初沉池对污水中无机悬浮固体的影响

随着生物除磷脱氮工艺的大量使用,初沉池的设置和取消一直在学术和工程界存在争议。以重庆市某污水厂为对象,从对无机悬浮固体(ISS)、COD和TN去除效果的角度探讨了初沉池在污水处理系统的重要性。研究结果表明,在合流制排水体制下,该污水厂进水污染物浓度非常高,COD、SS和ISS的平均浓度分别为560、1 100和780 mg/L;初沉池对COD、SS和ISS的去除率分别为61%、78%和85%,对ISS的去除率比COD高20%左右;污水经过初沉池沉淀之后,ISS/COD从1.7下降到0.7左右,COD/TN从8.0左右下降到4.3,粒径由40μm下降到30μm。初沉池对大粒径的ISS具有较好的去除效果,未能被去除的小粒径ISS容易悬浮在混合液中,降低MLVSS/MLSS。从ISS/COD的削减和保持混合液MLVSS/MLSS正常的角度来讲,初沉池不应取消。     

浸没板式MBR处理生活污水造成膜堵塞的关键因素

采用浸没板式膜生物反应器对大学学生宿舍与食堂混合排水进行处理,试验系统应用A/O工艺,设置硝化槽与反硝化槽,日处理生活污水4 m3.当进水ρ(BOD₅)和ρ(COD_Cr)分别为90～450和120～900 mg/L时,出水ρ(BOD₅)和ρ(CODCr)分别为5～25和8～45 mg/L,去除率均较高.同时对膜污染进行了试验研究,阐述了ρ(MLSS),污泥粒径分布以及原水成分造成膜污染的机理.发现污泥粒径分布随ρ(MLSS)变化而发生改变,当ρ(MLSS)达到20.000 g/L以上时,污泥粒径明显减小,同时可导致膜污染的细微颗粒分布相对增高,这一现象得到ρ(MLSS)超过20.000 g/L时膜污染加剧的试验验证.      

Releasing characteristics of phosphorus and other substances during thermal treatment of excess sludge

The releasing characteristics of phosphorus,nitrogen compounds,organics,and some metal cations during thermal treatment of excess sludge were investigated.It was found that during heating not only phosphorus,but also nitrogen compounds,organics,and some metal cations could be released in abundance.The maximum orthophosphate (ortho-P) release of about 90 mg/L in concentration was observed at 50℃in 1 h.Except for volatile fatty acids (VFAs),comparatively little total nitrogen (TN),total organic carbon (TOC),and metal cations were released at the same time.Such results might favor further process of phosphorus recovery.VFAs were considerably released only at 50℃.Acetic,butyric,and propionic acid were the most abundant components in turn and their releasing profiles exhibited good linear relationship with time (R~2=0.9977,0.9624,and 0.8908,respectively).The concentrations of Mg~(2 ) and K~ increased with time and temperature during thermal treatment,but Ca~(2 ) decreased.The release of Mg~(2 ) and K~ agreed well with TP release (R~2=0.9892 and 0.9476,respectively).Temperature in the experimental range had very little impact on the linear relationships, especially of Mg~(2 ).Moreover,the parameter of mixed liquor suspended solids (MLSS) was found to be an important factor for thermal sludge treatment as the released ortho-P and total phosphorus (TP) at 50℃increased more than one-fold when MLSS was increased from 4000 to 8000 mg/L.     

Characteristics of anoxic phosphors removal in sequence batch reactor

The characteristics of anaerobic phosphorus release and anoxic phosphorus uptake were investigated in sequencing batch reactors using denitrifying phosphorus removing bacteria （DPB） sludge. The lab-scale experiments were accomplished under conditions of various nitrite concentrations （5.5, 9.5, and 15 mg/L） and mixed liquor suspended solids （MLSS） （1844, 3231, and 6730 mg/L）. The results obtained confirmed that nitrite, MLSS, and pH were key factors, which had a significant impact on anaerobic phosphorus release and anoxic phosphorus uptake in the biological phosphorous removal process. The nitrites were able to successfully act as electron acceptors for phosphorous uptake at a limited concentration between 5.5 and 9.5 mg/L. The denitrification and dephosphorous were inhibited when the nitrite concentration reached 15 mg/L. This observation indicated that the nitrite would not inhibit phosphorus uptake before it exceeded a threshold concentration. It was assumed that an increase of MLSS concentration from 1844 mg/L to 6730 mg/L led to the increase of denitrification and anoxic P-uptake rate. On the contrary, the average P-uptake/N denitrifying reduced from 2.10 to 1.57 mg PO4^3--P/mg NO3^--N. Therefore, it could be concluded that increasing MLSS of the DEPHANOX system might shorten the reaction time of phosphorus release and anoxic phosphorus uptake. However, excessive MLSS might reduce the specific denitrifying rate. Meanwhile, a rapid pH increase occurred at the beginning of the anoxic conditions as a result of denitrification and anoxic phosphate uptake. Anaerobic P release rate increased with an increase in pH. Moreover, when pH exceeded a relatively high value of 8.0, the dissolved P concentration decreased in the liquid phase, because of chemical precipitation. This observation suggested that pH should be strictly controlled below 8.0 to avoid chemical precipitation if the biological denitrifying phosphorus removal capability is to be studied accurately.     

