Kitchen Food Waste Recycling Options
Thursday, 6 November 2014 | HOTBIN Composting
Recycling Kitchen Waste - What are the Options?
As a nation every year we waste 7 billion tonnes of food and drink, which is bad for the environment and bad for our pockets.
Households are becoming increasingly under pressure to reduce the amount of waste they send to landfill and to recycle more. Reduced frequency of waste collections have been introduced, bin sizes are being squeezed and food caddies becoming a familiar site in many kitchens as the councils ask us to collect and leave out our food waste for recycling.
However ongoing council collections still mean a large weekly carbon footprint for the collection of waste. So what are the options of recycling kitchen waste at home and how do they measure up with the HOTBIN?
Options for recycling kitchen waste fall primarily into three main categories, anaerobic digesters, wormeries and aerobic hot composting, we have omitted cold composting based on the limitations applied to the types of food waste that can be recycled with this method.
Council collections mainly go to large anaerobic digestion plants across the country to be made into compost and digestate creating methane gas which is pumped back into the grid. Anaerobic digestors allow microorganisms to break down waste with the exclusion of oxygen. Smaller systems for the home are available such as the compact Bokashi system or the Green Cone a much larger system designed to be situated outside.
Most food waste can be added to anaerobic digesters with the addition of an accelerator producing a black digestate which can be collected via a tap (Bokashi system) or in the case of the Green cone designed to seep directly back into the soil the cone has been dug into. For this reason The Green Cone can be classified as a waste disposal unit rather than a recycler with no real means of collecting the digestate which can if situated on heavy clay-based soils sometimes prove problematic.
Bokashi meaning “fermentation”, literally pickles the waste over a period of 14 days (without being disturbed) at which point it can then be dug into the soil. To continually compost, two systems are really needed.
Wormeries are another popular home composting method, relatively small and suited for gardens, they stack layer upon layer with worms breaking down the waste inside into fine vermicompost. Worms are however fussy creatures when it comes to food so you may find yourself sorting out food waste to prevent feeding them any acidic food waste such as citrus and onions.
Unlike its anaerobic counterpart, HOTBIN requires oxygen to feed bacteria as they break down waste, this means the production of methane and associated smells is absent. The addition of bulking agent however is required to keep air flowing through the bin, this is typically partially composted wood chip which creates air spaces in the waste. The heat generated by bacterial breakdown reaches 40-60°c, creating compost in 30-90 days. At these temperatures breakdown is 32 times faster at 60°c then at 10°c, it does mean however though that worms will dislike the hotter temperatures in the bin.
The same size as a wheelie bin, HOTBIN requires 5kg of waste a week to keep the bin operational, which can be difficult for small households with no garden. However HOTBIN is a continuous composter with the ability to divert waste from landfill all year round and produce compost.
When choosing a system its always worth considering the environmental impact; anaerobic breakdown produces methane gas which it is claimed is as much as 30 times worse than carbon dioxide in terms of greenhouse gas and climate impact.
The suitability of a system will also depend on the quantity of waste and how much space you have available whether you want compost for your garden or just a disposal unit.
Whichever system is chosen diverting food waste from landfill is most certainly a good thing however it’s worth bearing in mind that some form of ongoing investment will always be required whether in the form of bran, accelerating powders, worms or bulking agent to ensure good quality speedy composting.