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Schoumans O.F.,Wageningen University | Bouraoui F.,European Commission - Joint Research Center Ispra | Kabbe C.,KompetenzZentrum Wasser Berlin gGmbH | Oenema O.,Wageningen University | van Dijk K.C.,Wageningen University

Food production in Europe is dependent on imported phosphorus (P) fertilizers, but P use is inefficient and losses to the environment high. Here, we discuss possible solutions by changes in P management. We argue that not only the use of P fertilizers and P additives in feed could be reduced by fine-tuning fertilization and feeding to actual nutrient requirements, but also P from waste has to be completely recovered and recycled in order to close the P balance of Europe regionally and become less dependent on the availability of P-rock reserves. Finally, climate-smart P management measures are needed, to reduce the expected deterioration of surface water quality resulting from climate-change-induced P loss. © 2015, The Author(s). Source

Remy C.,KompetenzZentrum Wasser Berlin gGmbH | Jekel M.,TU Berlin
Water Science and Technology

This study investigates the cumulative energy demand (CED) of different systems for the management of urban wastewater, following the methodology of Life Cycle Assessment. In a hypothetical case study for an urban area (5,000 inhabitants), all relevant processes for wastewater collection and treatment and the construction of infrastructure are described in a substance flow model. The conventional system requires 1,250 MJ/(pe*a), with the operation contributing 45%, the infrastructure 7%, and the system expansion (production of mineral fertilizer and electricity) 48% to the total CED. The separation systems have a CED of 930-1,182 MJ/(pe*a) depending on their configuration. Results of the impact assessment show that recovering energy from the organic matter of toilet wastewater and household biowaste in a digestion process can decrease the cumulative energy demand by 13-26%. Energetic benefits of mineral fertilizer substitution are relatively small compared to the energy recovered from organic matter. Decisive parameters for the energy analysis are the amount of biowaste which is co-digested with toilet wastewater and the energy demand of the vacuum plant. © IWA Publishing 2012. Source

Muller B.,Eawag - Swiss Federal Institute of Aquatic Science and Technology | Bryant L.D.,Eawag - Swiss Federal Institute of Aquatic Science and Technology | Bryant L.D.,ETH Zurich | Matzinger A.,KompetenzZentrum Wasser Berlin gGmbH | And 3 more authors.
Environmental Science and Technology

The oxygen-consuming processes in the hypolimnia of freshwater lakes leading to deep-water anoxia are still not well understood, thereby constraining suitable management concepts. This study presents data obtained from 11 eutrophic lakes and suggests a model describing the consumption of dissolved oxygen (O2) in the hypolimnia of eutrophic lakes as a result of only two fundamental processes: O2 is consumed (i) by settled organic material at the sediment surface and (ii) by reduced substances diffusing from the sediment. Apart from a lakes productivity, its benthic O2 consumption depends on the O2 concentration in the water overlying the sediment and the molecular O2 diffusion to the sediment. On the basis of observational evidence of long-term monitoring data from 11 eutrophic lakes, we found that the areal hypolimnetic mineralization rate ranging from 0.47 to 1.31 g of O2 m-2 d-1 (average 0.90 ± 0.30) is a function of (i) a benthic flux of reduced substances (0.37 ± 0.12 g of O2 m-2 d-1) and (ii) an O2 consumption which linearly increases with the mean hypolimnion thickness (zH) up to ∼25 m. This model has important implications for predicting and interpreting the response of lakes and reservoirs to restoration measures. © 2012 American Chemical Society. Source

Lepot M.,INSA Lyon | Torres A.,Pontifical Xavierian University | Hofer T.,University of Graz | Caradot N.,KompetenzZentrum Wasser Berlin gGmbH | And 3 more authors.
Water Research

UV/Vis spectrophotometers have been used for one decade to monitor water quality in various locations: sewers, rivers, wastewater treatment plants (WWTPs), tap water networks, etc. Resulting equivalent concentrations of interest can be estimated by three ways: i) by manufacturer global calibration; ii) by local calibration based on the provided global calibration and grab sampling; iii) by advanced calibration looking for relations between UV/Vis spectra and corresponding concentrations from grab sampling. However, no study has compared the applied methods so far. This collaborative work presents a comparison between five different methods. A Linear Regression (LR), Support Vector Machine (SVM), EVOlutionary algorithm method (EVO) and Partial Least Squares (PLS) have been applied on various data sets (sewers, rivers, WWTPs under dry, wet and all weather conditions) and for three water quality parameters: TSS, COD total and dissolved. Two criteria (r2 and Root Mean Square Error RMSE) have been calculated - on calibration and verification data subsets - to evaluate accuracy and robustness of the applied methods. Values of criteria have then been statistically analysed for all and separated data sets. Non-consistent outcomes come through this study. According to the Kruskal-Wallis test and RMSEs, PLS and SVM seem to be the best methods. According to uncertainties in laboratory analysis and ranking of methods, LR and EVO appear more robust and sustainable for concentration estimations. Conclusions are mostly independent of water matrices, weather conditions or concentrations investigated. © 2016 Elsevier Ltd. Source

Sandoval S.,Pontifical Xavierian University | Torres A.,Pontifical Xavierian University | Pawlowsky-Reusing E.,Berliner Wasserbetriebe | Riechel M.,KompetenzZentrum Wasser Berlin gGmbH | Caradot N.,KompetenzZentrum Wasser Berlin gGmbH
Water Science and Technology

The present study aims to explore the relationship between rainfall variables and water quality/quantity characteristics of combined sewer overflows (CSOs), by the use of multivariate statistical methods and online measurements at a principal CSO outlet in Berlin (Germany). Canonical correlation results showed that the maximum and average rainfall intensities are the most influential variables to describe CSO water quantity and pollutant loads whereas the duration of the rainfall event and the rain depth seem to be the most influential variables to describe CSO pollutant concentrations. The analysis of partial least squares (PLS) regression models confirms the findings of the canonical correlation and highlights three main in fluences of rainfall on CSO characteristics: (i) CSO water quantity characteristics are mainly influenced by the maximal rainfall intensities, (ii) CSO pollutant concentrations were found to be mostly associated with duration of the rainfall and (iii) pollutant loads seemed to be principally influenced by dry weather duration before the rainfall event. The prediction quality of PLS models is rather low (R2 < 0.6) but results can be useful to explore qualitatively the influence of rainfall on CSO characteristics. © IWA Publishing 2013. Source

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