Food Waste Disposal Methods

            

            Food waste is an untapped energy source that mostly ends up rotting in landfills, thereby releasing greenhouse gases into the atmosphere. Food waste includes organic wastes generated in hotels, restaurants, canteens, cafeterias, shopping malls and industrial parks in the form of leftover food, vegetable refuse, stale cooked and uncooked food, meat, teabags, napkins, extracted tea powder, milk products etc. It is difficult to treat or recycle food waste since it contains high levels of sodium salt and moisture, and is mixed with other waste during collection. 

Food waste can be recycled by two main pathways:

·         Composting: A treatment that breaks down biodegradable waste by naturally occurring micro-organisms with oxygen, in an enclosed vessel or tunnel or pit

·         Anaerobic digestion or biogas technology: A treatment that breaks down biodegradable waste in the absence of oxygen, producing a renewable energy (biogas) that can be used to generate electricity and heat.

Composting

​​Composting provides an alternative to landfill disposal of food waste, however it requires large areas of land, produces volatile organic compounds and consumes energy. Compost is organic material that can be used as a soil amendment or as a medium to grow plants. Mature compost is a stable material with a content called humus that is dark brown or black and has a soil-like, earthy smell. It is created by: combining organic wastes (e.g., yard trimmings, food wastes, manures) in proper ratios into piles, rows, or vessels; adding bulking agents (e.g., wood chips) as necessary to accelerate the breakdown of organic materials; and allowing the finished material to fully stabilize and mature through a curing process. 

Anaerobic Digestion

Anaerobic digestion (AD) is a microbial decomposition of organic matter into methane, carbon dioxide, inorganic nutrients and compost in oxygen depleted environment and presence of the hydrogen gas. This process, also known as bio-methanogenesis, occurs naturally in wetlands, rice fields, intestines of animals, manures and aquatic sediments, and is responsible for the carbon cycle in the ecosystems. Natural and anthropogenic sources account for 30 and 70 %, respectively, of the total methane released in the atmosphere every year. Major natural sources of methane are the wetlands and animal guts (mainly insects and ruminants) while the main anthropogenic sources have been identified in the fossil fuel processing industries, rice fields and landfills. Biological activity has been identified to be the cause for more than 80% of the flux of the atmospheric methane (Palmisano et al. 1996). 
  

Of the different types of organic wastes available, food waste holds the highest potential in terms of economic exploitation as it contains high amount of carbon and can be efficiently converted into biogas and organic fertilizer. Food waste can either be utilized as a single substrate in a biogas plant, or can be co-digested with organic wastes like cow manure, poultry litter, sewage, crop residues, abattoir wastes etc. 

Source: https://www.ecomena.org/food-waste-disposal/