Food waste and yard waste may not be the first topics in many conversations about sustainability, but organics recycling is one of the most promising and environmentally beneficial opportunities for the waste sector. Still, there is much work to complete before the sector meets its potential to offer both environmental and economic sustainability, and the technology and infrastructure needed to convert organic waste into valuable products are evolving.

Two compelling trends make this a promising period for the recycling of organic material. The economics of “waste” are changing as waste service companies reconsider the value contained in waste materials and work to capture value from the organics they manage. At the same time, residential, commercial and municipal customers are demanding more organics recycling services to meet their own sustainability goals.

Supply and demand incentives are aligning to increase the amount of organics processed, and by most measures the market is ripe for growth. North America generates more than 80 million tons of organic waste each year, which includes food waste, yard waste, and clean wood from forestry projects and the construction and demolition sector. In the United States, the Environmental Protection Agency estimates that about two-thirds of the municipal solid waste (MSW) stream consists of organic waste. While approximately 65 percent of yard waste is diverted for recycling, only around 2.5 percent of food waste is currently being recycled. There is clearly abundant room for expansion, provided the sector can navigate the technological, regulatory, logistical and economic challenges associated with recycling food, yard and other types of green waste.

The Various Technologies

As the sector matures, we can expect to see a variety of approaches to recycling organics develop. Certainly, composting is currently the most common organics management process; however, companies are investing in a variety of other technologies to capture more value from organic materials.

Organics processing generates value from organic waste in the form of salable products — and it provides waste service companies with a service that can help maintain customer loyalty. The current and future merits of the various approaches depend primarily on local factors, including the kinds of organic material available, local processing facilities and the market for end products.

Composting, which uses natural biological processes to break down organic materials aerobically, likely will comprise the bulk of the organics management industry in the coming years. Composting technology is well understood and can scale to meet growing volumes.

At the end of the process, operators are left with a nutrient-rich product that has value as a soil amendment or as an ingredient of other value-added lawn and garden products. Increasingly, consumers are demanding alternatives to conventional chemical fertilizers for lawn and garden care, and municipalities and companies are seeking to put their organic material to beneficial use. Organic compost is considered part of the green retail market, which is growing at 20 percent annually.

While compost and soil amendments represent valuable end products, other more technologically advanced methods of organics recycling show even greater potential. As with most aspects of business, greater risk can result in greater reward, and though new technologies may not scale as rapidly as traditional composting techniques, they offer opportunities to generate energy and high-value materials from organic wastes.

One of the fastest growing technologies is anaerobic digestion, a biochemical process that produces methane-rich biogas. Anaerobic digesters have been around for decades in one form or another, particularly in the agricultural industry. However, companies have realized that this technology can be used effectively to process food and yard waste. Harvest Power, for example, uses anaerobic digestion technology to break down food and yard waste to generate biogas that can be used be used for, among other things, electricity generation or industrial applications.

Anaerobic digestion also produces solids that can be recovered for soil amendments, usually after a short aerobic composting process. Because it relies on a biological process, however, anaerobic digestion can be sensitive to the composition of organic waste entering the digester, making materials handling a potential challenge. Reliable feedstocks often are necessary to ensure consistent performance in an anaerobic digester.

Another company developing a fermentation technology based on anaerobic digestion is Terrabon, a Texas-based company that uses a unique technology to create high-octane fuel from organic materials, particularly food and cellulosic yard waste. The bio-derived gasoline has an energy density similar to gasoline and can fuel a range of vehicles without modification.

Thermochemical approaches also offer the waste industry opportunities to generate higher value materials from organic materials. For example, gasification, the heating of materials in a controlled environment to generate synthetic gas (or “syngas”), provides the industry with a powerful technique to recover materials in organic waste. Gasification is very different from combustion. The resulting syngas, a mixture of carbon monoxide and hydrogen gas, can be burned for electrical energy, used to produce chemical compounds or turned into transportation fuels. Gasification has the added benefit of recovering value from carbon-containing material other than food and yard waste such as construction and demolition wood, as well as agricultural and forest residues.

Issues Remain

Despite promising developments in the recycling of organic wastes, landfill-based approaches to organics management will continue to dominate until the technological, financial and regulatory issues associated with organics processing facilities are resolved. While the transition to new technologies takes place on a local and regional level, it is important to capture value from the decomposing organics rather than allowing those resources to go to waste.

Modern landfills can capture the methane-rich landfill gas produced by decomposing organics to generate electricity or provide fuel for nearby industries. New technologies can also help generate more value from this methane. For example, Waste Management and Linde operate a project at the Altamont, Calif., landfill to convert landfill gas into LNG, which powers more than 300 of Waste Management’s vehicles and reduces greenhouse gas emissions by more than 30,000 tons per year.

Such landfill-based projects represent the middle of the green value chain: they recover value from the organic material, but are less efficient at producing high-value renewable end products compared to the more advanced organics recycling technologies.

As the organics recycling industry grows in the coming years, it will be vital to align the interests of all members of the value chain. Securing consistent access to uncontaminated organics is a priority for composting, since much of the process’s value resides in selling clean soil amendments. Waste companies and facility managers must work to obtain clean source-separated organics and ensure practices follow guidelines to protect the integrity of the compost product.

Regulatory issues, too, must adapt to foster the organics recycling industry. To meet their own sustainability goals, many municipalities are encouraging or demanding that organic material be diverted from traditional disposal facilities. Truly sustainable waste management practices incorporate robust environmental and operating requirements to protect air, soil, surface and groundwater, and allocate sufficient capital to address any facility problems and enforce compliance.

Successful policies also should provide for the establishment of viable organics processing systems before mandating such recycling. In advance of mandates, local municipalities can encourage organics programs through rate incentives, convenient collection programs, public education and the development of local end-markets for recycled products.

Several cities have followed this model, including Seattle, which encouraged voluntary programs for a decade before banning recyclable paper from the waste stream. The city is now poised to ban commercial food waste from the MSW stream in 2014, but is working well in advance of that deadline to ensure a robust commercial food waste processing system is functioning smoothly.

Increasingly, the financial and environmental incentives for organics recycling are aligning in many regions across North America. With cooperation between waste producers and processors, as well as a healthy regulatory framework, we can look forward to seeing a growing share of organic materials destined for recycling. Beneficial uses and increasing financial incentives to recover value in waste should ensure that organics processing continues to climb the green value chain in the years to come.

Tim Cesarek is the managing director of organic recycling solutions for Waste Management.

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Sidebar: Want to Know More About Composting?

The 2011 WasteExpo conference program includes the "Potato Peels and Brussels Sprouts: The Future of Food Composting" session, which will be held on Tuesday, May 10, from 1:45 p.m. to 3 p.m. For complete information on this and other conference sessions, visit www.WasteExpo.com.