A modified active disturbance rejection control for a wastewater treatment process

Waste water treatment process(WWTP)control has been attracting more and more attention.However,various undesired factors,such as disturbance,uncertainties,and strong nonlinear couplings,propose big challenges to the control of a WWTP.In order to improve the control performance of the closed-loop system and guarantee the discharge requirements of the effluent quality,rather than take the model dependent control approaches,an active disturbance rejection control(ADRC)is utilized.Based on the control signal and system output,a phase optimized ADRC(POADRC)is designed to control the dissolved oxygen and nitrate concentration in a WWTP.The phase advantage of the phase optimized extended state observer(POESO),convergence of the POESO,and stability of the closed-loop system are analyzed from the theoretical point of view.Finally,a commonly accepted benchmark simulation model no.1.(BSM1)is utilized to test the POESO and POADRC.Linear active disturbance rejection control(LADRC)and the suggested proportion-integration(PI)control are taken to make a comparative research.Both system responses and performance index values confirm the advantage of the POADRC over the LADRC and the suggested PI control.Numerical results show that,as a result of the leading phase of the total disturbance estimation,the POESO based POADRC is an effective and promising way to control the dissolved oxygen and nitrate concentration so as to ensure the effluent quality of a WWTP.

Advanced Treatment of Wastewater Treatment Plant Effluent by Using Biofilms on Filamentous Bamboo

[ Objective ] The study aimed at treating wastewater treatment plant （WWTP） effluent by using bio-film reactor with filamentous bamboo as bio-carrier. [ Method] With the aid of a continuous flow reactor, a bio-film reactor using filamentous bamboo as bio-carrier was used to treat WWTP effluent with low C/N ratio, and the removal effects of CODc,, TN （total nitrogen）, and NO3--N in the wastewater were analyzed.[ Result ] The average removal rates of CODcr, TN, and NO3- -N reached 47.7%, 23.6% and 34.5% when the C/N ratio of influent was around 2. In addi- tion, a stable bio-film was formed very well in the secondary effluent with low C/N ratio and hardly degradable organic pollutants. The pollutants could be removed effectively because of the excellent surface characteristics and compositions of filamentous bamboo. [ Conclusion] The research provides a new method to treat WWTP effluent with low C/N ratio.

Full scale application of combined SBF-AS process for municipal wastewater treatment in small towns and cities in China

The combined submerged biofilm （ SBF）-activated sludge （AS） process for treatment of municipal wastewater in a small city in China is described in this paper. The process exhibited high removal efficiencies for carbonaceous substances, nitrogen and phosphorus which mainly took place in the combined SBF-AS biore- actor. The SBF-AS bioreactor was divided into pre-anoxic, anaerobic, anoxic and aerobic zones from inlet to outlet, in which fixed biofilm carriers were packed. Excellent performance had been obtained under normal operating conditions in more than one year of operation in Dong＇ e municipal WWTP, Shandong province, with mean removal efficiencies of BOD5 93.4%, COD 88%, SS 92%, NH4 - N 82. 1%, TP 75% and TN 66.7%, and quite high effluent quality such as BOD5 6 to 10 rag/L, COD 20 to 40 rag/L, SS 5 to 10 rag/L, TN 10 to 20 rag/L, NH4 - N 4 to 8 mg/L and TP 0. 6 to 1.0 mg/L. The effluent was reused multi-purposely, such as toilet flushing, green belt watering and artificial lake pounding. Simultaneous nitrification and denitrification took place due to the DO gradient in biofilm in aerobic zone of the SBF-AS bioreactor, which made TN removal efficiency improved remarkably in system. Some activated sludge was returned from final clarifiers to the bioreactor for phosphorus removal. The process had the advantages of low investment and low operational/ maintenance （O/M） costs, low sludge yield and was preferably employed in small towns and cities.

