LAWR

COMPOSTING Diversionary tactics The composting of organic waste in the UK has grown rapidly in the last ten years, with the vast majority of councils now providing a food waste and green waste col- lections to households. Yet, anaerobic digestion gains more attention in the media. Liz Gyekye considers the role of in-vessel composting in redirecting food waste from landfill. ising costs for the dis- posal of residual waste are making separate collection and pro- cessing of food waste more financially attractive to local authorities. Currently, local authori- ties are collecting around 4.7m tonnes of food waste each year. Yet, UK house- holds throw away around 7m tonnes of food waste away per year, according to WRAP. This creates an opportunity to improve diversion rates. However, there needs to be a clear diversion route, a proven treatment process and developed markets for the resulting end products. The most common technologies used for dealing with food waste are in-vessel compost- ing (IVC) and anaerobic digestion (AD) which are both effective processing methods. Every year, WRAP publishes an annual survey on the organics indus- try and figures from WRAP show that the IVC industry is growing. It's most recent survey analysed the sector in 2012. Figures from WRAP show that IVC operators of enclosed in-vessel com- posters processed 346,579 tonnes of organic waste in 2010. In 2012, they processed 1.1 million tonnes of organic waste. In contrast, IVC operators man- aging facilities in the open processed 1.5 million tonnes in 2010 but only 1.1 million tonnes in 2012. Recent estimates suggest that all IVC facilities have the capacity to physically handle around 2.7 million tonnes of organic materials, suggesting a 85% utilisation of capacity. A total of 47% of local authorities in the UK are providing a food waste collection service to householders and an increasing number are looking to collect food waste from small busi- nesses and schools. Figures from WRAP show an esti- mated 7.54m tonnes of organic waste was input into composting and anaero- bic digestion organic waste treatment facilities in 2012. However, compost- ing continues to be the treatment that processed the majority of this waste (5.9mt). It also employs 1,370 people. As composting continues to grow more eyes will be looking at IVC as a proven treatment process. There are many advantages to using IVC as a means of diverting organic materi- als from landfill. Bio-waste technology company TEG Group specialises in AD and IVC solutions. Chief executive Michael Fishwick argues that IVC is much better suited to process food and green waste mixed together. He also says it is cheaper to collect 14 Local Authority Waste & Recycling July 2014 R A growth sector: around 5.9m tonnes of waste was composted in the UK in 2012 • Overall, 1.68 million tonnes of waste was processed at AD sites from an overall operating capacity of 2.07 million tonnes, suggesting a 82% utilisation of capacity • Data for 2011 has not been produced by WRAP due to a decision to use information purely from operators rather than regulators for the latest survey. Previous surveys used data from regulators on material outputs, which is not available for at least 11 months after the period it relates to. Key facts from organic waste survey from WRAP: July 2014 Local Authority Waste & Recycling 15 COMPOSTING mixed food and green waste. The AD system, on the other hand, is very dependent on "clean" and "consistent feed- stock" such as food waste. The process has higher capi- tal costs and Fishwick says that it can be more expensive for councils to collect food waste separately. TEG has observed an upward trend in green and food waste over the last few years and the company's IVCs have been operating at 100% capacity for the last three years. Fishwick argues that it "has reached the point now that during the peak from spring to the end of autumn there is virtually no available capacity in the UK. This is down to two reasons – the increase in demand and regulatory pressures on cur- rent operators. As an exam- ple, we understand the num- ber of permitted IVC facili- ties in the UK dropped by some 10% between 2011 and 2012 as regulators enforced odour control measures on IVC operators". Another disadvantage to the IVC system is that it cannot produce biogas, which provides revenue for AD operators.Fishwick says that IVC does not lend itself to power production so does not benefit from subsidies through Feed-in-Tariffs (FITs) or Renewable Obligation Certificates (ROCs). However, in order for an AD plant to be commercially viable, markets also need to be found for the solid and liquid digestates. Potential markets include regeneration of contaminated soils.. Solid digestate could also poten- tially be used as a biofuel. Nevertheless,"compost is a much more established prod- uct with a well-established market whilst the digestate market is very much in its infancy," Fishwick says. Recent WRAP figures show that the overall market value of compost is currently worth £11.4m and has been helped by an overall rise in outputs. This is despite a decrease in the mean price of compost for nearly all mar- kets. Meanwhile, the largest market for compost remains agriculture and field horticul- ture at 68%. The survey also found that sites certified to produce PAS 100 generally achieve higher price for their outputs. Yet, for the industry to grow more it needs serious investment. Fishwick says: "The biggest challenge for the growth of the industry in general, for both IVC and AD, is funding. We all know the waste is there but the issue is having the confidence that the customers will segregate and collect it if the capacity is made available and there remains a 'chicken and egg' situation. It is a risk for developers to construct sites if they haven't secured waste contracts but we need to have the secure capacity to encourage the market to continue to supply the waste in the first place!" IVC is not the panacea but it has its place alongside AD. It can help save time and money for customers and feedstocks do not need to be managed as closely as those for AD. Like AD, IVC is an important technology in allowing food waste to be effectively recycled and diverted from landfill. For some local authorities AD may be an attractive option, particularly because of its potential to generate renew- able energy. But there will always be a market for com- post and operators still face challenges in finding suitable markets for digestate. See us on stand H 087 AD & Biogas Show Effective and reliable odour & H 2 S removal from ERG Effective and reliable odour & H 2 S removal from ERG

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