C/N值是保证混合污水(由渗滤液、粪便水和城市污水构成)氮和有机物高效去除的关键。为此,采用A-倒置A2/O法,在水温为25-32℃、SRT为20 d、HRT为10 h、预缺氧池与厌氧池进水流量分配比为6:4、DO质量浓度为2.5 mg/L、外回流比为80%、内回流比为100%的条件下,在混合污水C/N值为2.7-12.8范围内进行了相关实验。结果表明,TN去除受C/N值影响相对明显;低C/N值(3.4-3.9)下,将进水流量分配比增至7:3,可保证出水TN质量浓度达到GB 18918-2002一级B标准;进水C/N值控制在3.4-7.9可保证出水达标排放,相应地渗滤液混入比例为0.02%-0.23%,粪便水混入比例为0.25%-0.63%;为维持系统相对较高的脱氮水平,C/N值最适范围为6.0-7.9。
C/N ratio is critical to ensure the efficient removal of nitrogen and organic compounds in mixed wastewater which consists of leachate, fecal sewage and municipal wastewater. For this reason, the article has conducted the relevant tests in mixed wastewater by utilizing the process of A-reversed A2/O while under the conditions that water temperature raises from 25 ℃ to 32 ℃, SRT is 20 days, HRT is 10 hours, the pre-anoxic phase and anaerobic tank influent flow distribution ratio is 6:4, dissolved oxygen is 2.5 mg/L, external reflux ratio is 80%, internal reflux ratio is 100%, and the C/N ratio ranges from 2.7 to 12.8. The results have shown that TN removal is affected by the C/N ratio obviously. In the condition of low C/N ratio (which raises from 3.4 to 3.9), increasing the infiuent flow distribution ratio to 7:3 can ensure the effluent quality of TN concentration to meet the first class B emission standard of the Discharge Standard of Pollutants for Municipal Wastewater Treatment Plant (GB18918-2002). Also, controlling influent C/N ratio between 3.4 and 7.9 can ensure the effluent quality up to the emission standard, while leachate mixing ratio should be controlled to raise from 0.02% to 0.23% and fecal water mixing ratio is 0.25% to 0.63%, respectively. In order to maintain the relatively high level of systemic nitrogen removal, the optimal value of the C/N ratio should be 6.0-7.9.