Landfills are a common source of contaminated runoff that needs special handling. Since many landfills contain rotting food and similar waste products from homes and businesses, leachate from a landfill commonly contains high levels of bacteria in addition to chemical contaminants. Both operational and closed landfills can produce large amounts of leachates each year, but open and operating waste systems tend to generate more runoff than properly capped, closed systems. Stormwater contributes to the total amount of leachate, but much of it is generated from within the mounds of decomposing waste. Evaporation in a tightly sealed, shallow pond is usually the best way to safely handle this material.
No Other Uses
Unlike many other leachates and liquid by-products from industrial and mining operations, landfill leachate has little value or alternative use after being collected. It’s a mix of organic matter broken into tiny particles, inorganic macro components, various heavy metals, and other organic compounds. The small amounts of useful minerals and metals found in the liquid is rarely worth the effort of separation. High levels of salt and ammonia also make this liquid irritating and hazardous to the health of landfill workers. Bulk pond evaporation allows for easier handling without the extra work of refining and reusing certain materials. Any solids left can either be refined, if it’s worth the effort, or buried in a hazardous waste containment area so it can’t escape into the local environment.
Alone or as Part of a System
Evaporation ponds are generally part of a larger wastewater treatment system when used for industrial leachate handling. This is also true for landfill liquid management. However, some landfills only need an evaporation pond as their main method of treatment. This is more likely to work for older capped landfills that are discharging a relatively stable mix of leachates. For operating and newer closed landfills, a more complete treatment system may involve:
- Reverse osmosis to remove both organic and inorganic compounds
- Filtration of varying methods to accumulate particles and dissolved solids
- Water softening to deal with high salinity, mineral content, or pH balance issues
- Evaporation at the end to reduce the amount of water being release as much as possible.
Leachate testing is the best way to determine if you can rely on a simple evaporation pond system or need a more complex form of filtration and processing.
Costs of Management Methods
Evaporation typically offers the most affordable option for dealing with unwanted landfill leachates. Other options for wastewater management are based around releasing most, or all, of the liquid into a river, ocean, or local sewage system. Only 6% of landfill facilities surveyed by the Environmental Research & Education Foundation in 2018 were using zero discharge evaporation methods. The majority of landfills are still either discharging leachates directly to local sewers or trucking it to more distant treatment facilities. Waste Management, a US company that operates nearly 300 active landfills across the country, spent an extra $97,000,000 on leachate costs in 2016 alone. Evaporation ponds may require an upfront investment, but when built with a durable multi-layer, RPE liner, they can last for decades to offer constant, low-cost options for leachate processing.
Varying Regulations
Changing regulations designed to protect the waterways and soil around the landfill may improve the environment, but they also make it hard on landfill operators to manage their leachate releases. As more and more publicly owned treatment works (POTW) are restricting or banning the release of landfill runoff, it’s becoming challenging to find viable options for managing thousands of gallons of liquids per day. Evaporation ponds remain relatively easy to construct even as regulations grow stricter with each passing year. When designed with the right materials from BTL Liners, it’s easier than you think to build an evaporation pond that will meet future regulation changes as well. If you need to upgrade your ponds in the future, lining it with a durable geomembrane will assist in the renovation process to reduce costs.
Constant Supply
Unlike other wastewater sources, that release leachates on a regular schedule in expected amounts, landfills tend to release somewhat random amounts of liquid on a daily basis. Even with careful planning based on average rainfall amounts and storm warnings, it’s all too easy to get overwhelmed with a sudden increase in leachates. Evaporation ponds are the most adaptable system for managing changing levels of liquids from day to day. Simply build ponds with enough total volume to handle the highest possible levels of release, then let unneeded ponds stand empty when release levels drop. Since the empty ponds are always standing by and ready for use with proper maintenance, there’s no need to panic or spend millions of dollars on unexpected leachate processing.
Evaporation vs Recirculation
When aiming for a zero-discharge system to control leachate release costs, you’ve got to choose primarily between evaporation and recirculation ponds. Both systems involve collecting and holding the leachate water in a pond so it can’t leach into the soil or water. However, evaporation ponds are designed to reduce water as much as possible so there’s only a small amount of waste to dispose of in the end. Recirculation ponds aim to reuse the water by pumping it back into the capped landfill mass. By running water full of organic waste back through the mass of covered trash, extra methane is generated for power generation. This keeps the water in use for a few months at most because the landfill is constantly producing more water and absorbing storm water. Eventually all recirculation ponds must be drained and hauled away for disposal. Evaporation ponds only produce a fraction of the total water by the end of the process, dramatically reducing disposal costs over even recirculation systems.
No matter the size or type of landfill leachate pond you need to build, BTL Liners is here to help. Our ArmorPro liner, in particular, is tough enough to contain any kind of leachate for evaporation.
