复合式MUCT工艺用于城市污水除磷脱氮的研究

采用复合式MUCT工艺在天津某城市污水处理厂进行试验研究,重点考察了该工艺在不同泥龄条件下的脱氮除磷效果。试验结果表明,投加组合填料可以强化系统的硝化性能。在一定范围内,泥龄的降低有利于提高系统除磷效果。当泥龄为8 d时,出水NH3-N、TP的平均质量浓度分别为5.1、0.8 mg/L,TN的质量浓度小于20 mg/L;当泥龄为6 d时,出水NH3-N的平均质量浓度为7.7 mg/L,达到《城镇污水处理厂污染物排放标准》(GB18918-2002)的一级A标准。     

Membrane filtration characteristics in membrane-coupled activated sludge system - the effect of physiological states of activated sludge on membrane fouling

The effect of sludge physiology on membrane fouling was investigated in a membrane-coupled activated sludge (MCAS) system. A series of ultrafiltrations were performed to assess the flux behaviors according to foaming potential, solids retention time (SRT), growth phase and nutrient condition of the activated sludge. The foaming sludge showed greater flux decline than the non-foaming sludge. The extraordinary increase, that is, more than 100 times in membrane fouling for the foaming sludge, was attributed to the hydrophobic and waxy nature of the foaming sludge surface, which was confirmed by a comparison with relative hydrophobicity. Membrane fouling tendency was increased as SRT decreased. A greater flux decline was observed at the endogenous phase than at the log growth phase. The activated sludge acclimated to the nitrogen deficient substrates produced less extracellular polymeric substances (EPS) and exhibited higher flux than the control activated sludge. The quantitative measurements of EPS content in order to estimate the extent of membrane fouling in various activated sludges showed that, in any physiological states of activated sludge, the higher the content of EPS the activated sludge had, the greater the membrane fouling proceeded. The EPS content of activated sludge is suggested as a probable index for the membrane fouling in a MCAS system.     

Comparison of different fluid dynamics in activated sludge system for the treatment of a stimulated milk processing wastewater: Process analysis and optimization

Wastewater from the milk industry usually undergoes activated sludge ahead of refining treatments, final discharge or reuse. To identify the most effective bioreactor hydraulic regime for the secondary treatment of wastewater resulting from the milk industry in an activated sludge system, two lab-scale activated sludge systems characterized by a different configuration and fluid dynamics (i.e., a compartmentalized activated sludge (CAS) with plug flow regime and a complete mixed activated sludge (AS)) were operated in parallel, inoculated with the same microbial consortium and fed with identical streams of a stimulated dairy wastewater. The effect of three process and operational variables??influent chemical oxygen demand (COD) concentration, sludge recycle ratio (R) and hydraulic retention time (HRT)??on the performance of the two systems were investigated. Experiments were conducted based on a central composite face-centered design (CCFD) and analyzed using response surface methodology (RSM). The region of exploration for treatment of the synthetic wastewater was taken as the area enclosed by the COD _in (200, 1,000 mg/l), R (1, 5), and HRT (2, 5 h) boundaries. To evaluate the process, three parameters, COD removal efficiency (E), specific substrate utilization rate (U), and sludge volume index (SVI), were measured and calculated over the course of the experiments as the process responses. The change of the flow regime from complete-mix to plug flow resulted in considerable improvements in the COD removal efficiency of milk wastewater and sludge settling properties. SVI levels for CAS system (30?C58 ml/g) were considerably smaller that for the AS system (50?C145 ml/g). In addition, the biomass production yield could be reduced by about 10% compared to the AS system. The results indicated that for the wastewater, the design HRT of a CAS reactor could be shortened to 2?C4 h.     

