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The performance of wastewater treatment plants (WWTPs) depends on various technical, non-technical, and human factors. A total of 245 small and medium-size WWTPs were studied during 2014-2015 and evaluated according to a novel method for rapid assessment of their performance and complexity. The suggested method creates a comparable system of ratings for all treatment solutions by analysing simultaneously influential characteristics, system complexity, operational practices, and process parameters in comparison with designed and/or standardized values and their impact on the overall system performance. Total evaluation of complexity and total evaluation of performance are new unified tools, which were applied for comparing WWTPs that applied different technologies and had a wide variety of loadings. The study revealed that the greater the designed loading, the more treatment steps were usually needed and employed. The complexity of these treatment steps can vary a lot depending on the plant capacity. There was a positive relationship between complexity and performance: a higher complexity provided a better performance of WWTPs. This suggests that combining automation as a tool for the process control with a more advanced equipment (higher complexity) could prevent many process disturbances and therefore improve the overall plant performance. [ABSTRACT FROM AUTHOR]

The efforts for implementing the anammox process at mainstream conditions with high nitrogen removal rates have gained much attention in the race for achieving an energy-positive urban wastewater treatment plant. Here, the successful and stable long-term operation of an Upflow Anammox Sludge Bed (UAnSB) reactor treating a low-strength synthetic influent amended with ammonium and nitrite for 420 days, and a nitrite-amended pre-treated real urban wastewater for 110 days at temperatures as low as 11 °C is presented. The short and long-term effects of temperature on anammox activity were assessed when the synthetic influent was treated, and the UAnSB reactor was demonstrated to be a robust reactor to confront low temperatures, typically found at mainstream conditions. In fact, a nitrogen loading rate as high as 1.8 ± 0.1 g N L −1 d −1 with 82 ± 4% of nitrogen removal was achieved at 11 °C treating the low-strength synthetic influent. Furthermore, the effect of treating a nitrite-amended pre-treated real urban wastewater at 11 °C at long-term in the UAnSB reactor was evaluated, and a stable operation was achieved with a high average nitrogen removal rate (1.2 ± 0.5 g N L −1 d −1 ). The relative abundance of anammox bacteria was maintained higher than 70% according to fluorescence in situ hybridization during the whole operation, being Candidatus Brocadia anammoxidans the predominant microbial species. The presence of heterotrophs in the sludge bed was surmised through heterotrophic batch tests, but anammox activity was demonstrated to be higher than heterotrophic activity, even when the synthetic influent was replaced by the nitrite-amended pre-treated real wastewater. The feasibility of operating an enriched anammox reactor at high nitrogen removal rate at long-term at mainstream conditions was demonstrated in this study. [ABSTRACT FROM AUTHOR]

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 and the heterotrophic yield ( Y) required calibration. The value 0.42 was used for Y 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 $(Y_{PO_4 } )$) used in ASM2, ASM2d, and ASM3P, 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. [ABSTRACT FROM AUTHOR]

The article discusses the significance of the Nereda technology unveiled by environmental biotechnologist professor Mark van Loosdrecht for sewage treatment plants in 2005. Topics discussed include the views of Andrew Thompson, technical manager of wastewater and sludge at Imtech Water, Waste and Energy, regarding the same, the Dutch National Nereda Development Program and the discovery of activated sludge by Great Britain's engineers Edward Ardern and W.T. Lockett. INSETS: GOING WITH THE FLOW;ANAEROBIC DIGESTION.

To varying degrees throughout New England, the cost of labor, sludge disposal, electricity, and chemicals compose the lion's share of a facility's operating costs. Over the past 10 to 15 years, new sludge dewatering technologies have been introduced into the municipal wastewater market that has historically been dominated by belt filter presses and centrifuges. These new technologies, coupled with improvements to the traditional belt press and centrifuge technologies, have led to a wider array of mechanical dewatering alternatives than ever before. The proper selection of a dewatering technology can result in substantial savings in operating costs by maximizing cake solids; reducing recycle loadings, polymer dosage, electrical consJmption, and maintenance/operator attention; and containing odors. When evaluating sludge dewatering alternatives, all available options should be explored to determine the best fit for each treatment facility. Pilot testing in advance of making an equipment selection can provide valuable data during the evaluation process. [ABSTRACT FROM AUTHOR]

Organisms exposed to wastewater treatment works (WwTW) effluents accumulate complex mixtures of xenobiotics but there is a scarcity of information on the nature and impacts of these chemical mixtures. We applied metabolomics techniques as a novel approach to identify xenobiotics and their metabolites (the xenometabolome) that bioconcentrate in fish exposed to a WwTW effluent. Exposed juvenile rainbow trout (Oncorhynchus mykiss) accumulated surfactants, naphthols, chlorinated xylenols, and phenoxyphenols, chlorophenes, resin acids, mefenamic acid, oxybenzone, and steroidal alkaloids in the bile or plasma, and there were perturbations in the plasma concentrations of bile acids and lipids. Exposure of adult roach (Rutilus rutilus) to 50% or 100% concentrations of the same effluent resulted in dose-dependent increases in plasma concentrations of xenometabolites as well as cyprinol sulfate and taurocholic acid, lysophospholipids, and a decrease in sphingosine levels (a key component of cell membrane lipids). Our findings reveal the highly complex nature of xenobiotics accumulating in effluent-exposed fish, and the great potential of metabolomics for both identifying plasma marker (bio)chemicals for monitoring exposure to wastewater effluents, and for targeting studies on potential consequent impacts on fish health. [ABSTRACT FROM AUTHOR]

