Food Waste - Response - Disposal

Disposal

Like other waste, food waste can be dumped, but it can also be fed to animals, or it can be biodegraded by composting or anaerobic digestion, and reused to enrich soil.

Dumping food waste in a landfill causes odour as it decomposes, attracts flies and vermin, and has the potential to add biological oxygen demand (BOD) to the leachate. The EU Landfill Directive and Waste Regulations, like regulations in other countries, enjoin diverting organic wastes away from landfill disposal for these reasons. In countries such as the US and the UK, food scraps constitute around 19% of the waste dumped in landfills, where it ends up rotting and producing methane, a greenhouse gas.

Food waste can be composted at home, avoiding central collection entirely, and many local authorities have schemes to provide subsidised composting bin systems. However, the proportion of the population willing to dispose of their food waste in that way may be limited.

Anaerobic digestion produces both useful gaseous products and a solid fibrous "compostable" material. Anaerobic digestion plants can provide energy from waste by burning the methane created from food and other organic wastes to generate electricity, defraying the plants' costs and reducing greenhouse gas emissions.

Food waste coming through the sanitary sewers from garbage disposal units is treated along with other sewage and contributes to sludge.

Commercially, food waste in the form of wastewater coming from commercial kitchens’ sinks, dishwashers and floor drains is collected in holding tanks called grease interceptors to minimize flow to the sewer system. This often foul-smelling waste contains both organic and inorganic waste (chemical cleaners, etc.) and may also contain hazardous hydrogen sulfide gases. It is referred to as fats, oils, and grease (FOG) waste or more commonly “brown grease” (versus “yellow grease”, which is fryer oil that is easily collected and processed into biodiesel) and is an overwhelming problem, especially in the USA, for the aging sewer systems. Per the US EPA, sanitary sewer overflows also occur due to the improper discharge of FOGs to the collection system. Overflows discharge 3 billion US gallons (11,000,000 m3) - 10 billion US gallons (38,000,000 m3) of untreated wastewater annually into local waterways, and up to 3,700 illnesses annually are due to exposure to contamination from sanitary sewer overflows into recreational waters.

In US metropolitan areas, the brown grease is taken by pumpers or grease-hauling trucks to wastewater treatment plants, where they are charged to dump it. In other areas, it may be taken to a landfill or it may be illegally dumped somewhere unknown, to avoid charges. This unmonitored disposal process is not only harmful for our environment and our health, but it also hurts businesses which have no idea where their business waste ends up, or indeed how much liquid waste is in their grease interceptors at any point in time, leaving them vulnerable to illegal dumping into their own grease traps or interceptors. Some companies now market computerized monitoring services along with in situ bioremediation, which produces byproducts of CO₂ and gray water that can safely flow into sewer systems. Other new technologies offer ex situ treatment to process brown grease into some form of transportation fuel. This may not be as environmentally friendly as in situ treatment, since it still requires vehicles to pump and transport the brown grease waste to the plants.

Estimating how much brown grease food waste is produced annually is difficult, but in the US alone, number is thought to be in the billions of gallons. In 2009, the city of San Francisco stated it produces about 10 million US gallons (38,000 m3) of brown grease a year. It is starting the first city-wide project in the US to recycle brown grease into biodiesel and other fuels.