Membrane bioreactor application in wastewater re-use from the effluent of Bali primary WWTP, northern Taiwan.

Two MBR pilot systems were constructed and tested in the Bali Primary WWTP. The pilot study shows that two MBR systems, i.e. the Green-MenBio system (MBR-1) and the Bio-MF system (MBR-2), can both fulfill the requirement of wastewater reclamation standard. The MBR-2 system is more economical compared with MBR-1 system. The cost of US dollars 0.10-0.16/m3 is estimated to reclaim the effluent of primary WWTP in Taiwan. The Bali Primary WWTP has the capacity of 1,320,000 cmd which is the biggest in Taiwan. The domestic wastewater of partial Taipei City and Taipei County are collected and transported to the Bali Primary WWTP. The effluent of the Bali Primary WWTP is then discharged into the ocean through two 3.8 m marine outfalls. The AO processes are installed in both MBR systems. More than 90% of the NH3-N can be removed through the AO and membrane processes. The outflow of the MBR systems (without RO) can reach the quality of COD <30 mg/l, BOD <10 mg/l, SS <5 mg/l, NH3-N <3 mg/L. The outflow of the MBR system is proposed to transport 40 km south to the Taoyuan County where four new industrial parks are to be constructed. Part of the reclaimed water is to be used on irrigation and another portion is to be sent to the industries after RO treatment.     

Integrated operation of sewer system and WWTP by simulation-based control of the WWTP inflow.

In recent years numerical modelling became a standard procedure to optimise urban wastewater systems design and operation by integration. For dynamic control of the wastewater teatment plant (WWTP) inflow, a model-based predictive concept is introduced aiming at improving the receiving water quality. An on-line simulator running parallel to the real WWTP operation reflects the actual state of operation and provides this model information to a prognosis tool which determines the best option for the WWTP inflow. The investigations showed that it is possible to reduce the NH4-N peak concentrations in the receiving water by dynamic WWTP inflow control based on predictive scenario analysis.     

An integrated approach for improving the wastewater discharge and treatment systems

Since treatment plants have been built all over Germany during the last decades, the water quality of receiving streams has been improved remarkably. But there are still a lot of quality problems left, which are caused e.g. by combined sewer overflows (CSO), treatment plant effluents or rainwater discharges from separate sewer systems. At present different efforts are undertaken to control sewer systems in order to improve the operation of urban drainage systems or more generally, design processes. The Emschergenossenschaft and Lippeverband (EG/LV) are carrying out research studies, which are focusing on a minimization of total emissions from sewer systems both from wastewater treatment plant (WWTP) effluents and from CSO. They consider dynamic interactions between rainfall, resultant wastewater, combined sewers, WWTP and receiving streams. Therefore, in an advanced wastewater treatment, a model-based improvement of WWTP operation becomes more and more essential, and consequently a highly qualified operational staff is needed. Some aspects of the current research studies are presented in this report. The need and the use of an integrated approach to combine existing model components in order to optimize dynamic management of combined sewer systems (CSS) with a benefit for nature are outlined.     

Plant-wide (BSM2) evaluation of reject water treatment with a SHARON-Anammox process.

In wastewater treatment plants (WWTPs) equipped with sludge digestion and dewatering systems, the reject water originating from these facilities contributes significantly to the nitrogen load of the activated sludge tanks, to which it is typically recycled. In this paper, the impact of reject water streams on the performance of a WWTP is assessed in a simulation study, using the Benchmark Simulation Model no. 2 (BSM2), that includes the processes describing sludge treatment and in this way allows for plant-wide evaluation. Comparison of performance of a WWTP without reject water with a WWTP where reject water is recycled to the primary clarifier, i.e. the BSM2 plant, shows that the ammonium load of the influent to the primary clarifier is 28% higher in the case of reject water recycling. This results in violation of the effluent total nitrogen limit. In order to relieve the main wastewater treatment plant, reject water treatment with a combined SHARON-Anammox process seems a promising option. The simulation results indicate that significant improvements of the effluent quality of the main wastewater treatment plant can be realized. An economic evaluation of the different scenarios is performed using an Operating Cost Index (OCI).     

