Jamie Thomson and Chris Lemme of Silver City Recycles monitor composted sludge from the wastewater treatment plant in a demonstration project funded by the Town of Silver City to show that processed human waste can be successfully diverted from the landfill, and instead composted for large-scale agricultural, parks and other uses.Silver City -- Where some see waste, others see opportunity. Jamie Thomson and Chris Lemme of the non-profit Silver City Recycles have partnered with the Town of Silver City in a fairly simple yet profoundly promising demonstration project to transform solids from the wastewater treatment plant - a hazardous waste - into compost.
On behalf of Silver City Recycles, Lemme and Thomson presented a detailed proposal to Town Manager Alex Brown, who agreed to give the non-profit $15,000 to fund the demonstration project. Human waste, even after processing, is classified by the Environmental Protection Agency (EPA) as a bio hazard, and is currently disposed of in the local landfill, a difficult and potentially dangerous process for landfill workers, and a costly one for the town. Disposal of this waste costs the town nearly $57,000 annually, and volatile, airborne compounds are a potential health hazard to landfill workers, who "absolutely hate dealing with this stuff," said Lemme.
"We're really grateful to town management for partnering with us on this project," he added. "In just one week we've already succeeded in establishing that this is a viable project that can be scaled to provide compost for agricultural use, town parks and many other uses."
Currently, this hazardous sludge is transported by truck to the landfill, which is a potentially risky process for the town, which would be liable for clean-up if an accident ever occurred and waste was spilled. Once processed through the wastewater treatment plant, the remaining sludge is dumped into large, cement drying beds at the wastewater treatment plant where it is then loaded into dump trucks for transport to the landfill. Some 125 tons or 18 dump truck loads of this hazardous waste are taken to the landfill each month.
In their pilot project, Lemme and Thomson mixed the waste with bio char, a charcoal which Thomson creates from tree trimmings, slash and other biomass, which sequesters carbon when added to soil and isn't released back into the atmosphere. They also added pecan shells, which they were able to obtain for free from orchards in Las Cruces, placed the mix on top of a large waterproof tarp to ensure that nothing could leach into the ground, and tested the temperature daily. The compost pile must reach and maintain an internal temperature of at least 130 degrees Fahrenheit to ensure that harmful bacteria, especially E coli, are destroyed.
For more than a week, temperatures reached the mid-140s and stayed there consistently. The next step is to send a sample to a state-certified lab for testing, to ensure that all bacteria has been destroyed, and the material can be safely used as compost.
Jamie Thomson and Chris Lemme of Silver City Recycles monitor composted sludge from the wastewater treatment plant "We've successfully demonstrated that this is a viable project, and a win-win for the town," said Thomson, adding that the next steps will be to scale the project to divert all of the waste from the landfill, and create massive compost piles, preferably at the wastewater treatment plant to minimize transportation and other logistical and capital costs. "I'm confident that working with town staff we can find a way to do the composting right here at the treatment plant, which is the easiest and least costly solution."
In the meantime, both Lemme and Thomson continue to monitor the demonstration project compost, and work with town management and wastewater treatment staff to determine next steps.
"This is a terrific, environmentally sound project," added Town Councilor Stan Snider, a project champion and a former supervisor at the wastewater treatment plant. "I would really like to see Silver City start composting all its sludge. I'm really grateful to Chris and Jamie for demonstrating that we can make this work, and to Utilities Director Robert Esqueda and Manny Orosco, treatment plant supervisor, and his staff for their support and cooperation."
For more information about the demonstration project, please contact Chris Lemme at
