Domestic waste needs to be categorised into three very different components:-
- Biodegradable food and garden waste
- Dry and non-biodegradable waste (eg plastics, cans, bottles, paper and cardboard)
There are now many technologies available that allow the proactive household to handle all of these waste streams effectively and conveniently. Most of the dry, non-biodegradable wastes can be recycled without having to pay local councils to handle this.
Some new technologies completely remove the need to have a sewage system served to your house by the water companies. Sewage can be treated safely with a lower environmental impact than the sewage processing plants used by the water companies.
Here’s a list of the waste processing technologies currently available to the average UK household:-
- Garden composting bins. This is the old and very effective method of dealing with garden waste. It is also capable of processing of the food waste, though that would involve some separation which most people don’t want to get in to. Garden composting are not ideal for process waste meats and protein because that usually attracts vermin and can produce unpleasant odours.
- Wormeries. Wormeries have been available for decades but they have become more sophisticated in recent years, as a market demand is growing significantly. They consist of some sort of plastic bin, where food waste is placed. Within the bin is a colony of Tigers worms (or some similar species) who feed on the food waste producing a dark brown liquid which is drawn out through a tap at the bottom and can be used immediately and directly as a plant fertiliser. Wormeries can process all types of food waste, some garden waste and some can also process pet faeces. Wormeries capable of processing human sewage are also under development.
- Composting Toilets. These are another recent development of a very old technology. Naturally occurring bacteria, yeast and fungi are aerobically mixed with human faeces within the base of the toilet. Recent development of this technology has focussed on automating humidity and odour control. There are now products available that are very compact and look perfectly ‘at home’ in the average bathroom. There are models that can process three months of family sewage before requiring any compost removal. Just as with the wormeries, the compost from the composting toilet is perfect for garden soil conditioning and fertilising.
- Domestic Anaerobic Digester (micro AD). Anaerobic Digesters take wet biodegradable materials and liquids, and in the absence of air methanogen bacteria turn the material into biogas. The biogas produced (~60% methane) can be used to fuel cooking hobs, boilers and generators. UFL have designed their own micro Anaerobic Digester.
- Incinerating Toilets. Products are available to instantly incinerate all sewage waste immediately within the toilet. They usually require propane as their fuel and are generally found on temporary commercial sites but could be used very effectively within the domestic environment. They do consume fossil fuels, so they are only included here for completeness.
- Combustion – is by far the oldest technology for disposing of waste. It can be effective on all types of waste except metal and glass. The disadvantages of using combustion as a method of waste disposal include:- 1) the by-products (ash) are of less value (than fertilisers); 2) any moisture in the waste will make combustion more difficult.
Plastics are extremely easy to dispose of via combustion, but many plastics have chlorine in them which causes the formation of a group of chemicals dioxins when burnt. Dioxins are one of the most potent types of carcinogens known to man. One day plastics manufacturers will be banned from putting chlorine in their products.
At UFL, we believe that the current method of dealing with domestic waste is wrong. There is still too much going in to landfill, and the current recycling scheme works on a ‘cherry picking’ basis. We also don’t like the CO2 cost of having waste collected, and think it lunacy to pay a council to remove what belongs to us and what should be considered a great asset – domestic waste has a very high calorific value.
In an attempt to put this situation right, we at UFL have designed a domestic scale waste pyrolyser. Once fully developed, this device will take any hydro-carbon waste (anything excluding glass, metal and ceramics) and turn it into a fuel that can be used to generate electricity and heat.