Membrane bio-reactor for textile wastewater treatment plant upgrading.

Textile industries carry out several fiber treatments using variable quantities of water, from five to forty times the fiber weight, and consequently generate large volumes of wastewater to be disposed of. Membrane Bio-reactors (MBRs) combine membrane technology with biological reactors for the treatment of wastewater: micro or ultrafiltration membranes are used for solid-liquid separation replacing the secondary settling of the traditional activated sludge system. This paper deals with the possibility of realizing a new section of one existing WWTP (activated sludge + clariflocculation + ozonation) for the treatment of treating textile wastewater to be recycled, equipped with an MBR (76 l/s as design capacity) and running in parallel with the existing one. During a 4-month experimental period, a pilot-scale MBR proved to be very effective for wastewater reclamation. On average, removal efficiency of the pilot plant (93% for COD, and over 99% for total suspended solids) was higher than the WWTP ones. Color was removed as in the WWTP. Anionic surfactants removal of pilot plant was lower than that of the WWTP (90.5 and 93.2% respectively), while the BiAS removal was higher in the pilot plant (98.2 vs. 97.1). At the end cost analysis of the proposed upgrade is reported.     

Spatio-temporal statistical models for river monitoring networks.

When introducing new wastewater treatment plants (WWTP), investors and policy makers often want to know if there indeed is a beneficial effect of the installation of a WWTP on the river water quality. Such an effect can be established in time as well as in space. Since both temporal and spatial components affect the output of a monitoring network, their dependence structure has to be modelled. River water quality data typically come from a river monitoring network for which the spatial dependence structure is unidirectional. Thus the traditional spatio-temporal models are not appropriate, as they cannot take advantage of this directional information. In this paper, a state-space model is presented in which the spatial dependence of the state variable is represented by a directed acyclic graph, and the temporal dependence by a first-order autoregressive process. The state-space model is extended with a linear model for the mean to estimate the effect of the activation of a WWTP on the dissolved oxygen concentration downstream.     

Statistical assessment of seafront and beach water quality of Mumbai, India

The water quality of seafronts and beaches of Mumbai is under pressure and deteriorating due to discharge of partially treated sewage and wastewater through point and nonpoint sources. The objective of the study was to assess the water quality and to correlate physico-chemical and bacteriological parameters for establishing relationship, association and dependence on each other. The water quality parameters were selected as per SW II standards specified by Central Pollution Control Board, India and nutrient parameters as strong indicators of sewage pollution. Box and whisker plots were generated for evaluating spatio temporal variation of water quality which suggest influence of organic pollution mostly at Mahim and Dadar in the form of outliers and extremes. Pearson's correlations were estimated between parameters and found significant correlation with each other indicating influence of sewage on water quality. The water quality of beaches and seafronts were found unsafe for recreational purposes. The study suggested that designated water quality can be achieved by restricting nonpoint source through improvement in wastewater collection systems, appropriate level of treatment and proper disposal.     

Potentials of real time control, stormwater infiltration and urine separation to minimize river impacts: dynamic long term simulation of sewer network, pumping stations, pressure pipes and waste water treatment plant.

River Panke (Berlin, Germany) suffers from hydraulic peak loads and pollutant loads from separate sewers and combined sewer overflows (CSOs). Pumping the wastewater through long pressure pipes causes extreme peak loads to the wastewater treatment plant (WWTP) during stormwater events. In order to find a good solution, it is essential not to decide on one approach at the beginning, but to evaluate a number of different approaches. For this reason, an integrated simulation study is carried out, assessing the potentials of real time control (RTC), stormwater infiltration, storage and urine separation. Criteria for the assessment are derived and multi-criteria analysis is applied. Despite spatial limitations, infiltration has the highest potential and is very effective with respect to both overflows and the WWTP. Due to a high percentage of separate systems, urine separation has a similar potential and causes the strongest benefits at the WWTP. Unconventional control strategies can lead to significant improvement (comparable to infiltrating the water from approximately 10% of the sealed area).     

