HDR Solid Waste Innovations

HDR Solid Waste Innovations

In 2010 the U.S. generated 250 million tons of trash, or municipal solid waste (MSW), and recycled and composted almost 85 million tons. On average, Americans recycled and composted 1.51 pounds of their individual waste generation of 4.43 pounds per person per day. Consistent with these changes, the generation, recycling, composting and disposal of MSW have changed substantially throughout the past few decades. While sold waste generation has increased by .77 pounds per person per day between 1980 and 2010, the recycling rate has also increased from less than 10 percent in 1980 to 34 percent in 2010. In addition, waste disposal to a landfill has decreased from 89 percent in 1980 to 54 percent in 2010, according to the Environmental Protection Agency (EPA) report, Municipal Solid Waste Generation, Recycling and Disposal in the United States: Facts and Figures for 2010.

Like many agencies, for decades the Austin, Texas, Solid Waste Services Department focused on collecting trash and putting it in landfills. However, as proof of the way it now perceives and manages solid waste, it is working on an ambitious long-term plan to manage waste as a resource. Austin, whose new focus is reflected in its new name, Austin Resources Recovery, is far from alone in turning its attention to “reduce, reuse, recycle.” Communities throughout the United States and Canada are doing things never imagined 20 years ago, such as using solar panels to turn landfills into energy sources. In other cases, everything old is new again, as waste-to-energy management comes full circle.

America’s Waste-to-Energy (WTE)

Waste-to-Energy (WTE) used to be all the rage in the United States. During its heyday in the late 1970s and early 1980s, 180 facilities were in operation. It was the answer to stringent regulations and a lack of acceptance of long-distance trash hauling. In the early 1990s, although combustion with energy recovery was at an all-time high of 14.3 percent, WTE construction had come to a halt as project economics, regulations and the advent of mega-landfills with cheap tipping fees came into play. Today, the number of WTE facilities in the United States is less than one-half the total in the 1980s. Yet even with this reduced presence, WTE facilities manage roughly 12 percent of America’s trash and generate enough electricity to meet the power needs of 2.8 million homes.

However, some agencies never lost sight of the benefits provided by WTE. Lee County, Fla., is widely regarded as having one of the most progressive solid waste systems in the nation. In recent years, it undertook a 636-ton-per-day expansion to its facility. The plant burns waste at more than 1,800 degrees Fahrenheit and generates up to 53 megawatts of electricity. It operates as a zero-discharge facility, using recycled wastewater from a municipal wastewater treatment plant for additional sustainability.

WTE facilities are also compatible with recycling, as they remove more than 700,000 tons of ferrous materials and more than three million tons of glass, metal, plastics, batteries, yard waste and ash at on-site recycling centers. Again, Lee County can serve as an example; as it expanded its WTE facility, it also expanded its Recovered Material Processing Facility (RMPF). The RMPF has more than 300 tons per day of sorting capability, which means Lee County residents don’t have to separate recyclables into two streams to set at the curb.

 

© HDR|Lee County Florida’s waste-to-energy facility.© HDR

Lee County Florida’s waste-to-energy facility.

Canada’s Energy from Waste (EFW)

While people often hear about how much trash U.S. consumers generate, Canada actually has the highest per capita rate of waste generation among 17 developed countries. And, it relies heavily on landfilling. Nationwide, 74 percent of its waste is disposed of in landfills and only two percent is processed in Energy from Waste (EFW) facilities. Like its neighbor to the south, the Canadian view on managing solid waste is changing.

Ontario has had reduce, recycle and reuse policies in place for many years. In 1994, it introduced the 3R regulations requiring municipalities with more than 5,000 residents to provide recycling services as part of their curbside trash collection. The Waste Diversion Act of 2002 added even more requirements.

Still, more than 70 percent of the non-hazardous solid waste left after reusing and recycling in Ontario is sent to landfills with approximately 45 percent of it shipped to Michigan landfills. However, that practice ended pursuant to agreements made in 2006 between Ontario municipalities, U.S. Federal representatives and Michigan state representatives.

