In addition to this, when organic matter such as food scraps and green waste are landfilled they are compacted and covered. This removes the oxygen and causes it to break down in an anaerobic process. One of the byproducts of this is methane, a greenhouse gas that is 25 times more potent than carbon dioxide.
Diverting waste from landfill is one way to address these issues.
Biffa Waste Services, Horsham
The Road Sweepings Recycling system at West Sussex involves screening, scrubbing, chemically treating and classifying 50,000 tonnes of street cleansing residues per year. The aims are two-fold: firstly to remove contaminants and oversized matter so as to end up with high quality recycled water; and secondly to divert road sweepings material from landfill. In terms of the latter, the company claims a 99% success rate.
Although originally purchased only to process street cleansing residues, the system has been so effective it is now used for multiple waste streams, including glass from locally based material recycling facilities (MRFs). Mark Harley, national development manager at Biffa, said:
We trialled numerous residual materials from MRFs through the system and the results are extraordinary in comparison to our previous traditional approach. A fantastic aggregate product is generated, ready to supply to the market, giving our clients a true circular economy solution.
Food Waste Trial, Portsmouth
According to Portsmouth City Council 40% of the content of our black bin bags is food waste. This rots and turns into methane when landfilled- a very potent greenhouse gas- or has to be burnt which also adds carbon emissions and toxic gases to our atmosphere.
To tackle this, in late 2019, the local authority started collecting food waste from around 4,800 homes across the city. This has now been extended to 24 000 homes and the intention is to extend this further to 60 000 homes by September 2021. Two caddies are provided for each home - a 5 litre one for the kitchen and a 23 litre one for collection. Items that can be put in the caddy include all raw and cooked food, as well as teabags and coffee grounds, and cut flowers.
As part of the scheme the leftovers are taken to a plant in Bournemouth for treatment where they are converted into biogas and used to generate electricity, heat or transport fuels as well as a fertiliser for agriculture. In the first full year of the trial, 812 tonnes of waste were diverted to food waste recycling.
Cllr Steve Pitt, Deputy Leader of the council, said:
We are keen to improve opportunities for residents to recycle more. A city-wide separate food waste collection could improve not only the recycling in the city by as much as 8%, but also reduce carbon emissions by around 36 tonnes per year. There are so many benefits to recycling food waste and we are excited to give residents the opportunity to help make our city cleaner and greener.