Adaptation of the CAS test system and synthetic sewage for biological nutrient removal. Part I: development of a new synthetic sewage

A new synthetic medium has been developed for routine use in laboratory-scale sewage treatment simulation and biodegradation tests, such as OECD guideline 302A & 303A or ISO method 11733. The new medium, Syntho, was designed to meet the following objectives: 1) to be more representative of real sewage than the existing standard OECD synthetic sewage, 2) the COD:N:P ratio and mineral composition must allow a good degree of biological nutrient (N, P) removal, and 3) the medium should result in stable unit operation, including good sludge settling and minimal need for control actions. The IAWQ Activated Sludge Model No. 2 (ASM2,) was used to help design the medium and predict reactor performance for different possible media compositions. The results obtained with Syntho indicate that Continuous Activated Sludge (CAS) units with or without nutrient removal can be operated routinely on this feed. The new medium was also characterized by means of a respiration test. The different influent fractions applied in the model were validated, and a respiration profile indicated that Syntho is a close approximation of real sewage.     

Application of computational fluid dynamics to closed-loop bioreactors: II. Simulation of biological phosphorus removal using computational fluid dynamics.

Based on the International Water Association's (London) Activated Sludge Model No. 2 (ASM2), biochemistry rate expressions for general heterotrophs and phosphorus-accumulating organisms (PAOs) were introduced to a previously developed, three-dimensional computational fluid dynamics (CFD) activated sludge model that characterized the mixing pattern within the outer channel of a full-scale, closed-loop bioreactor. Using acetate as the sole carbon and energy source, CFD simulations for general heterotrophs or PAOs individually agreed well with those of ASM2 for a chemostat with the same operating conditions. Competition between and selection of heterotrophs and PAOs was verified using conventional completely mixed and tanks-in-series models. Then, competition was studied in the CFD model. These results demonstrated that PAOs and heterotrophs can theoretically coexist in a single bioreactor when the oxygen input is appropriate to allow sufficient low-dissolved-oxygen zones to develop.     

活性污泥处理系统的计算机模拟

介绍了以活性污泥1号模型(ASMI)和固体通量沉淀模型为基础．结合反应器原理．用VB6．0计算机语言建立城市污水活性污泥模拟器的方法,探讨了生物反应器和二沉池的模拟工艺流程、各组分的物料平衡关系和欧拉法数值积分的步长选取等问题。模拟器的校准结果表明,该模拟器建立的思路和方法是可靠的．可以用于城市污水生物处理系统的模拟和预测。     

Estimation of autotrophic maximum specific growth rate constant--experience from the long-term operation of a laboratory-scale sequencing batch reactor system

The autotrophic maximum specific growth rate constant, muA,max, is the critical parameter for design and performance of nitrifying activated sludge systems. In literature reviews (i.e., Henze et al., 1987; Metcalf and Eddy, 1991), a wide range of muA,max values have been reported (0.25 to 3.0 days(-1)); however, recent data from several wastewater treatment plants across North America revealed that the estimated muA,max values remained in the narrow range 0.85 to 1.05 days(-1). In this study, long-term operation of a laboratory-scale sequencing batch reactor system was investigated for estimating this coefficient according to the low food-to-microorganism ratio bioassay and simulation methods, as recommended in the Water Environment Research Foundation (Alexandria, Virginia) report (Melcer et al., 2003). The estimated muA,max values using steady-state model calculations for four operating periods ranged from 0.83 to 0.99 day(-1). The International Water Association (London, United Kingdom) Activated Sludge Model No. 1 (ASM1) dynamic model simulations revealed that a single value of muA,max (1.2 days(-1)) could be used, despite variations in the measured specific nitrification rates. However, the average muA,max was gradually decreasing during the activated sludge chlorination tests, until it reached the value of 0.48 day(-1) at the dose of 5 mg chlorine/(g mixed liquor suspended solids x d). Significant discrepancies between the predicted XA/YA ratios were observed. In some cases, the ASM1 predictions were approximately two times higher than the steady-state model predictions. This implies that estimating this ratio from a complex activated sludge model and using it in simple steady-state model calculations should be accepted with great caution and requires further investigation.     

