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A comprehensive assessment of full-scale enhanced biological phosphorus removal (EBPR) plants (five plants, 19 independent tests) was undertaken to determine their effectiveness in terms of aerobic and anoxic P removal. By comparing parallel P uptake tests under only aerobic or under anoxic-aerobic conditions, results revealed that introducing an anoxic stage led to an overall P removal of on average 90% of the P removed under only aerobic conditions. This was achieved with negligible higher PHA and glycogen requirements, 30% lower overall oxygen consumption and with the simultaneous removal of nitrate, reducing up to an estimate of 70% of carbon requirements for simultaneous N and P removal. Varying fractions of denitrifying polyphosphate accumulating organisms (DPAOs), from an average of 25% to 84%, were found in different plants. No correlation was found between the DPAO fractions and EBPR configuration, season, or the concentration of any of the microbial groups measured via quantitative fluorescence in situ hybridisation. These included Type I and Type II Ca. Accumulibacter and glycogen accumulating organisms, suggesting that chemical batch tests are the best methodology for quantifying the potential of anoxic P removal in full-scale wastewater treatment plants. [ABSTRACT FROM AUTHOR]

The main objective of this paper is to demonstrate the importance of applying dynamic modelling and real energy prices on a full scale water resource recovery facility (WRRF) for the evaluation of control strategies in terms of energy costs with aeration. The Activated Sludge Model No. 1 (ASM1) was coupled with real energy pricing and a power consumption model and applied as a dynamic simulation case study. The model calibration is based on the STOWA protocol. The case study investigates the importance of providing real energy pricing comparing (i) real energy pricing, (ii) weighted arithmetic mean energy pricing and (iii) arithmetic mean energy pricing. The operational strategies evaluated were (i) old versus new air diffusers, (ii) different DO set-points and (iii) implementation of a carbon removal controller based on nitrate sensor readings. The application in a full scale WRRF of the ASM1 model coupled with real energy costs was successful. Dynamic modelling with real energy pricing instead of constant energy pricing enables the wastewater utility to optimize energy consumption according to the real energy price structure. Specific energy cost allows the identification of time periods with potential for linking WRRF with the electric grid to optimize the treatment costs, satisfying operational goals. [ABSTRACT FROM AUTHOR]

A rapid methodology for intracellular storage polyphosphate (poly-P) identification and monitoring in enhanced biological phosphorus removal (EBPR) systems is proposed based on quantitative image analysis (QIA). In EBPR systems, 4'6-diamidino-2-phenylindole (DAPI) is usually combined with fluorescence in situ hybridization to evaluate the microbial community. The proposed monitoring technique is based on a QIA procedure specifically developed for determining poly-P inclusions within a biomass suspension using solely DAPI by epifluorescence microscopy. Due to contradictory literature regarding DAPI concentrations used for poly-P detection, the present work assessed the optimal DAPI concentration for samples acquired at the end of the EBPR aerobic stage when the accumulation occurred. Digital images were then acquired and processed by means of image processing and analysis. A correlation was found between average poly-P intensity values and the analytical determination. The proposed methodology can be seen as a promising alternative procedure for quantifying intracellular poly-P accumulation in a faster and less labour-intensive way. [ABSTRACT FROM AUTHOR]

Pharmaceuticals and personal care products (PPCPs) are becoming increasingly recognised as important micropollutants to be monitored in wastewater treatment plants (WWTPs), since WWTP effluents represent an important point source to natural aquatic systems. In this study, the abundance of 65 PPCPs was analysed in 5 Portuguese WWTPs during the spring and autumn. Due to the fact that analytical approaches normally used to quantify the abundance of these compounds are labour intensive and require various specific procedures, this study proposes a set of simplified analytical methods for the quantification of pharmaceutically active compounds (PhACs) and polycyclic musks in liquid and sludge samples. The analytical methods were validated using influent wastewater matrices, showing comparable limits of detection and quantification as literature values for most PPCP s, with the exception of the estrogenic compounds. The PhAC concentrations detected in the WWTP survey were in the range of 0.050-100mg L21 in the influent and up to 50mgL21 in the effluent, where the non-steroidal anti-inflammatory drugs (NSAIDs) were the most abundant and frequently detected group. Some musks were detected up to 11.5mg L21 in the influent and 0.9mg L21 in the effluent, and adsorbed in the sludge up to 22.6mgg21. [ABSTRACT FROM AUTHOR]

