Digital Twins for Wastewater Treatment:A Technical Review

The digital twins concept enhances modeling and simulation through the integration of real-time data and feedback.This review elucidates the foundational elements of digital twins,covering their concept,entities,domains,and key technologies.More specifically,we investigate the transformative potential of digital twins for the wastewater treatment engineering sector.Our discussion highlights the application of digital twins to wastewater treatment plants(WWTPs)and sewage networks,hardware(i.e.,facilities and pipes,sensors for water quality and activated sludge,hydrodynamics,and power consumption),and software(i.e.,knowledge-based and data-driven models,mechanistic models,hybrid twins,control methods,and the Internet of Things).Furthermore,two cases are provided,followed by an assessment of current challenges in and perspectives on the application of digital twins in WWTPs.This review serves as an essential primer for wastewater engineers navigating the digital paradigm shift.

Performance of a Horizontal Flow Constructed Reed Bed Filter for Municipal Wastewater Treatment: The Case Study of the Prototype Installed at Gaston Berger University, Saint-Louis, Senegal

In Saint-Louis, Senegal, a constructed wetland with horizontal flow reed beds (FHa and FHb) has demonstrated significant efficacy in treating municipal wastewater. Analyzing various treatment stages, the system showed only a slight temperature variation, from an influent average of 26.3°C to an effluent of 24.7°C. Electrical conductivity decreased from 1331 mS/cm to 974.5 mS/cm post-primary treatment, with suspended solids (SS) dramatically reduced from 718.9 mg/L to 5.7 mg/L in the final effluent. Biochemical oxygen demand (BOD5) and chemical oxygen demand (COD) saw a notable decrease, from initial levels of 655.6 mg/L and 1240 mg/L to 2.3 mg/L and 71.3 mg/L, respectively. Nitrogenous compounds (N-TN) and phosphates () also decreased significantly, indicating the system’s nutrient removal capacity. Microbiological analysis revealed a reduction in fecal coliforms from 7.5 Ulog/100ml to 1.8 Ulog/100ml and a complete elimination of helminth eggs. The presence of Phragmites and Typha was instrumental in enhancing these reductions. The system’s compliance with the Senegalese standards for disposal into natural environments, WHO recommendations for unrestricted water reuse in irrigation, and the European legislation for water reuse was established. The effluent quality met the stringent criteria for various classes of agricultural reuse, illustrating the system’s potential for sustainable water management. This wetland model presents a robust solution for water-stressed regions, ensuring environmental protection while supporting agricultural needs. The study calls for ongoing research to further refine the system for optimal, reliable wastewater treatment and water resource sustainability.

Sludge reduction with Tubificidae and the impact on the performance of the wastewater treatment process

To reduce excess sludge, a Tubificidae reactor was combined with an integrated oxidation ditch with vertical circle （IODVC）, and a new integrated system was developed for wastewater treatment, A pilot-scale of this integrated system was tested to investigate the sludge reduction with Tubificidae and the impact on effluent quality and sludge production. The dominant worm was Branchnria Sowerbyi in the Tubificidae reactor after inoculation of Branchnria Sowerbyi and Limnodrilns sp., and the maximal volume density of wet Tubificidae in vessels of the Tubificidae reactor was 17600 g/m^3. Two operational modes, treating the excess sludge （first mode） and the returned sludge （second mode） of IODVC by the Tubificidae reactor, were used in this experiment. The results showed that the excess sludge reduction rate was 46.4% in the first mode, and the average sludge yield of the integrated system was 6.19× 10^-5 kg SS/kg COD in the second mode. Though the sludge returned to IODVC via the Tubificidae reactor, it had little impact on the effluent quality and the sludge characteristics of the IODVC. No new type of recalcitrant substance in the supernatant was discharged into the environment when the sludge was treated by Tubificidae. The experimental results also indicated that no significant changes occurred on the viscosity, specific resistance, and the floc size distribution of the sludge.

Advances in Control Technologies for Wastewater Treatment Processes:Status, Challenges, and Perspectives

This paper presents a thorough review of control technologies that have been applied to wastewater treatment processes in the environmental engineering regime in the past four decades. It aims to provide a comprehensive technological review for both water engineering professionals and control specialists, giving rise to a suite of up-to-date pathways to impact this field in light of the classified technology hubs. The assessment was conducted with respect to linear control, linearizing control,nonlinear control, and artificial intelligence-based control. The application domain of each technology hub was summarized into a set of comparative tables for a holistic assessment. Challenges and perspectives were offered to these field engineers to help orient their future endeavor.

