Waste Stabilization Ponds in Europe

The European countries where sewage treatment in waste stabilization ponds is largely developed and commonly used are West Germany (more than 2000 operational systems) and France (about 2500 plants). Portugal has over 50 systems at present and will have about 100 by the year 1993. Spain has more than 10 operational plants and in Denmark there are 50 ponds for tertiary treatment. A survey on the present practice in the countries where the process is largely applied, including size of plants, type of ponds, type of influent and design criteria, is presented. It is found that waste stabilization ponds are particularly appropriate for full treatment of effluents from small communities (less than 5000 population equivalent) and for tertiary treatment following conventional larger plants.     

An integrated environmental plan for the reuse of treated wastewater effluents from WWTP in urban areas

The reuse of treated wastewater effluents from wastewater treatment plants (WWTP) is a recent practice in the environmental restoration of marginal areas in combination with tree and shrub planting. In urban areas, an integrated approach to the application of this practice implies (a) reuse of treated domestic wastewater for irrigation of hardy plant species and (b) design of environmentally friendly outdoor landscape including the planting of species acceptable for irrigation with such kind of wastewater.     

Productivity growth of wastewater treatment plants – accounting for environmental impacts: a Malmquist-Luenberger index approach

As the number of wastewater treatment plants (WWTPs) has increased, the economic considerations associated with their management have become more relevant. Measuring the productivity of WWTPs allows the best practice to be identified and resource use to be optimized. Previous studies assessing the productivity change of WWTPs have ignored undesirable outputs; thus, wastewater treatment was considered to be free of environmental impacts. To overcome this limitation and for the first time, we assessed the productivity growth of a sample of Spanish WWTPs, while also accounting for the emission of greenhouse gases and sludge production. The Malmquist-Luenberger productivity index (MLPI) and its components, the efficiency and technological changes, were estimated. To explore the role of environmental impacts in the measurement of the productivity growth of WWTPs, the MLPI was contrasted with the conventional measurement of productivity change: namely, the Malmquist productivity index (MPI). The omission of undesirable outputs led to an underestimation of the productivity growth, with statistically significant differences between the MLPI and MPI results. The comparison of the MPI and MLPI illustrated that WWTP operators and water agencies have internalized some good environmental practices into their production process costs.     

Anaerobic treatment of domestic wastewater in temperate climates: treatment plant modelling with economic considerations.

Although research suggests that anaerobic treatment of low-strength domestic wastewater is possible in temperate climates, to date, full-scale applications have only been pioneered in hot regions. However, burgeoning environmental legislation in developed countries is giving the impetus to develop anaerobic wastewater treatment systems due to potential economic and environmental benefits they hold over traditional aerobic techniques. In this paper a design rationale for low-temperature, low-strength (COD < 1,000 mgl(-1)), two-phase anaerobic wastewater treatment is developed through empirical modelling of data from published research, and from assumptions arising from a literature review. Model calculations are applied to typical domestic sewage characteristics at two different flow rates, based on population equivalents. Results indicate that soluble COD production in the model hydrolytic tank are similar to those achieved in pilot scale plants in the Netherlands. Model anaerobic reactor sludge characteristics are similar to those achieved in pilot and full-scale anaerobic reactors treating low-strength wastewaters. Indicative cost figures for a two-phase anaerobic treatment plant are given, but are incomplete without an assessment of the cost of post-treatment processes. Anaerobic treatment is likely to become more attractive in the future as new legislation relating to sludge disposal and renewable energy generation are introduced.     

