The pressure to maintain our groundwater fresh and safe to use becomes more challenging as populations grow yet there is still no focus on the proper urbanization of water systems and landfill sites. How are these linked? Through a highly toxic problem called Leachate.
What is Leachate then, and why should we be aware of it?
Leachate is a liquid that drains or “leaches” to the bottom of a landfill. It forms from the natural rotting and decomposition of organic matter within the landfill, and it is mostly composed of dissolved salts combined with organic compounds and high levels of ammonia and metal ions. Seemingly, just like all other garbage, it is not, since the heavy metal ions mixed in with organic compounds create a terrible filtering challenge for landfill sites, creating hazards such as environmental damage and contamination of our water systems.
Why is Leachate a problem if it’s naturally occurring?
The average active landfill site will produce around 100-250 m3 of leachate per day, according to the Water & Wastewater Treatment paper, established by engineers working on these sites.
This absurd volume is a problem especially since the landfills will not know how to size the plant to estimate the potential amounts accurately. It is particularly true in cases of landfill sites becoming overfilled and holding more waste than they are expected to.
There also comes a secondary problem which is that once the actual leachate begins draining, it must be taken out, filtered and disposed of properly. When trying to treat the drainage, modern landfills incorporate an adapted style of treatment involving biological and membrane treatment. However, this is not ideal since it is a costly process to invest in the appropriate equipment required for the procedure. Moreover, the dense mixture of solvents creates a challenge for current filtering systems as the water treatments are not prepared to deal with a combination of unknown compounds but rather specific ones, therefore allowing for smaller compounds to seep through the membranes.
Then, the ‘filtered’ leachate must be heated to high temperatures to incinerate the toxic organic compounds within. That adds to the costs, on top of the expensive filtering equipment and solutions. Lastly, the treated solution must be disposed of correctly, away from any potential sites of contamination. Additionally, incurring high transportation costs.
These techniques are just not an answer when it comes to less developed countries with fewer resources.
Why is no one addressing this issue, then?
Today, there are agencies, such as the Environment Agency, working on the problem and financing projects on filtering technology such as the LAT (Low-temperature Ambient pressure Technologies). The LAT process significantly reduces the costs of the process since it requires no pre-treatment and no chemical post-treatment, implementing a remineralization and UV disinfection system to achieve the correct balance of minerals for safe storage and disposal.
Meanwhile, more cost-effective methods are being put into place by government agencies, who are making a more considerable effort to monitor the way things operating at landfills. The technique is called UASB (Upflow Anaerobic Sludge Blanket). It is a method of wastewater treatment that essentially creates a sludge blanket which will sink to the bottom of the tank while filtering the wastewater which flows upwards in a series of biological processes.
So, is the future an optimistic one?
It is crucial to be hyper-aware of how we dispose of the waste we create because it will all come back in a cycle, if not sooner then later. Leachate is a severe problem to be considered, but with government agencies working on practical and accessible solutions while raising awareness amongst each other, there is an optimistic future to the treatment of wastewater from landfills and the future of landfills, in general.