Application of Constructed Wetlands on Wastewater Treatment for Aquaculture Ponds

A group of constructed wetlands （CWs） were applied to the recirculating aquaculture system. This study assessed the performance of CWs in treating the aquaculture wastewater, examined the water quality condition of aquaculture ponds and the growth and the survival rate of ＂target＂ species （Ictalurus punctatus and Megalobrama amblycephala）. The results showed that CWs were effective on reducing the concentrations of 5-day biochemical oxygen demand （BOD5, at 70.5%）, total suspended solids （TSS, at 81.9%）, chlorophyll a （Chl-a, at 91.9%）, ammonium （NH4^＋, at 61.5%） and nitrate nitrogen （NOa-N, at 68.0%）. Effect of CWs on phosphate （PO43 -P） removal was relatively lower （at 20.0%）. The concentrations of BODs, TSS, Chl-a, NH4^＋ and TN, TP in the recirculating culture pond were significantly lower than that in the control pond（ p〈0.05 ）. CWs could help to increase total yield, survival rate of the ＂target＂ species and significantly decrease feed conversion ratio （ p〈0.05 ）.

A two-stage anaerobic system for biodegrading wastewater containing terephthalic acid and high strength easily degradable pollutants

The high strength easily biodegradable pollutants (represented by COD E) are strong inhibitors of terephthalic acid (TA) anaerobic biodegradation. At the same time, TA can inhibit easily biodegradable pollutants removal under anaerobic conditions to a limited extent. This mutual inhibition could happen and cause a low removal efficiency of both TA and COD E, when the effluent from TA workshops containing TA and easily biodegradable pollutants are treated by a single anaerobic reactor system. Based upon the treatment kinetics analysis of both TA degradation and COD E removal, a two stage up flow anaerobic sludge blanket and up flow fixed film reactor(UASB UAFF) system for dealing with this kind of wastewater was developed and run successfully at laboratory scale. An UASB reactor with the methanogenic consortium as the first stage removes the easily biodegradable pollutants(COD E). An UAFF reactor as the second stage is mainly in charge of TA degradation. At a COD E loading of 15.3 g/(L\5d) and a TA loading of 1.4 g/(L\5d), HRT 18.5h, the COD E and TA removal rate of the system reached 89.2% and 71.6%, respectively.

Why Should We Bother on Measurement in Wastewater Treatment Operation?

The question of wastewater treatment and control is reflected from a very specific viewpoint: the low priority given to accurate and useful measurements within wastewater treatment. The matter is discussed from four various perspectives, that may be labelled “Legal understanding”;“Needs for accurate measurement results already in the planning and design stage”;“The measurement problem and human behaviour”;“The understanding of the short term and long term dynamics and changes in pollution and flow loads on a wastewater treatment plant (WWTP)”. All these aspects bring about much improved needs for an accurate and frequent measurement scheme both for pollutants and flows entering a WWTP. The conclusion is stated as follows: A far more and well elaborated on-line measurement system at the plants would become a needed tool for improved water environment protection at lower costs.

Rapid infiltration wastewater treatment for small communities in Beijing

This rapid infiltration (RI) system is proposed as the first one in China. The RI system treated 500 m3/d of municipal and industrial wastewater. About 0.36 ha of field was used. It has been evaluated that the RI system has an excellent ability to treat the wastewater. The infiltration rate was 50.3 m/a.

Ecological engineering land treatment systems──A new development in China

This paper elucidated the necessity and possibility of developing the technology of land treatment on the basis of the analysis of shortage and pollution status of water resources in China.The historical development of this technology in the world was briefly reviewed and the distinction between land treatment and conventional wastewater irrigation was discussed in details. The fundamental characteristics and functions as well as the integrity and compatibility of this ecological engineering were also summarized. It was finally concluded that this technology for wastewater treatment has broad prospects of application in China.

Purification and reclamation of wastewater by an integrated biological pond system

The feasibility of an inexpensive wastewater treatment system is evaluated in this study.The experiment was conducted in 3 phases with different treatment combinations for testing theirpurification efficiencies. The pond system was divided into 3 functional regions: influentpurification, efficient upgrading and multi-utilization. Various kinds of aquatic organisms, wereeffectively cooperated in this system. The system attained high reduction of BOD_5, COD, TSS, TN,TP and other pollutants. The mutagenic effect and number of bacteria and virus significantly de-clined during the process of purifieation. After the wastewater flowed through the upgrading zone,the concentrations of pollutants and algae evidently decreased. Plant harvesting did not yield drama-tic effects on reductions of the main pollutants, through it did affect remarkably the biomassproductivity of the macrophytes. The wastewater was reclaimed for various purposes.