Effectiveness of a Wastewater Treatment Plant located at EPZ in reducing Pollutants Discharged into River Athi, Kenya

Information about effectiveness of a wastewater treatment plant is vital in ensuring the quality of water discharged into water bodies and the environment in general meet set standards.In this study,the performance of a wastewater treatment plant located at the Export Processing Zone(EPZ)along River Athi in Machakos County,Kenya was assessed because the final effluent from the treatment plant is released into the river where water is used downstream.Effectiveness of the plant was assessed through the reduction percentage of pollutants between influent and effluent during the dry and wet seasons.Samples of water were collected from the following points i.e.inlet,outflow pool,outlet and along the river.The samples were analyzed for heavy metals,Total Dissolved Solids(TDS),Total Suspended Solids(TSS),Chemical Oxygen Demand(COD),Biological Oxygen Demand(BOD),organic nitrogen,phosphate,color,temperature,pH,and total coliforms.The resulting data was compared with the established standards.Standard methodologies of laboratory analysis were employed as per Kenyan regulations of 2006 on waste water treatment and discharge.From the results,the waste water treatment plant was not effective in reducing nitrates,phosphates,TDS,TSS,color,and heavy metals i.e.mercury,lead,selenium,copper and cadmium.The inefficiency was more pronounced in rain season.Nitrates(-2.04%),phosphates(-66%),mercury(-48%),lead(-48%),selenium(-2.29%)and copper(-9.75%)were high in the effluent after treatment process during the rains than in the influent.However,the treatment plant was effective in reducing Chemical Oxygen Demand(COD)and Biological Oxygen Demand(BOD).Some parameters like pH,conductivity,temperature,color and TSS were within allowable values described by Kenyan and International standards for effluent discharge into public waters.The study recommends expansion or re-designing of the treatment plant and better monitoring of the sources or types of wastewaters received at the plant for efficient and proper treatment process.Further research required on the seasonal fluctuation of pollutants along River Athi to reduce pollution of the waters.This should be coupled with studying the role of river gradient in self-cleansing of the pollutants.

Dynamic multi-objective intelligent optimal control toward wastewater treatment processes

Wastewater treatment plays a crucial role in alleviating water shortages and protecting the environment from pollution.Due to the strong time variabilities and complex nonlinearities within wastewater treatment systems,devising an efficient optimal controller to reduce energy consumption while ensuring effluent quality is still a bottleneck that needs to be addressed.In this paper,in order to comprehensively consider different needs of the wastewater treatment process(WTTP),a two-objective model is to consider a scope,in which minimizing energy consumption and guaranteeing effluent quality are both considered to improve wastewater treatment efficiency.To efficiently solve the model functions,a grid-based dynamic multi-objective evolutionary decomposition algorithm,namely GD-MOEA/D,is designed.A GD-MOEA/D-based intelligent optimal controller(GD-MOEA/D-IOC)is devised to achieve tracking control of the main operating variables of the WTTP.Finally,the benchmark simulation model No.1(BSM1)is applied to verify the validity of the proposed approach.The experimental results demonstrate that the constructed models can catch the dynamics of WWTP accurately.Moreover,GD-MOEA/D has better optimization ability in solving the designed models.GD-MOEA/D-IOC can achieve a significant improvement in terms of reducing energy consumption and improving effluent quality.Therefore,the designed multi-objective intelligent optimal control method for WWTP has great potential to be applied to practical engineering since it can easily achieve a highly intelligent control in WTTP.

Sludge thickening in a wastewater treatment plant using a modified hydrocyclone

The main application of hydrocyclones in most industry sectors is the separation of particles from liquids.For thickening,however,the separation properties of the cyclone should be adjustable,which requires a different operating mode.Therefore,we investigated an add-on thickening module,consisting of a conical plug and a secondary vortex finder in the underflow of the hydrocyclone.Laboratory scale experiments are carried out to investigate the function of the concept of annular gap modification by the use of the thickening module.In the second step,we transferred this concept to industrial scale for field tests at a municipal wastewater treatment plant.In the field tests,geometrical properties(annular gap modification)and operational parameters(volume flow rate,sludge type)were investigated.The results show that thickening in terms of increasing the total solids content of sludge is possible with the modified hydrocyclone.In the field tests,a thickening factor(total solids content of thickened sludge related to feed sludge)of 1.31(average)was reached for digested sludge.Hence,a hydrocyclone could be a promising addition in wastewater treatment plants for dewatering of sludge.