确定排污水域的优化计算模型研究

如何根据接受水体如湖泊、河流、海岸水域等的水环境承载能力或水质保护目标区域（或敏感区域）的水质标准,选择污水源排放位置区域使得保护目标区域的水质标准得以维护,是一个非常值得研究的重要问题。该问题利用常规的水动力学模型加上污染物输移模拟技术通过试－错方法求解,存在一是耗时、二是受主观影响,三是只能对少数个排放点给出有限的解等缺点,有鉴于此,专门针对区域规则中污水排放位置优化控制问题,应用逆问题求解理论,提出了一种显示的共轭水质模型,该模型可应用于确定一、二维自由面水流系统中可行的污水排放位置或区域,以维持规则目标区域所期望的水质标准。     

Performance indicators for wastewater treatment plants

The Swedish Water & Wastewater Association has operated a web-based system, VASS, for the collection and compilation of key data from the Swedish water utilities since 2003. The VASS system will now be expanded to include data on operation of individual wastewater treatment plants (WWTP). The objective is to provide performance indicators (PIs) for performance and economy and the use of resources such as energy, chemicals and manpower. A set of PIs has been developed that also includes explanatory factors to compensate for differences in the condition of operation between plants. This paper discusses the data required for the calculation of PI but also for explanatory factors, quality checks and for plant operation context. The discussion is based on the experiences from a test round with the participation of 24 WWTP.     

Water reuse for urban landscape irrigation: aspersion and health related regulations.

The Mediterranean seaside resort of Le Grau du Roi includes 40 hectares of landscaped areas spray irrigated with river water supplied through a separate network. Wastewater collected from several municipalities is treated in an activated sludge wastewater treatment plant (WWTP) and polished in waste stabilization ponds (WSPs). Planned substitution of treated wastewater for river water is hindered by spray irrigation prohibition within a 100 m distance from houses and recreational areas. WWTP and WSP effluents were monitored for pathogens with a particular attention to Legionella in Spring and Summer 2006. Helminth eggs, salmonellae and enteroviruses were never detected neither in WWTP effluent nor in the ponds. Legionella spp content was slightly higher or of the order of magnitude of river water contents. Regarding Legionella pneumophila contents, WSP effluent did not significantly differ from the river water. E.coli and enterococci contents in WSP effluents complied with the "excellent quality" criteria of the European Directive for coastal bathing waters. Therefore, substituting WSP effluents to river water is unlikely to alter health risks related to spray irrigation and, in this case, the buffer zone required by the French water reuse guidelines appears being short of support.     

The effect of reclaimed wastewater on the quality and growth of grapevines

The effect of the use of treated wastewater on the growth of cabernet sauvignon and merlot grapes from the Guadalupe Valley, Mexico was evaluated. Secondary advanced effluent was used to irrigate the grapevines at a rate of 66 L/vine/week. Wastewater quality results confirmed that all parameters complied with Mexican legislation for crop irrigation as well as reuse in activities in which the public would be in direct or indirect contact with the reclaimed water. Results showed that the number of leaves per shoot and the overall biomass increased in plants irrigated with wastewater and grape production per plant was 20% higher. The concentration of carbohydrates, organic acids and pH were similar in grapes from vines irrigated with wastewater to those irrigated with groundwater. Throughout the experiment, no fecal coliform bacteria were detected in the cultivated grapes. The wastewater caused an increase in the biomass of the grapevines and there was no presence of microbial indicators in the final product so a higher wine production could be achieved without an increase in health risk related problems. If 200 L/s of reclaimed wastewater would be returned to be used for grapevine irrigation in Valle de Guadalupe (the same amount that is currently being sent as drinking water to Ensenada), assuming an irrigation application of 6,000-7.500 m3/ha/year, approximately 837-1046 hectares (ha) of grapevines could be irrigated. Part of ongoing research includes an economical analysis of the best options for Ensenada and the Valle de Guadalupe in order to establish the optimum volume of water to be returned, the cost of its transportation, as well as the cost of irrigation.     

