Water and Effluent Treatment Magazine
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october 2015 WET NEWS 23 ThE CoNCEpT • Magnesium phosphate is added to form magnesium ammonium phosphate • this is then heated up, and the vapour is collected • Vapour and nitrogen are blown into a water tank • the water tank collects nitrogen which can be used as fertiliser NEED To KNoW 1 the technology has received eU funding for further development and research 2 Around 8kWh of electricity is used per kg of separated ammonium in a traditional wastewater treatment system 3 Up to 90% of the ammonium content can be collected and heated up, producing a fertiliser that can be used for industrial or agricultural purposes ThE VERDICT "With our system, 0.7kWh per kg of separated ammonium is used which means that we can save more than 7kWh per kg of ammonium" Karsten Poulsen, NUtrec inventor I n traditional WwTWs the sludge coming from primary and secondary treatments goes to an anaerobic digester to produce biogas. Subsequently, the sludge needs to be dewatered before being reused in soils or deposited in landfills. The reject water resulting from this process has high concentration of ammonium and phosphorus, which can drastically increase the total concentration of these nutrients in the biological (secondary) treatments, if recycled without any treatment. When ammonia and phosphorous are both present at high concentrations, a prior step can be included to remove them by adding magnesium or calcium granulates. Due to significant performance and efficiency gains, the consortium believes the technology will represent a modal shi• of wastewater treatment practises in the EU and add a significant contribution to the current best available technique. Nutrient discharge Nutrient recovery from wastewater has been receiving growing interest, driven by stringent nutrient discharge limits from wastewater treatment plants and by the potential to enhance the recovered nutrients, e.g. for application as fertilisers, that can represent an additional revenue source to water companies. The consortium behind the NUTREC project – a group of European SME suppliers of the trend to recover as much nutrients as possible in the wastewater treatment process is on the increase. but what happens if high concentrations of ammonia and phosphorus are present? The challenge: Waste not, want not the reject water featured a high concentration of ammonia and phosphorus INSIGHT SeWAge & SlUdge treAtMeNt A technology that can provide energy and cost savings at wastewater treatment plants is being trialled in denmark. A solution: Revolutionising wastewater treatment T he consortium says the NUTREC technology will help make traditional plants up to 25 times more effi- cient as well as reduce costs by up to 40% through substantial energy savings. The new system enables plants to produce in- dustrially exploitable fertiliser by accumulating ammonium. The technology, which has EU funding for further development and research, allows for up to 90% of the ammonium content to be collected and heated up, producing a fertiliser that can be applied for industrial or agricultural purposes. Karsten Poulsen, inventor, patented his system for biologi- cally separating ammonium from wastewater 15 years ago, but has recently developed a method whereby the ammo- nium can be collected instead of released as nitrogen. In princi- ple, a CO2 neutral wastewater treatment process is thereby achieved. By using this method, wastewater can be turned into a resource while saving energy, chemicals and costs related to the treatment process. In traditional treatment plants, the ammonium is usually reduced to nitrogen that is sent back into the air, explains Poulsen. He says: "About 8kWh of electricity is used per kg of sep- arated ammonium in a tradi- tional wastewater treatment system with a biogas plant for cleaning the wastewater. With our system, 0.7kWh per kg of separated ammonium is used which means that we can save more than 7kWh per kg of ammonium. "One kilogram of nitrogen collected from the air uses approx 10kWh. One kilogram of nitrogen collected by using our system costs 0.7kWh, which means that the system is approx 25 times more cost effective." The plant is expected to be marketed by GreenAqua Solutions, and the system will also be exported to other European countries such as Germany. Earlier this year a team of scientists from German research institute Fraunhofer and the Danish Knowledge Centre for Agriculture as well as partners from Germany, Portugal and Spain gathered in Hobro in Den- mark, where the future research and development of the project was discussed. The visit also included a demonstration of a full scale pilot system. The system has been patented, and a pilot system is in use at Mariager£ord Vand, a wastewater treatment plant in Hobro, Denmark. water and wastewater treatment technologies – believes there is a major market opportunity in the supply of a novel technology system for the removal and recovery of nutrients, namely nitrogen (N) and phosphorus (P), from wastewater. Recognising that wastewater is a renewable resource, the consortium, which includes GreenAqua Solutions, Bioazul, OHT Group and Videncentret, aims to develop, optimise and demonstrate the commercial and technical viability of "a novel green treatment method" that not only treats the wastewa- ter but also recovers added value through the use of an innovative thermochemical method for struvite precipitation and sub-sequent ammonia release.