动态污水处理过程的多模型动态矩阵控制

针对活性污泥法污水处理系统的强耦合和动态变化特性,提出一种用于前置反硝化脱氮工艺的多模型动态矩阵(DMC)解耦控制方法;通过K-均值聚类分析法对外界入水中氨氮浓度进行聚类,获得以聚类中心为入水氨氮浓度的静态模型集合,分别设计线性DMC解耦控制器;再以当前时刻外界进水氨氮浓度和聚类中心为基本元素,构造切换函数,实现多模型切换。将该方法应用于活性污泥1号模型(ASM1)中,获得了较好的动态仿真效果。     

高负荷活性污泥法中污水有机组分表征

污水有机组分表征是高负荷活性污泥法(HRAS)模型建立的基础。针对经典活性污泥1号模型不适用于HRAS这一问题,提出了相应的双水解模型,即将污水有机组分中水解型有机物分为快速水解型与慢速水解型2种,发现两者水解动力学参数具有明显差异。对原水氧利用速率进行参数拟合,通过灵敏度和共线性分析,估计了快速生物降解型有机物、快速水解型有机物、慢速水解型有机物以及异养菌等4种污水有机组分,探讨了污水有机组分与增加HRAS碳源捕获率的关系。结果表明：以上4种有机组分均可被准确识别,共线性指数γ_K低于经验限值,各组分比例分别为13.9%、11.6%、12.6%和12.8%;从污水组分角度来说,提高HRAS碳源捕获率的3个方向分别为：反应器中的异养菌尽可能将快速生物降解型有机物和快速水解型有机物同化生成细胞物质;避免絮体污泥中的慢速水解型有机物过量水解;抑制异养菌衰减,减少内源呼吸产物的产生。双水解模型对污水有机组分成功表征有助于HRAS的设计、运行及优化。     

表观气速对好氧污泥颗粒化过程中生化动力学模型参数变化的影响

在高径比120/6,结构相同的2个SBR反应器中培养好氧颗粒污泥,并以修订ASM3模型为基础进行反应过程模拟,并分析表观气速(2.0 cm·s⁻¹和3.0 cm·s⁻¹)对好氧污泥颗粒化过程中动力学参数的影响。结果表明,反应器运行初期(t=4 d),表观气速2.0 cm·s⁻¹时的半饱和系数K_S、基质降解动力学参数v_max、污泥衰减系数K_d、污泥比增殖速率μ_H和污泥的产率系数Y_H均大于表观气速3.0 cm·s^-1时的参数值,说明微生物在表观气速2.0 cm·s⁻¹时更易适应环境变化。然而,随着初始好氧颗粒的形成(t=10~28 d),各参数值在表观气速3.0 cm·s⁻¹时变得更高,尤其对K_S、μ_H及K_d的影响更明显。修订的ASM3可模拟好氧颗粒污泥形成过程中溶解氧DO、好氧速率OUR、COD、NH₄⁺-N的变化,说明模型预测的可行性和有效性。反应器内表观气速不同,影响了微生物生长的各动力学参数和反应器内的流态,从而导致污泥的特性和结构发生了变化,最终使得SV₃₀/SV₅、污泥粒径、污泥密实度D₂和规则程度D_pf,COD和NH₄⁺-N等参数出现差异。本研究结果可为运用数学模型反映生物反应器中参数变化以优化反应过程提供参考。     

快速生物活性测定方法的仪器化

好氧活性污泥法在污水处理中应用广泛.保持污泥活性,是良好处理效果的前提,也是运行控制的主要目标.活性污泥的呼吸速率,或者氧利用速率(oxygen uptake rate,OUR),能够指示污泥的活性变化.本研究开发的快速生物活性测定仪(rapid biological activity tester,RBAT),能够快速测定污泥活性参数,满足工程设计与运行的迫切要求.     

