Conventional landfilling of municipal solid waste (MSW) appears to be a widely accepted waste management method still in use today in many parts of the world. The state of the art waste disposal technologies did not take root in low income countries because of the related high costs. Consequently, considerable part of disposed of waste ends up in poorly controled landfills and dumps, posing potential threats to the adjacent aquifers. However, it has been known for decades that old, unlined, loosely compacted, small MSW landfills which were active in developed countries during the 70's and 80's generaly stabilised quickly after closure and posed little if any threat to the environment afterwards, which is not the case with highly engineered, dry entombment landfills. In this context, applied research has been carried out at one pilot-scale waste disposal site in the Vipava valley, Slovenia, during the period between 2002 and 2020 in order to explore the supposed environmental and economic benefits of landfilling MSW in above-ground, low-density deposits. A new type of low-cost, semiaerobic landfill was developed, called ''high- permeability landraise'' (HPL). As is the case with somewhat similar Fukuoka type of landfill, passive aeration is designed to be the main driving process to accelerate waste stabilisation. Since no reliable methods for measuring air fluxes into the landfill existed, alternative calculations were performed instead considering all the relevant mechanisms involved. Monitoring results from the pilot landfill were compared to monitoring results derived from landfills of different types. It was confirmed that concentration of pollutants within the primary leachate and methane to CO2 generation ratios within the landfill gas characteristic for HPL were much smaller when compared to those characteristic for modern, dry-type landfills of the same age. Also, waste stabilisation half-life appeared to be much shorter. In this way, pollutant concentrations at the bottom of the landfill can be reduced to unharmful levels decades before the pollutants manage to penetrate the designed clayey liner and break through. The ability to promptly stabilise closed landfill cells can have profound positive effects not only on the long-term management of environmental risks, but also on long-term developmental opportunities of the site. Quantitative comparative analysis performing long-term risk assessments demonstrated HPL performs on a par with modern bioreactor landfills in terms of environmental safety despite the low cost of such kind of facility.
|
