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Composting technology latest

Food waste accounts for 14.5% of all generated waste in the US according to EPA report, and only a small portion of it is recovered (1.6%). At the same time, food waste contains loads of nutrients that can be returned to the environment, but it should be done the right way. Disposing of the organic waste in the landfill results in the generation of methane, which can pose a threat or contribute to the greenhouse effect. Hence, developing composting technologies is an important part of a sustainable waste management system.

Compost is a stable organic mixture resulting from the breakdown of organic components; it is typically dark brown or black and contains humus which provides soil-like, earthy smell. Compost is widely used as fertilizer and soil amendment in agriculture. It is created by piling organic wastes (garden waste, leaves, food waste, manure) with bulking agents (e.g., wood chips) to provide environment for anaerobic bacteria and fungi to manage the chemical decomposition process. Compost is stabilized through maturation and curing process.

According to US EPA, there are a number of benefits of the composting process. These include:

• reduction and elimination of the need for chemical fertilizers;
• increasing of crop yields;
• facilitation of reforestation, wetland restoration, and habitat revitalization by amending contaminated, compacted, and marginal soils;
• cost-effective remediation of soils contaminated by hazardous waste;
• absorption and removal of solids, oil, grease, and heavy metals from stormwater runoff;
• avoidance of methane and leachate formation in landfills;
• decreased need for water, fertilizers, and pesticides in agriculture;
• serving as a marketable commodity and as a low-cost alternative to standard landfill cover;
• capturing and destruction of 99.6 percent of industrial volatile organic chemicals (VOCs) in contaminated air;
• more cost effective soil, water, and air remediation compared to conventional technologies;
• extension of municipal landfill life by diverting organic materials from landfills.

Certain physical conditions need to be provided for proper composting process. There are different types of processes, which are overviewed in the following reading.

Reading Assignment:

EPA Website: Types of Composting(link is external), US Environmental Protection Agency, 2013.

Watch this short video that illustrates industrial-scale composting facility in UK. This is only one of the ways to do it. Which type of composting (from those listed by EPA) is this facility using?

Click here for a transcript of the Hi-Tech Composting Plant video.

While having obvious benefits, composting is far from being environmentally clean. When organic components are mixed and concentrated during waste collection, they create aggressive gases and liquid effluents, which should be carefully controlled. In the diagram in Figure 5.3. the side inputs and outputs accompanying the composting process are shown. The pre-composting weighing and pre-processing stages generate liquid leachate, gas exhausts, and solid residue as by-products. Composting stage requires input of air and water, while generating more potentially polluting exhaust and effluents. Some of the residue is reusable, but some is not and need to be disposed of as non-recyclable waste.