低有机负荷下三槽式氧化沟运行参数的调整实践.pdf

低有机负荷下三槽式氧化沟运行参数的调整实践 周淑香 1 曹国凭 2 孙锦程 1 1.唐山市城市污水处理有限责任公司, 河北 063000;2.河北理工大学市政与环境工程系, 唐山 063009 摘要 由于唐山某污水处理厂进水的有机负荷远低于设计运行进水条件, 致使三槽氧化沟运行不正常。 针对这种情 况, 对低有机负荷状态下三槽式氧化沟的运行参数进行了调整, 探索出了低有机负荷状态下三槽式氧化沟的运行模式。 关键词 污水处理 有机负荷 三槽式氧化沟 曝气 污泥负荷 泥龄 0 引言 在进行污水处理厂的设计时 , 水量及污水中 BOD5的含量是其最重要的设计原始数据。但在污水 处理厂的运行中 ,由于种种原因, 实际的进水量与水 质常常会与设计指标相差甚远。唐山某污水处理厂 就因为其原水汇集范围内, 工业企业的迅速增加, 和 居民区的改造、迁移等 , 使污水处理厂进水的有机负 荷远低于原设计进水浓度 。一般设计时 ,出于长远考 虑或是由于对预期水量估计的偏差 ,使得设计水量远 远大于实际进水量; 设计 BOD5浓度大于实际运行的 BOD5浓度 。而实际进水的 BOD5浓度若远低于设计 运行条件 ,会造成许多运行问题。因为进水中有机物 总量的多少直接影响着污水厂运行工艺参数的调整, 过低的有机物总量 ,不利于微生物的培养和驯化; 微 生物极易老化; 进而影响出水水质 。不同的工艺, 处 理低有机底物的方法是不同的 ,对于三槽式氧化沟工 艺,由于曝气方式的特殊性 ,其各项运行参数与正常 情况下的会有较大的差异 。 1 唐山某污水处理厂三槽式氧化沟工艺简况 唐山市某污水处理厂工艺采用由 3 组处理 5 万 t d污水的三槽式氧化沟组成, 按A 2 O 工艺模式 运行 , 见图 1 三槽氧化总底面积约10 000 m 2 , 水深 3. 5 m ,采用转刷表面曝气 ; 排泥泵可分别从中沟和北 边沟排泥。 设计水质 CODCr为 180 mg L , BOD5为 130 mg L 。从 2002 年 7月起, 由于原有的污水管网的 分离 、 改造 ,进入污水处理厂的污水水质有了很大的 变化, 改造后进入氧化沟的污水最初仅有 1. 2 万t d 其中包括3 000 ～ 4 000 t 的造纸厂废水 , 无法维持 正常的运转 , 通过污水管网的重新划分改造 , 到 2003 年10 月份水量增加到 2. 5 万 t d 左右, 此时, 进 水的 CODCr为 290 mg L ,BOD5为 90 mg L。水量仍显 不足, 并且 BOD5明显偏低。为此在原设计运行程序 的基础上, 进行了探索性的调整, 使各项出水指标均 达到了国家二级排放标准 。 运行参数调整后的污水处理厂出水水质见表 1。 表 1 唐山市某污水处理厂进出水水质mg L 项目 CODCrBOD5 悬浮物总氮氨氮总磷 进水2909031830. 28. 31. 81 出水55102220. 57. 00. 37 图 1 唐山市某污水处理厂氧化沟平面概图 2 工艺参数的调整 2. 1 曝气 三槽式氧化沟的 2 个边沟各有 8台转刷曝气机, 中沟 5 台,分列在 4 道梁上, 这些转刷中 ,一部分为双 速转刷 可分别以高 、 低两种转速运行 。现在的运行 方式是以 12 h 为 1 个周期,2 个边沟交替作沉淀池和 曝气池 ,运转时曝气 4 h; 延时曝气 1 h 边沟各曝气 5 h ; 预沉 1 h ; 随后出水 6 h,中沟曝气 12 h,经计算, 每1 组三槽式氧化沟的曝气时间为总量的 61。原 来的运行程序是根据设定的氧化沟中溶解氧值,由自 控程序控制转刷逐台开启 。在运行时,由于有机底物 浓度低 ,用这种控制方式 ,在氧化沟内的活性污泥还 没有充分被搅动起来时, 溶解氧就达到了设定值, 转 刷便不再继续开启 ,因此 ,氧化沟内的活性污泥全逐 22 环 境 工 程 2006年 8 月第24 卷第4 期 渐沉降下来,并且越沉越多,最后形成沉积性的死泥。 减小了氧化沟的有效工作容积。并由于污泥状态不 好,出水水质也不理想 SS 一般在30 mg L以上 ,CODCr 在100 mg L 左右 。 对这种情况进行了曝气量的简单分析和计算 每天去除 BOD5为 25 000 m 3 d 90 mg L - 10 mg L 1 000 2 000 kg d 去 除 N 为 25 000 m 3 d 30. 2 mg L - 20. 5 mg L 1 000 242. 5 kg d 需氧量 [ 3] O2 O2Q S a-Se 1 -e -kt-1. 42Px VSS SS 4. 6Q No-Ne-0. 56Px VSS SS -2. 6QΔ NO - 3 式中 Q 进水量 m 3 d 为 25 000 ; Sa 进水 BOD5 mg L 为 90 ; Se 出水 BOD5 mg L 为 10 ; k BOD5速率常数 d -1 为 0. 23[ 3] ; t BOD5实验天数 d 为 5 ; Px 剩 余 污 泥 排 放 量 kg d 为 1 565. 7 kg d ; VSS SS 污泥中挥发性固体百分数 据 检测为 35 ; No 进水总氮浓度 mg L 为 30. 2 ; Ne 出水总氮浓度 mg L 为 20. 5 ; Δ NO - 3 还原的硝酸盐氮浓度 mg L 为 11 。 则O2 2 242. 1 kg d 每台转刷标准供氧量 72 kg h, 经有效系数校验 后,实际供氧量约为 72 0. 7 50. 4 kg h 根据实际情况 ,对转刷的开启方式进行了调整, 转刷由溶解氧控制改为时间控制。在边沟由沉淀池 转为曝气池时, 8台转刷全开10 min,充分搅动池底部 的活性污泥 ,然后再交替开启其中的 4 台转刷 ,以保 持污泥的悬浮状态。 由于转刷开的较多, 氧化沟内的溶解氧也居高不 下,曝气池的 DO 值在 8 mg L 以上 ,沉淀池在 4 mg L 以上, 由于过高的溶解氧易使污泥老化 , 并且会提高 运营成本 ,为此 ,根据实际进水情况 ,在水量比较少的 时段 ,将一部分高速转刷间隔地变为低速运行 。实践 证明这样运行可以降低一部分溶解氧, 但是如果低速 转刷的运行时间过长 ,溶解氧反而会不降反升 。分析 原因, 是由于活性污泥再次下沉, 导致污泥不能与污 水充分接触 ,微生物不能进行充分的呼吸作用有关。 因此对于氧化沟工艺, 在低有机底物状态下 ,不能按 常规经验控制溶解氧 如 2 mg L ,而应以不使污泥沉 降,作为转刷曝气运行的基本控制条件。 2. 2 污泥的絮凝性 氧化沟中的污泥浓度 MLSS 大约在 200 mg L 左 右,边沟为2 400 mg L, MLVSS MLSS ≈35, 沉降比 SV 在 4左右 , 污泥指数 SVI 值不到 20 mL g 。