城镇污水处理自动控制策略研究进展

全过程自动化控制是未来城镇污水处理厂的发展方向,但由于污水处理过程具有非线性、多变量、时变性等特点,自控系统中关键运行参数的测量以及控制决策的制定都存在困难,目前实际应用的系统大多停留在实现单一参数或单一反应器控制的层面上。自动控制策略是整个自动控制系统的头脑,是充分发挥系统软硬件效能、保证系统鲁棒性的关键。总结了城镇污水处理厂自动控制方案依据的数学模型,描述了活性污泥模型(ASM)和仿真基准模型(BSM)的基本特征,综述了自动控制策略在城镇污水处理曝气、化学除磷以及多目标优化控制方面的研究进展,分析了目前研究中存在的挑战和机遇,发现理论研究与工程实践相结合是加快城镇污水处理厂自动化进程的必要途径。     

Field study using two immunoassays for the determination of estradiol and ethinylestradiol in the aquatic environment

The effluent of four sewage treatment plants (STP) and eight surface water samples from the river Rhine in Germany and two smaller rivers were monitored for the hormones estradiol (E2) and ethinylestradiol (EE2). The studied STPs are using different treatment processes. Two facilities include an activated sludge treatment, one is a constructed wetland, and one is just an aerated lagoon. For analysis of E2 and EE2 in the aquatic environment two immunoassays have been developed allowing a very cost-effective screening for both hormones in environmental samples. Detection limits could be established at 0.05 ng L(-1) for E2 and 0.01 ng L(-1) for EE2, taking a 50-fold enrichment into account. Median concentrations for E2 and EE2 in effluent samples were 12 and 1.8 ng L(-1), in surface water 4.0 and 0.7 ng L(-1), respectively. The highest estrogen concentrations were found in the effluent of the lagoon, equipped with very basic means of wastewater treatment.     

Identifying the performance drivers of wastewater treatment plants through conditional order-m efficiency analysis

In European countries, wastewater treatment service is often provided by utilities, which have to comply with environmental laws and, at the same time, should control costs in order to restrain tariff growth and earn profits. By applying a conditional order-m efficiency method, this study provides some insights to the operational variables affecting the efficiency of 137 plants owned by a water utility operating in Tuscany, Italy. These performance drivers are categorized as: 1) wastewater features, 2) plant technology, 3) other plant features, 4) output quality, and 5) sludge disposal method. Starting from some controversial results from prior literature, this paper provides some useful insights on the best policies that could be adopted by a utility to catch cost savings.     

Occurrence and removal of N-nitrosamines in wastewater treatment plants

The presence of nitrosamines in wastewater might pose a risk to water resources even in countries where chlorination or chloramination are hardly used for water disinfection. We studied the variation of concentrations and removal efficiencies of eight N-nitrosamines among 21 full-scale sewage treatment plants (STPs) in Switzerland and temporal variations at one of these plants. N-nitrosodimethylamine (NDMA) was the predominant compound in STP primary effluents with median concentrations in the range of 5-20 ng/L, but peak concentrations up to 1 μg/L. N-nitrosomorpholine (NMOR) was abundant in all plants at concentrations of 5-30 ng/L, other nitrosamines occurred at a lower number of plants at similar levels. From concentrations in urine samples and domestic wastewater we estimated that human excretion accounted for levels of <5 ng/L of NDMA and <1 ng/L of the other nitrosamines in municipal wastewater, additional domestic sources for <5 ng/L of NMOR. Levels above this domestic background are probably caused by industrial or commercial discharges, which results in highly variable concentrations in sewage. Aqueous removal efficiencies in activated sludge treatment were in general above 40% for NMOR and above 60% for the other nitrosamines, but could be lower if concentrations were below 8-15 ng/L in primary effluent. We hypothesize that substrate competition in the cometabolic degradation explains the occurrence of such threshold concentrations. An additional sand filtration step resulted in a further removal of nitrosamines from secondary effluents even at low concentrations. Concentrations released to surface waters were largely below 10 ng/L, suggesting a low impact on Swiss water resources and drinking water generation considering the generally high environmental dilution and possible degradation. However, local impacts in case a larger fraction of wastewater is present cannot be ruled out.     

