“Waste management (including both collection and disposal) is the fourth largest area of council spend at £7 billion a year. As a valued universal service affecting all households, it is perhaps the most visible and well understood of all the services that councils provide. This makes the effective management of waste services absolutely critical.”
So starts the webpage of the LGA Productivity Team’s Waste projects. In the current economic climate it is not surprising the innovations in waste are coming from the Productivity section of the LGA. With the unit cost of waste collection increasing, there is a willingness to investigate different ways of dealing with our household waste.
Low and Behold is currently managing the Food Waste Disposer Pilot project for the LGA’s Productivity Team. The aim of this project is to explore the impact of food waste disposers on householder behaviour, residual waste and the sewer network. While current Defra research suggests that source-separated collections of food waste are the best environmental option, there are certain housing types, such as flats, where these collections are more difficult. The project therefore aims to investigate the potential for food waste disposers to be used in some of these households as an option for taking food waste out of the residual.
The project began at the end of 2011 with a comprehensive review of the available literature on the usage of food waste disposers (FWD). FWD units are small macerators that are installed in the kitchen sink outlet of domestic households. The householder separates food waste and flushes this into the unit with a small flow of cold water. Most foods are reduced to small particles and pass via the kitchen drain to the public sewer. They then move to the waste water treatment works where, in a large number of cases, the sewage sludge is treated by Anaerobic Digestion.
Low and Behold reviewed and collated all the available literature and studies that have been undertaken into the use and impact of FWD. In order to make sure that we found all of the available research, we formed a Technical Advisory Group, which includes representatives from OFWAT, the Environment Agency, Defra, DCLG, Water UK and WRc. With their support we identified 147 pieces of literature, going back to 1947. Of these, 95 were deemed to be relevant and were included in our report, which is available to download from the LGA website, or by emailing Nicola@lowandbehold.co.uk
One of the interesting things about the available research is that each study is looking at a different impact. Some investigate levels of suspended solids in the sewer network, some have looked at any changes to the operations of waste water treatment works and others examine householder attitudes. Because of this, it is impossible to group the research together and say categorically whether it is in favour or against the use of FWD. Instead we first looked at whether the research was primary, secondary or just a summary of other pieces of work. We then categorised the literature based on whether the impacts that were being observed or measured showed a positive, negative or neutral impact from the use of FWD. Overall, 63% showed a positive and 7% a negative, measured or observed impact.
The aim of the literature review was to highlight potential issues with FWD in order to establish a run a live pilot in the UK. This began in 2012, and we are currently continuing to install FWD in all the properties in a new-build David Wilson Homes development in Shropshire. As the first pilot of its kind in the UK, and one of the largest anywhere in the world, we aim to undertake a comprehensive review of the impacts of FWD. We will not only be undertaking qualitative surveys of householders, but also measuring the levels of food waste in the residual stream and the any blockages, or changed operational levels of the sewers and their downstream processing facilities. The Pilot will run for 12 months and the first householders have started to move in. While it is far too early to say what the results will be, we are pleased with the collaborative nature of this project and the support of the different relevant partners. A second site is now under construction in Shropshire and we are actively working on a third site in the south of England.
This article first appeared in the February 2013 edition of the CIWM Journal.