重力出流式膜生物反应器污泥浓度的优化控制

采用重力出流式膜生物反应器(Membrane Bioreactor, MBR)工艺对生活污水进行了实验研究. 重力出流式MBR是利用液位水头重力驱动出水,整个系统结构紧凑,操作简便. 结果表明,随着污泥浓度增大(3.9~18.4 g/L),同样的曝气强度对膜表面滤饼层的剪切能力降低,膜通量下降;污泥粘度从5.4 mPa×s上升到680 mPa×s,相应的污泥中的传氧系数与清水中的传氧系数之比a从0.89降到0.10. 因此,从提高膜通量、氧传递速率和降低能耗的角度出发,将MBR的污泥浓度控制在适当范围是非常必要的. 此外,当污泥浓度大于4.8 g/L,污泥浓度的提高对有机物的去除、硝化以及反硝化速率的提高没有明显的贡献. 因此,从MBR的处理能力和运行能耗的双重影响确定MBR的最佳处理污泥浓度值为4~6 g/L,在该浓度区间,生物反应器系统对冲击负荷有较好的抵御能力,同时系统的运行能耗也较低.     

膜生物反应器中微生物特征与膜污染的相关性

采用Anoxic/Oxic(A/O)工艺的浸没板式膜生物反应器处理城市生活污水。以PCR-DGGE和FISH等分子生物学方法对系统中的微生物学特性与膜污染的相关性进行了研究。结果发现:当MLSS为1.10×104mg/L时,占据最大体积分数的污泥颗粒的直径为47.75μm,小于2μm的微粒子体积分数为1.01%,同时,动胶菌比例达到最高值36.5%,膜组件操作压力达最低值4.5 kPa;而MLSS为2.05×104mg/L时,占有最大体积分数的污泥颗粒直径为24.54μm,小于2μm的微粒子体积分数为2.07%,动胶菌占全菌的比例为最低值15.5%,同时膜组件的操作压力大于17 kPa。结果表明,具有较佳的菌群多样性和较高比例动胶菌的活性污泥中,菌胶团的颗粒较大,且易造成膜孔堵塞的微小粒子相对较少,致使膜组件的操作压力降低。研究显示膜生物反应器中的微生物学特性也是膜污染的重要影响因素之一。     

Mathematical modeling of aerobic membrane bioreactor (MBR) using activated sludge model no. 1 (ASM1)

Activated sludge model no. 1 (ASM1) was applied to an aerobic membrane bioreactor (MBR) treating dilute municipal wastewater. The model for the aerobic MBR was calibrated using the data collected from a lab-scale aerobic MBR using AQUASIM 2.0. The performance of MBR process in terms of chemical oxygen demand (COD) removal and ammonia nitrogen (SNH) nitrification was studied at different operating conditions such as hydraulic retention time (HRT), solid retention time (SRT) and mixed liquor suspended solids (MLSS) concentrations. The characteristics of influent wastewater, pre-settled primary effluent from a wastewater treatment plant (City of Elmhurst WWTP, Elmhurst, IL, USA), were determined in the laboratory and used for the calibration of the model. The results from the simulations provided a better understanding of the mechanisms and kinetics of the MBR process including sludge removal.     

污泥转移SBR工艺中EPS对生物除磷的作用

采用新型强化生物除磷工艺--污泥转移SBR处理合成废水,探讨胞外聚合物（EPS）在工艺强化除磷过程中的作用。当污泥转移量为0、15%及30%时,污泥中的EPS含量分别为（108.14±9.68）mg·（g MLSS）^-1、（128.17±1.45）mg·（g MLSS）^-1和（123.35±22.98）mg·（g MLSS）^-1;工艺的除磷率分别为82.14%±0.85%、96.35%±1.25%及98.99%±0.98%,反应末端EPS中TP含量占污泥中TP的比重分别为27.9%±2.55%、57.23%±2.33%和63.88%±2.87%。此外,污泥中EPS在该工艺的好氧吸磷过程中吸磷量分别为（2.04±0.32）mg·（g MLSS）^-1、（5.90±0.38）mg·（g MLSS）^-1和（6.00±0.52）mg·（g MLSS）^-1,在污泥吸磷量中的贡献率均达到90%以上。研究结果表明：污泥转移SBR工艺中随着污泥转移量的增大有利于提高EPS中的磷含量,从而提升了工艺的除磷性能,EPS在该工艺的吸磷过程中起主要作用。但污泥转移对污泥中EPS含量影响不显著。     

印染-生活混合废水PVA生物处理工艺研究

采用PVA生物处理工艺对印染-生活混合废水进行处理,研究PVA工艺处理该废水的可行性.试验结果表明:经过45 d运行,PVA工艺容积负荷提高至3.0 kg [CODcr]/(m3·d),废水CODcr降低至120 mg/L以下,NH3-N降低至3 mg/L以下,色度降低至30倍以下.运行期间污泥产率仅为0.02 MLSS/CODremoved,系统基本无污泥外排.SEM研究发现PVA凝胶小球表面和内部的微生物通过自我氧化抑制污泥产量是此工艺具有良好污泥减量效果的根本原因.     