硅藻土固定化颗粒污泥对海水养殖废水除氨性能

针对实际海水养殖废水低碳高氮的特点,采用间歇式活性污泥法(SBR)和好氧活性污泥添加硅藻土载体的方式,考察硅藻土载体和活性污泥共同作用下的好氧曝气系统对海水养殖废水中氨态氮(NH4+-N)、亚硝酸态氮(NO2--N)和化学耗氧量(COD)的去除效果,以及对污泥沉降性能和硝化细菌特征的影响。实验结果表明,常温条件下,溶解氧(DO)≥ 4.5 mg/L,pH控制在7.0 ~ 8.0,HRT为11 h,沉降时间10 min,反应器可以处理NH4+-N浓度在50 mg/L左右的海水养殖废水,NH4+-N和COD去除率分别达到98.93%左右和76.62%以上,NO2--N出水浓度低于0.028 mg/L。载体污泥颗粒照片和扫描电镜结果表明,添加硅藻土载体内核后,颗粒污泥的成熟期缩短,颗粒的稳固度和沉降性能提高。在系统启动成功稳定运行后,通过FISH分析表明,在氨氧化菌(AOB)与亚硝酸盐氧化菌(NOB)成为优势菌群后,AOB大约占总菌群的33.5%,并且AOB与NOB菌群数量约为1:1.33,AOB和NOB两大类菌群之和约占总菌群的77.2%,成为系统中优势菌群。     

Treatment of chemical mechanical polishing wastewater by electrocoagulation: system performances and sludge settling characteristics

Treatment of copper chemical mechanical polishing (CMP) wastewater from a semiconductor plant by electrocoagulation is investigated. The CMP wastewater was characterized by high suspended solids (SS) content, high turbidity (NTU), chemical oxygen demand (COD) concentration up to 500 mgl(-1) and copper concentration up to 100 mgl(-1). In the present study, electrocoagulation was employed to treat the CMP wastewater with an attempt to simultaneously lower its turbidity, copper and COD concentrations. The test results indicated that electrocoagulation with Al/Fe electrode pair was very efficient and able to achieve 99% copper ion and 96.5% turbidity removal in less than 30 min. The COD removal obtained in the treatment was better than 85%, with an effluent COD below 100 mgl(-1). The effluent wastewater was very clear and its quality exceeded the direct discharge standard. In addition, sludge settling velocities after electrocoagulation were measured and the data were employed to verify the empirical sludge settling velocity models. Finally, the sludge settling characteristic data were also utilized to establish the relation between the solids flux (G) and the initial solids concentration.     

Modeling external carbon addition in biological nutrient removal processes with an extension of the international water association activated sludge model

The aim of this study was to expand the International Water Association Activated Sludge Model No. 2d (ASM2d) to account for a newly defined readily biodegradable substrate that can be consumed by polyphosphate-accumulating organisms (PAOs) under anoxic and aerobic conditions, but not under anaerobic conditions. The model change was to add a new substrate component and process terms for its use by PAOs and other heterotrophic bacteria under anoxic and aerobic conditions. The Gdansk (Poland) wastewater treatment plant (WWTP), which has a modified University of Cape Town (MUCT) process for nutrient removal, provided field data and mixed liquor for batch tests for model evaluation. The original ASM2d was first calibrated under dynamic conditions with the results of batch tests with settled wastewater and mixed liquor, in which nitrate-uptake rates, phosphorus-release rates, and anoxic phosphorus uptake rates were followed. Model validation was conducted with data from a 96-hour measurement campaign in the full-scale WWTP. The results of similar batch tests with ethanol and fusel oil as the external carbon sources were used to adjust kinetic and stoichiometric coefficients in the expanded ASM2d. Both models were compared based on their predictions of the effect of adding supplemental carbon to the anoxic zone of an MUCT process. In comparison with the ASM2d, the new model better predicted the anoxic behaviors of carbonaceous oxygen demand, nitrate-nitrogen (NO3-N), and phosphorous (PO4-P) in batch experiments with ethanol and fusel oil. However, when simulating ethanol addition to the anoxic zone of a full-scale biological nutrient removal facility, both models predicted similar effluent NO3-N concentrations (6.6 to 6.9 g N/m3). For the particular application, effective enhanced biological phosphorus removal was predicted by both models with external carbon addition but, for the new model, the effluent PO4-P concentration was approximately one-half of that found from ASM2d. On a PO4-P removal percentage basis, the difference was small, that is, 94.1 vs. 97.1%, respectively, for the ASM2d and expanded ASM2d.     

