Project: BioTechnology for a high rate Aerobic Granular process, to remove excess nitrogen from sludge and digestate wastewater
_x000D_In Switzerland, the production of sludge from Wastewater Treatment Plants (WWTP) is estimated at 4'000'000 metric tons per year (Swiss federal environment agency, Report 181, 2004). Since 2003, the Swiss environmental legislation does not allow the disposal of sludge via agricultural outlets as nutrients or in landfill. The only way to legally manage sludge is thermal oxidation or incineration. Only 5% of sludge is solid mass that can be incinerated, however. The rest is so-called reject water or (after anaerobic pre-treatment) digestate wastewater. The energy balance of incineration of sludge is one of the drawbacks of thermal oxidation. _x000D__x000D_The management of sludge is a challenge for Swiss WWTP because 95% of liquid waste from sludge, i.e 3'800'000 metric tons, have high nitrogen loads (around 1'500 mg/L), which cannot be treated with conventional biological processes. The average load of nitrogen allowed in conventional WWTP is 21 mg/L, i.e 75 times less than the typical reject water. Swiss legislation does not allow dilution of pollutants, but, in practice, dilution is still used as a "solution" for excess nitrogen. The situation is almost the same in most EU-countries and many other countries worldwide._x000D__x000D_The CO outcome of implementing the TAGAN project would be removal of high nitrogen loads from reject water, without dilution and with a better overall energy balance._x000D__x000D_GENERAL DESCRIPTION OF THE PROBLEM_x000D__x000D_Due to increasing costs of municipal sludge management (dewatering, storage, transport to landfill or incineration), disposal of sludge is becoming an escalating problem (Strong et al., 2011). One can estimate that treatment of sludge represent 50% of current operating costs of wastewater treatment (Baeyens et al., 1997). Anaerobic digestion is the most commonly used disposal method, which both reduces the amount of final sludge solid for disposal and enables the process to generate a product in the form of biogas. After anaerobic digestion, biogas is removed and liquid (reject water) is returned at the inlet of wastewater treatment plant. This recycle stream typically contributes 0.3 to 1.5% of the influent flow and up to 20 - 30% of the influent total nitrogen load to the plant. _x000D__x000D_The CO objective of the project TAGAN is to develop a novel aerobic granular process in order to remove ammonia from reject/digestate wastewater cost-efficiently. Ammonia is considered to be one of the strongest inhibitor compounds affecting the activity of large number of microorganisms (Kayhanian et al., 1994), like those used in WWTP. _x000D__x000D_This approach was chosen, since so far no successful full-scale application of aerobic granular process for nitrogen removal from reject water has been reported. Studies have shown that the well-cultivated granules and stable granular structure can be achieved only on high strength organic wastewater (Moy et al., 2002), thus it can be an excellent substrate for growth of aerobic granules and efficient nitrogen removal. _x000D__x000D_Nitrogen content in rejected wastewater is a common issue, which has to be faced by most of the WWTP across the EU. The European Commission study on “investment and employment related to EU policy on air, water and waste” (2000), estimates that about 152 billion Euro were invested for waste water infrastructure over the period 1990-2010. According to EC directive (91/271), concerning urban wastewater treatment, all municipalities with more than 15,000 inhabitants (until the end of 2000) and more then 10,000 inhabitants (until the end of 2005) must dispose of secondary treatment facilities, i.e. a biological purification processes._x000D__x000D_Since the nitrogen (in form of ammonia) in reject water represents 20-30% of total nitrogen at the inlet on municipal wastewater treatment plant (WWTP), reducing that percentage of nitrogen, the overall nitrogen load will be reduced, which as a consequence will provide more capacity and stable WWTP performance. The proposed project aims to develop a new aerobic granular technology, which can be applied in global municipal wastewater treatment market, where reject water is produced. _x000D__x000D_The TAGAN project consists of 8 well-integrated work packages (WP). Whereas WP1-5 are technical, WP6 includes dissemination and WP7 exploitation activities, while WP8 is for overall project management. The project will be realized within three years. This time scale can ensure that the outcome of the project, i.e. new technology, is developed and well-tested, so that, even after the second year, marketing activities can be envisaged._x000D_ _x000D_The consortium is composed of a well-suited and well-balanced group of dedicated experts, committed to the tasks assigned to them, chosen based on their experience in execution and development of engineering and bioengineering projects in wastewater treatment.
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Acronym
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TAGAN
(Reference Number: 7830)
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Duration
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04/02/2013 - 31/01/2016
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Project Topic
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No successful full-scale application of aerobic granular (AG) processes for nitrogen removal from reject water or digestate have yet been reported. The TAGAN project aims to develop new AG technology in order to efficiently remove excess ammonia, cost-efficiently and at an industrial scale.
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Network
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Eurostars
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Call
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Eurostars Cut-Off 9
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Project partner