内循环一体式工艺同步硝化反硝化的研究

文章提出了一种内循环一体式同步硝化反硝化工艺,它是在反应器中加隔板,将反应器从空间上分成好氧区、缺氧区和沉淀区。实验在连续曝气的条件下,对该工艺同步硝化反硝化脱氮的主要影响因素污泥浓度、水力停留时间、碳氮比和反应区内的溶解氧进行研究。结果表明：污泥浓度为4 g/L左右、水力停留时间为4 h、碳氮比为8.3、溶解氧为2.0 mg/L时,反应器内产生了较好的同步硝化反硝化现象,NH4＋-N和TN去除分别达到95.6%和89.3%。     

细微泥沙对污水生化处理系统的影响及其归趋特性

大量运行数据表明,取消初沉池的污水厂泥沙淤积严重、污泥MLVSS/MLSS比值低,严重影响了污水厂的正常运行和功能提升。以取消初沉池后不能被有效去除的粒径≤200μm的细微泥沙为研究对象,通过对比实验的方法研究了不同粒径细微泥沙对污水生化处理系统的影响及其归趋特性。运行结果表明,当在污水中分别投加粒径为26、73、106、165和210μm的细微泥沙300 mg/L时,运行40 d后,生化系统活性污泥的MLVSS/MLSS比值将从启动初期的0.84分别下降至0.27、0.29、0.59、0.65和0.73,且随MLVSS/MLSS比值的下降,混合液SVI值也明显降低,反应器底部淤积泥沙量分别相当于进水泥沙总量的31.0%、47.4%、75.2%、75.9%和91.6%,表明小粒径颗粒更容易被活性污泥包裹,引起污泥MLVSS/MLSS下降,大粒径颗粒更容易淤积在反应器底部;由于泥沙淤积致使颗粒粒径越大,通过排放剩余污泥除砂的量越少,按照粒径递增的顺序,通过剩余污泥外排的除砂量分别相当于进水泥沙总量的44.5%、31.3%、20.3%、20.5%和7.2%。     

污泥脱水性能的关键影响因素研究

针对目前污泥脱水性能影响因素不明的问题,研究通过对SBR在7种运行工况条件下活性污泥胞外聚合物(extracellular polymeric substances,EPS)的提取和测试,并采用SPSS软件分析,探讨MLVSS/MLSS、胞外蛋白质/胞外多糖、胞外蛋白质含量、胞外多糖含量、EPS总含量对污泥脱水性能的影响。研究结果表明,MLVSS/MLSS、胞外蛋白质/胞外多糖是影响污泥脱水性能的关键因素,并建立了脱水污泥含水率和污泥结合水含量的影响因素模型:脱水污泥含水率=0.229×(MLVSS/MLSS)+0.023×(胞外蛋白质/胞外多糖)+0.539、污泥结合水含量=2.876×(MLVSS/MLSS)+0.335×(胞外蛋白质/胞外多糖)-0.012,通过对7个城市污水厂污泥脱水性能测试比较表明,模型对脱水污泥含水率和污泥结合水含量预测值相对误差分别在±1%和±5%以内,对污泥脱水性能预测效果良好。     

Novel strategy of nitrogen removal from domestic wastewater using pilot Orbal oxidation ditch

A pilot-scale Orbed oxidation ditch was operated for 17 months to optimize nitrogen removal from domestic wastewater of average COD to total nitrogen ratio of 2.7, with particular concern about the roles of dissolved oxygen （DO）, mixed liquor suspended solids （MLSS） and return activated sludge （RAS） recycle ratio. Remarkable simultaneous nitrification and denitrification （SND） was observed and mean total nitrogen （TN） removal efficiency up to 72.1% was steadily achieved, at DO concentration in the out, middle and inner channel of 0.1, 0.4 and 0.7 mg/L, respectively, with an average M LSS of 5.5 g/L and RAS recycle ratio of 150%. Although the out channel took the major role in TN removal, the role of middle channel should never be ignored. The denitrification potential could be fully developed under low DO, high MLSS with adequate RAS ratio. The sludge settleability was amazingly improved under low DO operation mode, and some explanations were tried. In addition, a scries of simplified batch tests were done to determine whether novel microorganisms could make substantial contribution to the performance of nitrogen removal. The results indicated that the SND observed in this Orbal oxidation ditch was more likely a physical phenomenon.     

简化MSBR系统污泥量计算方法

第3代MSBR工艺的系统分7个单元，计算污泥泥龄时必须知道系统污泥总量，而在日常运行管理中，一般只须测定对工艺调整起重要作用的3、6单元MLSS质量浓度；对能否利用已测MLSS质量浓度值计算系统平均污泥浓度值进行了初步探讨。     

厌氧反应器与好氧MBR组合工艺中HRT对有机物去除效果的影响

为探讨水力停留时间(HRT)对厌氧反应器与好氧MBR组合工艺处理效果的影响,以印染废水为研究对象,进行了实验室研究.结果表明,在溶解氧(DO)浓度为1.8～2.6 mg/L的条件下,HRT为7.5、4.5和2.5 h时,反应器对COD的去除效率分别为88.7%～96.5%、87.3%～97.2%和81%～92%,出水COD的浓度分别为78.9～51.2、81.6～50.8、93.4～65.8 mg/L.试验同时考察了不同HRT条件下,活性污泥浓度(MLSS)对COD去除率的影响.结果表明,在试验条件下,本工艺中一体化膜生物反应器中最佳污泥浓度应控制在6 500 mg/L左右.