A2O-MBBR+CWs组合技术处理农村生活污水的效果

Effect of A2O-MBBR+CWs combined technology in treating rural domestic sewage

  • 摘要: 农村生活污水水质、水量变化较大,传统A2O工艺易受负荷冲击,设施内生物质浓度难以稳定,存在出水水质易波动、运行稳定性差等问题。采用A2O-MBBR工艺、潜流人工湿地及生态塘技术构建了A2O-MBBR+CWs组合工艺,探究了组合工艺实际运行处理效果以及季节性水温变化对其处理效果的影响,并分析工艺的经济性。结果表明:试验装置最大污水处理量为180 L/d,在好氧池气水比6∶1~10∶1及混合液回流比50%~150%条件下,组合工艺对TN、\mathrmNH_4^+ -N、COD和TP的平均去除率分别达68.40%、89.45%、93.94%和94.02%,平均出水浓度为11.69、3.50、26.90和0.22 mg/L,出水水质达到DB 34/ 3527—2019《农村生活污水处理设施水污染物排放标准》一级A标准。A2O-MBBR单元对污染物去除贡献最大,其中折流厌-缺氧接触池对TN、\mathrmNH_4^+ -N、COD和TP去除率分别达44.25%、59.46%、43.38%和32.61%,好氧膜池的去除率分别达9.55%、24.24%、14.69%和59.51%。TP及COD的去除不受季节性水温变化影响,冬季低水温仅影响TN及\mathrmNH_4^+ -N的去除,水温大于12 ℃时,TN、\mathrmNH_4^+ -N平均去除率达75.61%、95.70%;水温低于12 ℃时,TN、\mathrmNH_4^+ -N平均去除率达58.56%、80.40%;即便水温低至0 ℃时,TN、\mathrmNH_4^+ -N平均去除率仍达51.38%、74.77%,该工艺可高效利用污水中的有机物作为碳源,保证了低水温时的脱氮性能。试验期间,组合工艺处理费用约0.46元/m3

     

    Abstract: The rural domestic sewage is characterized by significant fluctuations in both quality and quantity. The traditional A2O (Anaerobic-Anoxic-Oxic) process faces challenges such as susceptibility to load shocks, instability in biomass concentration within the facilities, fluctuations in effluent quality, and poor operational stability. The A2O-MBBR+CWs combined process was developed using the A2O-MBBR process, subsurface flow constructed wetlands, and ecological ponds. In this study, we examined the actual operational treatment performance of the combined process, evaluated the impact of seasonal water temperature variations on its treatment efficiency, and analyzed the economic viability of the process. The results indicated that the maximum sewage treatment capacity of the test device was 180 L/d. Under the conditions of an air-to-water ratio of 6∶1-10∶1 and a mixed liquor recirculation ratio of 50%-150%, the combined process achieved average removal rates of TN, \mathrmNH_4^+ -N, COD and TP were 68.40%, 89.45%, 93.94% and 94.02%, respectively. The corresponding average effluent concentration was 11.69, 3.50, 26.90 and 0.22 mg/L, respectively. The effluent quality reached Grade A of the Discharge Standard of Water Pollutants for Rural Domestic Sewage Treatment Facilities (DB 34/ 3527-2019). The A2O-MBBR unit contributed the most to pollutant removal. Specifically, the removal rates of TN, \mathrmNH_4^+ -N, COD and TP achieved by baffled anaerobic-anoxic contact tank reached 44.25%, 59.46%, 43.38% and 32.61% respectively. Meanwhile, the aerobic membrane tank achieved removal rates of 9.55%, 24.24%, 14.69% and 59.69%, respectively. The removal of TP and COD was not affected by seasonal water temperature variations. Low water temperature in winter only impacted the removal of TN and \mathrmNH_4^+ -N. When the water temperature exceeded 12 ℃, the average removal rates for TN and \mathrmNH_4^+ -N were 75.61% and 95.70%. However, when the water temperature dropped below 12 ℃, the average removal rates for TN and \mathrmNH_4^+ -N decreased to 58.56% and 80.40%, respectively. But even when the water temperatures dropped to 0 ℃, TN and \mathrmNH_4^+ -N removal rates remained at 51.38% and 74.77%, respectively. The process can efficiently utilize organic matter in sewage as carbon source and ensure nitrogen removal performance at low water temperatures. The treatment cost of the combined process was approximately 0.46 yuan RMB per ton of wastewater during the study period.

     

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