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Apeldoorn, Netherlands

Van Bijnen M.,Gemeente Utrecht | Van Bijnen M.,Technical University of Delft | Korving H.,Witteveen Bos Consulting Engineers | Korving H.,Delft Institute of Applied Mathematics | Clemens F.,Technical University of Delft
Water Science and Technology | Year: 2012

In-sewer defects are directly responsible for affecting the performance of sewer systems. Notwithstanding the impact of the condition of the assets on serviceability, sewer performance is usually assessed assuming the absence of in-sewer defects. This leads to an overestimation of serviceability. This paper presents the results of a study in two research catchments on the impact of in-sewer defects on urban pluvial flooding at network level. Impacts are assessed using Monte Carlo simulations with a full hydrodynamic model of the sewer system. The studied defects include root intrusion, surface damage, attached and settled deposits, and sedimentation. These defects are based on field observations and translated to two model parameters (roughness and sedimentation). The calculation results demonstrate that the return period of flooding, number of flooded locations and flooded volumes are substantially affected by in-sewer defects. Irrespective of the type of sewer system, the impact of sedimentation is much larger than the impact of roughness. Further research will focus on comparing calculated and measured behaviour in one of the research catchments. © IWA Publishing 2012. Source

Scherrenberg S.M.,Technical University of Delft | Menkveld H.W.H.,Witteveen Bos Consulting Engineers | Bechger M.,Waternet | Van Der Graaf J.H.J.M.,Technical University of Delft
Water Science and Technology | Year: 2011

In the near future the WWTP Horstermeer will be confronted with more stringent requirements. Important factor in this respect is the European Water Framework Directive 2000/60/EC. Within the WFD approach the focus is more and more on low nitrogen (<2.2 mg N-total/L) and phosphorus concentrations (<0.15 mg P-total/L) in WWTP effluent. Therefore, research has been initiated at the Horstermeer WWTP to investigate the possibilities of simultaneous nutrient removal with filtration techniques. After nitrite accumulation, caused by phosphorus limitation, was measured in the filtrate water of the 1-STEP® filter, research has started. The objective of this research is to minimise the risk on the inhibition of denitrification by phosphorus limitation and to decrease the dosage of coagulant. Therefore a new coagulant dosage system is developed. The back-ground of the coagulant dosage system, the results and cost savings are discussed in this article. When the PO4-P/NOx-N ratio in the WWTP effluent becomes below 0.06 mg/mg phosphorus limitation may occur. The results for phosphorus and nitrogen removal are equal or improved compared to the yearly average of 2008. The results show a more stable removal process and a reduction of the coagulant dosage for the coagulant dosage system of 11% when compared to a continuous dosage ratio of MeP 4 mol/mol. © IWA Publishing 2011. Source

Scherrenberg S.M.,Technical University of Delft | Postma P.,Witteveen Bos Consulting Engineers | Neef R.,Witteveen Bos Consulting Engineers | Menkveld H.W.H.,Witteveen Bos Consulting Engineers | And 2 more authors.
Water Science and Technology | Year: 2011

This research is legislation driven by the European Water Framework Directive (WFD) and the Dutch Fourth Memorandum on Water Management. The objective of this research is to achieve the removal of total nitrogen and total phosphorus by Dual Media Filtration. The target value during this research for total nitrogen is 2.2 mg/L and for total phosphorus 0.15 mg/L. The results show that for NOx-N concentrations in the WWTP effluent up to 10 mg/L, a stable operation of the process can be reached with removal rates of 80% to 90%. The maximum nitrogen removal rate was 3.5 kg N/(m3.d). Above 10 mg/L a risk of filter bed clogging occurred. When the orthophosphorus concentration in the WWTP effluent exceeds the maximum of 0.3 mg/L, the total phosphorus concentration in the filtrate water will exceed the target value of 0.15 mg P-total/L. Temperature has a large impact in the phosphorus removal; the optimum temperature range is within 13°C-18°C. In conclusion, Dual Media Filtration is capable of producing reusable water with total phosphorus concentrations of <0.15 mg/L, under the condition that the wastewater treatment plant produces WWTP effluent with steady concentrations for orthophosphorus (<0.3 mg PO4-P/L). To reach total nitrogen concentrations in the filtrate water of <2.2 mg/L a NOx-N removal efficiency of nearly 100% is required. © IWA Publishing 2011. Source

Bluemink E.D.,Witteveen Bos Consulting Engineers | Van Nieuwenhuijzen A.F.,Witteveen Bos Consulting Engineers | Wypkema E.,Waterboard Brabantse Delta | Uijterlinde C.A.,STOWA
Water Science and Technology | Year: 2016

Valorisation of components from municipal 'waste' water and sewage sludge gets more and more attention in order to come to a circular economy by developing an efficient 'waste' to value concept. On behalf of the transition team 'Grondstoffenfabriek' ('Resource factory') a preliminary research was performed for all the Dutch water boards to assess the technical and economical feasibility of polyhydroxy-alkanoate (PHA)-production from sewage sludge, a valuable product to produce bio-plastics. This study reveals that the production of bio-plastics from sewage sludge is feasible based on technical aspects, but not yet economically interesting, even though the selling price is relatively close to the actual PHA market price. (Selling price is in this particular case the indicative cost effective selling price. The cost effective selling price covers only the total production costs of the product.) Future process optimization (maximizing the volatile fatty acids production, PHA storage capacity, etc.) and market developments are needed and will result in cost reductions of the various sub-processes. PHA-production from sewage sludge at this stage is just a technology; every further research is needed to incorporate the backward integration approach, taking into account the market demand including associated product quality aspects. © 2016 IWA Publishing. Source

Scherrenberg S.M.,Technical University of Delft | Te Kloeze A.M.,Witteveen Bos Consulting Engineers | Janssen A.N.,Technical University of Delft | Van Nieuwenhuijzen A.F.,Technical University of Delft | And 3 more authors.
Water Science and Technology | Year: 2010

In 2000 the European Union introduced the Water Framework Directive (WFD). The aim of the WFD is having an ecological and chemical balance for all surface waters in Europe in 2015. The European Commission identified 33 priority substances and their maximum allowable concentrations, FHI-values (Fraunhofer Institute), which are specified in the Annex of the WFD. The objective of this research is to achieve the removal of suspended solids, nitrogen and total phosphorus together with priority substances. All these substances will be removed in one filter called a "One Step Total Effluent Polishing filter" i.e. 1-STEP® filter. For this purpose a filter pilot plant was tested at the WWTP Horstermeer. The results show that the filter can fulfil the target values in the filtrate water for total nitrogen (2.2mg Ntotal/L) and total phosphorus (0.15mg Ptotal/L). The majority of the priority (hazardous) substances in the WWTP effluent are already below the detection limit. Due to the low concentration ranges, the results on the removal of medicine and pesticides are only indicative. A decreasing tendency in the removal efficiency is shown for all measured compounds. The average specific ultrafiltration resistance (SUR) value decrease of the filter is 55% and the final value is always below 5·1012m-2. This indicates that the filtrate water of the filter is very well filterable and can be used as ultrafiltration feedwater. © IWA Publishing 2010. Source

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