基于MFC电场强化的MBR膜污染控制

将膜生物反应器(MBR)与微生物燃料电池(MFC)相结合,设计了一种MFC-MBR耦合工艺。对不同运行条件下MFC电场对MBR运行的影响与常规MBR(CMBR)工艺进行了对比。结果表明:以污水为基质的MFC产生的生物弱电场能有效控制膜污染速率,抑制不可逆污染。在不同污泥浓度下,MFC电场对于控制松散胞外聚合物(LB-EPS)中多糖类小分子污染物具有明显的优势,但对紧密胞外聚合物(TB-EPS)的控制并不明显。附加电场后,污泥zeta电位的绝对值分别降低2.7、7.1和4.1 mV,并促进了丝状菌的生长,使污泥絮凝性增强,污泥粒径变大。     

超声波破碎联合ClO_2氧化污泥的效能研究

采用先超声波对取自SBR的剩余污泥进行物理破碎,然后投加ClO_2进行化学氧化溶胞破解污泥,通过单因素试验考察主要影响因素对污泥破解效果的影响;通过正交试验研究超声波联合ClO_2对剩余污泥细胞破解的效率,得出各主要因素的影响规律及最佳污泥破解条件。结果表明,污泥上清液各相关指标的变化幅度与声能密度、ClO_2投加量正相关,但随着时间的延长及ClO_2投加量的增加,变化幅度趋缓。最佳处理条件为:超声波声能密度为1.0 W/m L,作用时间为6 min,ClO_2投加量为6 mg/g[干泥],能使SCOD增幅达2 213%,TN增幅达203.67%,TP增幅达827.08%,MLSS减幅达6.48%。     

污泥负荷对UBF处理农村污水的影响

研究了在常温条件下不同污泥负荷对UBF反应器污水处理性能的影响。结果表明在进水浓度为1200 mg/L、水力停留时间（HRT）为10 h、污泥负荷为0．59 kg COD/kg MLSS·d时,UBF对COD的去除效果最佳,达80．14％;在污泥负荷达到1．01 kg COD/kg MLSS·d之前,污泥中生物量比例随着污泥负荷的增加而增加,MLVSS/MLSS值可达0．89;UBF反应器对污水可生化性有较好的改善效果,BOD5/CODCr比值增幅可达28．52％,且低污泥负荷更有利于污水可生化性的改善。     

Performance evaluation of a modified anaerobic/anoxic/oxic (A/O) process treating low strength wastewater

A full scale modified A²/O process which combined pre-anoxic selector and the staging strategy treating low strength wastewater was investigated. In South China, domestic wastewater is always low in strength due to the high level of groundwater and setting of septic tank at the beginning of wastewater collection system. The results suggested that inadequate denitrification could result in deterioration of phosphorus removal. In addition, influent phosphorus concentration had effect on phosphorus removal. The pre-anoxic selector in modified A²/O process changed the distribution of nitrogen denitrified in different tanks. Characteristics of 3-stage aeration tanks were also studied. The simplified design of rectangular aeration tank could also perform as plug flow as conventional channel aeration tank. In 3-stage aeration tanks, mixed liquid suspended solid (MLSS) increased from one tank to another, while specific oxygen uptake rate (SOUR) of sludge, chemical oxygen demand (COD) and total phosphorus (TP) removal rate decreased, however ammonia nitrogen (NH₃-N) and nitrate nitrogen (NO₃-N) reaction rate remained constant. Furthermore, high MLSS concentration was not suitable for treating low strength wastewater. Waste sludge discharge could improve removal efficiency of COD, NH₃-N, and TP. Without waste sludge discharge, nitrite accumulated in settler.     

