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Bugs will give us free power while cleaning our sewage - tech - 07 May 2010 -New Scie... Page 1 of 2 <br /> Home I Tech I Environment I Life I News I Back to article <br /> Bugs will giveus free power while Gleaning our sewage _ <br /> 12:47 07 May 2010 by Helen Knight <br /> For similar stories,visit the Micro-organisms and Energy and Fuels Topic Guides <br /> ADVERTISEMENT <br /> You might think a constant supply of fresh air <br /> would be essential for a sewage treatment <br /> plant, but some bacteria cannot stand the _ <br /> stuff.These bugs could be the key to <br /> cleaning waste water so efficiently that the <br /> process could generate power rather than <br /> consume it. — <br /> In conventional sewage plants,micro- Sta mY connected t0 a <br /> organisms digest solid waste in"activated , world of knowledge <br /> sludge".They convert the organic matter into <br /> methane but leave liquid waste containing <br /> ammonium and phosphates,which must be <br /> removed before the water can be poured into j <br /> rivers. Sustainable sewage(Image:Jonathan Hordle/Rex <br /> Features) <br /> Existing treatment plants use a lot of energy <br /> to get rid of the ammonium.The process uses bacteria that convert ammonium into nitrate,and the <br /> bugs that do this need oxygen,which must be constantly supplied to the treatment tanks by electric <br /> r, <br /> pumps.The nitrate is then converted into nitrogen gas by still more bugs,known as denitrifying s y' <br /> bacteria.These require methanol,which must also be added to the mix. <br /> This process consumes an average of 44 watt-hours per day for each person who adds waste to the - <br /> sewage system.This can add up to megawatts in a big city. <br /> Cut out the middle bug <br /> i <br /> But now Gijs Kuenen at Delft University of Technology in the Netherlands and colleagues are <br /> developing a technique that cuts out the energy-consuming processes.The key is a recently <br /> bacteria that can munch ammonia without <br /> discovered type•f iJ�ct oxygen.So-called anammox bacteria <br /> short-cut the nitrogen cycle by converting ammonium directly into nitrogen gas. <br /> I <br /> When the activated sludge and anammox processes are combined,one by-product is methane, <br /> which Kuenen proposes to harvest and use as fuel.The team calculates that,far from consuming <br /> energy,the process could generate 24 watt-hours per person per day."This is about trying to make <br /> waste water treatment plants completely sustainable,in the sense that they could even produce <br /> energy,which is not the case in present treatment facilities,"says Kuenen. <br /> This month the team will begin building a pilot plant to demonstrate the technology at the Dokhaven <br /> waste water treatment plant in Rotterdam,the Netherlands,working with from Radboud University <br /> Nijmegen and water purification firm Paques,based in the Dutch town of Balk. <br /> Michael Wagner,a microbiologist at the University of Vienna in Austria,points out that anammox <br /> bacteria were discovered only 20 years ago and hold great promise for a new generation of <br /> sustainable waste water treatment plants."The anammox story shows how fundamental discoveries <br /> by microbiologists can revolutionise waste water treatment,"he says. <br /> Journal reference: Science, DOI: 10.1126/science.1165941 <br /> hveeets <br /> tweet PRINT SEND SHARE <br /> http://www.newscientist.coin/ai ticle/dnl 8 872-bugs-will-give-us-free-power-while-cleanin... 4/19/2012 <br />