A sustainable landfill would be a landfill designed to be cleaned of all harmful substances that could cause a harmful emission within a generation. That way, each generation would take care of its own waste and pass on a clean environment to each successive generation.
A sustainable landfill would be a wonderful achievement, and paradoxically, without even trying, our ancestors managed it once, before the advent of the industrial revolution. Unfortunately, life is not that simple for our generation and it will be much harder for future generations unless we can find a way to achieve sustainability in much of what we do today, which is far from it.
The first step in designing a sustainable landfill would be to speed up the time needed for total decomposition and then continue to flush the landfill with clean, fresh water. What do we mean by redness in this context? We are referring to putting enough water into the landfill to remove all of the water-soluble components of a landfill, including all of the soluble organic content, so that we no longer need to keep it sealed from the environment to protect the surrounding environment.
The first step in flushing would be to pump a lot of water through the landfill and recirculate it to ensure rapid decomposition. Then all that water that is recirculated will eventually have to be treated as leachate.
Leachate treatment can be done on-site or off-site, but in both cases the residual components must be discharged off-site. If this is not done and the treated leachate continues to be recirculated, components of the leachate, such as chlorides, will remain at high concentrations and sustainability goals will not be achieved. Compounds such as chlorides (as in common table salt) can be contaminants if suddenly released into the environment in concentrations significantly higher than the normal background concentration, and thus the landfill would continue to pose a threat to the environment. environment.
A strategy consisting solely of recirculation of leachate is therefore not sustainable. Many landfill operators use reverse osmosis to treat leachate, however that is short-sighted and goes completely against any sustainable landfill philosophy, returning as these sites often do, all residual components and disposing of only pure water . (By the way, the resulting elevated ammonia nitrogen is also expected to have a very negative impact on landfill gas production.)
The volume of leachate and certainly the concentration of contaminants in that leachate will vary as the site ages. Of the components of the leachate that will require treatment, the ammoniacal nitrogen content is often the most expensive to treat. As the waste is discharged into the landfill, the concentrations of components such as ammoniacal nitrogen will decrease.
Ammoniacal nitrogen concentrations may initially exceed 2,500 mg/l and should be reduced to less than 10 mg/l. As nitrogen is leached from the site, supplying a constant daily load of ammoniacal nitrogen to a treatment plant would require the daily treated volume to increase as the leachate becomes more dilute.
Degradable materials, ammoniacal nitrogen and degradable organic compounds measured as BOD, can be successfully reduced in an SBR (sequential batch reactor) biological leachate treatment plant to an acceptable level for recirculation or discharge to the environment. Poorly degradable organic compounds and inorganic salts will be residual components that can be problematic for discharge in some circumstances.
If the discharge is to a relatively small surface watercourse, the size of the treatment plant may be limited by the amounts of chloride and non-degradable chemical oxygen demand (COD) that can be discharged. Any limits on the discharge of non-degradable components may have obvious implications for the size of the landfill that can be sustainably operated in a given location.
If the leachate discharge is to the sewer, then the chlorides will pass through the sewer works without treatment other than dilution. Poorly degradable organic compounds will also pass through sewage treatment plants, apart from a small degree of treatment and possibly some adsorption in the sludge. Receptacle works’ own discharge limits may restrict the volume or load of leachate that can be accepted into the sewer and thus restrict flushing opportunities.
Treating the large quantities of leachate required, either in a purpose-built plant or in a sewage treatment plant, will obviously involve higher rates of expenditure than are normally allocated for this at many landfills today. However, current practices lead to the same pollution load being produced, treated and discharged, implying similar total costs, but simply on longer time scales. Therefore, the difference is primarily a function of how accounting practices treat short-term and long-term expenses.
It is ethically and morally wrong for our generation to subject future generations to ever-increasing emissions from landfills that harm groundwater quality once landfill containment systems fail, and eventually will fail, before they have been cleaned up. . That is unavoidable.
Therefore, all governments should try not only to reduce waste going to landfills and clean up their landfills, but also to biologically treat their leachate and start doing so as soon as the first waste is placed in a new landfill. Full sustainability will not be achieved with current standard landfill practices, but at least the discharge process will have started.
