泥水混合水解酸化预处理下同步硝化反硝化除磷颗粒污泥运行

Operation of granular sludge for simultaneous nitrification-endogenous denitrification and phosphorus removal (SNEDPR) under mixed hydrolysis acidification pretreatment of sewage and sludge

摘要:

为实现生活污水下同步硝化内源反硝化除磷（SNEDPR）系统的稳定运行,选用SBR接种人工配水培养的SNEDPR颗粒污泥,以实际生活污水和污泥经混合水解酸化预处理为进水基质,通过优化预处理单元水力停留时间（HRT）联合SBR排泥方式实现该系统稳定运行。结果表明,预处理单元HRT从12 h降至4 h时,水解酸化液提供的乙酸、丙酸质量浓度和挥发性脂肪酸（VFA）占比提高,好氧颗粒污泥（AGS）内厌氧聚羟基烷酸（PHA）储存量增加,同步硝化反硝化（SND）效率提升至58.1%,出水TN降至7.8 mg/L左右。同时,底部排泥的SBR内小颗粒占比上升、LB-EPS增加,系统沉降性能变差；顶部排泥下成熟老化的大颗粒占比上升,颗粒含水率和强度下降；而选择性排泥的SBR内颗粒粒径集中在0.5~0.9 mm,颗粒结构密实、强度高,颗粒内细菌分层分布增强SND效果,批次实验表明,NOB和GAOs活性降低,系统内以NO-₂为电子受体的DPAOs占比提升至40.5%,同步硝化内源反硝化除磷效率得到提升。预处理单元较短的HRT联合选择性排泥处理生活污水颗粒性能稳定,系统出水TN和TP均达到GB 18918—2002《城镇污水处理厂污染物排放标准》中所规定的一级A标准,可实现氮磷的高效稳定去除。

Abstract:

For the stable operation of simultaneous nitrification-endogenous denitrification and phosphorus removal (SNEDPR) system under domestic sewage, sequencing batch reactor (SBR) was selected to inoculate SNEDPR granular sludge under artificial water distribution. The actual domestic sewage and sludge were pretreated by mixed hydrolysis acidification and taken as the influent matrix, and the stable operation of the system was realized by optimizing the pretreatment unit hydraulic retention time (HRT) combined with SBR sludge discharge modes. Results showed that when the HRT of the pretreatment unit decreased from 12 h to 4 h, the content of acetic acid, propionic acid, and the proportion of volatile fatty acids (VFA) provided by the hydrolytic acidification solution increased, the anaerobic poly-hydroxyalkanoate (PHA) storage in aerobic granular sludge (AGS) increased, the simultaneous nitrification and denitrification (SND) efficiency increased to 58.1%, and the effluent TN decreased to about 7.8 mg/L. At the same time, under bottom sludge discharge, the proportion of small particles in SBR increased, LB-EPS increased, and the settlement performance of the system became worse. The proportion of mature and aged large particles under top sludge discharge increased, and the moisture content and strength of particles decreased. Under selective sludge discharge, the particle size in SBR was concentrated in 0.5-0.9 mm, with dense particle structure and high strength. The layered distribution of bacteria in the particles enhanced the SND effect. Batch experiments showed that the activities of nitrite-oxidizing bacteria (NOB) and glycogen accumulating organisms (GAOs) were reduced, the proportion of denitrifying polyphosphate accumulating organisms (DPAOs) with NO-₂ as electron receptor in the system was increased to 40.5%, and the efficiency of simultaneous nitrification and endogenous denitrification phosphorus removal was improved. The short HRT combined with selective sludge discharge of the pretreatment unit had stable performance in the treatment of domestic sewage particles. The effluent TN and TP met the first-level A standard specified in GB 18918—2002 Discharge Standard of Pollutants for Municipal Wastewater Treatment Plant. The system can achieve efficient and stable removal of nitrogen and phosphorus.