长泥龄改良A2/O工艺的短程硝化反硝化除磷

为解决传统A²/O工艺硝化与除磷泥龄(SRT)之间的矛盾,进一步提高低C/N(P)比生活污水同步脱氮除磷效率,采用一种改良A²/O工艺在长SRT条件下处理生活污水.试验结果表明,该工艺可有效筛选和强化反应器内活性污泥,并大量富集长SRT的反硝化除磷菌(DPAO).通过亚硝酸盐氧化菌(NOB)淘洗阶段后,反应器在SRT=19.6d、A²O段污泥浓度(MLSS)=5.5 g·L^-1、水力停留时间(HRT)=8.2 h、污泥回流比(R)=90%、硝化液回流比(r)=250%、溶解氧(DO)=1.5～0.3 mg·L^-1,间歇曝气段HRT=4 h、曝气周期1 h曝气1 min(DO=0.3～0.5 mg·L^-1)、沉淀59 min条件下长期运行,COD、NH₄⁺-N、TP和TN的平均去除率分别为88.71%、99.2%、93.77%和89.52%,出水亚硝化率(NO₂^--N/NO_x^--N)可达97.2%,DPAO占聚磷菌(PAO)比为95.5%.污水中约72.96%的COD被DPAO合成PHA除磷,15.75%的COD由异养反硝化消耗,约41.96%和31.31%的N分别通过反硝化除磷和异养反硝化去除.剩余污泥主要由DPAO和反硝化菌增殖产生,分别占82.74%和17.24%,较传统脱氮除磷途径减少了58.76%的碳源消耗和44.6%的污泥排放.     

厌氧／缺氧SBR反硝化除磷过程的研究

Removal of denitrifying phosphorus was verified in a laboratory anaerobic/anoxic sequencing batch reactor (A/A SBR). The results obtained demonstrated that the anaerobic/anoxic strategy can enrich the growth of denitrifying phosphorus removing bacteria (DPB) and take up phosphate under anoxic condition by using nitrate as the electron acceptor. The phosphorus removal efficiency was higher than 90% and the effluent phosphate concentration was lower than 1mg·L^-1 after the A/A SBR was operated in a steady-state. When the chemical oxygen demand(COD) of influent was lower than 180mg·L^-1, the more COD in the influent was, the higher efficiency of phosphorus removal could be attained under anoxic condition. However, simultaneous presence of carbon and nitrate would be detrimental to denitrifying phosphorus removal. Result of influence of sludge retention time (SRT) on denitrifying phosphorus removal suggested that the decrease of SRT caused a washout of DPB and consequently the enhanced biological phosphorus removal decreased with 8 days SRT. When the SRT was restored to 16 days, however, the efficiency of phosphorus removal was higher than 90%.     

SRT对膜生物反应器出水水质的影响及其控制途径的研究

膜生物反应器中MLVSS为4000-5000mg／L时,COD的去除率可达98％左右,但随SRT的继续延长,污泥浓度的增加,使得内源呼吸加剧和大量微生物死亡,导致上清液COD上升,SMPnd含量增加,出水COD存在波动性,但COD的去除率仍在94％左右。高污泥浓度下的MBR反应器中投加粉末活性炭后,由于粉末活性炭对SMPnd有很强的吸附作用,因此反应器对COD的去除率增加。     

Filterability of activated sludge in membrane bioreactors

The filterability of activated sludge is an important factor for the economical operation of membrane bioreactors (MBR). In the literature mainly investigations on sludge dewaterability in respect to further disposal are published. In this study, a procedure for determining filterability in a crossflow test cell is introduced. Its features are: no increase in sludge concentration during batch trials, crossflow conditions, and little impact on the sludge structure. The activated sludge filterability is given as the ratio of permeate flux after 40 min of operation to clear water flux. Sludge samples of eight different MBR and one conventional wastewater treatment plant (wwtp) have been examined and compared. Contrary to the literature, no impact of suspended solids (SS) concentration, sludge viscosity, or extractable extracellular polymer substances (EPS) concentration on the filterability was found. Instead, the composition of the liquid phase was found to effect most the filterability of activated sludge, a major influence being the concentration of suspended EPS: the higher the suspended EPS concentration, the lower the filtration index. Suspended EPS concentration increases with high mechanical stress in the MBR and high F/M ratios, if the treated wastewater contains considerable amounts of proteins or polysaccharides.     

