Leachate Treatment
Regulators often suggest that leachate should be pumped to a sewer for treatment at a urban wastewater treatment plant (WWTP). However, this may historically have been driven by concerns that leachate treatment on site is challenging and difficult to achieve reliably, than by a detailed appraisal of the best options available. This however is changing and increasing pressure and emphasis is being placed on local treatment solutions.
It is not generally a good policy to treat strong leachate from modern sanitary landfills after discharging it into sewer, mixing it with sewage. Leachate has an extremely high ammoniacal nitrogen ("ammonia”) concentration when compared with the much weaker contamination levels in domestic, commercial, and industrial foul sewage. Treating strong leachate at a UWWTP, as if it were sewage, is inefficient and unnecessarily costly. Unless the UWWTP has a highly nitrifying type process, one of the most potentially damaging types of contaminants in leachate may simply be diluted by the weaker strengths of those contaminants in the sewage, and not treated.
Ways of treating leachate on site reliably, without dilution, are available. Proven processes exist for biological and chemical treatment of the leachate in specially designed plants tailored specifically to the special needs for producing a very high quality effluent, which will then be capable of discharge either to a sewer with greatly reduced volumetric charges, or directly to a watercourse.
Such treatment solutions normally include nitrification, and may also include denitrification, depending on local regulatory requirements, and environmental needs. These on site leachate treatment solutions are, when done in the correct way, not only more environmentally sustainable than off-site treatment, but usually incur lower cost, and most importantly are not nearly as subject to future unknowns, such as:
- rising volumetric charges / levies
- possible withdrawal of sewage discharge consents
The final reason for this is that leachate which is removed from a landfill which is producing landfill gas (40% - 60% methane), will contain some of this explosive, high risk gas, in solution. That means that, at least in theory, leachate could be a danger to the sewer when the methane it contains is released into the airspace of the sewer, as this release could occur when it flows in the sewer.
Why not contact us today to learn more about on site treatment solutions