An integrated modelling concept for immission-based management of sewer system, wastewater treatment plant and river.

Today's planning standards deal with the individual urban drainage components (sewer system, wastewater treatment plant and receiving water) separately, i.e. they are often designed and operated as single components. As opposed to this, an integral handling considers the drainage components jointly. This novel approach allows a holistic and more sustainable planning of urban drainage systems. This paper presents an integrated modelling concept. The aim is to analyse fluxes through the total wastewater system and to integrate pollution-based control in the upstream direction, that is, e.g., managing the combined water retention tanks as a function of state variables in the WWTP or the receiving water. All models of the different subsystems are based on the Activated Sludge Model (ASM) concept of IWA, including River Water Quality Model No. 1 (RWOM). Simulations can be done in truly parallel mode using the simulation environment SIMBA. The integrated modelling concept is applied to the river Dhuenn and the urban wastewater system of the municipality of Odenthal (Germany). An optimised operation of the system using RTC proves to be a very effective measure.     

国外污水处理厂改造工程实例分析

对国外4座污水处理厂改造工程实例进行了分析研究,通过对原有工艺流程改造,部分单元采用新技术、新工艺,调整工艺参数等改造方案,在充分利用原有污水处理设施的前提下,满足了处理水量增加或水质标准提高的要求.     

Trends in instrumentation, control and automation and the consequences on urban water systems.

In recent years more and more on-line sensors have been used on different structures of urban water systems (UWS, i.e. wastewater treatment plants (WWTP), waterworks (WW), sewer systems). This development is influenced and driven by numerous trends, which will be discussed in this paper. For a better understanding, the discussion is illustrated with a factual example. The new possibilities of on-line measurement and automation technologies will also change the way as UWS will be planned, built and operated.     

Effluent treatment by multi-media filtration, microfiltration and ultrafiltration: results of a pilot investigation at WWTP Hoek van Holland.

Upgrading of wastewater treatment plant (WWTP) effluent as a part of the Dutch governmental policy to close the water cycle has increasing interest now. The Water Board Hoogheemraadschap van Delfland together with the project team of Witteveen + Bos Consulting Engineers, Delft University of Technology and Rossmark water treatment investigated the reuse possibilities of WWTP effluent in the region of Delfland. Therefore pilot research was carried out at WWTP Hoek van Holland applying different filtration techniques: multi-media filtration, micro- and ultrafiltration. The results show stable process performances of the different filtration techniques when proper pre-treatment was applied. For microfiltration the filtration characteristics were strongly influenced by particles which were not retained in the multi-media filter. For ultrafiltration the filtration characteristics were strongly influenced by organic components < 0.2 microm. The upgraded WWTP effluent could not be used directly as process water or for agriculture purposes, due to high concentrations of COD and salts in the WWTP effluent and filtrates. However WWTP effluent or floc filtrate could be applied directly as water for the washing of sea-sand.     

Membrane bioreactors in industrial wastewater treatment--European experiences, examples and trends.