基于FNA处理污泥实现城市污水部分短程硝化

为实现城市污水短程硝化厌氧氨氧化生物脱氮,以去除有机物的实际污水为研究对象,考察了游离亚硝酸盐(FNA)处理污泥实现城市污水部分短程硝化的可行性。 结果表明,FNA处理活性污泥后,亚硝酸盐氧化菌(NOB)的亚硝酸盐氧化速率下降程度大于氨氧化菌(AOB)的氨氧化速率,且在0～0.75 mg HNO₂-N·L^-1范围内随着FNA浓度的增加抑制作用增强。接种实际污水厂活性污泥后,系统亚硝酸盐(NO₂^--N)积累率仅为1%,即为全程硝化。在控制污泥龄约为15 d的条件下,采用FNA处理污泥可使系统亚硝酸盐积累率增加至90%以上。水力停留时间调至2.5 h时,实现了部分短程硝化,且出水NO₂^--N/NH₄⁺-N平均值为1.24,可满足厌氧氨氧化脱氮反应的要求。因此采用FNA处理污泥,结合水力停留时间和污泥龄控制可实现城市污水部分短程硝化。     

温度对AOA-SBR工艺同步脱氮除磷的影响

为了提高脱氮除磷的效率,采用序批式生物反应器（SBR）工艺处理模拟生活污水,考察了不同温度下N/P、污泥龄（SRT）对厌氧/好氧/缺氧序批式生物反应器（AOA-SBR）工艺同步脱氮除磷效能的影响。结果表明：当温度为10 ℃、N/P为2～3、SRT为20 d时,NH4+-N、TN和TP去除率分别为78%、69%和56%,污泥产率YS为0.339 kgSS/(kgBOD5),污泥含磷率PC为4.68%。当温度为25 ℃、N/P为3～5、SRT为15 d时,NH4+-N、TN和TP的去除率分别为88%、83%和91%,污泥产率YS为0.253 kgSS/(kgBOD5),污泥含磷率PC为6.35%。当温度为35 ℃、N/P为5～7、SRT为10 d时,NH4+-N、TN和TP去除率分别为80%、66%和73%,污泥产率YS为0.225 kgSS/(kgBOD5),污泥含磷率PC为7.42%。污泥产率YS随着温度和污泥龄的增加而降低,通过调节温度和污泥龄能够实现污泥减量。     

Treatment of a combined dairy and domestic wastewater in an up-flow anaerobic sludge blanket (UASB) reactor followed by activated sludge (AS system)

The feasibility of using an up-flow anaerobic sludge blanket (UASB) reactor followed by activated sludge (AS system) for the treatment of wastewater discharged from dairy factory was explored. The UASB reactor was operated at a hydraulic retention time (HRT) of 24 h and organic loading rates (OLRs) ranging from 1.9 to 4.4 kgCOD/m³.d. The average total chemical oxygen demand (COD_total) and total biological oxygen demand (BOD_5total) concentrations of the UASB reactor effluent were 1385 and 576 mg/l, corresponding to percentage removal of 69% and 79%, respectively. Total suspended solids (TSS) and volatile suspended solids (VSS) removal averaged above 72% and 75%, respectively. Residual phosphorous and oil and grease concentrations of the UASB reactor effluent were 8.2 and 44 mg/l, corresponding to percentage removal values of 63% and 83%, respectively. This good performance could be attributed to the relatively long sludge residence time (SRT = 76 d) imposed to the reactor. Total and faecal coliform counts were reduced in the treated effluent by a value of 1.07 and 0.9 log₁₀, respectively. The net sludge yield coefficient was found to be 0.2 g VSS per g COD_total removed per day, corresponding to 20% of the total influent COD imposed to the UASB reactor. The volatile solids / total solids (VS/TS) ratio of 0.66 of excess sludge revealed its good quality. Preliminary batch experiments of the AS system treating UASB reactor effluent indicated first-order removal kinetics between total organic carbon (TOC) and contact time. The TOC removal reached 80%, resulting in only 47 mg/l in the final effluent at a HRT of 2.0 h. Accordingly, the AS system was operated at a HRT of 2.0 h. The system achieved a substantial reduction of COD_total, BOD_{5 total}, TSS and oil and grease resulting effluent quality with residual values of only 35.0, 7.0, 14.0 and 2.8 mg/l, respectively. The geometric mean of total and faecal coliform counts was reduced by a value of 1.28 and 1.64 log₁₀, respectively. Based on these results, it is recommended to use of an integrated system consisting of a UASB reactor followed by the AS system for the treatment of a combined dairy and domestic wastewater to produce a good effluent quality complying with the standards for discharge into agricultural drains.     

