Landfill leachate results when water from precipitation and rotting waste percolate. They may become toxic when high concentrations of organic and inorganic pollutants mix with the liquids. As little as 36 inches of precipitation can result in one million gallons of heavily polluted water per acre of landfill. In fact, it has been estimated that a total of 30 million tons are produced each year and every single ton of landfill leachate has the equivalent amount of pollutants found in 100 tons of urban wastewater. In most countries, landfills are required to collect, store, and treat leachate.
Within that pollution, Contaminations of Emerging Concern (CECs) have been measured. Anesthetics, products of nicotine breakdown, muscle relaxants, components of plastic, and anticonvulsants are most commonly found in large quantities in leachate. Also found are ammonia, nitrogen, and heavy metals. Unfortunately, all landfills do not have the same resulting leachate; what is thrown into an individual landfill changes the composition. As treatment depends on what composes the leachate, it is not possible to have a single way of cleaning it.
Currently, there are a variety of methods that are used to treat landfill leachate. According to ScienceDirect.com, they include:
- Aerobic Biological Treatment such as aerated lagoons and activated sludge
- Anaerobic Biological Treatment such as anaerobic lagoons, reactors
- Physiochemical treatment such as air stripping, pH adjustment, chemical precipitation, oxidation, and reduction.
- Coagulation using lime, alum, ferric chloride, and land treatment.
- Advanced techniques such as carbon adsorption, ion exchange.”
Another system that has been used is a rotating biological contractor process. This involves using a large disk that has passages cut into it. The disk slowly rotates, and as it does, close to 40% of water that has been in contact with the media is in the wastewater. Exposure to oxygen allows a variety of pollutants to form a thin layer of biomass. These organisms cause degradation of organic pollutants which are then removed in a clarifier.
By Ellie Cabell