In wastewater treatment, micro- and ultra-filtration membranes are used for the separation of the activated sludge (biomass) from the treated water. This offers the advantages of a complete removal of solids and bacteria, as well as most of the viruses, namely those attached to the suspended solids. Compared to the conventional activated sludge process (CAS) this technology allows a much higher biomass concentration (MLSS) whereby the reactor volume and the footprint decreases. With increasing MLSS, the viscosity of the sludge increases, which leads to reduced oxygen transfer rates. Depending on the type of membrane and membrane module, the pre-treatment has to be more sophisticated to prevent clogging and sludging of the modules. Due to fouling and scaling, the flux through the membranes will decrease with time. The decrease depends on the water quality as well as on the measurements taken to minimize fouling. Mainly, three strategies are available: lowering the flux, increasing the "crossflow" and cleaning of the membranes. Different strategies including backwash and chemical cleaning "in situ", "on air" and "ex situ" can be applied. It has been proven more effective to apply preventive regular cleaning. Besides the energy demand for oxygen supply--which is typically in the range of 0.3 kWh/m3 for municipal wastewater--the energy for fouling prevention is substantial. Immersed membranes need approximately 0.4 to 1 kWh/m3 for the coarse bubble aeration, whereas tubular modules require 1 to 4 kWh/m3 pump energy. For proper design of industrial wastewater treatment, the verification of applicability and the development of adequate cleaning strategies, it is a precondition to run pilot tests for a sufficient period of time with the wastewater to be treated. More than 100 industrial wastewater treatment membrane bioreactors (MBR) are in operation in Europe. Data of three case studies for a sewage sludge dewatering plant in UK (12,000 m3/d), a plant for the treatment of pharmaceutical wastewater in Germany (3600 m3/d), as well for revamping of an chemical WWTP >2000 m3/d in Italy, are given. MBRs will be used in future wherever high quality effluent is required, because of a sensitive receiving water body or due to the fact of water reuse as process water. MBRs are a perfect pre-treatment in industrial applications when further treatment with nanofiltration or reverse osmosis is considered. The technique is advanced and can be applied both in municipal and industrial wastewater treatment. Higher operational costs must be balanced by superior effluent quality.     

Fish living near two wastewater treatment plants have unaltered thermal tolerance but show changes in organ and tissue traits

Municipal wastewater treatment plants (WWTPs) are a significant source of anthropogenic pollutants and are a serious environmental stressor in Laurentian Great Lakes ecosystems. In this study, we examined whether three freshwater fish species (bluegill sunfish Lepomis macrochirus, green sunfish Lepomis cyanellus, and round goby Neogobius melanostomus) collected near two wastewater effluent outflows in Lake Ontario showed altered measures of somatic investment and thermal tolerance. Fish of all three species collected near the WWTPs were larger with 50–60% heavier body masses compared to those collected at reference sites. Green sunfish had higher body condition and increased haematocrit at wastewater-contaminated sites, and both round goby and bluegill sunfish had larger livers (controlling for body mass) at wastewater-contaminated sites. Thermal tolerance (critical thermal maximum, CT_max) differed between species (green sunfish > bluegill sunfish > round goby), but was similar in fish collected at wastewater-contaminated sites compared to cleaner reference sites. Wastewater-contaminated sites had poorer water quality, higher nutrient loadings, and higher concentrations of anthropogenic contaminants (measured via polar organic chemical integrative samplers, POCIS) than reference sites. Our results suggest that fish in the wild may have some capacity to cope with WWTP effluent and avoid any potential impairments in thermal tolerance. Our findings also suggest that treated wastewater is changing water quality locally in Great Lakes watersheds, and that many fish species may be able to access extra nutrients provided by such effluent outflows. However, if outflow areas become preferred foraging areas this will inadvertently increase exposure to anthropogenic stressors and pollutants.     

Direct precipitation on demand at large Scandinavian WWTPs reduces the effluent phosphorus load

On demand use of direct precipitation of wastewater has been successfully implemented at several large Scandinavian wastewater treatment plants (WWTPs) as a cost-efficient method of treating wastewater bypassing secondary treatment. During wet weather situations or when the capacity of secondary treatment is reduced excess wastewater can be treated through efficient direct precipitation. This increases the total capacity of the WWTP to remove phosphorus during these periods. This treatment strategy allows the WWTPs to meet stringent effluent phosphorus limits without extending secondary treatment of the main plant, despite high wet weather flows. The gain in terms of reduced phosphorus emissions varies depending on local conditions such as climate, collection system and secondary treatment capacity. It also varies from year to year depending on the weather and reductions of capacity due to planned refurbishing or unplanned breakdown of equipment. Operating chemical precipitation on demand has proved to contain challenges to operation and organisation of the WWTP. These challenges include logistics of start-up, training of staff and maintaining the system between occasions of operation. Sufficient up-stream storage capacity, reliable weather forecasts and good contracts with suppliers of chemicals are keys of success.