May 2008

LA County investigates advanced solid waste conversion technology

At the facility in Carthage, Missouri, the thermal depolymerization system developed by Changing World Technologies transforms ordinary poultry guts into diesel fuel.

Los Angeles County (LAC) has a solid waste problem. The county generates 80,000 tons of solid waste daily, and even though 50 percent of the material is diverted through reduction, recycling and other programs, much of the remainder (residual waste) is sent to landfills, which results in transport costs and tipping fees.

“We end up with a tremendous volume of residual,” says Michael Theroux, president of Sacramento-based Theroux Environmental. “It makes so little sense for us to throw our resources into a hole when we can actually better our recovery and do so economically and super cleanly.”

With the Puente Hills Landfill, the main landfill in Los Angeles County, closing in 2013, a solution has to be found to manage the waste.

Realizing the problem must be dealt with and in a way that supports the existing recycling infrastructure, LAC is bringing forward select conversion technology demonstration projects, in a program that is being developed by the County’s Alternative Technology Advisory Subcommittee (ATAS), which falls within the jurisdiction of the Integrated Waste Management Task Force and consists of technical experts who have been working in the field of solid waste and recycling for many years. In recent years, the ATAS has evaluated hundreds of technologies, and is now moving to promote the development of conversion technologies in all of Southern California.

Created in 2004, ATAS’s first task was to assess technologies that could maximize conversion of residual solid waste to divert this material from landfill disposal, while recovering benefits from this material, such as the generation of electricity, the production of liquid fuel and gases, and various chemical compounds that can be used by industry.

The ATAS investigated over 400 technologies being developed in the United States and abroad, and produced an exhaustive study in its Phase 1 report (2005).

“We wanted to make sure that these technologies were capable of managing solid waste,” says Coby Skye, an associate civil engineer with the County Department of Public Works, who is the lead staff for the ATAS. “We identified those technologies that were most promising, had reached at least a pilot scale for processing solid waste, and were interested in developing in Southern California.”

The soil amendment product produced via the ArrowBio anaerobic digestion process is currently being used in farms in Israel near ArrowBio's operational facility.

The Phase 2 report (October, 2007) identified four technologies that were recommended for demonstration projects (Phase 3) that will potentially be built at up to four local material recovery facilities. The report evaluated the technical, economic and environmental feasibility of these technologies, which are the key elements required for the creation of an eventual infrastructure for managing solid waste in a whole new way.

“The four recommended technologies are able to handle whatever comes to them on an ongoing basis,” says Theroux. “Post-recycling residual materials have highly variable constituents in the feedstock. The four technologies all clean­­ly convert the residual to energy but each do so differently with both strengths and weaknesses.”

The four technologies are: International Environmental Solutions (IES), which has developed a single-chamber endothermic pyrolysis unit that has been tested for conversion of post-MRF residual at their Romoland facility in Riverside County, California (8 to 125 tons per day processing capacity modules); Ntech Environmental of Australia, which has a more complicated thermal system (pyrolysis to gasification) and can also handle between 10 and 100 tons per day, per module; Interstate Waste Technology’s licensed Thermo-Select process, a Swiss design for a pyrolysis to gasification system that is larger and can handle up to 1,000 tons per day (currently operating in Japan); and Arrow Ecology, an Israeli firm that uses water to create a biomass-laden “soup” via mechanical separators to remove the solid objects in the residual. The soup is then put through anaerobic digestion to create methane.

The MRFs that may potentially partner with these technologies are a facility in Ventura County (negotiations still ongoing), Robert A. Nelson in Riverside County, CR&R, also in Riverside County, and Rainbow Disposal MRF of Huntington Beach, in Orange County. The technology suppliers and MRF operators will come together and determine who will be partnered with whom. The actual development of the demonstration projects (Phase 3) is expected to begin this fall.

Coby Skye

Once the demonstration projects are completed, the County hopes to replicate the success of these systems where conversion technologies can handle as much residual solid waste as possible.

“Ideally we want to manage all of the waste locally and we are doing that with a combination of several things,” says Skye. “Currently, about 5 percent is going to 2 waste-to-energy facilities in Los Angeles County, about 20 percent is exported to out-of-county landfills and the rest goes to landfills within the county. Because many of our landfills are facing closure very quickly, we want to accelerate these new technologies.

“The purpose of the demonstration projects is to send a signal to the marketplace that we want to see more of these technologies developed on a commercial scale,” says Skye. “The clock is ticking and it is imperative for us to spur the market and bridge the gap between pilot-scale facilities and facilities operating overseas, and the commercial-scale technologies that we hope to see developed in California.”

“We want to do a three-fold approach to maximize in-county capacity for solid waste management; First, we need to maintain and expand an efficient in-county solid waste management infrastructure network that brings together transfer stations, MRFs and landfills, in order to make sure we can protect public health and safety. Our second priority is reducing the amount of waste that is left over for disposal. Right now we have met our 50 percent state mandate and we want to keep increasing that recycling rate.

Third, we want to maximize the development of conversion technologies to manage the residual solid waste that remains after reducing, reusing and recycling, especially the fraction of the waste stream currently being shipped to remote out-of-county landfill sites.”

The pilot projects are expected to handle about 300-500 tons per day.

“It’s still a minor amount, but we are starting,” says Theroux. “Our demonstration projects will focus on the residual waste left after recycling, but convert almost all of that to energy. The IES process, for example, only ends up with 2 or 3 percent left at the back end of it – a non-hazardous char.”

While LAC is encouraging the development of these technologies, it is counting on the private sector to join the effort.

“We have to let business take care of itself,” says Theroux. “There were no conversion facilities in use in the United States when we started, so this is groundbreaking. California is in the lead on this. There is nothing simple about it and the county is deeply dedicated to doing this in spite of all the challenges.”

Theroux is confident that private sector investment will occur.

“The attention from the financial community on ‘going green’ these days has just been a J-curve,” he says. “I’m seeing major sources of funding moving in. Municipalities will find ways to support this, but our premise is that these technologies must be economically feasible.”

Knowing that the demonstration projects will require clean material for processing, Theroux has noted that additional pre-processing at the co-located MRFs will increase the number of cans, bottles, glass and cardboard that are removed from the waste stream beyond what currently is removed.

The process for the county’s conversion technology program is public and on-line, complete with data, templates, technological assessments, financial implications, potential sites and how to integrate conversion with the existing recycling industry.