FAQs
INSTALLATION
How much does a food waste disposer cost to purchase and install?
Basic models start from about £80. Depending on the sink and plumbing a food waste disposer (FWD) may not necessarily cost anything to install, as it requires no special tools it can be installed by the owner.
Are they suitable for older properties and are there any special plumbing or sink requirements?
A FWD can be installed into an existing sink and kitchen with standard plumbing. A disposer will fit into a single bowl or half bowl. The standard 3.5 inches (90mm) sink opening is ideal, however accessory flanges are available for most non-standard sink drains. It must be firmly attached to the sink, connected to the kitchen waste water pipe and an electricity supply.
Do food waste disposers require maintenance?
No. Food waste disposers are designed to be maintenance free. Regular usage is the best way to keep the disposer in good condition. A moderate stream of cold water following each use will keep the FWD clean.
SAFETY
Are food waste disposers dangerous to use? Do they have blades?
They do not have knives or blades and comply with the EU standard of safety for food waste disposers.
Is it safe to have an electric power switch so close to wet hands?
There is a new type of switch called an air switch that makes it easy to operate a FWD with wet hands. The air switch has been developed to deliver a puff of air to operate an electric switch remote from the operator. Conventional electric switches should be correctly insulated and operated with dry hands.
How much electricity and water do they use? What would be the householder’s running cost?
The cost of operating a FWD is relatively low. Because disposers grind fast (estimated run time is 15 seconds) they use a limited amount of electricity. Annual energy use is about 2-3 kWh per household and at current average electricity prices this represents a cost of approximately 46 pence p.a.
The average water use around 6 litres per day per household, is less than the equivalent of one extra toilet flush.
What can go down the food waste disposer and what cannot?
Everyday food waste scraps can go down all models, however some FWDs cannot take grinding large amounts of vegetable peels, hard materials such as bones and fruit pits and fibrous materials such as celery, corn husks, and artichokes. Some models can deal with all food waste.
PLUMBING AND WATER WASTE
Can the discharge block the household pipes or drains?
No. The food waste is ground up into miniscule particles making it similar in chemical composition to other black water which is easily transported through household pipes or drains.
Can older waste water systems and sewers cope with output from food waste disposers (FWDs)?
Research from the United States, Germany, Italy, Japan and the Netherlands has consistently demonstrated that the output of FWDs flows easily through the sewers, does not settle and does not contribute to fat, oil and grease (FOG) in the sewers. All sewers are designed to carry waterborne waste from the home. Ground food waste produced by FWDs is over 70% water and is similar in chemical composition to other black water which can be easily be transported through any existing sewer system.
How does the ground food waste affect existing waste water treatment processes?
Numerous studies have proved there is a negligible impact on existing waste water treatment processes including no increase in water usage, no increase in sewer blockages, nor accumulation of solids, fat oil and grease (FOG), hydrogen sulphide or corrosion. Also there is no change in wastewater treatment cost.
ENVIRONMENT
How do food waste disposers compare with other methods of recycling food waste?
FWDs have a good carbon footprint, avoiding jamming the roads with the additional rubbish trucks needed for separate food waste collection at the kerbside.
The waterborne waste sludge from FWDs can provide sustainable energy in the form of biogas which can be converted into electricity. This is its main advantage over centralised composting which naturally has a good carbon footprint but does not provide an opportunity for energy recapture.
What are the possible end uses for the waste sludge?
Protein-rich slurry can provide renewable energy. It is passed through the sewers to anaerobic digestion plants, where the biogas is captured and can be transformed into electricity. Or it can be used as fertilizer or soil improver
What is anaerobic digestion?
Water waste from the treatment plant is sent to an anaerobic digester in which microorganisms break down the material in the absence of oxygen to release energy. The process produces a methane and CO2 rich biogas – a more environmentally friendly alternative to fossil fuels.