城市污水处理厂环境影响评价案例分析

城市污水处理厂的建设与运行直接关系到对周边环境的影响。结合具体案例的分析，认为进行环境评价时应重点关注厂址选择、尾水排放、中水回用以及污泥的处置和综合利用等问题，并提出切实可行的对策和建议。     

Environmental status at the Indian Antarctic station — Maitri

A set of procedural guidelines have been developed in 1991 for evaluating the environmental impact of scientific research programs and their associated logistic support facilities in Antarctica. In view of this, an Environmental Impact Assessment (EIA) study of the Indian Antarctic station — Maitri was conducted during the austral summer of 1994–95. Studies covered different components of environment, viz. air, noise, water, wastewater, solid waste and land. Different sources of pollution were identified and the samples were analyzed to assess the current status of environment. The present communication delineates not only the details of the studies undertaken, but also suggests guidelines towards effective Environmental Management Plan (EMP) so as to mitigate the adverse impacts likely to be caused by various activities.     

Estrogenic and AhR activities in dissolved phase and suspended solids from wastewater treatment plants

The distribution of estrogen receptor (ERα) and Aryl Hydrocarbon Receptor (AhR) activities between the dissolved phase and suspended solids were investigated during wastewater treatment. Three wastewater treatment plants with different treatment technologies (waste stabilization ponds (WSPs), trickling filters (TFs) and activated sludge supplemented with a biofilter system (ASB)) were sampled. Estrogenic and AhR activities were detected in both phases in influents and effluents. Estrogenic and AhR activities in wastewater influents ranged from 41.8 to 79 ng/L E₂ Eq. and from 37.9 to 115.5 ng/L TCDD Eq. in the dissolved phase and from 5.5 to 88.6 ng/g E₂ Eq. and from 15 to 700 ng/g TCDD Eq. in the suspended solids. For both activities, WSP showed greater or similar removal efficiency than ASB and both were much more efficient than TF which had the lowest removal efficiency. Moreover, our data indicate that the efficiency of removal of ER and AhR activities from the suspended solid phase was mainly due to removal of suspended solids. Indeed, ER and AhR activities were detected in the effluent suspended solid phase indicating that suspended solids, which are usually not considered in these types of studies, contribute to environmental contamination by endocrine disrupting compounds and should therefore be routinely assessed for a better estimation of the ER and AhR activities released in the environment.     

High occurrence of hepatitis E virus in samples from wastewater treatment plants in Switzerland and comparison with other enteric viruses

Hepatitis E virus (HEV) is responsible for many enterically transmitted viral hepatitides around the world. It is currently one of the waterborne diseases of global concern. In industrialized countries, HEV appears to be more common than previously thought, even if it is rarely virulent. In Switzerland, seroprevalence studies revealed that HEV is endemic, but no information was available on its environmental spread. The aim of this study was to investigate –using qPCR– the occurrence and concentration of HEV and three other viruses (norovirus genogroup II, human adenovirus-40 and porcine adenovirus) in influents and effluents of 31 wastewater treatment plants (WWTPs) in Switzerland. Low concentrations of HEV were detected in 40 out of 124 WWTP influent samples, showing that HEV is commonly present in this region. The frequency of HEV occurrence was higher in summer than in winter. No HEV was detected in WWTP effluent samples, which indicates a low risk of environmental contamination. HEV occurrence and concentrations were lower than those of norovirus and adenovirus. The autochthonous HEV genotype 3 was found in all positive samples, but a strain of the non-endemic and highly pathogenic HEV genotype I was isolated in one sample, highlighting the possibility of environmental circulation of this genotype. A porcine fecal marker (porcine adenovirus) was not detected in HEV positive samples, indicating that swine are not the direct source of HEV present in wastewater. Further investigations will be necessary to determine the reservoirs and the routes of dissemination of HEV.     