按一般情 况,如此低的污泥指数,会致使污泥的絮凝性较差 ,很 难保证出水水质 。但是实际效果却不是如此 ,现实情 况只是出水的悬浮物略高 22 mg L , 但不超标。下 面从几个指标对其进行探讨。 2. 2. 1 BOD5污泥负荷 F M F M QSa XV 25 000 90 35 000 0. 61 2 267 0. 046 kg kg d 式中 Q 污水流量 m 3 d; Sa 原水的 BOD5浓度 mg L ; V 曝气池容积 10 000 3. 5 35 000 m 3 ; X 混合液悬浮固体平均浓度 2 0002 2 400 3 2 267 mg L ; 0. 61 氧化沟的曝气时间百分数 。 由上述计算可以看出 , 在低有机底物状况下, Q 和Sa较小,所以其污泥负荷要比正常状态下的三槽 式氧化沟工艺的污泥负荷低, 要维持一定的负荷率, 就必须保证较低的悬浮液固体浓度, 但是2 000 mg L 应该是底线 ,通过,现场实际悬浮液的量筒实验,低于 2 000 mg L ,絮凝沉淀效果不佳 ,很难保证污泥的絮凝 沉淀性,从而影响出水的水质 。因此, 本工艺将悬浮 液固体浓度控制在2 400 mg L。 2. 2. 2 泥龄 氧化沟工艺的泥龄一般控制在 18～ 30 d, 按 30 d 计,则氧化沟 1 d 排污泥量为 ΔX VX θ 35 000 2 267 30 1 000 2 644. 8 kg 其中含挥发性污泥 VSS 约占 35 2 644. 8 0. 35 925. 7 kg 而实际上按此量排泥, 污泥浓度会越来越低。按 23 环 境 工 程 2006年 8 月第24 卷第4 期 BOD5的总量及污泥转化率计算,生成的挥发性污泥为 Δ X Y Sa-Se Q -KdVXV 式中 Sa 进水 BOD5 mg L 为 90 ; Se 出水 BOD5 mg L 为 10 ; Y 产率系数 取 0. 73; Kd 活性污泥自身氧化率 取 0. 075; V 有效曝气池容积 10 000 3. 5 0. 61 21 350 m 3 ; XV 挥发 性污泥浓 度 2 267 0. 35 793. 5 mg L 。 每天应排的干泥量 189. 4 0. 35 541. 1 kg ; 排泥量应为 按含水率 p99. 8计 ; 总重 水重 干泥重 ; 总重 270. 6 t 。 可见每天的排泥量是很少的 , 由于所用系数 Y 是生活污水经验值, 与厂实际污水水质有着较大的差 异,并且进水的 BOD5是每天 6 个瞬时化验值的加权 平均值,与实际情况比偏低。因此, 现在按每天大约 600 m 3的曝气池混合液量排泥 , 含水率 99. 8, 泥 龄为 θ VX ΔX 35 000 2 267 600 2 267 58. 3 d。实践证明 ,在如此长的 泥龄里 ,还是可以维持一定的污泥浓度并保持活性 的,在这种条件下,由于可以生长更多种类的微生物, 因此可降解某些不易降解的有机物 。但是另一方面, 由于泥龄过长, 微生物长期处于衰亡期, 污泥老化 ,结 构松散,结果导致了 SS 不易沉淀 。 3 结论 1 曝气 应按不是污泥沉淀为标准, 不能按氧 化沟中的 DO 值来操作转刷 。 2 氧化沟中的污泥浓度 MLSS 应按污泥的 沉淀性来控制。 3 问题 泥龄太长,微生物长期处于衰亡期 ,污 泥老化,结构松散; 曝气量过大 ,不节能。我们希望本 文能对有类似情况的污水处理厂有所启示,共同探索 低有机底物状态下三槽式氧化沟的科学运行模式 。 参考文献 [ 1] 李军, 杨秀山, 彭永臻. 微生物与水处理工程. 北京 化学工业出 版社, 2002. [ 2] 张自杰等. 排水工程. 北京 中国建筑工业出版社, 2003. [ 3] 汪大等. 水处理新技术及工程设计. 北京 化学工业出版社, 2001. 作者通讯处 曹国凭 063009 河北省唐山市新华西道 46 号 河北 理工大学建工学院 2005- 09-05 收稿 上接第 21页 3 中温 UASB 反应器对高浓度皂素废水进行接 种驯化时, 启动期 CODCr容积负荷为 0. 2 kg m 3d , 水力停留时间为 24 h 。完全启动用了 100 d 左右, 相 对较快。 4 UASB 提高负荷阶段,在温度、 pH 值等影响因 素相对稳定的情况下, 控制进水的有机负荷尤为重 要,负荷提高幅度太大,容易造成挥发酸积累 ,此时需 要减小有机负荷或投加纯碱的方法来加以调节。 5 该工程总设计处理规模为 120 m 3 d, 工程总 投资为150万元, 运行电耗为 1. 55 元 m 3 ,主体工艺的 直接运行成本为 2. 65 元 m 3 。 参考文献 [ 1] R. E. 斯皮思著. 李亚新译. 工业废水的厌氧生物技术. 北京 中国 建筑工业出版社,2001. [ 2] 贺延龄. 废水的厌氧生物处理. 北京 中国轻工业出版社, 1998. [ 3] 张自杰主编. 排水工程 第四版 . 北京 中国建筑工业出版社, 2000. 作者通讯处 陆晓华 430074 湖北省武汉市 华中科技大学环境 科学研究所 电话 027 87792159 E -mail lxhhust -esri. com 2005- 08-22 收稿 24 环 境 工 程 2006年 8 月第24 卷第4 期 TEST OF AmOnINTEGRATIVE BIOREACTOR FOR WASTEWATER TREATMENT Liu Changqing Zhang Yalei Zhao Jianfu et al7 Abstract The bench-scale study on AmOnintegrative process was discussed. The result shows that AmOnintegrative process has high efficiency of removing CODCrand nitrogen, and the concentration of CODCr, NH3-N and TN in effluent reaches the national effluent ernission standard. AmOnintegrative process has widespread prospect for application and high value for further research. But the process has poor efficiency on TP removal, and it will be