In view of these changes, Ontario municipalities have taken various approaches to meeting this challenge. For instance, Toronto purchased a remote landfill. But, the Regions of Durham and York decided to seek a local solution by focusing on converting waste-to-energy instead of developing a new landfill. After years of careful planning, in 2008 the latter two Regions issued Request for Proposals to five qualified vendors to design, build and operate an EWF facility. The Durham/York facility will create energy in the form of steam, electricity and heat with an approved capacity of 140,000 tons per year.

The facility, the first new EWF facility to be constructed in North America in more than 15 years, broke ground on August 17, 2011.

Out-of-the-Box Options

© HDR|Tessman Road solar panels.© HDR

Tessman Road solar panels.

Affixing solar panels to a landfill cover instead of covering it with dirt and grass can convert something that takes up space and requires costly maintenance into something that produces energy and creates revenue. The Tessman Road Landfill near San Antonio, Texas, was the first to use this innovative approach, which emerged not from years of study but from a client and consultant simply tossing out ideas.

Other landfills around the world have since followed suit, including the Hickory Ridge Landfill near Atlanta, Ga. Seven thousand solar panels cover approximately 10 acres of the landfill’s 35 acres, thus converting sunlight into more than 1 megawatt of electricity.

In contrast with a traditional Subtitle-D prescribed closure system, the exposed geomembrane cover is anchored directly to the landfill, instead of being draped over it, and held in place with layers of soil that eventually shift and erode. A system of horizontal and vertical anchors strengthens the overall liner system by limiting stresses the system encounters. This design provides a stable landfill cover system, which protects the landfill during storms and wind events.

And, in the “solar is so yesterday” category, how about using onion waste to produce energy? That’s exactly what Gills Onions did when it created its Advanced Energy Recovery System. Gills Onions is the largest fresh-cut onion processor in the United States, and they faced a growing problem disposing of waste from their onion processing plant.

The innovative treatment facility includes a system to grind and dewater more than 200,000 pounds per day of onion peels, thus reducing waste by 75 percent. It produces 30,000 gallons per day of onion juice and 20 tons per day of onion cake.

The cake is hauled to the Central Valley as cattle feed, and the juice is digested in a high-rate anaerobic reactor to create methane-rich biogas, which is treated to remove moisture and sulfur compounds and then fed into two 300 kW fuel cells. Fuel cells were selected because of their lower atmospheric emissions and reduced carbon footprint. The 0.6 MW of electricity generated supplies more than 80 percent of the Gills Onions processing facility base load.

The $9.5 million system is expected to pay for itself in less than six years.

Next Generation Conversion

If waste-to-energy is an old technology made new again, organic waste conversion is something new. Wastewater treatment challenges dealing with biosolids and solid waste challenges dealing with organics pose unique opportunities for different reasons. Biosolids face increasingly stringent land application requirements or increased land disposal costs while organics diversion face problematic feedstock with odor challenges and increasingly stringent air emissions regulations. The organic component of the solid waste stream and wastewater biosolids enjoy many similar characteristics that enable them to be processed together for both environmental protection and as a renewable source of energy.

These two materials can be used in a biological process that produces a renewable power and a marketable compost by-product while reducing greenhouse gases and reducing liabilities. This process uses biomodules, sealed geomembrane vessels that use anaerobic digestion and accelerated aerobic composting to process organics that have been separated from the solid waste stream. The process converts organic solid waste (and can include wastewater biosolids) into a useable natural gas using a relatively low technology/low cost process. This waste-to-energy process requires only a fraction of the capital costs of the traditional waste conversion systems generally available to communities. Think of it as composting on steroids.

By some estimates, 70 percent of what goes into a landfill is organic. One of the biggest benefits of using biomodules is that they allow significant volumes of organics to be processed at relatively low costs. Another big benefit is they allow the airspace to be reused. When a traditional landfill cell is full, it’s full. In contrast, biomodules allow the space to be used over and over again. The biomodule cells can also be mined for metals, other non-biodegradable materials and reusable compost materials, and improve leachate and gas collection – two big issues for landfills.