ICA技术在污水厂的应用现状及发展

详细说明了仪表、控制和自动化（Instrumentation，Control and Automation，ICA）技术在污水处理系统中应用的限制性因素和发展动力，介绍了ICA技术在国内和欧洲部分国家的应用现状，给出了污水处理厂常用的实时控制方法，强调传感器已不是污水处理系统在线控制的主要瓶颈，指出污水处理厂的运行缺乏灵活性以及管理人员水平较低是难以实现在线控制的主要原因。     

Challenges for a proposed environmental impact assessment system in norway

Since the middle of the 1970's the idea of developing a general requirement for Environmental Impact Assessment (EIA) in Norway has slowly emerged. At the end of 1983, a Planning Act Commission has presented a proposal for a mandatory EIA process for major physical developments likely to have a significant impact on the environment or the communities affected. The paper presents two background studies on the present EIA practice in Norway and points out major areas for improvement in the present assessment and decision‐making processes. Furthermore, the paper gives a short presentation of the proposed EIA system in Norway. With reference to this proposal and studies of EIA systems in other selected countries and provinces, ten different problem areas or challenges for a satisfactory EIA process are identified and discussed.     

Institutional, geographic, and facility factors affecting differences in prices for wastewater services

The provision of wastewater services is an important infrastructure service that affects social welfare. It improves the quality of community life by promoting sanitary conditions and minimizing the negative impact of wastewater on ecosystems. The price for this important public service, however, varies considerably across regions and localities. In this paper, we examine the physical factors and institutional characteristics that affect wastewater service prices across regions and localities. Our major concerns are the following: (1) institutional arrangements and characteristics of a wastewater utility, (2) government regulations, (3) supply factors and characteristics, and (4) natural environments and local characteristics. To analyze the price differences, we employ the demand and price equations for wastewater services using a simultaneous equations framework. For empirical estimation, we utilize a seemingly unrelated regression (SUR) method to account for the correlations between the residuals in the four price equations for wastewater services. Our empirical results are that the institutional arrangement of services, including monthly charges (versus bi-monthly or quarterly charges), provision of other infrastructure services in addition to wastewater services, and long-term debt, explain much of the price difference. In addition, the wastewater prices are influenced by state environmental regulations as well as supply factors, such as the number of wastewater treatment plants and infiltration and inflow into the sewer system. Interestingly, local geographic and meteorologic factors that were hypothesized to affect the selection of treatment processes were not found to be associated with price. These findings suggest ways wastewater services might be offered at lower prices for users.     

Reactivity and chemical characterization of effluent organic nitrogen from wastewater treatment plants determined by Fourier transform ion cyclotron resonance mass spectrometry

In advanced wastewater treatment plants that achieve high levels of nitrogen (N) removal, up to one-third of the N in effluent is organic, herein referred to as effluent organic N (EON). While we know that inorganic N is highly labile, it is unclear what fraction of EON is bioavailable. In this study, we demonstrate the utility of a method that can be used to examine the reactivity of EON in natural receiving waters to better understand both the ecosystem response and the potential bioavailability of EON. The technique is suitable for analyzing polar organic matter in natural waters; electrospray ionization coupled with Fourier transform mass spectrometry. Bioassays were performed on samples collected at the end of the biological process from two wastewater treatment plants achieving advanced N removal. The samples were concentrated, and then added to natural water samples collected from the oligohaline James River, a major tributary of the Chesapeake Bay. Our results demonstrate that while the lignin-like fraction of the effluent dissolved organic matter (some of which contains N) was conserved, a large portion of aliphatic and aromatic compounds containing N was removed (79-100%) during incubations, while other compounds were produced. Furthermore, the two effluents exhibited differences in the degree of degradation and type of degradation, which can be related both to the various processes employed in the two WWTPs and the dramatic differences in the type of influent they received. These findings suggest that EON is highly reactive in the natural environment and that simple assays examining net consumption or production of bulk dissolved organic N pools are inadequate for assessing the bioavailability of EON.     

