【作者】 许延营；

【导师】 郑西来；

【作者基本信息】 中国海洋大学 ， 环境工程， 2008， 博士

【摘要】 随着水体污染不断加剧,“富营养化”问题日益突出,与此同时,严重的水资源短缺状况要求污水处理后回用。长期以来,在污水处理工程中应用的悬浮污泥和附着污泥工艺各自具有不可克服的缺陷,处理水质也难以达到回用水标准。在此背景下,通过对现有污水生物脱氮除磷理论及工艺进行详细分析,结合悬浮污泥和附着污泥工艺各自的特性,开发了“双泥SBR-BAF复合工艺”,以期能为现有污水处理厂的技术改造及新建污水处理厂的优化设计提供新思路和技术支持。为考察SBR-BAF工艺的运行特性和处理效能,本课题以人工模拟的高浓度城市生活污水为研究对象,结合模型试验和批式试验,对工艺去除污染物的机理进行了初步探讨和分析,考察了进水条件、工艺参数对运行效果的影响,并采用在线检测手段,就应用EC、ORP、DO、pH等水化学参数揭示脱氮除磷过程中的变化规律进行了探讨。首先采用接种城市污水处理厂悬浮污泥的方法对SBR-BAF系统进行启动。SBR-BAF工艺为双污泥系统,聚磷菌呈悬浮污泥生长于SBR反应器,硝化菌和反硝化菌呈附着污泥生长于BAF反应器。根据PAOs（phosphate accumulating organisms）和硝化菌在泥龄上的差异,采用8d的泥龄,在SBR反应器中逐步将硝化菌淘洗出去。经过21天的培养驯化,完成了SBR-BAF系统的启动,此时NH₄⁺-N、TN、TP去除率分别达到83%、71%、80%。继而对SBR-BAF系统的工艺运行条件和工艺参数进行了优化,分析了SBR-BAF工艺的特性和机理。通过分析SBR反应器同一周期内水质连续监测结果和在线测量的EC、ORP、DO、pH值等水化学参数,结果表明:EC数值变化与生物除磷过程中PO₄^3-浓度变化具有很好的一致性;在反应器内尚存在硝化/反硝化反应时,pH值在好氧段和缺氧段的峰值分别是硝化反应开始和反硝化结束的标志;ORP数值在厌氧释磷结束后趋于稳定,但在好氧段没有清晰的的特征点。根据这些结果,将厌氧反应时间和好氧反应时间分别调整为60min、150min。此后分别研究了碳源类型及浓度、pH值、SRT对除磷效果的影响,结果表明:乙酸钠对厌氧释磷的诱导能力高于葡萄糖,但两者对系统最终除磷效果的影响作用无明显区别;生物除磷过程COD/TP应在30以上;对生物除磷过程最适宜的pH范围是7.0⁷.5;对于以除磷为目的的生物处理系统,污泥龄应控制在8¹0天。BAF反应器连续流试验结果表明:最佳气水比为4:1,硝化类型以短程硝化为主,NO₂^--N占到NOx--N的72%;综合考虑对TN的去除率和动力消耗,最佳回流比为200%;最佳缺氧/好氧容积比为3:5;由于短程反硝化较全程反硝化碳源需求量低,在BAF反应器进水NH4+-N 40mg/L左右的情况下,乙酸钠投加量为80mg/L（以COD计）;设定水头损失达到6cm时进行反冲洗,随水温不同,反冲洗周期为17²0d,产水率为98.7%。最后,以上述最佳运行参数控制SBR-BAF系统运行,长期运行结果表明:系统中悬浮污泥的絮凝、沉降性能良好,SV值为22³0,SVI值为58⁸0,不再有污泥膨胀之虞,而且可以对剩余污泥进行重力浓缩,浓缩后污泥浓度可以达到3⁴%;短程硝化和反硝化使得系统可以维持碱度平衡,无需额外补充碱度;系统在高负荷（SBR反应器COD负荷为2.08kgCOD/kgMLSS.d,TP负荷为41.68gTP/kgMLSS.d,BAF反应器NH4+-N负荷为1.16kgNH₄⁺-N/m³.d）、低水力停留时间（SBR反应器9h,BAF反应器1h,总计10h,约为同步脱氮除磷悬浮污泥工艺的一半）下稳定高效运行,对COD（不计BAF加入的外碳源）、TP、NH₄⁺-N、TN的平均去除率为96%、98%、93%、84%,出水COD、TP、NH4+-N、TN、SS的平均浓度为20mg/L、0.23 mg/L、3.24 mg/L、7.68 mg/L、5 mg/L,各项水质指标均达到《城镇污水处理厂污染物排放标准》（GB 18918-2002 ）一级标准的A标准的要求。更多还原

