污水模型单一服务区节点流量的日变化模式分析

为了应用管网模型技术对污水系统水力状况进行分析,对模型重要输入条件——节点流量的日变化模式进行了分析研究,从理论结合实践的角度出发,提出分析的详细步骤及方法,包括单一服务区监测节点的选择、流量监测序列奇异点的去除、时变化无因次系数频率分布的拟合及检验,并最终实现了节点流量日变化模式的不确定性表达.通过广州实例研究,获得了5种单一类型污染源节点的日排水变化模式,并通过与国内外同类型污染源排水规律对比,验证了实例获得分析结果的适用性.

基于水动力模型与大数据分析的污水干线优化调度策略

随着我国城市化的快速发展与国家污水处理要求的逐渐提高,城市的污水排水系统越来越复杂。单纯依靠人工经验来进行污水系统的运维与优化调度的难度逐渐越大。文章以上海市白龙港片区污水主干系统为案例,创新性地提出了通过水动力模型耦合历史大数据分析来进行污水干线系统优化调度的技术方案:该方案通过历史大数据挖掘出各个泵站在污水厂不发生溢流情况下的启闭策略,并将此策略放入经过严格率定验证的排水模型中进行评估。目前得到的优化方案通过模拟可以将2021年的白龙港污水厂的旱天溢流天数从现状的58 d降低至50 d。该优化方案于2022年进行了试运行:相比2021年,在试运行的两个月内将旱天溢流总量降低了13%。基于此案例分析,最终总结出一种城市污水主干系统获取优化调度策略的方法。

一类污水处理数学模型的定性分析

污水处理是环境保护的主要内容之一,通过机理分析为污水处理提供理论依据是非常重要的.基于经典微生物和底物的物料守恒的数学模型,通过计算该数学模型的雅可比矩阵,分析了模型平衡点的存在性和动力学性质,给出了模型平衡点稳定的充分性条件,用数值模拟的方法对分析结果进行了有效验证,从数学分析的角度对污水处理过程中参数的设置提出了一些建议,以提升污水处理效果,并用数值模拟验证建议的正确性.

农村生活污水生物处理数学模型研究现状与展望

基于生物处理在农村生活污水处理中的发展历程和目前的应用现状,阐述了其针对农村生活污水处理的过程,体现了适应性强,能实现在线测量、节省人力物力、在农村地区适用性佳等优点。综述了污水生物处理的数学模型研究进展,提出优化模型,增强模型的适应性和动态性是当前主要的研究难点。对于推动农村污水生物处理过程建模、实时观测与控制,实现自动化智能管理的目标具有非常重要的意义。

城镇污水收集系统提质增效对策研究——以某污水处理厂A片区为例

针对研究范围污水量较大,超过用水量,污水水质浓度低及现状污水管网长期高水位运行等问题,对片区内污水收集系统进行排查,通过管网基础信息、污水井液位水质、附近河道水位及水质分析污水收集系统存在的问题,同时构建污水收集系统水力模型模拟现况污水运行情况,最终提出溯源排查和污水系统提质增效方案。

基于BSM1的城市污水处理优化控制方案研究

城市污水处理过程中,降低能耗具有重要意义。基于污水处理1号基准模型(Benchmark Simulation Model No.1,BSM1),设计5组线性自抗扰控制方案,获得了针对污水处理过程的线性自抗扰控制的有效参数整定方法;同时,根据活性污泥法工艺,确定影响污水处理水质和能耗的主要因素,并分析了各种控制方案下的出水水质和能耗,获得了污水处理的优化控制方案。仿真结果表明,在保证出水水质指标的前提下,利用线性自抗扰控制方法合理控制污水处理工艺中的硝化和反硝化反应可有效降低污水处理的能耗,为工程应用提供了思路。

改造国内污水管网系统需要综合考虑的四个因素:定量分析

污水管网外来水入侵、管网污水收集率、市政用水量和污水处理厂处理量是影响城市污水系统和城市水环境质量的四个主要因素。污水系统改造不仅提升污染物收集率和污水管网中污染物(如COD)浓度,同时直接影响到对受纳水体的污染物排放溢流负荷。使用简化的城市污水系统模型和国内外实际数据,定量表征和讨论了四个因素对污水管网污水COD浓度和排放到受纳水体的溢流污染物负荷的影响,并就污水稀释倍数、污水处理厂处理量、污染物去除效率、排放标准和溢流排放负荷之间的多重对应关系进行了分析和讨论,根据国内现状,提出改造和升级污水管网及污水处理厂需要考虑的三点建议。