Phytoremediation of urban wastewater by model wetlands with ornamental hydrophytes

Phytoremediation offers a cost-effective, non-intrusive, and safe alternative to conventional cleanup techniques. In this study, we used ornamental hydrophytes plants as constructed wetlands to treat urban or rural domestic wastewater. Most ornamental hydrophytes adapted to the wastewater well, and were fairly efficient in scavenging BOD5 （biological oxygen demand 5 d）, COD （chemical oxygen demand）, TN （total nitrogen）, TP （total phosphorus） and heavy metals （Cr, Pb, Cd） in the wastewater. However, the efficiency varied a lot for various species to different contaminants, Iris pseudacorus L. and Acorus gramineus Soland were good choices for treatment of composite-polluted urban wastewater. Some variation in the change of membrane peroxidation and endogenous protective system in responses to wastewater was found among six hydrophytes, which have a correlation with the efficiency of wastewater treatment. It may demonstrate that the developed antioxidative systems of L pseudacorus and A. gramineus contributed much to their superiority. On the other hand, interaction of different components in the wastewater might have certain effects on phytoremediation.

Approaches to municipal wastewater irrigation and environmental protection

To reuse the water and nutrient resources from ecological point of view the goals, criteria and constraint conditions of the scientifically municipal wastewater irrigation are discussed as well as the practice in major municipal wastewater irrigation areas in China is introduced, of which particularly the effects of municipal water irrigation mixing with oil refinery wastewater on the agricultural ecosystem are studied and described. It has been revealed that benzo(a)pyrene in various parts of paddy crop is attributed to air pollution, water-soil pollution and biosynthesis of plant. Of exogenous contributions of benzo(a)pyrene in paddy shoot system under natural condition, the dominant factor is the air pollution, whereas the water-soil factor is considered to be secondary. Therefore, it is mostly urgent to control the air pollution source of benzo(a)pyrene, to which the edible parts of various green plants are exposed directly.

大型综合性医院旧院区污水处理系统再规划与建设实践

本研究介绍了某大型综合性医院旧院区污水处理系统改造实践。该实践通过对污水处理系统设计处理能力、整体布局进行重新规划,以及对污水处理工艺流程、日常运营进行优化,实现对整个院区污水处理能力的整合,提升污水处理运营效率,给其他医院的污水处理系统优化改造提供参考。

城市污水净化对受纳河流水生态系统的改善——以丁山河流域为例

以丁山河流域为研究对象,沿城市河流设计了3种旁路生态处理系统,用作污水处理厂或工业废水的附加净化措施,研究河流水质经旁路生态系统处理前后的变化情况,并采用高通量测序方法研究细菌和真菌多样性和群落结构变化,以更全面地反映城市污水经生态系统处理后对受纳河流的影响.结果表明,生态系统出水COD、NH_(4)^(+)-N和TP等营养盐指标明显低于湿地进水,水质明显提升,且污水对生态处理系统和受纳河流微生物影响显著,微生物多样性增加.对旁路生态系统水体理化指标进行统计分析,发现旁路生态系统对COD(55.7%~64.0%)、NH_(4)^(+)-N(63.1%~89.4%)和TP(27.6%~76.7%)的去除效果均较好,水质从地表水劣Ⅴ类提高到Ⅲ类,受纳河流的水质显著改善.对生态系统进出水和河道上下游水体微生物多样性进行统计分析,发现在门水平上,各生态处理系统主要的优势菌门基本相同;在纲水平上,各生态处理系统的真核微生物群落结构差异较大;受纳河流下游水体Chao1、Faith’s PD和Shannon指数大于上游,物种丰富度和多样性显著提高.其中,变形菌门(Proteobacteria,77%~95%)、拟杆菌门(Bacteroidetes,1.0%~10%)、放线菌门(Actinobacteria,0.36%~12%)和厚壁菌门是旁路生态系统主要优势菌门;γ-变形菌纲(Gammaproteobacteria)、α-变形菌纲(Alphaproteobacteria)和拟杆菌纲(Bacteroidia)是受纳河流主要优势菌纲.通过对微生物群落结构进行研究,能够更加全面地揭示尾水经过生态处理系统处理对受纳河流引起的复合生态效应,对城市河流生态系统保护具有重大意义.