活性污泥模型研究及其工艺软件的发展

本文综述了活性污泥模型从基于Monod方程的稳态模型到以ASM1、ASM2、ASM3为代表的动态模型的发展过程 ,介绍了各代表性模型的特点并对当前典型的活性污泥工艺软件作了评述 ,提出其研究方向及发展趋势     

常温下IC反应器启动过程中的颗粒污泥性能研究

在常温下用自配葡萄糖废水启动IC反应器,研究了厌氧颗粒污泥的形成过程和特性。IC反应器进水浓度为3 000 mg COD/L,水温为14.5～26℃,25 d内形成了颗粒污泥。结果表明,随着运行时间和容积负荷的增加,颗粒污泥粒径逐渐增大。反应器启动完成后,反应器中2 mm的颗粒污泥增加到6.6%,0.3 mm的颗粒从57.7%减少到39.4%;VSS浓度从24.7 g/L上升到48.2 g/L;VSS/SS从34.4%增加到72.8%。颗粒污泥的沉降速度与颗粒粒径成正比,0.3～3 mm的颗粒污泥的沉降速度介于34.05～109.75 m/h之间,具有良好的沉降性能。初始接种污泥几乎没有产甲烷活性,与第30 d的初期颗粒污泥相比,成熟的颗粒污泥的产甲烷活性提高了46.7%。     

混合碳源的好氧颗粒污泥培养及其除污效果分析

以葡萄糖和乙酸钠为混合碳源,采用调控耗氧有机污染物浓度(以COD计)、表面上升气速和污泥沉降时间的方法培养好氧颗粒污泥,对污泥颗粒化过程中的污泥特性变化和污染物去除效果进行研究.结果 表明:第110天,好氧颗粒污泥培养成功,颗粒粒径主要分布在1.43～2.26 mm,污泥容积指数(SVI30)为28 mL·g-1,沉降...     

低浓度LAS对活性污泥性质和去除污染物行为的影响

采用SBR处理模拟废水,考察了不同浓度阴离子表面活性剂——烷基苯磺酸钠（LAS）对反应器活性污泥的影响。实验结果表明,低浓度表面活性剂LAS的投加,有利于提高SBR中活性污泥对COD和氨氮处理效率,并且活性污泥的沉降性以及微生物活性也随着LAS投加浓度的升高而升高。但是,当LAS的投加浓度过高时（1 mg/L）,污泥表面产生起泡、乳化和微粒悬浮等现象,使大量固体陷入漂浮泡沫层,降低曝气池的充氧效率,最终导致污泥解体,沉降性变差,活性下降。     

Biological solids reduction using the Cannibal process.

A laboratory study of the Cannibal process was undertaken to determine if the Cannibal system would generate less sludge compared with a conventional activated sludge system. Side-by-side sequencing batch reactors were operated--one using the Cannibal configuration and the other as conventional activated sludge. It was found that the Cannibal process generated 60% less solids than the conventional activated sludge system, without any negative effect on the effluent quality or the settling characteristics of the activated sludge. The oxygen uptake rate for the centrate from the Cannibal bioreactor showed that readily biodegradable organic matter was released from the recycled biomass in the Cannibal bioreactor. It is proposed that the mechanism for reduced solids from the Cannibal system is that, in the Cannibal bioreactor, iron is reduced, releasing iron-bound organic material into solution. When the Cannibal biomass is recirculated back to the aeration basin, the released organic material is rapidly degraded.     