高寒地区污水厂升级改造中技术分析及应用

北方某县级污水厂原设计规模为1.0×10^(4)m^(3)/d,原有CASS工艺难以满足水量增倍、排放标准由《城镇污水处理厂污染物排放标准》(GB 18918-2002)一级B标准提标至一级A标准的要求。在现有工程的基础上,将原有的CASS工艺改造为改良AO工艺+磁混凝多效沉淀系统,实现了出水水质稳定达到一级A标准,高寒气温下稳定的脱氮效率。该提标改造方式具有不需扩大占地、原有土建改动小、出水效果好等优势,减少工程投资和运行成本,可为高寒地区污水厂的升级改造提供参考。

深圳沙河水质净化厂及3#调蓄池工艺设计要点及特点

沙河水质净化厂设计规模为旱季10万m^(3)/d,雨季额外处理10万m^(3)/d初期雨水,3#调蓄池设计规模为15.3万m^(3)。污水及初期雨水处理采用预处理+多段厌氧-好氧(AO)+二沉池+磁混凝高效沉淀池+精密过滤+紫外消毒的工艺,出水水质执行深圳市地方标准《水质净化厂出水水质规范》(DB 4403/T 64—2020)B级标准,其中总氮(TN)≤8 mg/L。污泥处理采用离心浓缩+低温热干化工艺,处理后含水率≤40%。作为国内首个将水质净化厂与初期雨水调蓄池深度融合的全地下式水污染治理综合体,项目采用多段AO耦合“3W法”(Wet-Weather-Wastewater法),并以此为核心提出了一种实现大规模污水及初期雨水高标准协同处理的系统解决方案,且无需大幅度增加污水处理设施体量、投资和运行成本。

污水处理厂温室气体排放特征与减排技术研究

污水处理厂是温室气体的重要排放源,必须探索和应用有效的减排技术,提升温室气体减排能力。深入分析污水处理厂温室气体排放特征,有助于更好地应用减排技术。直接排放与间接排放是污水处理厂温室气体的两种主要排放形式。结合污水处理厂温室气体的来源,以山东省某污水处理厂为例,核算2018-2020年温室气体直接排放量与间接排放量,然后根据污水处理厂温室气体排放特征,分析污水处理厂温室气体的减排措施。总体来说,要科学选择污水处理工艺,合理调节工艺运行参数,有效减少温室气体排放量。

超薄玻璃基板深加工项目生产废水预处理工程设计

某废水处理工程建设规模为17800 m^(3)/d,文中介绍了该处理工程的概况、工艺流程以及主要构筑物的工艺设计。工程预计进水组成中,工业废水占有相当的比例,主要以电子废水为主。为解决废水可生化性较差、污水处理难度较大的问题,预处理采用高效水解工艺,降低工业废水毒性,改善废水可生化性,确保二级处理系统稳定运行。污水处理主体工艺推荐采用较长泥龄延时曝气,强化脱氮两级AO工艺,提高难降解有机物去除率。绝大部分进水都具有强酸性或者强碱性,且酸碱性波动范围较大,容易对污水处理流程造成冲击,对污水处理建构筑物造成较大腐蚀。此外,在废水处理站进水端设置较长停留时间的调节池,对来水进行均质调节,在一定程度上可以使废水的pH处在较为稳定的范围内;在废水处理站设置监测排放池,尾水排放前仍有应急调节pH的可能,确保尾水达标排放。通过技术经济比较论证,本次扩能工程拟采用不同类污水分质组合处理的工艺技术路线,提高处理效率,降低建设及运行成本。采用先进的上流式水解污泥床水解反应池池型,并加盖除臭、景观绿化,收集和处理构筑物内的臭气。调试运行结果表明,项目工艺流程及参数设置能够满足各类废水处理排放要求。

