.57%，化学作用占40.49%，基质微生物作用占2.66%，污水微生物作用占2.53%，基质和污水综合微生物作用占4.26%。复合基质2的物理作用最明显、化学作用比较恒定，COD去除率高达92.32%，河砂可以作为垂直流人工湿地的最优选择基质。.（2）基质的粒径大小、不均匀性、阳离子交换量（CEC）、细菌总数和脲酶活性是影响基质COD去除的主要因素。.（3）人工土柱有机质的积累随着基质深度的增加呈下降趋势，并且主要积累在表层。.（4）水力负荷20 cm/d，有机负荷0.06kgCOD/(m2.d)，间歇曝气的最优参数运行条件下，小型湿地试验中，种皇竹草系统、种象草系统、对照系统对TN和COD去除都比较好，其中皇竹草系统TN、COD、TP去除率高达66%、 87%和42% 。.（5）在小型湿地系统中，皇竹草系统表现出明显的优势，表层积累TN含量为1.65g/kg，TP含量为3.7 g/kg，有机质含量为22 g/kg。象草和皇竹草吸收氮含量分别高达15.75%和 11.47%；吸收磷量分别达9.61%和8.56%。垂直流人工湿地微生物群落结构均以变形菌门、厚壁菌门为主，种植植物和不种植系统微生物种群差异表较大，随着湿地基质深度增加，绿弯菌门和绿硫细菌量增大，厚壁菌门和硝化菌属减小。.（6）COD去除效果最佳的单因素参数分别是有机负荷0.08kgCOD/(m2.d)，水力负荷20cm/d和间歇曝气；正交试验和验证试验中结果表明有机负荷0.04kgCOD/(m2.d)、水力负荷60 cm/d和间歇曝气参数组合可以保证湿地长期运行。.（7）在小型垂直流人工湿地中，基质截留吸附、微生物降解是有机物去除的主要途径。基质吸附有机物比率小于1%；基质积累有机物在10%左右；微生物分解百分比高达90%。种植植物湿地基质截留和吸附作用(10%)高于不种植植物湿地，且表层高于中层和底层；STELLA模型能够较好地模拟垂直流人工湿地系统对COD的去除效果。