微丝菌型污泥膨胀的工艺负荷调控方法

提出调控工艺局部污泥负荷分布来处理污水处理厂冬季微丝菌污泥膨胀。在某AAO工艺污水处理厂开展平行反应器实验,进行显微观测和工艺模拟,发现反应器前端厌/缺氧区污泥去除负荷的差值与微丝菌丰度、污泥粒径和沉降性能有相关性。比较多种运行模式的改善效果,发现AO模式沉降性能最好,优于AAO和多点回流。反应器前端污泥去除负荷梯度可作为调控指标,实验中AO模式负荷梯度可达0.54 kg COD·（kg SS·d）-1,明显高于AAO、多点回流和多点进水。因此,通过优化回流和排泥操作,可以调控污泥去除负荷的沿程分布,有可能缓解冬季的微丝菌型污泥膨胀。     

低碳排放的生物絮凝中试系统污染物去除特性及污泥EPS变化

用中试规模生物絮凝工艺处理含化学絮凝剂的生活污水,分别研究了HRT和进水SS对生物絮凝系统污染物去除特性、剩余污泥产量、污泥特性和温室气体排放的影响。结果表明：生物絮凝系统对COD、TN和TP有较好的去除效果,且污染物去除效果受进水SS影响较大;生物絮凝系统平均污泥产量和平均有机物产量最高可达 53.63 kg·d⁻¹和21.14 kg·d⁻¹;污泥胞外聚合物EPS浓度和PN/PS均与有机负荷呈反比;化学絮凝剂通过影响PN/PS和EPS浓度,可间接影响污泥的沉降性能;生物絮凝系统与AAO工艺相结合,可降低50.12 g·m⁻³温室气体的排放。因此,生物絮凝工艺可为污水处理厂节能降耗运行奠定基础,有望得到广泛应用。     

生物脱氮除磷活性污泥系统复合模拟方法

为避免繁琐的参数校核工作,提出了活性污泥2 d号模型(ASM2d)和人工神经网络(ANNs)相结合的复合模拟方法。考察了复合方法在某污水处理厂生物脱氮除磷工艺中的应用情况。研究表明,ANNs能够准确地模拟出水实测值与未经校核的ASM2d机理模型的估计值之间的差值。利用Levenberg-Marquardt算法,对出水氨氮、总氮和总磷分别建立网络结构为5-12-1、5-8-1和5-8-1的ANNs子模型,将这些子模型输出同ASM2d机理模型输出相加便得到复合模型输出。复合模型估计值对前10.4 d(ANNs子模型训练数据时段)出水氨氮、总氮和总磷浓度的拟合平均绝对百分比误差分别为0.267、0.055和0.048;其对后2.6 d(ANNs子模型测试数据时段)出水氨氮、总氮和总磷浓度的预测平均绝对百分比误差分别为0.332、0.083和0.069。均方根误差、平均绝对误差等评价指标也表明复合模型能够给出合理的模拟结果。     

表面活性剂对污泥脱水性能的影响及其作用机理

研究了阳离子表面活性剂十六烷基三甲基溴化铵(CTAB)和阴离子表面活性剂十二烷基硫酸钠(SDS)对活性污泥脱水和沉降性能的影响,及其改善活性污泥脱水效能的作用机理。结果表明,质量分数8%的CTAB可使污泥比阻(SRF)从8.5×1012 m/kg降为7.5×1011 m/kg,滤饼的含水率降至75%左右,污泥的沉降性能最好,上清液的浊度也较小。相比之下,SDS对污泥沉降、脱水性能的改善效果明显逊于CTAB。实验表明, 表面活性剂主要是通过溶出胞外聚合物(EPS)破坏污泥结构释放内部结合水来加快污泥的沉降速度和提高其脱水性能。