Setting the Stage
The Governor of Rhode Island recently signed legislation that requires organizations that send at least 2 tons of food waste to the landfill to divert these scraps to a compost or anaerobic digester facility. This law will extend the life of the landfill, create jobs and create clean renewable energy. REI is bringing the developers, law makers, investors and food dispensary companies together in a two-part program designed to understand the challenges and opportunities about this law. Program details to be announced.
(Image Source: US EPA)
Anaerobic Digestion A Solution for Waste-to-Energy.
By John Hays and Larry Cosenza
Microbial anaerobic digestion (MAD) is a process that uses bacteria in an oxygen free environment to convert organic waste into energy. Bio-gas is one product produced from the breakdown of organic matter in the anaerobic process. Anaerobic digesters come in many different styles, shapes and configurations but, they all operate in the absence of oxygen, in a sealed vessel and at elevated temperatures. Anaerobic digesters can simply be considered as mechanical cows that are fed organic waste and in the process make bio-gas and other products. Bio-gas is a mixture of methane and carbon dioxide. If carbon dioxide is removed from bio-gas the remaining material is called bio-methane and is nearly the equivalent of natural gas. The other products that result from anaerobic digestion are remaining solids and nutrient rich liquid often referred to as digestate.