生物预酸化处理明胶废水对活性污泥减量化的作用

明胶废水具有高钙、高COD等特点而难于处理。通过对明胶废水进行生物预酸化处理,研究了活性污泥法处理明胶废水过程中COD去除率、MLSS、MLVSS以及无机灰分的变化。结果表明,经过生物预酸化处理后,明胶废水的p H由11.8降至7.4左右,COD由1 058 mg/L降至671 mg/L。后续活性污泥法处理过程中,与未进行生物预酸化处理相比,MLSS、MLVSS呈明显下降趋势,最终COD去除率达到90%;同时由于反应器维持在较低的p H下运行,避免了曝气生成CaCO_3沉淀,污泥无机灰分减少。生物预酸化处理对污泥减量化有明显贡献。     

PAC投加量对MBR混合液性质及膜污染的影响

比较了1g／L及2g／L的PAC投加量对膜生物反应器中混合液性质及膜污染速率的差异。发现两系统上清液COD差距不明显,说明1g／L的PAC投加量忆足以吸附小分子的有机物。当PAC从1g／L增至2g／L时,从微生物絮体中提取的多糖平均值分别为：14．92mg／gMLSS、15．38mg／gMLSS;蛋白质平均值分别为18．82mg／gMLSS、17．58mg／gMLSS;且膜丝内部累积的多糖和蛋白质含量基本相同。当PAC投加量为2g／L时,部分破碎的PAC颗粒会进入膜孔内部,引起不可逆污染。     

管式膜MBR在印染废水处理工艺中的运行规律研究

以模拟印染废水为研究对象,探讨管式膜MBR在印染废水处理过程中的运行情况.试验结果表明,当MLSS质量浓度为8g·L~(-1)左右,HRT为8h时,管式膜MBR对COD的去除率为82%,对色度的去除率为80%.有机物的去除主要取决于生物反应的效果,膜的截留作用进一步强化了MBR对色度和COD的去除效果.污泥浓度对膜通量的整体衰减程度影响很小,但对初始膜通量的影响较大.     

Microbial growth reduction in sewage sludge by stirred ball mill disintegration and estimation by respirometry

BACKGROUND: Excess biomass generation in wastewater treatment plants is an unavoidable byproduct of the degradation process. Treatment and disposal of sewage sludge from wastewater treatment plants accounts for about half or even up to 60% of the total operating cost. The present study focuses on the reduction of excess sludge generation by engineering the microbes through mechanical energy inputs by means of stirred ball milling. RESULTS: The significant achievement of this study is microbial growth reduction of up to 89% at an applied specific energy of 15301 kJ kg^?1. The degree of disintegration of microbial cells was substantiated by estimating the degree of inactivation (DD_O), degree of soluble chemical oxygen demand (COD) release (DD_COD), particle size and microscopic examination. The effect of disintegration on sludge microbial growth reduction is proved by respirometric studies. CONCLUSIONS: Sludge disintegration employing stirred ball milling is proved to be a worthwhile pretreatment process for reducing the sludge microbial growth in activated sludge treatment processes. Copyright © 2007 Society of Chemical Industry     

活性污泥性质检测方法的比较研究

以印染废水生物处理推流式曝气池中的好氧活性污泥为研究对象,采用污泥沉降比(SV)、污泥浓度(MLSS)、污泥容积指数(SVI)等常规指标检测活性污泥的性质,并与ATP法和TTC-脱氢酶活性法进行了对比.通过比较得出各种方法的适用范围和条件,结果表明:当活性污泥的SV和SVI值变化时,用ATP法能更加准确地反映活性污泥的...     

ABR反应器污泥减量化的研究

采用ABR+生物接触氧化组合工艺处理甲醇模拟废水,通过测定COD、SVI、MLSS、MLVSS等指标,对比考察了ABR和常规厌氧反应器处理有机废水过程中的污泥性能和减量效果。实验结果表明:ABR与常规厌氧反应器相比,其对废水有着更好的处理能力,且抗冲击负荷能力更强,ABR中厌氧污泥的沉降性能更稳定。另外,ABR在稳定运行过程中的无机泥比例更高,能够更好地实现污泥减量化,其中ABR 3#隔室以产甲烷为主的特点使其对污泥的减量化最明显。     

New automatic control strategies for sludge recycling and wastage for the optimum operation of predenitrification processes