基于模型辅助优化Carrousel氧化沟工艺除磷效率研究

TP超标成为长江流域水环境保护面临的新挑战,而城镇生活污水处理厂TP去除效率不高,是长江流域TP的主要来源之一.通过实地监测获得本地数据,对BioWin软件部分参数进行本地化改造,模型校验结果显示,稳态和动态模拟偏差控制在15%以内.利用BioWin软件模拟,分析了进水水质、运行参数等变化对污水处理厂出水TP的影响,提出了减少曝气、降低污泥回流、降低进水跌水高度等运行参数优化方案.经过实证,参数优化后运行,污水处理厂TP去除效率有显著提升,出水水质由《城镇污水处理厂污染物排放标准》(GB 18918—2002)一级B标准可以提升至一级A标准.

蚁群加速遗传算法在水环境优化问题中的应用

提出了水环境优化问题的一种新方法——蚁群加速遗传算法,给出了实施该算法的详细步骤。并对新方法的收敛性和全局优化性进行了理论和实例分析,在污水处理模型的参数识别问题中,新方法得到了精度较高的全局最优解。新方法具有精度高、速度快和鲁棒性强等特点,是一种既可以较大概率搜索全局最优解,又能进行局部细致搜索的较好的非线性优化方法,可广泛应用于各种水环境优化问题中。

Assessment of Point and Nonpoint Sources Pollution in Songhua River Basin,Northeast China by Using Revised Water Quality Model

Individual participation of pollutants in the pollution load should be estimated even if roughly for the appropriate environmental management of a river basin.It is difficult to identify the sources and to quantify the load, especially in modeling nonpoint source.In this study a revised model was established by integrating point and nonpoint sources into one-dimensional Streeter-Phelps(S-P) model on the basis of real-time hydrologic data and surface water quality monitoring data in the Jilin Reach of the Songhua River Basin.Chemical oxygen demand(COD) and ammonia nitrogen(NH 3-N) loads were estimated.Results showed that COD loads of point source and nonpoint source were 134 958 t/yr and 86 209 t/yr, accounting for 61.02% and 38.98% of total loads, respectively.NH 3-N loads of point source and nonpoint source were 16 739 t/yr and 14 272 t/yr, accounting for 53.98% and 46.02%, respectively.Point source pollution was stronger than nonpoint source pollution in the study area at present.The water quality of upstream was better than that of downstream of the rivers and cities.It is indispensable to treat industrial wastewater and municipal sewage out of point sources, to adopt the best management practices to control diffuse pollutants from agricultural land and urban surface runoff in improving water quality of the Songhua River Basin.The revised S-P model can be successfully used to identify pollution source and quantify point source and nonpoint source loads by calibrating and validating.

Model for seawater fouling and effects of temperature,flow velocity and surface free energy on seawater fouling

A kinetic model was proposed to predict the seawater fouling process in the seawater heat exchangers.The new model adopted an expression combining depositional and removal behaviors for seawater fouling based on the Kern–Seaton model.The present model parameters include the integrated kinetic rate of deposition(k d)and the integrated kinetic rate of removal(k r),which have clear physical signi ficance.A seawater-fouling monitoring device was established to validate the model.The experimental data were well fitted to the model,and the parameters were obtained in different conditions.SEM and EDX analyses were performed after the experiments,and the results show that the main components of seawater fouling are magnesium hydroxide and aluminum hydroxide.The effects of surface temperature,flow velocity and surface free energy were assessed by the model and the experimental data.The results indicate that the seawater fouling becomes aggravated as the surface temperature increased in a certain range,and the seawater fouling resistance reduced as the flow velocity of seawater increased.Furthermore,the effect of the surface free energy of metals was analyzed,showing that the lower surface free energy mitigates the seawater fouling accumulation.

