However, these organics are present in relatively low concentrations. This means that there is a lot of water in wastewater which can actually be potentially recovered and reused. In our Sewer Mining project we extract water from sewage by means of forward osmosis (FO) in combination with a reconcentration system e.g. reverse osmosis (RO), to produce high-quality water and to convert the subsequent concentrated sewage into a renewable energy source (i.e. biogas). The effectiveness of FO membranes in the recovery of water from sewage has been evaluated. Stable FO water flux values were obtained with settled sewage (screened, not treated) as a feed solution. Sewer Mining could lead to a more economical and sustainable treatment of wastewater, facilitating reuse of water and energy from sewage.

State-of-the-art wastewater treatment plants (WWTP) with a primary settler collect only about 30% of the wastewater organics. Direct collection of suspended solids from wastewater by innovative fine sieving of influent can result in the removal of approximately 50% of the organics. The rest of the organic matter is currrently converted in an aerobic process and used for nutrient removal from wastewater. Aeration energy represents approximately 60% of the total energy use of a WWTP. With the 'Adsorption-Belebung' system (AB-process), developed at the University of Aachen during the energy crisis in the nineteenseventies, more organics can be collected. More than 70% of the organic matter can be trapped in the first adsorption step (A-stage). Whereas the present AB-process is equipped with intermediate settling tanks a new separation technology is put forward to collect these organics by use of dynamic filtration. Dynamic filtration is a process in which on a coarse support material (typical pore size from 3 to 500 μm), a filtering cake layer is built-up with smaller pore sizes. In the DynaFil project we work on the optimization of process conditions in the A-stage, development of sludge separation based on dynamic filtration and study digestion with dynamic filtration. The results of the project are expected to contribute to an increased sustainable energy production at WWTP plants, reduced greenhouse gas emissions, and savings in energy use, costs and space. The latest results are presented, including results from dynamic filtration experiments. The presented projects show innovative possibilities for water reuse, energy and nutrient recovery from wastewater.

Partners 

The Sewer Mining project is initiated by KWR and together with the TU Delft, Waternet, Triqua, and US-based Hydration Technology Innovations an international Innowator grant from AgentschapNL has been obtained. The DynaFil project, in which KWR (project leader), TU Delft, Waternet, STOWA, Logisticon Water Treatment, Waterboard Brabantse Delta and Bert Daamen participate, is partly funded by AgentschapNL under the Energy and Innovation Grant, Effective and Efficient Digestion chain.

 

Kees Roest  

Kees Roest completed his MSc in medical biology and his PhD in environmental sciences, focused on the microbiological aspects of anaerobic wastewater treatment systems (combining culture-dependent and culture-independent approaches). As a Marie Curie research fellow, he arranged new microbiology laboratories for the investigation of environmental bioreactor processes in Spain (Department of Chemical Engineering and Environmental Technology of the Universidad de Valladolid) and in the UK (Sustainable Environment Research Centre (SERC) of the University of Glamorgan). Currently he is working as a scientific researcher at KWR watercycle research institute in Nieuwegein, the Netherlands. His research focuses mainly on innovative wastewater & reuse technologies.

 

More information:

 kees.roest@kwrwater.nl

Yesterday was the last day of the WQTC. The early bird session, starting at 7. 15 am was on the national drinking water strategy of the US. The USEPA now has a new approach, to group contaminants and relate the implications of this new approach to utilities.

 

I attended the lectures on “Evaluation and optimization of UV disinfection”. There were some very interesting lectures on CFD modeling, but only for disinfection, and not for Advanced Oxidation Processes, like Bas Wols does at KWR Watercycle Research Institute. Karin Lekkerkerker (Dunea, The Netherlands) went to presentations on biological treatment. Here there is a striking difference in the way of thinking between the USA and our country. In the Netherlands we try to remove as many nutrients as possible, in order to prevent micro organisms to grow in the piping system. In the US, on the contrary, nutrients are considered very useful, as they will enhance biological treatment. Here disinfection is not as important, as they keep adding chlorine to the water (which you can clearly taste all day).

 

Karin and I gave a presentation in the afternoon session, and fortunately for us there were a lot of people present. The focus of the afternoon session I attended was on advanced oxidation processes, and here there were some very good presentations. One, for example, was on a rapid method for measuring background hydroxyl radical scavenging for impacts on design of AOPs. At the end of the session two students received a price for the best presentation/paper. This was the end of the 2010 conference. Most people are going home now. We will stay for one more day, as we are having the final meeting on a large international project KWR carried out together with Dunea, Philips and the Greater Cincinnati Water Works.

 

Roberta Hofman-Caris