Food waste or loss of food are food that is discarded or lost without eating. The causes of waste or loss of food are numerous and occur in the stages of production, processing, retail and consumption.
Current estimates put the overall loss of food and waste between one-third and one-half of all food produced. Loss and waste occur at all stages of the food supply chain or value chain. In low-income countries, most of the loss occurs during production, while in developed countries much of the food, about 100 kilograms per person per year, is wasted at the consumption stage.
Generally, food loss or food waste are foods that are discarded or not consumed. However, the precise definitions are contentious, often defined on a situational basis (as is more generally the case with definitions of [residues]). Professional bodies, including international organizations, state governments and secretariats may use their own definitions.
Definitions of food waste vary, among other things, in what food waste is made up, how it is produced and where or what is discarded or generated. Definitions also vary because certain groups do not (or have not traditionally) considered food waste as a waste material because of their applications. Some definitions of what constitutes food waste are based on other definitions of waste (eg, agricultural waste) and what materials do not meet their definitions.
Commercially, food waste in the form of sewage from commercial kitchen sinks, dishwashers and floor drains is collected in holding tanks called grease interceptors to minimize flow to the sewer system. This often smelly waste contains organic and inorganic waste (cleaning chemicals, etc.) and may also contain hazardous hydrogen sulfide gases. It is known as fats, oils and grease (FOG) or more commonly "brown fat" (as opposed to "yellow fat", which is fryer oil that is easily collected and processed in biodiesel) and is an overwhelming problem, especially in Los USA, for the aging of sewage systems. By US EPA, sanitary sewer overflows also occur due to improper discharge of FOGs to the collection system. Overflows discharge 3 billion gallons (11,000,000 m3) - 10 billion gallons (38,000,000 m3) of untreated wastewater annually into local waterways and up to 3,700 annual diseases due to contamination of sewage drainage in recreational waters .
In US metropolitan areas, brown grease is taken by pumping or transporting grease to wastewater treatment plants, where they are charged to overturn. In other areas, it may be taken to a landfill or may be illegally dumped somewhere unknown to avoid charges. This uncontrolled disposal process is not only detrimental to our environment and our health, it also hurts companies who have no idea where their business waste ends, or even how much liquid waste is in their grease interceptors at any Leaving them vulnerable to illegal dumping in their own grease traps or interceptors. Some companies now market computerized monitoring services along with on-site bioremediation, which produces by-products of CO2 and gray water that can safely flow to sewage systems. Other new technologies offer ex situ treatment to process brown grease in some type of transport fuel. This may not be as environmentally friendly as on-site treatment, as it still requires vehicles to pump and transport brown fat waste to plants.
It is difficult to estimate the amount of brown fat residues that occur annually, but only in the United States it is estimated that the number is in the billions of gallons. In 2009, the city of San Francisco stated that it produces about 10 million US gallons (8,300,000 gallons, 38,000 m3) of brown fat per year. The first project of the city in the USA is starting. To recycle brown grease in biodiesel and other fuels.