issues that may have positive or negative results. Biological treatments In addition to reusing materials waste products can go through biological treatment. There are two types of biological treatments anaerobic digestion or composting. Simply stated, biological treatment is the breaking down of material through the action of micro-organisms. Materials are broken down to carbon dioxide, water and biomass. Biomass consists of wood, crops, yard and animal waste. Biomass is considered a renewable energy because more can be grown in a short amount of time. Biomass contributes to roughly four percent of our energy. Biomass energy although its burned, does not pollute the air as much as fossil fuels. Some materials easily break down, others do not. The environment in which the material is placed determines the speed of breakdown. Return waste to supplier of original materials It is possible in many production facilities to return waste product to the supplier of the original raw material. Some examples include the reuse of beer kegs by returning to the distributor to be refilled, reuse of propane tanks, and recycling batteries to be used again. These products are large contributors to the overgrowth of landfills. Many companies will offer incentives or credits for the returned product towards the next purchase. Reuse waste in the same or other steps of production process The development of more closed loop systems aides in diverting waste from landfills. Manufacturing and most production facilities will create waste to varying degrees. A closed loop system will recycle the waste back into the production process to maintain minimal levels of waste that is left to be disposed of. This is environmentally and economically friendly. Selling waste to a third party More unfamiliar than other types, it is possible for a company to sell its waste to a third party. This third party will purchase the waste for reuse in their own production process. In addition to the sale of waste, there are also third parties which will retrieve your waste for you if they are capable of disposing of it more efficiently and/or affordably. Waste to energy Other options for diversion are composting and waste-to-energy: converting primary waste into various types of energy such as heat or electricity. Types of landfills Open dump An open dump is an area where unwanted waste is disposed of with no regulations or restrictions; they often produce adverse effects on the environment. The Resources