An innovative integrated system utilizing solar energy as power for the treatment of decentralized wastewater

This article reports an innovative integrated system utilizing solar energy as power for decentralized wastewater treatment, which consists of an oxidation ditch with double channels and a photovoltaic （PV） system without a storage battery. Because the system operates without a storage battery, which can reduce the cost of the PV system, the solar radiation intensity affects the amount of power output from the PV system. To ensure that the power output is sufficient in all different weather conditions, the solar radiation intensity of 78 W/m 2 with 95% confidence interval was defined as a threshold of power output for the PV system according to the monitoring results in this study, and a step power output mode was used to utilize the solar energy as well as possible. The oxidation ditch driven by the PV system without storage battery ran during the day and stopped at night. Therefore, anaerobic, anoxic and aerobic conditions could periodically appear in the oxidation ditch, which was favorable to nitrogen and phosphate removal from the wastewater. The experimental results showed that the system was efficient, achieving average removal efficiencies of 88% COD, 98% NH 4 ＋ -N, 70% TN and 83% TP, under the loading rates of 140 mg COD/（g MLSS·day）, 32 mg NH 4 ＋ -N/（g MLSS·day）, 44 mg TN/（g MLSS·day） and 5 mg TP/（g MLSS·day）.

造纸污水处理自动监控系统设计

重点研究一种创新的造纸污水连续深度处理自动监控系统,满足造纸过程中对污水处理监测的需求。首先,分析了试验型造纸污水光电催化深度处理系统的技术原理和特点,明确了监控系统的功能需求、设计目标和总体架构。其次,详细阐述了上位机和下位机系统的设计方法和实现步骤。为了评估监控系统的性能和效果,选取甲基绿染料废水作为模拟造纸污水,进行了光电催化深度处理实验,并对监控系统进行了全面的调试和运行测试。实验结果表明,监控系统能够有效地实现造纸污水连续深度处理的自动化,具有较高的稳定性和可靠性。

Development of natural treatment system consisting of black soil and Kentucky bluegrass for the post-treatment of anaerobically digested strong wastewater

To develop a sound post-treatment process for anaerobically-digested strong wastewater,a novel natural treatment system comprising two units is put forward.The first unit,a trickling filter,provides for further reduction of biochemical oxygen demand and adjustable nitrification.The subsequent soil–plant unit aims at removing and recovering the nutrients nitrogen（N）,phosphorus（P）and potassium（K）.As a lab-scale feasibility study,a soil column test was conducted,in which black soil and valuable Kentucky bluegrass were integrated to treat artificial nutrient-enriched wastewater.After a long-term operation,the nitrification function was well established in the top layers,despite the need for an improved denitrification process prior to discharge.P and K were retained by the soil through distinct mechanisms.Since they either partially or totally remained in plant-available forms in the soil,indirect nutrient reuse could be achieved.As for Kentucky bluegrass,it displayed better growth status when receiving wastewater,with direct recovery of 8%,6% and 14% of input N,P and K,respectively.Furthermore,the indispensable role of Kentucky bluegrass for better treatment performance was proved,as it enhanced the cell-specific nitrification potential of the soil nitrifying microorganisms inhabiting the rhizosphere.After further upgrade,the proposed system is expected to become a new solution for strong wastewater pollution.

造纸污水深度处理自动监控系统设计研究

面对我国工业污水处理领域,特别是造纸污水处理的自动监控技术还显得较为滞后,相关学术成果匮乏,迫切需要加强此领域的技术研究与创新。当前,虽然多种智能控制技术各有所长,但也不无不足。因此,融合多元智能控制技术或将其与传统控制策略相结合的集成控制技术,对优化污水处理控制系统的设计,包括软件和硬件架构,显得尤为关键。实践证明,采用此类集成控制技术的污水处理系统能够实现稳定可靠的运行,不但满足了国家对污水排放的标准,而且符合节能减排的政策要求,带来了明显的经济与社会双重效益。这一领域的深入研究和技术进步,对促进我国环保事业的发展具有重要意义。

鞍钢鲅鱼圈焦化废水减量及回用改造实践

介绍了鞍钢鲅鱼圈焦化废水处理工艺运行概况,分析了焦化废水工艺存在的问题,通过提升预处理单元、生化处理系统和深度处理系统的功能,新增膜脱盐处理系统,大大提升了焦化废水系统出水水质,中水回用率达到70%以上。最终膜脱盐处理系统的浓水水质指标达到了《炼焦化学工业污染物排放标准》(GB 16171—2012)中的间排标准,全部回用于烧结混料,净水全部回用于循环水系统,实现了焦化废水零排放的目标。

基于PLC的污水脱盐处理自动控制系统

本文针对我国污水脱盐处理系统所存在的问题,介绍了一款基于PLC的自动化控制系统,将先进的超滤技术、反渗透膜技术和PLC技术结合,在提升系统的自动化水平和稳定性的同时实现双模工艺处理污水,保证处理后的高水质。