“曝气-沉淀-A2/O”工艺同步污泥减量与脱氮除磷性能及机理研究

The sludge reduction in the wastewater treatment process has become an ideal way to solve the increasingly serious sludge problems, however there are some problems existing in technologies, such as lower removal efficiency of nitrogen and phosphorus,pathway of pollutants removal and mechanisms uncertain,which result in difficulties with widely application. This project will combine "Aerobic-Settling" with A2/O to achieve the synchronization of nitrogen and phosphorus removal and sludge reduction. Firstly, studying the batch experiments and continuous experiments of "Aerobic-settling" process is to reveal the possible mechanisms of sludge reduction and contributions to the reduction, providing a theoretical basis for improving the reduction efficiency. Secondly, Investigationg the coupling process of "Aerobic-Settling-A2/O" is to optimize the process operating parameters and to determine the best conditions under which the sludge reduction and removal of nitrogen and phosphorus are simultaneously achieved. Finally, under the optimum conditions, investigating the sludge characterization and pollutants changes along the whole combination process of "Aerobic-Settling- A2/O" and analyzing the microbial structure and mass balance of nutrient elements are to discover the pathway and mechanism of nitrogen and phosphorus degradation, and functions between sludge reduction and wastewater treatment, as a consequence, providing theoretical support and experimental validation for this combined process to be widely applied.

污泥源头减量已成为解决日益严峻污泥问题较理想的途径，然而污泥减量技术中存在氮磷去除率低、污染物去除途径及减量机理尚不明确等问题，进而影响其推广应用。本课题将具有污泥减量功能的"曝气-沉淀"循环工艺与具有脱氮除磷功能的A2/O工艺相结合，力求实现脱氮除磷和污泥减量的同步完成。首先通过"曝气-沉淀"工艺段的连续和间歇实验研究，揭示可能存在的污泥减量机理及其对减量的贡献，为提高减量效果提供理论依据；然后以"曝气-沉淀-A2/O"耦合工艺为对象，优化工艺运行参数，确定污泥减量及脱氮除磷同步完成的最佳工况；最后在最佳工艺条件下对污泥变化特征与污染物去除效果进行研究，以及对微生物种群结构进行分析，揭示污泥减量与污水处理的相互协同作用和机理，分析耦合工艺中污染物的去除途径，为该技术的推广应用提供理论支撑和实验验证。

本项目提出了将污泥减量单元与脱氮除磷结合的组合工艺“曝气-沉淀-A2/O”，在项目开展初期，通过查阅文献及理论分析，提出将“曝气-沉淀-A2/O”耦合工艺调整为“升流式厌氧-升流式微氧-好氧”工艺。其中厌氧段及微氧段均采用升流式圆柱形反应器，在厌氧段实现污泥减量及除磷、在微氧段实现强化脱氮，其污泥减量同步脱氮除磷功能不变。.本项目搭建了两套对比实验装置，即“升流式微氧-好氧（Um/O）”与传统“A/O”对比装置，以及“升流式厌氧-升流式微氧-好氧（Ua/Um/O）”与传统“A2/O”对比装置。研究发现，在HRT为12h，内循环比为200%，外循环比为50%的条件下，Um/O和A/O对CODcr的平均去除率分别为88%和83%，Um/O比A/O高6%，出水均小于50mg/L；对氨氮的平均去除率分别为95%和93%，去除效果相差不大；而对TN的去除分别为67.5%和58%，Um/O比A/O高近16%，强化了脱氮效果。通过对比Ua/Um/O和A2/O发现，在HRT=10h，SRT=15d，内回流比为180%，外回流比为80%的条件下，Ua/Um/O与A2/O对COD的平均去除率分别为85%和83%，出水COD均小于50mg/L。对氨氮的平均去除率分别为90.75%和90.69%，去除效果相差不大。对TN的平均去除率分别为69.45%和60.74%，Ua/Um/O比A2/O高近10个百分点，对总磷的平均去除率分别为76.72%和62.88%，Ua/Um/O比A2/O高14个百分点。电镜扫描分析发现，升流式反应器微生物多样性更显著，且存在污泥浓度以及溶解氧梯度变化，使得脱氮除磷效果提高。通过长期实验发现，Ua/Um/O工艺具有较强抗冲击性，出水稳定。.在上述研究基础上，对Ua/Um/O工艺减少剩余污泥排放量进行脱氮除磷同步污泥减量研究，在HRT和内回流比相同条件下，减少Ua/Um/O工艺的剩余污泥排放量30%，与正常排泥的A2/O对比发现，CODcr和氨氮的效果基本相似，而TN的去除两者分别为67.62%和57.51%，TP的去除两者分别为88%和81.47%。证明该新型工艺Ua/Um/O可以实现同步脱氮除磷与污泥减量效果。