improved by equipment and technique modification next time. Keywords wastewater treatment, AmOn, integrative bioreactor and N P removal ENGINEERING PRACTICE OF TREATING CHEMICAL WASTEWATER BY THE HYDROLYSIS A O PROCESSLi Tong Yin Ailing Wang Yongqing 10 Abstract Lanzhou Petrochemical Company used the hydrolysisacidificationA O new process to treat chemical wastewater. After treatment, BOD5 CODCrof wastewater wasincreased from 0. 2 to 0 . 37 and the biodegradability of chemicalwastewater was raised. After treating the chemicalwastewater by facultative -aerobic microbes, the CODCrremoval rate was about 85 and NH3-N removal rate was about 85. Keywords chemical wastewater, wastewater treatment, hydrolysis acidification andA O treatment process TREATMENTOFHIGHCONCENTRATIONSLAUGHTERHOUSEWASTEWATERWITH ANAEROBIC UASB AND COAGULATION SEDIMENTATIONGuo Yongfu Chu Jinyu 12 Abstract The process of UASB reactor and coagulation -sedimentation was used to study treatment of high concentration slaughterhouse watewater. With UASB reactor to treat slaughterhouse wastewater, the volume load of CODCrcould reached 6. 8g Ld , and the removal rate of CODCrwas about 93. A certain quantity of poly -ferric sulfate and auxiliary agentMZ was added to the effluent of UASB, the experimental results showed the effluent of slaughterhouse wastewater system could be up to the second order of “ Discharge Standard of Water Pollutants for Meat Processing Industry” GB13457 -92. Keywords slaughterhouse wastewater, UASB, coagulation sedimentation and granular sludge TREATMENT OF WASTE WATER OF EXTRACTING SODIUM AESCINATE Su Hong Zhang Xiaojie Chang Xianbo 15 Abstract There are starch, pigment and pectin in the waste water of extracting sodium aescinate. Sodium aescinate in the extractant is easy to foam and difficult to be reclaimed and treated. The concentration of synthetic waste water was reduced by foam inhibitor YP -1, and was used to treat and recover residual effluent, thus reducing the concentration of the synthetic wastewater. The CODCrof effluent was less than 100 g L, which couldmeet the national discharge standard by three hours treatment of hydrolytic acidification and six hours treatment of aerobic biotreatment. Keywords waste water of sodium aescinate, hydrolytic acidification and treatment of waste water USING OXYGEN -LIMITED ANAEROBIC BIOLOGICAL DESULPHURIZATION PROCESS TO TREAT MOLASSES DISTILLERY WASTEWATERXie Qinglin Li Yawei Li Lifang 17 Abstract The molasses distillery wastewater, one of the typical high -concentration organic watewater with high sulfate, was treated using oxygen -limited anaerobic biological desulphurization process. The sulfate in molasses distillery wastewater was firstly reduced into sulfide by sulfate reducing bacterium SRB. Then, the sulfide ed in the er stage was oxidized biologically into