Dynamic modelling and simulation is increasingly being employed as an aid in the design and operation of wastewater treatment plants (WWTPs). In this paper a simulation model is used to investigate the control of an activated sludge process. Two different control strategies to optimise nitrogen removal in a predenitrification process are presented, which are based on the control of the sludge blanket height (SBH) or sludge age (sludge retention time, SRT) and mixed liquor suspended solids (MLSS) in the reactor, by adjusting the sludge wastage and sludge recycle flow rates, respectively. It is shown how the recycle and wastage flow rate variables can be employed to continually maintain plant operation in the presence of disturbances. The performance of the control strategies has been assessed by the COST 624 benchmark plant and a pilot plant. The results have shown the robustness of the implementation and the efficiency of the proposed control strategies, which have been operated automatically in a safe, stable and optimum operating point, improving effluent quality and reducing energy costs. Consideration is also given as to how plant operation could be optimised in the long‐term in order to meet the yearly total nitrogen standard. Copyright © 2005 Society of Chemical Industry     

MLSS concentration: Still a poorly understood parameter in MBR filterability

In this paper Membrane Bioreactor (MBR) activated sludge is obtained from full scale MBRs and submitted to cross-flow filtration using always the same membrane and operational conditions. Samples are diluted in order to create suspensions with different Mixed Liquor Suspended Solids (MLSS) concentrations. MLSS values varied between 3.6 and 18.3 g/L. Contrary to literature results filterability did not present a continuous increase with decreasing MLSS concentrations. Activated sludge with MLSS concentration exceeding 10 g/L originated dilution samples with worse filterability. The dilution caused an increase of particles in the range 10 to 20 μm and a decrease in the range 30 to 100 μm. The activated sludge samples had non- Newtonian viscosity and Soluble Microbial Products (SMP) concentrations varied between 60 and 11 mg/L. Activated sludge samples with MLSS concentrations exceeding 10 g/L are entrapping particles smaller than 20 μm in the activated sludge bulk that therefore are not contributing to the increase of resistance on the membrane. Activated sludge samples with lower MLSS concentrations do not show the capability to entrap particles. These different behaviours suggest that are optimal MLSS concentration ranges for MBR operation.     

Critical Review on the Effects of Mixed Liquor Suspended Solids on Membrane Bioreactor Operation

Abstract

One of the characteristics of MBRs is that they typically operate with higher mixed liquor suspended solids (MLSS) concentration than activated sludge with a conventional settling tank. While higher MLSS has obvious benefits in terms of increasing the volumetric loading or the solids retention time, it can have negative impacts on system operation and economics. We critically evaluate three hypotheses on how high MLSS may adversely affect MBR operation:

• (1)?reduced membrane flux with high MLSS,

• (2)?decreased aeration alpha (α) value with high MLSS, and

• (3)?poorer thickening characteristics of excess sludge wasted from an MBR based on the Sludge Volume Index (SVI) and the Capillary Suction Time (CST).

The results support the first and second hypotheses, but not the third. Increasing MLSS decreases the critical permeate flux, but the effect is strong only for MLSS<～5 g/L. For the typical MLSS zone (>～5 g/L), flux‐management techniques to prevent serious cake formation are more important than MLSS. The aeration α decreases with increasing MLSS concentration, although the strength of the correlation depends on system‐specific factors that are poorly understood. Thickening properties of IMBR sludge are not significantly poorer than those of traditional activated sludge, based on available CST tests.     

阻垢剂在含钙污泥减量化中的应用研究

研究了活性污泥处理磷钙废水(采用明胶生产企业排放的磷钙废水)过程中阻垢剂对污泥活性的作用及减量化效果。结果表明,在体积稀释比(磷钙水:自来水)为2:1时,将Ⅱ号阻垢剂按照0.4 mL.L-1的投加量投加到反应器中后,使得钙盐对活性污泥体积指数的压缩性得到缓解,压缩速率减缓69%,从而使得活性污泥絮凝体积有所释放,保持了较好的生物活性,MLSS的值低于未加阻垢剂的反应器,产泥速率可降低60.56%,明显减少了污泥中无机灰分的含量,从而减少了钙泥的产出量,达到钙质废水处理中污泥减量化的目的;同时投加阻垢剂的反应器COD去除率高于未加阻垢剂的反应器,平均可增加16.25%,说明阻垢剂的使用使得污泥活性有所恢复,提高了处理效果。     

新型磷营养药剂在造纸废水生化系统中的实验

在造纸废水生化段投加生物活性磷替代传统磷营养剂,改善了活性污泥SVI,提高了污泥沉降性能,丰富了活性污泥中微生物种类,增强了系统抗高负荷废水冲击能力,生化段CODCr去除率上升1.9%,出口总磷＜0.1 mg/L.