典型污水处理工艺各工序全氟化合物赋存及去除效果

全氟化合物(PFAS)是我国重点管控的新污染物,污水处理厂是其进入水体的重要节点,当前污水处理厂的工艺多为提标改造后的综合工艺,各工艺去除PFAS的效果不一。为探究当前不同污水处理工艺对PFAS去除效果的影响,对北京市某污水处理厂的2种典型污水处理工艺(改进型A^(2)O、改进型OD)各工序的PFAS浓度和组分特征进行了分析,并探讨PFAS去除机制。结果表明:1)该污水处理厂纳管范围内短链替代效应已经显现,2种典型污水处理工艺进水中主要PFAS均为短链PFAS的全氟戊烷羧酸(PFPeA)、全氟丁烷羧酸(PFBA)和全氟丁烷磺酸(PFBS);2)生化处理单元、紫外消毒池导致的PFAS前体物分解,格栅、MBR池、沉淀池等对PFAS的拦截滤除、吸附及沉淀作用是2种典型污水处理工艺中PFAS赋存特征变化的重要机制;3)改进型A^(2)O、改进型OD工艺对总PFAS的去除率分别为60.65%、82.62%,前者对PFPeA和PFBS去除效果突出,后者对除全氟己烷羧酸(PFHxA)以外的所有短链PFAS均有较好的去除效果。污水处理工艺提标改造后在一定程度上对部分PFAS的去除效果有所提高,尤其是改进型OD工艺对PFAS的去除效果较好。

好氧颗粒污泥技术处理化工园区工业污水

采用好氧颗粒污泥技术处理化工园区企业排放的工业污水,实现了污泥颗粒化。工艺启动和可靠性研究结果表明,直径不小于0.2 mm的球形或椭球形致密颗粒污泥占比约60%,为橙黄色,SV5接近300 mL/L。在冬季不加任何化学药剂的情况下,出水总氮小于10 mg/L。该技术运行平稳,水质波动适应性强,操作弹性大,吨水电耗为0.23 kW·h,与传统的A^(2)O相比,能耗节约明显,同时占地面积显著减小。

武汉市某污水处理厂地下式扩建设计案例

武汉市S污水处理厂已建规模为35万m^(3)/d,规划规模为60万m^(3)/d,扩建规模为10万m^(3)/d,出水标准高于《城镇污水处理厂污染物排放标准》(GB 18918—2002)一级A标准。厂内有多套处理工艺、多处进水入口和排放出口,改造难度较大。经论证,扩建工程选用地下式构筑物,最大限度节约现有用地,并为远期扩建预留条件。工艺流程采用“多级预处理+改良AAO生化池+膜生物反应器(MBR)池+次氯酸钠接触消毒”,运行至今出水稳定达标。S污水处理厂是武汉市唯一一座兼有地上式及地下式处理构筑物的污水厂,文章总结了污水厂地下式扩建的设计思路、设计参数和设计经验,作为同类污水厂改造的参考。

知识和数据驱动的污水处理反硝化脱氮过程协同优化控制

为有效提升城市污水处理过程的脱氮效果,提出一种知识和数据驱动的反硝化脱氮过程协同优化控制(Knowledge-data-driven cooperative optimal control,KDDCOC).所提方法主要有以下两个方面:首先,建立一种基于自适应知识核函数的协同优化控制目标模型,动态描述出水水质(Effluent quality,EQ)以及泵送能耗(Pumping energy consumption,PE)、关键变量的协同关系;其次,提出一种知识引导的协同优化算法(Knowledge guide-based cooperative optimization algorithm,KGCO),快速准确求解硝态氮(Nitrate nitrogen,SNO)优化设定值,提高KDDCOC的响应速度.KDDCOC利用比例−积分−微分(Proportional-integral-derivative,PID)控制器对硝态氮优化设定值进行跟踪,将提出的KDDCOC应用于城市污水处理过程基准仿真模型1号(Benchmark simulation model No.1,BSM1),实验结果表明,该方法能够提高出水水质,降低运行能耗,有效改善脱氮效果.

