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Shanghai, China

Hemmes K.,DHV | Luimes P.,DHV | Giesen A.,DHV | Hammenga A.,Waterboard Hunze en Aas | And 2 more authors.
Water Practice and Technology

Breakthrough technology for nutrient removal. The innovation involves the purification of wastewater and urine in combination with the generation of sustainable electricity and upcycling of phosphate. The process was recently developed by DHV, patented and is currently being put into use in a first pilot project. The social relevance is high: 1) nutrient reduction and clean water are important pillars in the global protection of scarce freshwater resources; 2) major building block for energy efficient "purification of the future"; 3) reduction of nutrient emissions in the agricultural sector. Degree of cost effectiveness is very high. In comparison with conventional solutions, the costs are lower by a factor of 2. It also delivers a saving of approximately € 3-12 million per 0.01 improvement of the ecological quality index for brooks, lakes, canals and ditches in comparison with current RWS (Directorate-General for Public Works and Water Management)/regional packages. Upscalability is large; it is applicable to virtually all STPs (Sewage Treatment Plants) in the Netherlands and abroad and is also applicable for decentralized urine (pre-) treatment. © IWA Publishing 2011. Source

Baart S.,Lievense Consulting Engineers | Ebbens R.,DHV | Nammuni-Krohn J.,Halcrow | Verhagen H.J.,Technical University of Delft
Proceedings of the Coastal Engineering Conference

Present design tools, as found in the Rock Manual or Coastal Engineering Manual, for the determination of toe rock size for rubble mound breakwaters are based on test data with a large spread: data is relatively dispersed around the centre and descriptive equations have limited applicability ranges. New research has been undertaken to contribute to a more accurate description of toe rock stability. Flume tests have lead to an empirical design criterion for toe bunds in very shallow water based on the Hudson-type stability number. Herein the foreshore slope turns out to have an important influence. An approach with theoretical background has been used for toe bunds in surging wave conditions. The resulting stability description, based on local flow velocities, has been verified with existing data sets. Additional flume tests were performed to measure flow velocities at the toe bund. Results are used to calibrate the velocity-approach, providing an improved design criterion. Source

Xu W.,China Institute of Water Resources and Hydropower Research | Zhang S.,China Institute of Water Resources and Hydropower Research | Jiang Y.,China Institute of Water Resources and Hydropower Research | Wei Q.,DHV
Shuili Fadian Xuebao/Journal of Hydroelectric Engineering

This paper proposes a scheme for the dredging and water pumping program in Songzi river and analyzes the impacts of this program on the water regimes in the Dongting lake area through numerical simulation with a 1D-2D coupling hydrodynamic model. It is showed that the program can effectively increase the runoff diversion from Jingjiang reach of the Yangtze to Songzi river, and make all the water levels in Songzi river, Qili lake and Muping lake become higher. This study provides a support to engineering measures for easing the water shortage in this area. © Copyright. Source

Winkler M.-K.H.,Technical University of Delft | Kleerebezem R.,Technical University of Delft | De Bruin L.M.M.,DHV | Verheijen P.J.T.,Technical University of Delft | And 4 more authors.
Applied Microbiology and Biotechnology

In this study, we investigated during 400 days the microbial community variations as observed from 16S DNA gene DGGE banding patterns from an aerobic granular sludge pilot plant as well as the from a full-scale activated sludge treatment plant in Epe, the Netherlands. Both plants obtained the same wastewater and had the same relative hydraulic variations and run stable over time. For the total bacterial population, a similarity analysis was conducted showing that the community composition of both sludge types was very dissimilar. Despite this difference, general bacterial population of both systems had on average comparable species richness, entropy, and evenness, suggesting that different bacteria were sharing the same functionality. Moreover, multi-dimensional scaling analysis revealed that the microbial populations of the flocculent sludge system moved closely around the initial population, whereas the bacterial population in the aerobic granular sludge moved away from its initial population representing a permanent change. In addition, the ammonium-oxidizing community of both sludge systems was studied in detail showing more unevenness than the general bacterial community. Nitrosomonas was the dominant AOB in flocculent sludge, whereas in granular sludge, Nitrosomonas and Nitrosospira were present in equal amounts. A correlation analysis of process data and microbial data from DGGE gels showed that the microbial diversity shift in ammonium-oxidizing bacteria clearly correlated with fluctuations in temperature. © 2012 Springer-Verlag Berlin Heidelberg. Source

Winkler M.K.H.,Technical University of Delft | Kleerebezem R.,Technical University of Delft | Khunjar W.O.,Hazen and Sawyer | de Bruin B.,DHV | van Loosdrecht M.C.M.,Technical University of Delft
Water Research

The specific solid retention time for different bacteria within flocculent and granular sludge was determined. Samples were collected from reactor and effluent sludge and the number of a specific bacterial group was evaluated in respect to the total bacterial community with quantitative polymerase chain reaction (qPCR). The ratio of the relative presence of a specific bacterial group in the reactor sludge and wasted sludge was established to observe if preferential wash-out occurred. From the data also the solid retention time for different microbial groups can be estimated. Using this tool, we were able to show that the SRT of populations found on the exterior of granules is slightly lower than the SRT for population in the interior. Archaea were not found in the flocculent system but were present in small amounts within the granular system. It was further observed that protozoa were grazing on the bacterial community within the system indicating that they have the potential to shorten the specific SRT of bacteria. © 2012 Elsevier Ltd. Source

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