The Three Rivers Regional Landfill maximizes value by evaporating leachate with Heartland’s Hybrid CoVAP™ Solution, which combines the exhaust from an onsite waste-to-energy plant with the thermal energy from a landfill gas flare.
By John Weigold
The Three Rivers Regional Landfill in Pontotoc, MS, with 207 acres permitted, receives an average of 900 tons of waste per day. Three Rivers, like many landfills, had a long-standing relationship with its local Publicly Owned Treatment Works (POTW), which had been accepting 12,000 to 24,000 GPD of its landfill leachate for many years.
Unfortunately, transport and disposal (T&D) costs were consistently rising and Three Rivers was paying more than $0.09/gallon for offsite leachate disposal. Adding to Three Rivers concerns was talk that the local POTW may discontinue accepting leachate and the T&D cost for the next closest disposal outlet would be more than $0.20/gallon.
In 2016, faced with rising costs and the threat of a steep change that could double or triple its costs without warning, operators of Three Rivers desired a simple onsite solution for managing their landfill leachate. Key for Three Rivers was controlling leachate management without having to rely on offsite trucking and disposal, reducing its leachate costs and creating long-term cost certainty.
Action
Taking proactive steps to ‘control its own destiny’, Three Rivers conducted a comprehensive RFP looking at onsite leachate management options. Three Rivers was clear on its requirements:
1. Find a trusted vendor with a proven solution onsite leachate treatment
2. Select a partner to completely design and install the solution
3. Find a solution that would not rob LFG from its existing waste-to-energy facility
4. The solution needed to be simple to operate.
5. Abide by its Title V Air permit requirements
6. Meet an expectation of a 20-year product life
After extensive analysis, Three Rivers selected the lowest total lifecycle cost option that met its requirements, which was Heartland Technology’s Concentrator in a 25,000 gpd Hybrid CoVAP™ configuration (see Figure 1).
Overhead view of the 25,000 gpd Hybrid CoVAP™ Leachate Evaporation Facility.
Hybrid CoVAP™ Configuration and Cogeneration
CoVAP™ stands for Cogeneration for Industrial Evaporation. The Heartland Concentrator was designed and patented for using waste heat from engines or turbines beneficially to evaporate wastewater. This is a classic cogeneration solution. A Hybrid CoVAP™ configuration combines cogeneration with additional heat from a landfill gas flare. This configuration is particularly valuable when you want to use the thermal energy from cogeneration beneficially, but there is insufficient heat to evaporate all of your leachate.
The Hybrid CoVAP™ solution provided clear economic benefit to Three Rivers by allowing Three Rivers to run at full capacity while using less LFG. This capability maximizes the value of landfill gas by always running the energy plant and never having to compromise between generating renewable energy and evaporating leachate.
The flare design provides sufficient thermal energy to run the evaporation plant at capacity, if required, without the need for the exhaust from the energy plant should the energy plant be down for any reason. A simple and easy-to-configure control system automatically balances thermal demand between the flare and the engine waste heat.
The Heartland Concentrator is designed to evaporate 25,000 gallons per day. Thermal energy from the exhaust of the onsite 2G supplied 999kW Caterpillar-MWM Landfill Gas engine is sufficient to evaporate 5,000 gallons of leachate per day. The balance of the required heat for evaporation is provided by the landfill gas flare (see Figure 2).
Figure 3, shows the integration between flare and onsite engine. This simple integration drafts the waste heat from the engine exhaust stack. Consequently, there is no backpressure whatsoever placed on the engine making this a safe, and fail-safe, integration.
Heartland Concentrator shown prior to building construction. 1) Heat source, 2) Evaporation zone, 3) Feed recirculation, 4) Droplet separator, 5) Sump blowdown, 6) Exhaust.
Hybrid configuration showing (1) integration to engine exhaust and (2) landfill gas flare.
Performance Optimization
Heartland’s proven LM-HT™ Concentrator met Three Rivers’ goals and more. Three Rivers uncovered unique value and flexibility by using Heartland’s proprietary Hybrid CoVAP™ solution. Hybrid CoVAP™ is a configuration where exhaust heat from Three Rivers existing waste-to-energy facility (e.g. Cogeneration) is combined with thermal energy from a landfill gas (LFG) flare (e.g. Hybrid) to evaporate leachate. The Hybrid CoVAPT™ solution allows Three Rivers to maximize the value of its landfill gas and realize the lowest lifecycle cost for its leachate management.
As very experienced operators, the Three Rivers team, in a joint development effort with Heartland Technology, collaborated on many aspects of performance optimization including additional automation to improve productivity and enhanced clean-in-place to extend routine maintenance cycle times. The teams continue to collaborate long past commissioning and strive to uncover new understanding and methods in the never-ending journey of continuous improvement.
“All around the country we are seeing Wastewater Treatment Plants limiting treatment or refusing to accept landfill leachate,” said Heartland CEO, Earl Jones. “Heartland is committed to providing technology to efficiently and cost-effectively treat their leachate onsite enabling our customer to control their own destiny. Our project with Three Rivers is an example of this approach. The Team from Three Rivers is smart, they know their business, they understand the challenges in treating leachate, and together we achieved our economic and operational goals. We are excited to be their solution provider and to be working with such a great team.”
As of September 2020, Three Rivers had treated an average of over 23K gallons per day of landfill leachate achieving volume reduction of more than 96 percent and over 90 percent uptime. Prior to installing the concentrator, Three Rivers was spending a minimum of $0.095 per gallon in transportation and disposal costs and faced the possibility of costs increasing to levels above $0.20 per gallon. With Heartland’s concentrator, Three Rivers estimates total cost, including operating costs and capital recovery, to be $0.06 per gallon. Importantly, the system is in place for the long-term, providing cost-certainty for Three Rivers and giving the landfill the full control of their leachate treatment.
Says Jon McDonald, Operation Manager for the Three River Landfill, “Controlling our own destiny, both in terms of our technology roadmap and our long-term operating costs, is an important goal for Three Rivers. The Hybrid CoVAP™ configuration of the Heartland Concentration has enabled us to do just that.” | WA
John Weigold is SVP Business Development for Heartland Water Technology. John can be reached at [email protected].