Detection and molecular characterization of noroviruses from five sewage treatment plants in central Italy

Noroviruses (NoVs) are the most frequent etiological agents of non-bacterial gastroenteritis. These viruses are transmitted through the fecal-oral route, leading to high viral loads in sewages. The objective of this paper was to study the environmental occurrence of the most prevalent NoV strains in different wastewater treatment plants. In addition, molecular characterization of the isolated strains was performed. Two different PCR-based methods were carried out and a novel strategy was used to verify the level of RT-PCR inhibition.From May to September 2007, a total of 97 inflow and outflow samples were collected from five wastewater treatment plants in central Italy. We detected NoV by nested PCR in 96.9% of influent samples: 89.1% contained both genogroups; 4.7% contained only GI and 3.1% only GII. In effluents, we detected NoV in 78.8% of samples: 30.3% contained both genogroups, and 48.5% contained only GI. The major genotypes detected by sequencing analyses were GI/2, GI/5, GII/b, GII/4 and GII/6.This work confirms the wide circulation of NoVs in Italy with a predominance of GI strains, and the widespread distribution of NoV variants in both raw and treated wastewater.     

Iron salts dosage for sulfide control in sewers induces chemical phosphorus removal during wastewater treatment

Chemical phosphorus (P) removal during aerobic wastewater treatment induced by iron salt addition in sewer systems for sulfide control is investigated. Aerobic batch tests with activated sludge fed with wastewater containing iron sulfide precipitates showed that iron sulfide was rapidly reoxidised in aerobic conditions, resulting in phosphate precipitation. The amount of P removed was proportional to the amount of iron salts added, and for the sludge used, ratios of 0.44 and 0.37 mgP/mgFe were obtained for ferric and ferrous dosages, respectively. The hydraulic retention time (HRT) of iron sulfide in sewers was found to have a crucial impact on the settling of iron sulfide precipitates during primary settling, with a shorter HRT resulting in a higher concentration of iron sulfide in the primary effluent and thus enabling higher P removal. A mathematical model was developed to describe iron sulfide oxidation in aerated activated sludge and the subsequent iron phosphate precipitation. The model was used to optimise FeCl₃ dosing in a real wastewater collection and treatment system. Simulation studies revealed that, by moving FeCl₃ dosing from the WWTP, which is the current practice, to a sewer location upstream of the plant, both sulfide control and phosphate removal could be achieved with the current ferric salt consumption. This work highlights the importance of integrated management of sewer networks and wastewater treatment plants.     

Economic feasibility study for wastewater treatment: A cost-benefit analysis

Water resource management should be made from a multidisciplinary perspective. In this sense, economic research into the design and implementation of policies for the efficient management of water resources has been emphasized by the European Water Framework Directive (WFD). Cost-benefit analysis (CBA) is one of the more widely accepted economic instruments since it is a rational and systematic decision-making support tool. Moreover, the wastewater treatment process has significant associated environmental benefits. However, these benefits are often left uncalculated because they have no market value. In this paper, using the concept of shadow price, a quantification of the environmental benefits derived from wastewater treatment is made. Once the environmental benefits are estimated and the economic costs of the treatment processes are known, a CBA is made for each of the wastewater treatment plants (WWTPs) under study. In this way, a useful economic feasibility indicator is obtained for WWTP operation.     

Ecological restoration of reclaimed wastewater lakes using submerged plants and zooplankton

High‐pollutant concentrations have led to the breakout of planktonic bloom and the breakdown of the ecosystem in many lakes in China and other countries. The removal of the organic and inorganic pollutants from industrial, agricultural and domestic wastewater and the restoration of the aquatic ecosystem of the polluted water bodies are persistent issues. Constructed wetlands are often used, and most depend on emerged plants. In this study, Daphnia magna, a type of zooplankton, and five species of submerged plants were used to remove nitrogen and phosphorus from reclaimed domestic wastewater in four scenery lakes of a garden in Peking, China. Water quality was assessed by the local environmental inspection station as the government inspection and a commercial company as the third party inspection, and the gathered data proved that ecological restoration was successful in this study.