多点进水改良型复合A2/O处理低C/N污水

以低C/N比城市生活污水为研究对象,重点考查了改良A²/O工艺的脱氮除磷性能。原水按一定比例分配给厌氧池和缺氧池,以合理分配厌氧释磷和缺氧反硝化所需的碳源;在好氧池和缺氧池中分别投加填料,以稳定系统的硝化和反硝化效果,提高系统的脱氮性能;厌氧池和缺氧池出水都直接进入好氧池。在进水COD/TN平均为5.54,HRT为11 h,SRT为15 d,MLSS为3000～4000 mg·L^-1,污泥回流比为50%条件下,通过三种不同进水分配比以及三种混合液回流比的对比试验研究,得到系统最佳进水分配比5:5,对分配脱氮和除磷所需碳源更加合理;而混合液回流比为200%,过高会破坏缺氧池的溶解氧环境,过低又会导致缺氧池反硝化作用不能充分发挥。在最优工况下COD、NH₃-N、TN和TP出水水质分别为29.7、0.1、11.8和0.42 mg·L^-1,平均去除率分别达到87.8%、99.7%、72.4%和91.3%,出水优于国家GB 18918-2002一级A排放标准,并且在缺氧池中发生了明显的反硝化除磷现象。     

低温下DO对SBR氮磷去除效果与EPS的影响

为了考察低温(7—15℃)下溶解氧(DO)对氮磷去除效果与胞外聚合物(EPS)质量浓度的影响,研究采用序批式生物反应器(SBR)处理屠宰废水。结果表明:混合液悬浮固体质量浓度(MLSS)为3 000 mg/L,在pH值和污泥龄(SRT)分别为6.5—8.0和20 d的条件下,当DO<2 mg/L时,TN和TP的去除率分别保持在79.4%和80.8%,EPS稳定在503.5 mg/L;当DO为2—3 mg/L时,TN和TP的去除率分别为78.5%和89.32%,EPS为544.2 mg/L。当DO为3—5 mg/L时,随着DO的升高,TN去除率逐渐降低至61.77%,TP去除率保持在85.5%,EPS提高至578.4 mg/L。     

改良倒置A~2/O工艺处理低温生活污水技术

生物脱氮除磷系统中磷的去除通过排放剩余污泥实现,需要短泥龄微生物;而硝化细菌为自养菌,需要较长的生长时间。在低温（≤10℃）条件下,硝化污泥泥龄一般为15～20 d,而聚磷菌泥龄为4～5 d,这种巨大的泥龄差距导致现有A2/O在低温下很难实现同时脱氮除磷。本文利用改良的倒置A2/O工艺,研究了低温条件下的生物脱氮除磷效果。结果显示：该工艺低温条件下COD的去除率在85％以上,氨氮去除率低温条件下可达到85%,磷的去除率低温条件下为80%,出水能够达到国家二级排放标准。     