Evaluation and improvement of wastewater treatment plant performance using BioWin

In this study,the activated sludge model implemented in the BioWin software was validated against full-scale wastewater treatment plant data. Only two stoichiometric parameters(Y p /acetic and the heterotrophic yield(Y H)) required calibration. The value 0.42 was used for Yp /acetic in this study,while the default value of the BioWin software is 0.49,making it comparable with the default values of the corresponding parameter(yield of phosphorus release to substrate uptake(YPO4)) used in ASM2,ASM2 d,and ASM3 P,respectively. Three scenarios were evaluated to improve the performance of the wastewater treatment plant,the possibility of wasting sludge from either the aeration tank or the secondary clarifier,the construction of a new oxidation ditch,and the construction of an equalization tank. The results suggest that construction of a new oxidation ditch or an equalization tank for the wastewater treatment plant is not necessary. However,sludge should be wasted from the aeration tank during wet weather to reduce the solids loading of the clarifiers and avoid effluent violations. Therefore,it is recommended that the design of wastewater treatment plants(WWTPs) should include flexibility to operate the plants in various modes. This is helpful in selection of the appropriate operating mode when necessary,resulting in substantial reductions in operating costs.

Ammonium Ion Adsorption and Settleability Improvement Achieved in a Synthetic Zeolite-Amended Activated Sludge

Municipal wastewater treatment plants typically exhibit two classic problems： high ammonium concen- tration in water after conventional biological treatment and, in some cases, poor activated sludge sediment ability. Potential solutions to these problems were investigated by adding a synthetic zeolite obtained from coal fly ash to different steps of activated sludge treatment. The experimental results for ammonium removal fit well with the theoretical adsorption isotherms of the Freundlich model with a maximum adsorption capacity of 13.72 mg.g-＇. Utiliza- tion of this kind of zeolite to improve activated sludge sediment ability is studied for the first time in this work. It is found that the addition of the zeolite （1 g. L-1） to an activated sludge with settling problems significantly enhances its sediment ability and comoact ability. This is confirmed by the sludge volume index （SVI）, which was reduced from 163 ml.g-1 to 70 ml.g-r, the V60 value, which was reduced from 894 ml.L-1 to 427 ml.L-1, and the zeta poten- tial （0, which was reduced from -19.81 mV to -14.29 mV. The results indicate that the addition of this synthetic zeolite to activated sludge, as an additional waste management practice, has a positive impact on both ammonium removal and sludge settleability.

Removal of lead(II) from aqueous solutions by activated carbon developed from surplus sludge

Activated carbon(AC) was prepared from surplus sludge using chemical activation method with the assistance of ZnCl2. The influences of process parameters on the AC's specific surface area and adsorption capacity for Pb2+ were examined to optimize these parameters. The optimal conditions for the preparation of AC were determined to be activation temperature of 500 °C, activation time of 1 h, impregnation ratio of 1:1(solid-to-liquid volume) with the 30% ZnCl2 solution(mass fraction), giving the BET surface area of 393.85 m2/g and yield of 30.14% with 33.45% ash. Also, the pyrolysis temperature was found to be the most important parameter in chemical activation. FTIR spectra provided the evidence of some surface structures such as C=C and C—O—C. In the adsorption studies, a rise in solution pH led to a significant increase in adsorption capacity when the pH value varied from 3.0 to 7.0, and the optimal pH for removal of Pb2+ was 7.0. It was observed that the pseudo-second-order equation provided better correlation for the adsorption rate than the pseudo-first-order and the Langmuir model fitted better than the Freundlich model for adsorption isotherm. The adsorption capacity of AC to Pb2+ was 11.75 mg/L at solution pH 7.0, the equilibrium time 480 min and 25 °C. Moreover, the adsorption process is endothermic according to the value of enthalpy change.

Study of Impact in Soil for Sewage Sludge Application

Land utilization is considered as a positive and effective method for sewage sludge disposal. This method takes use of a large number of rich nutrients for soil and crop. The application of sewage sludge in soil increases the concentration of heavy metals. Compared with 15-30 cm layer of soil, 0-15 cm layer increased significantly, especially for Cu, Zn and Ni. The concentration of Cd in soil is considered as the main limiting factor, which determines the years of land utilization. If the largest continuous application is 30 t/（hm2.a） to the soil, the largest application period will be 11.53 years. In this paper, set pair analysis model are used in safety evaluation of the soil. After one year application of sewage, the soil can be still safe. Finally, according to the process of the subject put forward some suggestions.

