FWDs are compact household appliances that may be installed under the kitchen sink, and their outlet is attached to the sink siphon. Their basic function is to grind and cut up organic kitchen waste such as vegetables, fruit rinds, coffee grounds, remainder of cooked meat and fish, small bones, therefore a slurry rich of energetic potential enters trhe drains. Besides the domestic use, small industrial units enable the same function in food processing for restaurants or food industries.

When it works, the kitchen food waste is shredded into a liquid pulp that is easily conveyed to the wastewater treatment plant (and to the anaerobic digester) through the drain and the sewerage net.These devices are designed to treat a homogeneous mix of food waste, they are very easy to install and extremely user-friendly.

A FWD consists of:

• a sink flange
• a grinding chamber for the food waste shredding
• an electric motor

In food waste disposers, food waste is fed into a chamber above the turntable and drops on the turntable together with the cold water. It reduces food waste, mixed with water, to a liquid pulp. Thanks to their design and functioning system, food waste disposers enable to achieve intrinsically highest selectivity with respect to organic waste, thus hindering the introduction into the drain system of foreign matters such as metals, plastics, etc.

Sewage treatment, or domestic wastewater treatment, is the process of removing contaminants from wastewater, both runoff and domestic. It includes physical, chemical and biological processes to remove contaminants. Its objective is to produce a waste stream and a solid waste or sludge suitable for discharge or reuse back into the environment.

Anaerobic digestion or biomethanization, occurs in the absence of oxygen, and is conducted in a completely enclosed silo or vessel. Anaerobic digestion is an endothermic process that produces a gas consisting primarily of methane and carbon dioxide. The gas is called biogas and can be captured and used for power or steam generation, or purified and used as a fuel.

Anaerobic digestion is a process in which microorganisms break down biodegradable material in the absence of oxygen. The process is already widely used to treat wastewater sludge and organic wastes because it provides volume and mass reduction of the input material.

As part of an integrated waste management system, anaerobic digestion reduces the emission of landfill gas into the atmosphere. Anaerobic digestion is a renewable energy source because the process produces a methane and carbon dioxide rich biogas suitable for energy production helping replace fossil fuels. Also, the nutrient-rich solids left after digestion can be used as fertilizer.