污泥停留时间对微波-厌氧消化联合处理水解酸化残余污泥的影响研究

研究了污泥停留时间( SRT)分别为7、14、28 d时,采用微波-厌氧消化联合处理水解酸化残余污泥的效果.试验同时设置进泥为不经微波处理的水解酸化残余污泥的对照组.结果表明,SRT为14d时微波组SCOD去除率可达最高值84.91％;微波组和对照组在SRT为7、14、28 d的条件下对SS的去除率差异不明显,SRT由28 d缩短至7d时SS去除率仅下降了3.95％; SRT为7、14、28d时,微波组的污泥产甲烷率比对照组的分别高出39.09％、27.48％和26.75％.说明采用该联合工艺处理水解酸化残余污泥在SRT为14d时即可达到较好的效果,同时微波处理可增加水解酸化污泥的产甲烷活性.     

SBR法处理豆制品废水工艺条件的研究

用SBR法处理豆制品废水的试验表明该系统具有较好的抗负荷冲击能力．进水COD在300～2000mg／L之间变化．对系统不造成任何影响;考察了曝气时问、曝气量和污泥浓度等对去除效果的影响。试验结果表明,曝气时间和曝气量对处理效果影响很大．确定该反应系统最佳曝气时间是8h,适宜的曝气量是800L／h,而污泥浓度控制在4000mg／L左右时处理效率最高。采用下进水顶出水的排水方式是可行的,确定系统的最佳排水比是3／5。厌氧段的插入可以减少剩余污泥的产量。     

Cu2+对生物膜及其胞外聚合物的影响

利用自行设计的生物膜培养装置进行挂膜,通过向生物膜反应器中投加不同浓度的Cu²⁺,探讨生物膜上的胞外聚合物（extracellular polymeric substance, EPS）与生物膜去除金属铜之间的关系。研究结果表明：生物膜法较活性污泥法对Cu²⁺具有更好的耐受性;当Cu²⁺ < 2 mg·L^-1,Cu²⁺会抑制生物膜分泌EPS,在2 mg·L^-1 < Cu²⁺ < 5 mg·L^-1时,生物膜分泌EPS的量增加,当Cu²⁺ > 5 mg·L^-1,生物膜系统表现为严重的不稳定性;比较蛋白质（proteins,PN）/多糖（polysaccharide,PS）值发现,Cu²⁺对生物膜的抑制主要是对生物膜上胞外多糖的抑制,而生物膜对Cu²⁺的抵抗表现为分泌更多的胞外蛋白;EPS与Cu²⁺的富集率关系呈线性正相关。     

EPS对活性污泥絮凝沉降性能与表面性质的影响

采用序批式生物反应器（SBR）处理模拟废水,在葡萄糖作为碳源的条件下,调整进水碳源浓度改变系统内EPS含量,考察EPS的变化对活性污泥絮凝沉降性能及其表面性质的影响。结果表明,出水悬浮固体浓度（ESS）愈小,污泥絮体重絮能力（FA）越大,絮凝效果愈好。随着EPS的增加,ESS和污泥容积指数（SVI）升高,FA和ZSV降低,导致活性污泥絮凝性能和沉降性能下降。EPS与ESS呈正相关,EPS与FA呈负相关（R2分别为0.9916和-0.9941）,EPS与SVI呈正相关性,EPS与区域沉降速率（ZSV）呈负相关性（R2分别为0.9451和-0.9805）。同时,EPS的增加对污泥表面性质产生重要影响,EPS的增加导致污泥表面Zeta电位下降,污泥相对疏水性RH逐渐降低。Zeta电位的下降和RH的降低直接引起SVI和ESS增大,导致污泥絮凝沉降性能下降。EPS总量与Zeta电位和RH的相关性系数R2分别为-0.99、-0.9979。     

Membrane bioreactor for treatment of pharmaceutical wastewater containing acetaminophen