【Abstract】 With the deterioration and eutrophication of water environment, it is essential to treat and reuse the municipal wastewater due to the increasingly severe water resource shortage in China. There are several limitations with the suspended growth and attached growth single-sludge system respectively. Moreover, the effluent quality can’t meet the wastewater reuse standard by means of gravity sedimentation in suspended growth sludge system. Under this background, an innovative two-sludge SBR-BAF process, combining the advantages of suspended growth and attached growth process, was developed to provide new brainstorm for the upgrade of built-up WWTPs （wastewater treatment plant） and the design of new WWTPs.In order to investigate the operation characteristics and removal efficiency of the SBR-BAF process, a series of bench-scale and batch experiments were carried out with synthetic municipal wastewater as influent. The mechanism of phosphorus and nitrogen removal was explored. Meanwhile, the operation and maintenance parameters were optimized by analyzing the wastewater sample quality and online hydrochemical readings such as EC （electric conductivity）, ORP （oxidation reduction potential）, DO （dissolved oxygen）, and pH value.Firstly, the SBR-BAF system was start up by seeding sludge from a municipal WWTP. The SBR-BAF system consists of an anaerobic/aerobic SBR （sequencing batch reactor） and an anoxic/aerobic BAF （biological aerated filter）. The nitrobacteria were elutriated from PAOs （phosphate accumulating organisms） and proliferated within the BAF because of the short 8 days’SRT （sludge retention time） of SBR. On the 21st day, the removal efficiency of NH₄⁺-N, TN, and TP increased to 83%, 71%, and 80% respectively, which meant the accomplishment of sludge cultivation and acclimation.Secondly, the SBR-BAF system was optimized. The characteristics and mechanism of the SBR-BAF process were discussed. The results of batch experiments show that: the variation of EC and PO₄^3- is identical; the peak values of pH in aerobic and anaerobic stage indicate the end of nitrification and denitrification respectively; ORP remains constant after phosphate having been released from PAOs. Based on these results, the anaerobic duration was shortened to 60 minutes, so did the aerobic duration to 150 minutes. The P-release rate is smaller when using the glucose as carbon source than using acetate, however, there’s no difference as for the final TP removal efficiency. Other optimal operation parameters of SBR are as flows: the influent COD/TP ratio more than 30; the pH value ranging from 7.0 to 7.5; the SRT ranging from 8 days to 10 days.The results of continuous experiments with BAF show that: the short nitrification occurs when the Qair/Qinfluent ratio is 4:1 with NO₂^--N accounting for 72% of NOx--N; the suitable recirculation rate is 200%; the ratio of external acetate dose （as COD） to NH4+-N concentration is 2:1 attributing to the short nitrification; BAF needs being backwashed when the headloss increases to 6 cm every 17²0 days; in the water reuse context, 98.7% water yield can be obtained.Lastly, the long-term operation of SBR-BAF system indicates it can treat the wastewater efficiently. The sludge settling characteristic is satisfying with SV varying from 22 to 30 and SVI varying from 58 to 80ml/g.The sludge bulking problem has been avoided successfully. The excess sludge can be thickened to 3%-4 %（ as solid mass proportion）. The alkalinity remains equilibrious between the nitrification and denitrification in SBR-BAF system. The COD and TP loading of SBR are 2.08kgCOD/kgMLSS·d and 41.68gTP/kgMLSS·d, respectively. The NH4+-N loading of BAF is 1.16kgNH₄⁺-N/m³.d. The total HRT （hydraulic retention time） is about 10 hours which is only about half of suspended growth process for simultaneous phosphorous and nitrogen removal. Under the above mentioned high loadings and short HRT, the mean removal efficiency of COD, TP, NH4+-N, TN is 96%, 98%, 93%, and 84%, respectively. The mean effluent concentration of COD, TP, NH4+-N, TN, SS is 20mg/L, 0.23 mg/L, 3.24 mg/L, 7.68 mg/L, 5 mg/L respectively, which means every index can meet the first class （A） of Discharge Standard of Pollutants for Municipal Wastewater Treatment Plant.更多还原