Collecting, Treating & Redistributing Leachate
Water is our most precious natural resource – we can’t survive without it. It is extremely important that we safeguard our water supply from harmful contaminants to ensure long-term sustainability. Leachate is one of the more common contaminants capable of seeping into our water supply. Fortunately, steps can be taken to minimize the negative impact of leachate.
What is Leachate?
Leachate is the liquid that drains to the bottom of a landfill. On its journey to the bottom, it passes through the various waste deposited in the landfill, steeping a concoction of hazardous materials that resemble a “toxic tea”.
The liquid that produces leachate typically comes from a combination of rainfall, snowmelt, and the waste itself. The composition of leachate varies depending on the age of the landfill and the type of waste it contains. Leachate usually consists of both dissolved and suspended materials.
4 Significant Contaminants Found in Leachate
Dissolved Organic Matter
- Alcohols, acids, aldehydes, short-chain sugars, etc
. Brokendown organic compounds (carbon-based) that come from plants and animals.
Inorganic Macro Components
- Sulfate, chloride, iron, aluminum, zinc, and ammonia
- Common anons and cations such as iron, chloride, sulfate, aluminium, zinc, and ammonia.
- Lead, Nickel, Copper, and Mercury
- Lead, Nickel, Copper, and Mercury that come from construction, mining, and manufacturing.
Xenobiotic Organic Compounds
- Halogenated organics (polychlorinated biphenyl, dioxins, etc.)
- Organic compounds that come from drugs, food additives, and pesticides.
How Does Leachate Contaminate the Water Supply?
Leachate is a major problem for municipal solid waste landfills. If not handled properly, it can be discharged into surface water and groundwater supplies. To prevent leachate from contaminating water supplies, an effective collection system must be in place.
Keys To An Effective Leachate Collection System
Leachate collection systems are comprised of pumps, manholes, discharge lines, and liquid level monitors. But the efficiency of the collection system is dictated by liners, filters, pumps, and sumps.
- Isolate and contain the leachate, protecting the soil and groundwater below
- Filters out solids and harmful contaminants before passing through the pipe network
Pumps & Sumps
- Collects leachate in a well and pumps it to be treated
How is Leachate Treated?
Off-site leachate treatment
This is the traditional method in which leachate is hauled or pumped to an off-site wastewater treatment facility for disposal. This method isn’t popular with treatment plant owners, as it puts an added strain on the facility’s operations.
On-site leachate treatment
This method is more common. On-site treatment facilities are designed to fulfill the unique characteristics of a particular landfill site. It allows for discharge to a sanitary sewer or a body of water, reducing added costs from hauling or disposal.
Leachate Treatment Technologies
The first step in treating landfill leachate involves using various filters to remove nitrogen and other harmful biological compounds.
A wet oxidation process is used when organic compounds can be oxidized. This process uses activated carbon adsorption, precipitation, flocculation, and ion exchange processes.
Leachate poses environmental risks due to high concentrations of harmful contaminants and ammonia. However, these risks can be drastically reduced with properly designed and engineered landfill sites.
We must keep our most precious resource safe and sustainable. Leachate needs to be properly collected and treated before being redistributed back into the ecosystem.