The Consultant - Q1 2009 - (Page 55) Waste Management Initiatives in Europe The 68-seat Water House has both a hot composter for vegetable waste and a wormery which digests unused raw food. Compost goes to vegetable gardens in the surrounding residential area. The building, which is positioned on the banks of a canal, also has washrooms with low water-use toilets as well as all kinds of renewable water-using technology such as heat pumps for energy efficient cooling. Growing interest in on-site composting While recycling processes such as anaerobic digestion and bio-gas conversion typically require the large-scale involvement of outside specialist contractors, composting is thought to offer a promising on-premises solution applicable at both large and small scale foodservice operations. A system tested at a UK prison (HMP Morton Hall) integrates three different systems developed by IMC, a Wales-based equipment manufacturer. The process starts with appropriate kitchen waste in semi-liquid form being passed through a grinder-type disposer, either an in-sink installation or a stand-alone unit. The resultant macerated slurry is then fed to a dewatering unit where it is forced through a rotating screen. This separates the waste into two streams: grey water for passage to drain and a damp pulpy material which, by volume, is only 20 percent of the original waste. Dewatering is a fairly widespread method for dealing with kitchen waste in Europe but this latest evolution adds a further important element. The dewatered material, after being expelled to lidded waste collection bins, goes to an in-vessel composter. This tank with built-in heating element is loaded up daily, with the waste material mixed with wood chips (typically 1 part chips to 4 parts waste.) Following a period of approximately six weeks in the vessel, the resultant contents are allowed to mature outside, resulting in high quality compost. Composting brings about a further reduction in waste volume with 100 kg of food waste ending up as 5 kg of compost. While large composters can be as big as road tankers, scaled-down, 2 metre long tanks are now available for smaller applications. While there were some built-in advantages at Morton Hall prison, including plenty of land and some existing farming activity to ensure ready usage of the compost, the results have proved convincing enough for more than 30 prisons as well as schools, universities and commercial foodservice locations to follow suit with similar composting systems. Installations to date suggest that the savings made on direct and associated waste disposal costs will offset the cost of the waste pre-treatment and composting equipment in little more than two years. As well as reduced volumes of food waste and reduced landfill, benefits include reduction in transportation (and thus, security issues, emissions and costs), reduced cost in procurement of compost and revenue from sales. Another large foodservice operation which has taken a significant interest in composting is the O2 Arena, an east London entertainment complex which has a dozen restaurants and cafes as well as concert, sport and exhibition facilities. The vast 365m diameter mastsupported canopy structure, close to the River Thames, was initially known as the Millennium Dome and subleased to Anschutz Entertainment Group (AEG)in 2007. AEG's target is to achieve the highest recycling rates of any public entertainment venue within three years, reducing the volume of waste water discharged from site and composting 100 percent of all food waste for use on local landscaping projects. Similar targets apply to glass bottles and waste cooking oil. A composter is used for breaking down kitchen waste at UK prison, HMP Lewes. First Quarter 2009 55
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