Pilot projects are taking place in Calgary, Alberta, and Leon County, Fla.

 

© iStockphoto.com/tolgakolcak|A typical landfill. © iStockphoto.com/tolgakolcak

A typical landfill.

Best Practices

Technology isn’t the only area that’s undergoing a sea change. Issues that arise when implementing zero waste policies and practices include the procurement and negotiation process, contracts and agreements, compensation and rates. Agencies and private contractors need to develop successful public-private partnerships, and some national efforts to provide best practices are under way.

The wonderfully named Zero Waste Brain Trust is an informal coalition of resource management professionals and others founded in 2010 to collect “game changing concepts” and identify key strategies and incentives that will benefit stakeholders working toward zero waste.

EPA Region 9 is doing something similar with its Zero Waste Franchise Project, initiated to obtain input from national experts on franchise and contract provisions, ordinances, procurement practices, rate structures and zero waste systems that achieve high levels of waste diversion. Its ultimate purpose is to create an online guide to help local governments develop service provider agreements supporting zero waste goals and policies. They are collecting innovative strategies, practices and contract language that motivate both service providers and generators to reduce consumption and increase reuse, remanufacturing, recycling and composting.

Some of the best practices they have collected include the following procurement best practices:

  • Consider collaborative negotiation,
  • Consider local government ownership of facilities,
  • Have separate collection and disposal contracts,
  • Provide the contract evaluation criteria weighting in the RFP,
  • Provide time and information to stimulate competition and
  • Evaluate the approach and qualifications prior to price.

 

Best practices for contracts include:

  • Separate compensation from rates,
  • Align the cost of service to rates, and pay for the value received,
  • Use a transparent process for adjusting rates and compensation,
  • Provide bonuses and penalties,
  • Provide independent contractors for technical assistance,
  • Require environmentally preferable, local purchasing and
  • Retain the ability to direct materials.

 

The Zero Waste Brain Trust has developed several case studies, including the partnership between the city of Berkeley, Calif., and Urban Ore. The Berkeley transfer station is publicly owned and operated. Berkeley contracts with Urban Ore to scavenge reusable materials from the public drop-off area.

Berkeley pays Urban Ore $40 per ton for every ton of reusable material removed from the transfer station. Berkeley saves $20 per ton for every ton of reusable material diverted by Urban Ore and earns $86 per ton based on the gate rate. Urban Ore diverts 7,000 tons per year – the same amount as Berkeley’s curbside recycling program.

Communication and transparency are key to the success of these types of partnerships. Goals and compensation need to be aligned among the public agency, service provider and generators. Best practice tools such as those being developed by the Zero Waste Brain Trust and the Zero Waste Franchise Project can contribute to their success.

One last consideration is the opportunity for local communities to partner with military installations on the U.S. Army’s Net Zero solid waste initiative. Solid waste systems are often capital-intensive and require large amounts of solid waste to realistically support building the infrastructure. While many military installations have large populations, they typically do not have as many people as neighboring cities or counties. By working together, municipalities and military installations can develop synergy and build bigger systems than either entity could on its own.

The Redstone Arsenal near Huntsville, Ala., can serve as an example of how this kind of partnership could work. This Army base uses steam heat produced by a waste-to-energy plant that is owned by the city of Huntsville Solid Waste Disposal Authority.

Bottom-Line Benefits

According to the EPA, the 85 million tons of MSW Americans recycled and composted in 2010 provided an “annual benefit of more than 186 million metric tons of carbon dioxide equivalent emissions reduced, comparable to the annual greenhouse gases (GHG) from more than 36 million passenger vehicles. [In addition,] recycling and composting nearly 85 million tons of MSW saved more than 1.3 quadrillion Btu of energy, the equivalent of more than 229 barrels of oil. . . . Every ton of mixed paper recycled can save the energy equivalent of 165 gallons of gasoline. . . . Recycling just one ton of aluminum cans conserves more than 207 million Btu, the equivalent of 36 barrels of oil or 1,665 gallons of gasoline.”

© iStockphoto.com/onurdongel© iStockphoto.com/onurdongel

 

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