constructed wetland composed of a pond- and a marsh-type wetland was employed to remove nitrogen (N) and phosphorus (P) from effluent of a secondary wastewater treatment plant in Korea. Nutrient concentrations in inflow water and outflow water were monitored around 50 times over a 1-year period. To simulate N and P dynamics in a pond- and a marsh-type wetland, mesocosm experiments were conducted. In the field monitoring, ammonium (NH) decreased from 4.6 to 1.7 mg L, nitrate (NO) decreased from 6.8 to 5.3 mg L, total N (TN) decreased from 14.6 to 10.1 mg L, and total P (TP) decreased from 1.6 to 1.1 mg L. Average removal efficiencies (loading basis) for NO, NH, TN, and TP were over 70%. Of the environmental variables we considered, water temperature exhibited significant positive correlations with removal rates for the nutrients except for NH. Results from mesocosm experiments indicated that NH was removed similarly in both pond- and marsh-type mesocosms within 1 day, but that NO was removed more efficiently in marsh-type mesocosms, which required a longer retention time (2-4 days). Phosphorus was significantly removed similarly in both pond- and marsh-type mesocosms within 1 day. Based on the results, we infer that wetland system composed of a pond- and a marsh-type wetland consecutively can enhance nutrient removal efficiency compared with mono-type wetland. The reason is that removal of NH and P can be maximized in the pond while NO requiring longer retention time can be removed through both pond and marsh. Overall results of this study suggest that a constructed wetland composed of a pond- and a marsh-type wetland is highly effective for the removal of N and P from effluents of a secondary wastewater treatment plant. [ABSTRACT FROM AUTHOR]

The fate and partitioning of the antimicrobial compound, triclosan, in wastewater treatment plants (WWTPs) is evaluated using a probabilistic fugacity model to predict the range of triclosan concentrations in effluent and secondary biosolids. The WWTP model predicts 84% to 92% triclosan removal, which is within the range of measured removal efficiencies (typically 70% to 98%). Triclosan is predominantly removed by sorption and subsequent settling of organic particulates during primary treatment and by aerobic biodegradation during secondary treatment. Median modeled removal efficiency due to sorption is 40% for all treatment phases and 31% in the primary treatment phase. Median modeled removal efficiency due to biodegradation is 48% for all treatment phases and 44% in the secondary treatment phase. Important factors contributing to variation in predicted triclosan concentrations in effluent and biosolids include influent concentrations, solids concentrations in settling tanks, and factors related to solids retention time. Measured triclosan concentrations in biosolids and non-United States (US) effluent are consistent with model predictions. However, median concentrations in US effluent are over-predicted with this model, suggesting that differences in some aspect of treatment practices not incorporated in the model (e.g., disinfection methods) may affect triclosan removal from effluent. Model applications include predicting changes in environmental loadings associated with new triclosan applications and supporting risk analyses for biosolids-amended land and effluent receiving waters. Integr Environ Assess Manag 2010;6:393-404. © 2010 SETAC [ABSTRACT FROM AUTHOR]

The influence of four planted soil filters substrate in the depuration of the primary settlement effluent of the wastewater treatment plant of the Central University of Las Villas was evaluated. The experimental installation consists of four independent filters, with 0,3 m of diameter and 0,8 m of height. The plant selected was Typha domingensis, the filters are passed the wastewater intermittent (four days of rest and two days working). It was obtained an increase of the dissolved oxygen in all the cases, as well as the high removal percent (more of 80 %) of the biochemical oxygen demand, chemical oxygen demand, total suspended solid and Kjeldhal nitrogen, being below the average permissible maximum limit (APML) for the discharging, according to NC-27-1999. There was no significant differences among the filters for these parameters, the phosphorus removal was low, being smaller in the filter that contains brown soil with carbonate soil as substratum, the values of this parameter didn't decrease below the APML (4 mg/L). It was also evaluated the function of the filters with the time, offering the best results the filter that contained mixture of powder zeolite and brown soil with carbonate and the filters that contained red ferralitic soil as substrate. In the rest of the filters were observed obstruction symptoms. [ABSTRACT FROM AUTHOR]

