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New Energy Efficient approach to the operation of Membrane Bioreactors for Decentralised Wastewater Treatment

Final Report Summary - PURATREAT (New Energy Efficient approach to the operation of Membrane Bioreactors for Decentralised Wastewater Treatment)

The Mediterranean basin is one of the poorest regions in the world in terms of water resources. An increased water consumption rate for irrigation purposes along with a high urban population growth, have had an adverse effect on water resources. Thus, most groundwater resources in the Mediterranean areas are at risk of being exhausted through overexploitation.

With limited renewable water resources, most countries of the area have been driven to reuse their wastewaters. However, especially in the eastern and northern Mediterranean regions, wastewaters are inefficiently treated or even re-used directly without treatment for irrigation or sanitary purposes, serving as a carrier for diseases or causing water pollution when discharged to water bodies. In the last decade, several water treatment technologies have been used in the region with little success in pathogen removal.

Membrane bioreactor (MBR) technology is a very promising alternative to those conventional water treatments as membranes act as a barrier against bacteria and viruses achieving a high degree of water purification. However, most membrane bioreactors currently in use have very high running costs because of the high pressure drop and high air-flushing rate required for their operation. The objective of the 'New energy efficient approach to the operation of membrane bioreactors for decentralised wastewater treatment' (Puratreat) project was to study a new approach to the operation of membrane bioreactors. This study included a comparison of the leading membrane technologies. The operating procedure studied expected to yield very low energy consumption and reduced maintenance costs. These characteristics would make the bioreactors working in these conditions suitable to be operated in peri-urban areas of the Mediterranean basin, where expenditure in public services is a critical factor.

The main goal of this project was to develop a method for decentralised wastewater treatment that allows the reuse of water with minimal operational and maintenance costs. This project studied the most suitable MBR wastewater technology applicable to peri-urban areas of the southern Mediterranean and Middle East countries. Pilot membrane bioreactors were to be built in order to study and compare different kinds of membrane modules working at different operating conditions. The most suitable technology and the optimum operational mode to achieve the minimum energy consumption and minimum maintenance will be investigated. The science and technology objectives of Puratreat were the following:

- to compare the performance of MBR bioreactors working under conventional operating conditions with the performance achieved under conditions specially adapted to the requirements of MENA countries.
- to compare the performance the most advanced membrane technologies available in the market working in different operating conditions.
- to study the performance, energy consumption and maintenance requirements of MBRs working at low solids retention times as a possible operating procedure for the application of these system in peri-urban areas of MENA countries.
- to study the characteristics of the microbial community present in the reactor for the different experimental conditions studied.
- to propose the most suitable technology for the application of decentralised MBR wastewater systems and its optimum operating conditions.
- to study the feasibility of decentralised wastewater treatment plants based on MBR technologies in the MPC countries.

One of the main dissemination tools was the project website, launched within the first reporting period, concretely in October 2006. It included a brief description of the project, project objectives and progress and information about the partnership. The website consisted in a public area and a secured area only for project partners, where all the work and deliverables developed would be uploaded. That allowed easier information transfer among the partners and smooth communication flow. The website was meant to be updated during the whole project duration. The location of visitors over the first reporting period of website operation came mainly from Germany, as could be expected, location of the web manager and web designers. Regarding the other locations, most were from Europe and the Middle East (partners), with visitors from across the globe (Australia, Canada, East Asia, Caribbean and South America), including non-profit organisations and international organisations amongst the visitors. The website was continually updated during the second reporting period, being one of the main tools for the wide dissemination of the project itself. It expanded over the duration of the second year and was visited by nearly 4,000 users. Most visitors, as would be expected, came from Europe, but visitors from five other continents were registered, representing a total of 66 countries. Outside of the countries represented by Puratreat partners, Switzerland, Brazil, Japan, Italy and Poland had numerous hits on the site, indicating the diversity of interest in Puratreat at an international level.

Another important dissemination activity was the development of a project flyer during the first year. 2,000 flyers were produced with the key project information listed. The flyer was to be distributed in those seminars, conferences, and other related events in which project partners would participate. It contains a summary of the project and indications of funding scheme, budget and consortium composition.