As the market for compost products matures and differentiates, the demand for compost will grow. The path to a sustainable society may be long, but composting organics is clearly a step in the right direction.
By Lorrie L. Loder
Just a decade ago, most public officials and business owners thought of waste materials such as grass clippings, food scraps and biosolids as items for disposal. But many public agencies and entrepreneurs are using this former waste stream to positively impact their operating budgets and the environment. Once converted into compost, organic wastes—which are the compostable portions of the solid waste stream—can be used for landscaping, enhance crop growth, enrich topsoil, mitigate erosion and nutrient run-off, offset fertilizer purchases and more.
With more municipal officials realizing that composting is a cost-effective, environmentally beneficial strategy for managing organic waste and dealing with dwindling landfill capacity, it is important for them to understand the elements of a successful composting enterprise that are discussed in this article.
Types of Composting Facilities and Equipment
Composting facilities are either aerated or unaerated and covered or not covered. Composting methods include passive piles, windrow composting, static piles and in-vessel composting (in bins, beds, silos, transportable containers and rotating drums).
A static pile is a passively aerated system that has no need for turning because air is supplied through perforated pipes embedded in the piles. The open ends of the pipes allow air to be drawn in and circulated through the piles or windrows through a chimney effect created by rising hot gases. A variation on this approach is the aerated static pile system, which uses a blower to supply air to the compost pile. This system allows larger piles, smaller facility footprint and composts materials in three to five weeks.
Equipment requirements depend on the technology used. All that is needed for a static pile is a front-end loader and a screen to sift the compost; an aerated static pile also needs perforated pipe, blower(s), and biofilter(s) for emission and odor control. For a windrow operation, equipment might include a front-end loader screen (for unground green waste), windrow turner (for large sites) and a dump truck. Equipment needed for in-vessel systems depends on the process. In any operation, having properly sized equipment makes manpower more efficient.
Setting an equipment maintenance schedule is important to keep the operation successful. Tools needed to maintain equipment may include an air compressor, pressure washer, power and air tools, and a used oil collection and handling system. In summary, while windrow can be the most cost-effective composting method, it is rarely neighbor friendly (odors) and has issues with providing a consistent end product. Static pile systems are typically low cost, easy to manage and offer a faster process with less odors. In-vessel composting can be faster, but usually carry high capital and operating costs at large scale.
Composting Facility Siting
The size of the location required for composting depends on the following factors: the anticipated volume of raw materials, the technology to be used (the higher the level, the less space required), the equipment to be used (which depends on the method and raw materials), pre-conditioning efforts and the projections for growth. Some factors that should be considered when choosing a site are: accessibility (roads suitable for traffic and convenient to feedstocks, or raw materials), population, logistics and other costs associated with final compost sales markets.
States typically classify solid waste compost facilities based on the type and amount of materials to be composted. Compost facilities must meet siting requirements for flood plain, buffers, surface water and groundwater standards. In addition, facility design requirements must address public access, sedimentation pollution, air quality and odor minimization. The following steps are some of the recommended elements for proper site development:
- Grade the site to a 2 to 4 percent slope
- Slope the site toward a storm water collection pond
- Potential paving under the compost feedstocks
- Build berms around the perimeter to control run-off and run-on
- Plan areas for raw materials storage, processing, composting, curing, storage and blending of compost
- Set up equipment in locations convenient to the process
- Construct retainer walls for storage piles
- Develop a screen around the site (fencing/plants/shrubs/trees)
- Build a fence and gate to control access to the site
- Consider truck volumes and splitting ingress/egress routes for incoming raw material and outgoing compost product
- Install appropriate utilities depending on the method and process (2-inch minimum water main, storage and tool building, office and lab, scales for weighing trucks, maintenance shed)
- Obtain proper permits (mandatory) for local zoning, building and land use; state water discharge, composting, transporting, air, health department
Odor Management
Some odor will occur with any composting operation, so odor control procedures are an important part of the planning, design and operation of compost facilities. Odors originate from three main sources: odorous raw materials, ammonia released from high-nitrogen materials and anaerobic conditions within piles. But strong-smelling raw materials cause most of the odors. Properly preconditioning raw materials, starting materials composting as soon as possible and keeping the process aerobic will help minimize odor.
Safety
It’s fairly easy for compost to go awry, particularly at large scale if the proper technologies, equipment, processes and environmental controls aren’t used. One of many rules to follow is to set up a meeting with your local fire department. Discuss compost fires, and agree on guidelines for handling compost fires once they begin. Have the correct firefighting gear on site. If your site is remote, a runoff pond can serve as source of water for the composting process as well as for fighting fires.
State and Federal Compost Regulations
The EPA link, https://archive.epa.gov/region9/organics/web/html/index-3.html, provides access to a state-by-state summary of permits for each respective state. For current and more detailed information about regulations governing composting as well as the sale and distribution of compost and fertilizer, contact your state agency, which is also listed on the site. Regulatory responsibility varies from state to state and may fall under departments or divisions such as Air Quality, Environmental Quality, Natural Resources, Ecology, Waste Management, Agriculture, Environmental Conservation, Water Commission, Solid Waste Management, and Health and Environmental Control.