sulfur with colorless sulfur bacterium CSB under oxygen -limited condition, inwhich the sulfide poisonous influence on methanogenesis could be eliminated. The experimental results showed that this process had a remarkable desulphurization effect. Keywords oxygen -limited anaerobic process, sulfate -reducing, biological desulphurization and molasses distillery wastewater DESIGN, DEBUGGINGANDOPERATIONOFSAPONINWASTEWATERTREATMENT PROJECTDanJinfeng Yuan Songhu Liu Lixiang et al 20 Abstract It is introduced the practical engineering of treating saponin wastewater by combination of inner -electrolysis, UASB, anaerobic, aeration and advanced treatment, and the quality of the effluent confirms to the first class of “ Integrated Discharge Standard of Wastewater” GB8978 -1996. The debugging and operation of the system are introduced as well. Keywords inner -electrolysis, UASB, anaerobic, aerobic and saponin wastewater THE ADJUSTED PRACTICE OF OPERATIONAL PARAMETERS OF THREE -TANK OXIDATION DITCH UNDER LOW ORGANIC LOADINGZhou Shuxiang Cao Guoping Sun Jincheng 22 Abstract Because the organic loading of the influent of a wastewater treatment plant on the east outskirts of Tangshan is far below the design 2 ENVIRONMENTAL ENGINEERING Vol. 24,No. 4, Aug . , 2006 standards, the ditch can not operate regularly. According to the condition, the working parameters of the ditch are adjusted to the pattern under the low organic loading and the operational pattern under this situation is also found out. Keywords wastewater treatment, organic loading , three -tank oxidation ditch, aeration, sludge loading and sludge residence time TREATMENT OF LEACHATE BY IMMOBILIZED MICROORGANISMS TECHNOLOGY Xiao Meilan Ye Zhengfang Ni Jinren et al 25 Abstract A full -scale plant of leachate treatment by immobilized microorganisms technology was built with a capacity of 60 m3 d. The running results showed thatwhenCODCrand ammonia -nitrogen of the influentwere about 1980 mg L and820mg L respectively, the effluentCODCr and ammonia -nitrogen were 130 mg L and 0. 80 mg L. The results also indicated that this technology had an ablity to resist loads fluctuating. Microorgannism especially the nitrobacteria was never restrained by the variation of the influent quality. Keywords immobilizedmicroorganisms, biological aerobic filter bed BAF system, leachate and high ammonia -nitrogen APPLICATION OF PROCESS OF USRIOD IN TREATMENT OF PIG FARM WASTEWATER Zheng Yuyi 27 Abstract The process of USR and IOD was used to treat the pig farm wastewater in an engineering example. Its design parameters and operationwere introduced. The monitoring results of completed engineering approval show that all effluent pollutant indices can meet the requirements of the Professional Discharge Standard. Keywords USR, IOD and livestock wastewater MIXINGTREATMENTTECHNOLOGYFOR