Water Journal : Water Journal November 2015
NOVEMBER 2015 WATER 85 Water Business WATER BUSINESS TREATING TODAY'S ORGANICS FOR TOMORROW'S ENERGY According to the Australian Bureau of Statistics, Australia generated approximately 12.8 million tonnes of organic waste in 2010, making it the nation's second largest waste stream after construction. But unlike post- construction resources, organics recovery remains low. Recovered organics is a resource stream with both an energy and a nutrient value and it has the potential to provide a more economical input to agricultural markets. When food production goes wrong, 20,000 litres of, for example, chocolate liquid can go from being a delicacy to a waste. For resource recovery companies, such feedstocks are dif cult to treat using conventional recovery infrastructure. They are too wet to send to composting, unsuitable for soil injection and are a written recipe for odour and leachate when sent to land ll. Thinking outside the box An emerging answer to these challenging organics streams is anaerobic co-digestion. Here, excess capacity available in anaerobic digesters at wastewater treatment plants is used to treat wet organics from municipalities and the food and beverage (F&B) market. The dual use of facilities is a result of an emerging trend in infrastructure planning, whereby the formerly parallel elds of water and waste management, and energy production are merging into the single offering of a new generation of resource management companies. Using the circular economy principles, all material ows are managed to maximise their economic value and minimise pollution. It is this thinking that drove this year's amalgamation of SUEZ's water and waste management companies under a single brand. A new approach SUEZ operates anaerobic digesters around the world, helping towns, cities and industry make the best use of their water and waste resources by providing smart and reliable solutions tailored to their customers' needs. Since September this year, SUEZ has assisted the Strasbourg Urban Community to become the rst in France to inject biomethane produced from a local Wastewater Treatment Plant (WWTP) into its natural gas network. In collaboration with the local distributor of natural gas, more than 1.6 million m3 of biomethane will be produced from wastewater each year. This provides a local, sustainable and low- carbon source of renewable energy. SUEZ has been pushing the boundaries of biogas recovery, including opening a dedicated biosolids methanisation laboratory, with more than $15 million invested in R&D in the last eight years in this area alone. Australia's rst co-digestion plant In Australia, SUEZ and its joint-venture partner, Trans eld Services, rst introduced co-digestion technology into the country through the Allwater Alliance, which in collaboration with SA Water, operates and maintains the water and wastewater services in metropolitan Adelaide. Following a successful research program in 2010, a fully automated co-digestion plant was commissioned at the Glenelg WWTP in July 2013. Jennifer Dreyfus, a site engineer at the Glenelg plant and a co-digestion expert, said the addition of sugars, alcohols and other organic rich substrates provide a healthy boost to the site's anaerobic digesters. Prior to the co-digestion upgrade, the digesters were only treating sludge from the plant that did not have enough organics to maximise biogas production. The addition of ve to six per cent dairy and liquid food waste increased gas production by around 25 per cent. In turn, this has reduced the reliance of the plant on natural gas and grid electricity. The plant is now helping the F&B industry put their waste to good use, with eight suppliers providing approximately 30 trucks a week of by-products from milk, cheese, beer, wine and soft drink, to the Glenelg plant. "This co-digestion stream would normally be sent to sewer or land ll. When sent to sewer, this material is corrosive and increases the energy required to treat the wastewater. "It is all about sending the right waste to the right place." Renewable energy with national potential Leveraging off the success at the Glenelg plant, Dreyfus said the next phase of the co-digestion program was an expansion to the Bolivar plant, South Australia's largest wastewater treatment site. With six large digesters on-site at Bolivar, there is a vast capacity for improved resource recovery and the generation of renewable energy, and this should not to be underestimated. For example, in the rst 16 months of operation the co-digestion plant at Glenelg received 13.2 ML of liquid waste products, which produced an extra 1,290 MW of energy. This makes the Glenelg plant a bigger source of renewable energy than any solar installation in South Australia. "People are now talking about wastewater treatment plants as resource recovery facilities," Dreyfus explained. "Our goal is to not only make our plants energy self- suf cient, but potentially become power plants in their own right."
Water Journal September 2015
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