Environmental Protection Agency
The U.S. EPA has delegated authority to the states for most composting programs. Composting facilities may need approvals/permits from the state before they can begin operating. The requirements for permitting composting facilities may vary among states. More EPA information about composting is available at https://archive.epa.gov/region9/organics/web/html/index-3.html.
40 CFR Part 503 under the Clean Water Act (CWA) pertains to biosolids use through composting, land application and combustion of biosolids. Many of the standards promulgated in this rule can be applicable to municipal solid waste compost.
Marketing
A successful composting operation needs a marketing or distribution program for compost products. In addition to consistent high-quality end products, sound marketing techniques and infrastructure, planning and knowledge about end-users help to ensure a robust, sustainable composting operation. Inability to off-take material from your facility may result in costly backups and potentially ruined material that might have to be disposed of in a landfill (just what you were trying to avoid in the first place).
Compost characteristics desired by end-users vary with intended uses, but most compost users look for the following elements (in order of importance):
- Quality (moisture, odor, feel, particle size, stability, nutrient concentration, lack of weed seeds, phytotoxic compounds and other contaminants)
- Competitive price (high quality and performance can justify a higher price)
- Appearance (uniform texture, relatively dry, earthy color)
- Smell (earthy)
- Information (product’s benefits, nutrient and pH analysis, application rates and procedures)
- Reliable supply and delivery
- Material consistency
Composting for an Economically Viable, Sustainable Future
The U.S. EPA’s “Waste Management Hierarchy” puts landfilling as the last resort, after reuse, recycling and energy extraction. According to the EPA, “Reducing, reusing, recycling and rebuying—the four “Rs”—is key to diverting organic materials from landfills or incinerators and protecting human health and our land, air and water. Waste reduction and recycling prevents greenhouse gas emissions, reduces pollutants, saves energy, conserves resources and reduces the need for new disposal facilities. Yard trimmings and food residuals by themselves constitute 24 percent of the U.S. municipal solid waste stream. Composting offers the obvious benefits of resource efficiency and creating a useful product.
The U.S. Composting Council is firmly opposed to landfilling yard debris and other source separated organics when viable alternatives are available. It is an inefficient way to use our organic feedstocks—wasting resources, reducing recycling and potentially increasing greenhouse gas emissions.
Compost for Reducing Operating Costs and Increasing Revenues
The development of facilities that produce cost-effective, marketable Class A biosolids products also addresses concerns about the sustainability of biosolids management on many levels, including:
- Resource recovery (water, biosolids, energy, nutrients)
- Improving operating efficiencies and offloading some costs to the private sector while maintaining AAA + rating
- Helping reduce the rising tide of municipal expenses (8.1 percent average annual increase)
- Massive investment shortfalls for renewal of aging collection and treatment infrastructure
- Varying and declining availability of federal/state/local government funding
- Increasing restrictions and tightening of limits on air and nutrient discharge
- Elevated standards for biosolids treatment
- New regulations about organics diversion gaining momentum
- Public perception and opinion driving green infrastructure and initiatives that encourage planet friendly processes, reuse, recovery and conversion
- Planning to meet community growth in the short-, medium- and long-term
Despite the well-recognized value of compost, municipalities considering biosolids and organics- related projects are balancing budget, sustainability, and energy challenges that include:
- Food waste processing
- Product marketing—nutrients, fertilizer, compost and other products
- Nutrient capture and control
- Emerging technologies
- Cost audits and best practice implementation
Proven Provider Solution
The economics of composting can be challenging without the assistance of a proven developer/operator who offers economies of scale with respect to the design, operation and monitoring of facilities to ensure sustainable success. A public-private partnership offers an attractive opportunity that mitigates risks and costs, especially for municipalities that want to upgrade their current facilities. An experienced provider of these services understands how to muster regulatory and public support and promote the use of composting.
Progress continues to be made. The U.S. EPA has estimated that of the 250 million tons of Municipal Solid Waste (MSW) generated, 13.5 percent was yard trimmings and 14.5 percent food waste (EPA, 2012). Therefore, the yard trimmings amount to about 34 million tons and the food waste to 36 million tons. Based on the findings of the Columbia Survey, of the total 70 million tons, 27.4 million are composted (39 percent). More information about MSW is available at https://www3.epa.gov/epawaste/nonhaz.
However, that progress may be in jeopardy. Many municipalities are backpedaling on waste collection initiatives due to rising costs and budget shortfalls. Composting done correctly, with a proven partner, can help sustain collection efforts that support increasing the diversion and conversion of beneficial waste streams by mitigating and offsetting expensive and unsustainable alternatives.
As a modern industry, composting is barely 30 years old. As the market for compost products matures and differentiates, the demand for compost will grow. The path to a sustainable society may be long, but composting organics is clearly a step in the right direction. | WA
Lorrie L. Loder is Director of Facilities Operations for NuTerra Management, LLC (Jacksonville, FL). Lorrie is a compost-manufacturing professional with more than two decades of experience spanning operations, compliance, communications, marketing, public relations, and regulatory permitting and compliance. She has served on the U.S. Composting Council’s Board of Directors since 2006 and is serving her third term as 2016 President/Chair of the Board. She can be reached at [email protected].
The patented Neutralizer solution has become the most installed Class A/EQ (Exceptional Quality) biosolids management solution in Florida because it is simple, safe, environmentally responsible and cost-effective for wastewater treatment plants of almost any size. Images courtesy of NuTerra Management.