Entsorga West Virginia LLC converts municipal solid waste and commercial and industrial (C&I) non-hazardous byproduct materials into alternative, clean energy. The company has been meeting the growing demand for solid recovered fuels by Argos USA’s Martinsburg plant in West Virginia, leading to environmental benefits and reduced operating costs. By Emily Dyson, BioHiTech Global, USA.
Entsorga West Virginia, LLC (EWV), owned by ReFuel America, a consolidated subsidiary of BioHiTech Global, is the first facility of its kind in the United States. Using the patented High-Efficiency Biological Treatment (HEBioTTM) technology designed and proven by Entsorga Italia S.p.A., the facility converts Municipal Solid Waste (MSW) and Commercial and Industrial (C&I) non-hazardous byproduct materials into a Solid Recovered Fuel (SRF). The U.S. Environmental Protection Agency has recognized the SRF as a valuable commodity and a non-hazardous secondary material. This designation allows the SRF to be used by industry, specifically the cement industry, as a fuel and not designated as waste.
The HEBioTTM technology utilizes mechanical and biological processes to convert MSW into SRF. The technology consists of three stages, The first stage of the process is reception and pretreatment. Following pretreatment is biooxidation, followed by refinement. At the reception stage, MSW is dumped into reception pits, where it becomes the feedstock (to put into manufacturing terms). Once the feedstock is in the reception pits, the biological process begins. The enhanced ventilation system begins providing air circulation to draw out the moisture and accelerate the composting process. The overhead crane moves the feedstock to the pretreatment area from the reception pits, separated by size. The more extensive materials are placed into an “Oversized Pit (greater than 7” [18 cm] large cardboard pieces, large plastics, fiber materials like sheets)” and the smaller materials (<7” [18 cm]) which include organics, smaller fiber materials, and inerts are placed in the “Undersized Pit.” The material in the Oversized Pit is taken by overhead crane directly to the primary shredder, where it is continuously blended with C&I feedstock.
The second stage of the process is biooxidation. The overhead crane moves feedstock from the Undersized Pit to the biooxidation hall. The hall can hold up to 4,500 tons of feedstock. The biooxidation hall includes a slotted concrete floor, and the Entsorga Italia patented ventilation system. The ventilation system is pulling or pushing fresh air into the feedstock piles, accelerating the composting process, and resulting in a dried, stabilized (no waste odor) feedstock, which is ready to be converted into SRF.
Feedstock from the biooxidation hall is moved with an overhead crane to the primary shredder and blended with additional conveyed C&I material. The blended materials proceed from the shredder into the refinement process, the last step in the process. In refinement, the feedstock goes through a trommel, which removes the glass, rocks, and dirt. This material has been U.S. certified laboratory characterized and meets the specification as fill/regulated fill in the United States. It can be used as landfill cover and fill material for some applications (e.g., road base, construction fill). The feedstock conveys through several magnets and an eddy current to remove ferrous and non-ferrous metals that can be recycled. A Near-Infrared Optical sorter removes the polyvinyl chloride (PVC) containing plastics. The removal of PVC ensures that the fuel has low chlorine levels, critical to the cement industry manufacturing process and emissions control. The final step of refinement is the sizing of the materials to 3” inch minus (7.6 cm minus) and the loading of the manufactured SRF into walking floor trailers.
Lessons Learned from Two Years of Operations
EWV began accepting MSW and C&I in March 2019 and manufactured its first fuel in May 2019. Since then, EWV has identified changes to its process based on waste composition, equipment modifications needed to maximize fuel quality, and changes in staffing/operating times to meet the demand for the manufactured SRF.
In Europe, HEBioT Technology is proven, and the SRF is used as an alternate fuel in the cement industry. The difference in waste between the US/West Virginia and Europe is significant. Europeans dispose of waste directly in tipping carts/rubbish cans. Americans dispose of garbage in bags before being placed in the carts or cans. EWV determined that additional equipment was needed in the pretreatment area to break open the considerable amount of bags associated with the inbound rubbish. Also, EWV found that the amount of metals found in the US waste stream was much higher than expected and has relocated and added magnets to the refinement process. EWV increased its operating hours to meet the growing demand for SRF from Argos USA, located in Martinsburg, WV. This extension of hours allows EWV to produce more significant volumes of SRF and conduct preventative maintenance during off-peak operating times. As new plants are designed and built in the US, Refuel America will be making changes to optimize the ability to create high-quality SRF. Additional design changes will include adding a conveying system to add C&I materials directly to the final product. The additional C&I materials will increase the BTU value of the fuel, while the conveyor will reduce the amount of time it takes to process the material.
Argos USA Feedback
Cement production is an energy-intensive process, where traditionally, approximately 30% of operating costs are related to fuels. By increasing the use of alternative fuels in the cement industry, their operating costs are significantly decreased. Juan Yanez, Production Manager for Argos – Martinsburg Plant, states, “Thanks to the strategic partnership between Entsorga WV and Argos, Argos achieved an average substitution rate of approximately 4.5% over the last six months (April 2020 – October 2020. COVID-19 halted Argos’ production for May). Argos’ process and operational results indicate that EWV’s SRF is an excellent material for use as an alternate fuel in the kiln since there has been no perceived impact on cement quality. The environmental benefits of using EWV’s SRF include reducing Argos’ greenhouse gas emissions from the plant, as shown by our data trends, which has also saved costs by sustainably lowering the consumption of additives like ammonia hydrated lime. Our 2021 goal is to achieve 12 to 15% substitution and be 20% by the end of 2022. Also, Argos disposes of plant waste at EWV, resulting in our domestic waste being converted into SRF.”
EWV understood the metals’ impacts in the fuel when it became apparent that the metals impacted the refractory in the calciner. EWV took steps to minimize the metals. Argos is also looking at different refractory types to increase the brick’s strength at the inlet to the calciner. Working together to identify these problems and develop solutions has led to a strong partnership and encourages additional HEBioTTM plants throughout the US.
Dina Didion, Environmental Manager for Argos – Martinsburg Plant, provided the documentation showing the correlation between the reduced calciner coal rate and the increased use of SRF. The graph shows the reduced NOx emissions and the reduced addition of ammonia (required to keep NOx emissions within regulatory limits). NOx emissions are an indirect greenhouse gas, and reducing those emissions increases the plant’s operating capacity while maintaining compliance with their Title V permit limits.
The Success of the EWV Plant
ReFuel America and Argos have seen the benefits of HEBioTTM technology and the development of SRF for the cement industry. EWV will continue to refine the process and identify optimization opportunities to increase SRF production and further improve the fuel’s high quality. ReFuel America is actively evaluating technological enhancements to create a more significant market for the SRF in industries outside of the cement industry. EWV and facilities like it are changing the way waste is thought of in the US – waste can be a valuable resource and doesn’t need to end up in landfills.