MBBR耦合多段AO工艺在大型市政污水处理厂的运行初探和实践成效

新建城市污水处理厂或提标改造老旧污水处理厂普遍存在出水水质差、污染物负荷与占地面积等不可调和的矛盾,基于纵向扩大池容会增加建设成本、高负荷运行具有超标风险,因此,急需一种污泥/容积负荷高、运行稳定、操作简单的污水处理新技术。对此,某大型市政污水处理厂利用移动床生物膜反应器(MBBR)泥膜共混技术提高生化池有效污泥浓度、实现功能微生物的强化和富集,耦合多段AO工艺,经历雨/旱、夏/冬季,已稳定运行227 d,当进水COD_(Cr)、氨氮、TN质量浓度分别为277.97、34.92、45.95 mg/L,对应出水质量浓度分别降低至12.68、0.33、7.55 mg/L,MBBR挂膜前后的氨氮污泥负荷为0.011、0.015 g氨氮/(g MLSS·d)、TN污泥负荷为0.014、0.020 g TN/(g MLSS·d)。系统稳定运行期间,好氧Ⅰ段氨氮硝化速率为7.27 mg/(L·h)、缺氧Ⅰ段NO-3-N还原速率为3.48 mg/(L·h)。结果表明,通过负载微生物和游离污泥的交互作用,寻求复杂微生物群落功能的强化和调控,可以设计出更加合理、高效的污水处理新工艺。

污水处理厂节能降耗措施及效益分析——以湖南省某再生水厂为例

本文以湖南省某再生水厂为例,介绍了污水处理厂节能降耗措施和效益,重点研究了改良式序批间歇反应器(MSBR)工艺技改对污水处理厂提质降耗、中水回用等方面的应用效果。结果表明,通过采用MSBR工艺技改,水质明显提升,实现了节能、节药、节水的效果。此外,通过推广中水回用和光伏等可再生能源利用,进一步降低了污水处理能耗。本案例对于污水处理厂节能降耗、减污降碳具有一定借鉴意义。

污水处理厂扩建工程设计及运行实例

北方某城市污水处理厂设计总规模18.0×10^(4)m^(3)/d,其中扩建工程设计规模8.0×10^(4)m^(3)/d,出水执行《城镇污水处理厂污染物排放标准》(GB 18918—2002)一级A标准。根据进水水质和排放要求,设计采用“初沉池-多级AO生化池-高速气浮池-反硝化深床滤池”工艺。介绍了扩建工程的工艺流程、主要构筑物设计参数、设计特点,并对运行效果进行分析。实际运行数据表明,出水各项指标均能稳定达标,COD、SS、NH_(3)-N、TN、TP平均去除率分别达到88.90%、96.24%、97.31%、78.00%、92.87%。

ATP法在生物处理工艺优化中的应用分析

活性污泥ATP(三磷酸腺苷)法具有操作快速、简单、灵敏的特点,可以及时反馈生物处理过程中微生物的活性状态。文章采用ATP检测法对细胞活性进行分析,确定活性污泥数量,并通过微生物镜检方式对生化系统状态进行观察,判断污水处理厂生物处理能力,同时考察活性污泥中溶解氧含量及系统搅拌程度对反硝化功能的影响情况。根据分析结果,将ATP指标列入污水处理厂日常检测,能有效定量分析污水处理厂活性污泥状态,也是判断运行工艺是否异常的有效手段。

上海中心城区污水处理厂提标改造工程调试总结及设计建议

通过“十三五”期间上海中心城区污水处理厂提标改造及新建工程的实施经验,就已有污水处理厂提标改造涉及改造切换方面要点、污水处理厂建成后的调试过程要点、污水处理厂整体设计优化方面要点等方面,提出需关注的重点内容。

CASS工艺在徐州市三八河污水处理厂三期扩建工程的应用

徐州市三八河污水处理厂(三期)设计规模为5万t/d,采用CASS生化池为主体工艺,深度处理采用转盘滤池+接触消毒工艺。出水执行《城镇污水处理厂污染物排放标准》(GB18918-2002)水污染物排放一级A标准,恶臭气体进入填充塔式生物脱臭罐进行处理,全厂异味控制参照执行《城镇污水处理厂污染物排放标准》(GB18918-2002)中关于厂界大气污染物排放最高允许浓度二级标准。污泥脱水含水率降低至80%后外运处置。污水厂实际运行结果表明:出水水质优于设计标准,对有机物的去除效果最好,对TN的去除率相对较低。吨水占地为0.26 m^(2) ,综合处理费用为0.5~0.6元/t水。