Treatment of pharmaceutical wastewater is a real challenge for wastewater engineers. In this study, a pilot-scale system including an external loop airlift membrane bioreactor (ELAMBR) was applied for treatment of a synthetic pharmaceutical wastewater. The performance of this system was evaluated in removal of acetaminophen as the main pollutant of a pharmaceutical wastewater. A conventional activated sludge (CAS process) laboratory system was used in parallel with this system to compare both systems in regard to their ability for acetaminophen removal. The performance of the ELAMBR system was monitored for approximately one month to investigate the long-term operational stability of the system and possible effects of solids retention time on the efficiency of removal of acetaminophen. The removal efficiency was significantly higher in the ELAMBR system than the CAS process. 100% of the acetaminophen was removed after 2 days in this system. The results also showed that initial concentration of acetaminophen, chemical oxygen demand (COD) and mixed liquid suspended solids (MLSS) are the most effective parameters in removal of a pollutant such as acetaminophen. This study demonstrates the usefulness of ELAMBR system for pharmaceutical wastewater treatment with the advantages such as: (i) simple operation and maintenance, (ii) efficient removal of pharmaceutical pollutant and COD and (iii) low-energy consumption.     

Enhanced biological nutrient removal in modified carbon source division anaerobic anoxic oxic process with return activated sludge pre-concentration☆

A pilot-scale modified carbon source division anaerobic anoxic oxic (AAO) process with pre-concentration of returned activated sludge (RAS) was proposed in this study for the enhanced biological nutrient removal (BNR) of municipal wastewater with limited carbon source. The influent carbon source was fed in step while a novel RAS pre-concentration tank was adopted to improve BNR efficiency, and the effects of an influent carbon source distribution ratio and a RAS pre-concentration ratio were investigated. The results show that the removal efficiency of TN is mainly influenced by the carbon source distribution ratio while the TP removal relies on the RAS pre-concentration ratio. The optimum carbon source distribution ratio and RAS pre-concentration ratio are 60%and 50%, respectively, with an inner recycling ratio of 100%under the optimum steady operation of pilot test, reaching an average effluent TN concentration of 9.8 mg·L?1 with a removal efficiency of 63%and an average TP removal efficiency of 94%. The mechanism of nutrient removal is discussed and the kinetics is analyzed. The results reveal that the optimal carbon source distribution ratio provides sufficient denitrifying carbon source to each anoxic phase, reducing nitrate accumulation while the RAS pre-concentration ratio improves the condition of anaerobic zone to ensure the phosphorus release due to less nitrate in the returned sludge. Therefore, nitrifying bacteria, denitrifying bacteria and phosphorus accumulation organisms play an important role under the optimum condition, enhancing the performance of nutrient removal in this test.     

Activated Sludge Clarification Using an Advanced DAF Process Based on the Down-Flow Floating Cover Filtration

A novel method for the clarification of activated sludge, using sludge blanket filtration, was proposed. The process was tested continuously with activated sludge over 250 days. The proposed process is based on DAF separation, where the mixed liquor is distributed to the surface of the tank, and the clarified effluent is partially recycled with compressed air to the bottom. As a result, a floating blanket of sludge is formed which provides efficient separation of the mixed liquor suspended solids. Various factors, including the extent of sludge bulking, surface loading rate, and the depth of sludge blanket, were evaluated for their effects on the effluent water quality. A pilot-scale study demonstrated that separation by downflow Sludge Blanket Clarification (dSBC) showed better performance than other conventional separation technologies using micro-bubbles, such as DAF. The average effluent solids concentration from dSBC was about 3.0 mg/l, even with a relatively large amount of bulking sludge with a total surface loading of 60 m³/m²/d and air/solids ratio (A/S) of 0.011. This result has not been achievable with either gravitational sedimentation or DAF, even when the total surface loading rate was reduced to 20 m³/m²/d, one third of the value applied for dSBC. Based on these results, the dSBC process may provide a more efficient option for achieving both higher and more stable water quality in an activated sludge system.