Biological nutrient removal (BNR) plants can reduce both carbon and oxygen requirements by increasing the fraction of phosphorus (P) removed by denitrifying polyphosphate accumulating organisms (DPAOs). Contrasting findings have been reported in literature concerning whether or not PAOs and DPAOs are different microorganisms. In this study, quantitative fluorescence in situ hybridisation (FISH) measurements from different EBPR sludges support the hypothesis that PAOs and DPAOs are phyogenetically different. This experimental evidence is discussed within the context of literature findings and suggestions for future research concerning the identity of PAOs and DPAOs are proposed. Further, this paper discusses the different methodologies available for assessing the DPAO fraction through chemical analytical techniques, where the relative fraction estimated is highly dependent on the methodology employed. Thus, we recommend an alteration to previously proposed methods in order to calculate the DPAO fraction through anaerobic-anoxic and anaerobic-aerobic batch tests. This information is expected to be valuable in studies focussed on optimising the amount of phosphorus removal achieved with simultaneous denitrification. [ABSTRACT FROM AUTHOR]

Glycolysis has been generally accepted to be the source of reducing power used for the synthesis of polyhydroxyalkanoates (PHAs) in the anaerobic metabolism of polyphosphate accumulating organisms (PAOs). However, the tricarboxylic acid cycle (TCA) has also been suggested to contribute to the generation of reducing equivalents, creating some controversy in this research field over the last two decades. Various research approaches have been applied in order to clarify this issue, including the analysis of intracellular compounds, labelled carbon substrates and gene expression. However, the conclusions of these studies seem not to be consolidated. The extent of TCA cycle involvement could be related to the experimental methods employed, the community structure of the cultures used, and also the operational conditions employed. This mini-review analyses the historical findings related to the source of reducing power in PAOs, and highlights the different approaches used in the previous studies. Key factors influencing the generation of reducing power through different metabolic pathways are discussed, and further research directions are also proposed. [ABSTRACT FROM AUTHOR]

Many unit process models are available in the field of wastewater treatment. All of these models use their own notation, causing problems for documentation, implementation and connection of different models (using different sets of state variables). The main goal of this paper is to propose a new notational framework which allows unique and systematic naming of state variables and parameters of biokinetic models in the wastewater treatment field. The symbols are based on one main letter that gives a general description of the state variable or parameter and several subscript levels that provide greater specification. Only those levels that make the name unique within the model context are needed in creating the symbol. The paper describes specific problems encountered with the currently used notation, presents the proposed framework and provides additional practical examples. The overall result is a framework that can be used in whole plant modelling, which consists of different fields such as activated sludge, anaerobic digestion, sidestream treatment, membrane bioreactors, metabolic approaches, fate of micropollutants and biofilm processes. The main objective of this consensus building paper is to establish a consistent set of rules that can be applied to existing and most importantly, future models. Applying the proposed notation should make it easier for everyone active in the wastewater treatment field to read, write and review documents describing modelling projects. [ABSTRACT FROM AUTHOR]

The effectiveness of enhanced biological phosphorus removal (EBPR) systems is directly affected by the competition of polyphosphate accumulating organisms (PAOs) and glycogen accumulating organisms (GAOs). This study investigated the short-term effects of carbon source on PAO and GAO performance. The tests were designed to clearly determine the impact of volatile fatty acid (VFA) composition on the performance of two types of biomass, one enriched for PAOs and the other for GAOs. The two populations were enriched in separate reactors using identical operating conditions and very similar influent compositions with acetate as the sole carbon source. The only difference was that a very low level of phosphorus was present in the influent to the GAO reactor. The abundance of PAOs and GAOs was quantified using fluorescence in-situ hybridisation. The results clearly show that there are some very distinctive differences between PAOs and GAOs in their ability to utilise different carbon substrates. While both are able to take up acetate rapidly and completely, the GAOs are far slower at consuming propionate than the PAOs during short-term substrate changes. This provides a potentially highly valuable avenue to influence the competition between PAOs and GAOs. Other VFAs studied seem to be less usable in the short term by both PAOs and GAOs, as indicated by their much lower uptake rates. [ABSTRACT FROM AUTHOR]

Addresses the control of nitrite recirculation flow in a predenitrification system. Elementary mass balance analysis of the utilization of the influent biodegradable COD for nitrate removal; Result of maintaining the nitrate concentration at the outlet of the anoxic zone.