LIVESTOCKANDPOULTRYCULTIVATION WASTEWATERDeng Shihuai Li Yuanwei Zheng Renhong et al 29 Abstract Aiming at the problem of high contents of CODCr, NH3-N and SS in wastewater, a combined process of airfloat-ABR -CASS- constructedwetland and ecological pond was used. Result showed that the contents of CODCr, NH3-N, SS of treatedwastewater couldmeet the first- level discharge criteria in GB8978 -1996. Keywords livestock and poultry cultivation wastewater, technique and discharge standard EFFECT ANALYSIS OF OPERATIONPRACTICE IN THE SEWAGE TREATMENT PLANT USING DAT-IAT PROCESSSu Qingyong Chu Jinyu 31 Abstract DAT -IAT process is used in a sewage treatment plant of Tianjin Economic and Technical Development Zone. The operating effect in both summer andwinter was compared and the removal effect of organic matter in both DAT tank and IAT tank was analysed. The discovery shows that the removal effect of CODCrand BOD5was almost the same in summer and winter. The removal effect of BOD5was much more complete. The removal rate of BOD5in DAT tank would make an unfavorable influence towards removing phosphorus and nitrogen. Keywords DAT -IAT, sewage treatment plant and removal effect INVESTIGATION ON PURIFYING TOLUENE WASTE GAS IN BIOTRICKLING FILTERS UNDER THERMOPHILIC CONDITIONSWang Juan Zhong Qin Li Jianlin 34 Abstract The objectives of this research were to investigate the potential to biologically treat toluene waste gas at thermophilic conditions and to examine the dominant strains to degrade toluene at high temperatures. The results showed that the dominant strains had poor adaptation to toluene gasafter cultured in toluene liquid. The biofilm edinpacking of a biotrickling filter BTFtendto stabilization after 120 h～ 140 h. The removal efficiency was highest at 40 ℃, and then at 30 ℃, 50 ℃, 60 ℃. The average removal efficiency were 82. 7, 74. 8, 59. 5and 55. 9. The dominant strain was bacillus and ball bacterium, of which the bacillus grew easier on the packing, but ball bacterium had good adaptation under thermophilic condition. New by -productwas found when the temperature was above 40 ℃. Keywords biotrickling filter BTF , thermophilic, toluene, treating waste gas and volatile organic compounds VOCs DUST COLLECTION OF HIGH -TEMPERATURE PURIFIED REACTION PRODUCT OF SMOKE BY INCINERATING REFUSESMei Hongsheng ChenDezhen Lin Yu et al 36 Abstract Removing the acidic gases in the flue gaswith lime particles at high temperature and separating the reaction product immediately benefit the operation of incinerator and improves its safety and economy. It was researched the separation efficiency of reaction product from a cyclone and the variation of particulate size distribution of lime particles by a Stairmand type model atmedium and hightemperatures. Experimental results showed that agglomerations happened among li