The maximum power generated in a single-chamber air-cathode microbial fuel cell (MFC) has previously been shown to increase when the spacing between the electrodes is decreased from 4 to 2 cm. However, the maximum power from a MFC with glucose (500 mg/L) decreased from 811 mW/m² (Rex = 200 Ω, Coulombic efficiency of CE = 28%) to 423 mW/m² (Rex = 500 Ω, CE = 18%) when the electrode spacing was decreased from 2 to 1 cm (batch mode operation, power normalized by cathode projected area). This decrease in power was unexpected as the internal resistance decreased from 35 Ω (2-cm spacing) to 16 Ω (1-cm spacing). However, providing advective flow through the porous anode toward the cathode substantially increased power, resulting in the highest maximum power densities yet achieved in an air-cathode system using glucose or domestic wastewater as substrates. For glucose, with a 1-cm electrode spacing and flow through the anode with continuous flow operation of the MFC, the maximum power increased to 1540 mW/m² (51 W/m³) and the CE increased to 60%. Using domestic wastewater (255 ± 10 mg of COD/L), the maximum power density was 464 mW/m² (15.5 W/m³ CE = 27%). Although flow through the anode could lead to plugging, especially for particulate substrates such as domestic wastewater, the system was operated using glucose for over 42 days without clogging. These results show that power output in this air- cathode single-chamber MFC can be increased by reducing the electrode spacing if the reactors are operated in continuous flow mode with advective flow through the anode toward the cathode. [ABSTRACT FROM AUTHOR]

Within the last years a trend towards in-situ monitoring can be observed, i.e. most new sensors for water quality monitoring are designed for direct installation in the medium, compact in size and use measurement principles which minimise maintenance demand. Ion-sensitive sensors (Ion-Sensitive- Electrode -- ISE) are based on a well known measurement principle and recently some manufacturers have released probe types which are specially adapted for application in water quality monitoring. The function principle of ISE-sensors, their advantages, limitations and the different methods for sensor calibration are described. Experiences with ISE-sensors from applications in sewer networks, at different sampling points within wastewater treatment plants and for surface water monitoring are reported. An estimation of investment and operation costs in comparison to other sensor types is given. [ABSTRACT FROM AUTHOR]

An improved methodology based on a nitrate biosensor is developed and applied successfully for in-depth monitoring and study of anoxic activated sludge activities. The major advantages of the methodology are its simplicity, reliability and high data quality. The resulting data allowed for the first time to monitor anoxic respiration rate of activated sludge (nitrate uptake rate (NUR)) at a high time resolution making it clearly comparable with high frequency oxygen uptake rate (OUR) measurements obtained under aerobic conditions. Further, the anoxic respiration data resulting from a pulse addition of carbon source to endogenously respiring anoxic activated sludge shows a clear start-up phenomenon and storage tail that is usually also observed in high-frequency OUR measurements. Finally, the improved methodology can be expected to serve as an anoxic respirometer for activated sludge treatment plants where denitrification process occurs in single-step. Further, it can be used for a variety of purposes e.g. for toxicity and activity monitoring, process control and parameter estimation of the activated sludge process, similar to the aerobic respirometers. [ABSTRACT FROM AUTHOR]

An in-situ UV spectrometer was applied to the effluent of a WWTP in Switzerland and calibrated using a multivariate calibration algorithm based on PLS regression. Except for nitrite, the calibration was based on comparative measurements of the effluent in the plant laboratory. Samples made of stock solution added to three different matrices prepared in the EAWAG laboratory were used for the nitrite calibration because the effluent concentrations were always in the range of 0.06-0.26 mg/l. The results show very good precision for nitrite and nitrate. The measuring range for COD and DOC was not completely covered by the measurements, so the meaningfulness of the results is limited. Nevertheless the precision obtained for soluble COD is high enough for most applications at WWTPs. The accuracy of the TSS measurement is unsatisfactory as regards effluent limits since the spectrometer used does not cover the wavelength region up to 700 nm, which gives better signals for TSS calibration due to its strong correlation with turbidity. [ABSTRACT FROM AUTHOR]

Extended studies of measuring and control systems in activated sludge plants at EAWAG revealed that the measuring devices remain the weakest point in control applications. To overcome this problem, a software package was developed which analyses and evaluates the residuals between a reference measurement and the sensor and collects the information in a database. The underlying monitoring concept is based on a two-step evaluation of the residuals by means of statistical evaluations using control charts with two different sets of criteria. The first step is a warning phase in which hints on probable errors trigger an increase in the monitoring frequency. In the second step, the alarm phase, the error hypothesis has to be validated and should allow immediate and targeted reactions from the operator. This procedure enables an optimized and flexible monitoring effort combined with an increased probability of early detection of systematic measuring errors. Beside the monitoring concept, information about the measuring device, the performed servicing actions and the responsibilities is stored. Statistical values for the quantitative characterization of the measuring system during operation will be given. They are needed to parameterise controllers or to guarantee the accuracy of the instrument in order to allow reliable calculations of effluent tax. In contrast to other concepts, not only is the measuring device examined under standard conditions, but so is the entire measuring chain from the liquid to be analysed to the value stored in the database of the supervisory system. The knowledge of the response time of the measuring system is then required in order to allow a comparison of the corresponding values. [ABSTRACT FROM AUTHOR]

Part I. Discusses the criteria that may be used by sanitation agencies in selecting the type of wastewater pump for a particular project or application. Types of wastewater pumps; Details on capital cost and operation and maintenance costs; Description of pump types.

The article presents a guide to best practices covering the maintenance of screening equipment at water and wastewater treatment plants in order to avoid clogging and corrosion and mentions inspection and cleaning tips.