Application study of coupled model between reservoir organic pollutant BOD5-DO and temperature

The BOD5-DO (Biochemical Oxygen Demand in five days and Dissolved Oxygen) are important indexes that reflect the organic pollution extent of water,but the variation of the indexes is closely related with water temperature. The study on the coupled mathematical model reflecting the BOD5-DO with temperature is the key to reveal the mechanism of the migration and distribution of BOD5-DO in the water. The authors presented 1-D mathematical model for the three variables in vertical direction,and gave accurate solution for the equations under steady state,the relation among the variables and the method for solving BOD5-DO concentrations at different depth and temperature.

Hydrodynamics research of wastewater treatment bioreactors

To optimize the design and improve the performance of wastewater treatment bioreactors,the review concerning the hydrodynamics explored by theoretical equations,process experiments,modeling of the hydrodynamics and flow field measurement is presented. Results of different kinds of experiments show that the hydrodynamic characteristics can affect sludge characteristics,mass transfer and reactor performance significantly. Along with the development of theoretical equations,turbulence models including large eddy simulation models and Reynolds-averaged Navier-Stokes (RANS) models are widely used at present. Standard and modified k-ε models are the most widely used eddy viscosity turbulence models for simulating flows in bioreactors. Numerical simulation of hydrodynamics is proved to be efficient for optimizing design and operation. The development of measurement techniques with high accuracy and low intrusion enables the flow filed in the bioreactors to be transparent. Integration of both numerical simulation and experimental measurement can describe the hydrodynamics very well.

Discovering Niche Market： Consumer Preferences and Willingness to Pay for Organic Pork

With the concern for environmental quality and food safety, organic food products are becoming more important in the global market. In recent years the organic food industry has been expanding and sales of organic products have been increasing. Abundant studies have been done focusing on organic fruits and vegetables which focused on the shortage of organic live stocks. In this paper we focus our attention on organic pork products. Using a sample of 400 Thais consumers, this study proposes the contingent valuation （CV） technique to measure the willingness of individuals to pay a price premium for organic pork in Thailand. In order to obtain the mean ＂willingness to pay＂ （WTP）, a bivariate probit model was applied to provide information about the crucial variables that affect the WTP. The study revealed that variables that better approximate WTP are based on the lifestyle and knowledge about organic foods rather than the usual socioeconomic factors. The mean WTP on the premium price for organic pork is approximately 34.30 Bath per kg. In order to access the market potential this study shows that the suitable attributes of organic pork which is consistent with consumer preferences are composed of modernized and environmental packaging with special product details. Marketing this product to the buyer it should be set at a reasonable price. Stimulating the market should be done by doing sales promotion and public relations on a regularly basis. In addition, organic pork should be available in any places and convenient for customers to buy.

Adsorption characteristics of construction waste for heavy metals from urban stormwater runoff

Stormwater runoff has become an important source of surface water pollution. Bioretention, a low impact development measure in urban stormwater management, has been proven to be effective in the removal of pollutants from stormwater runoff, with appropriate bioretention media. In this study, construction wastes were selected as bioretention media to remove heavy metals from stormwater runoff. Static and dynamic adsorption batch experiments were carried out to investigate the adsorption of heavy metals in simulated stormwater runoff system with construction wastes in different particle sizes. The experimental results show that the pseudo-secondorder kinetic model characterizes the adsorption process and the adsorption equilibrium data are well described by Freundlich isotherm model. The construction wastes used can remove heavy metals from stormwater runoff effectively, with their average removal rates all more than 90%. The particle size of construction wastes greatly influences the equilibrium time, rate and adsorption capacity for heavy metals.

Simulation of Water Quality of Neijiang River Based on RMA4 Model

Using the RMA4 water quality model to simulate the water quality of Neijiang river in Zhenjiang, the result showed that： in the dry season the ranges of the concentration of various pollutants simulation of Neijiang were BOD5 3.2-5.2 mg/L, CODMn 4.7-6.8 mg/L, NH3-N 0.46-1.8 mg/L, TP 0.23-0.48 mg/L, and in the rainy period, the ranges of the concentration of various pollutants simulation of Neijiang were BOD5 0.69-0.73 mg/L, CODM, 1.9-2.3 mg/L, NH3-N 0.25-0.38 mg/L, TP 0.14-0.17 mg/L.These simulated values were closed to the monitoring values of pollution concentrations of Neijiang, which indicated that RMA4 was certain practical in the river water quality simulation, and simulation results have a certain degree of reliability, and it provides a scientific planning and management method for the river pollution control.