by Hilary Haskell
India currently lacks an institutionalized municipal solid waste system and open landfill dumping proceeds without regulation, although an existing legal framework could be used to address this societal and environmental issue. A number of causes, both civilian and political, are at fault. Reliance on unregulated landfill dumping will likely continue, as this solid waste management practice tends to be the most cost-effective. However, landfills in India do not reflect the typical sanitary landfill seen in much of the developed world, lacking linings or covers that prevent groundwater pollution. Leachate liquid seepage generated by landfills due to rainwater or other infiltration— pollutes groundwater. The extent of pollution depends on the permeability of landfills, distance to water table, and toxicity of the leachate. Bhalla et al. (2014) used data from the Ludhiana City, Punjab, municipal landfill site in India and the Leachate Pollution Index to determine the effectiveness of leachate treatment within Indian Government Municipal Solid Waste Management and Handling Rules using permeable reactive barriers.
Leachate, which results from either percolated rainwater or landfill waste’s contact with groundwater sources, contains inorganic and organic compounds, toxic chemicals, heavy metals, and xenobiotic substances. This leachate poses a major threat to soil and water resources. Regulatory agencies around the globe have prioritized leachate collection and treatment in landfill engineering or improvements, but the costs of retrofitting or implementing leachate collection and treatment systems are high. Bhalla et al. recognized the need for prioritizing implementation of these systems at the most potentially contaminating sites.
Bhalla et al. used a leachate pollution index (LPI)), which assesses the potential threats a landfill’s leachate might pose to surrounding groundwater and soil. The LPI can rank landfill sites, determine resource allocation for landfill remediation, analyze trends, advise the public, and recommend regulations. With a single number grade ranging from 5 to 100, the LPI represents the level of leachate contamination potential at a landfill, with higher numbers indicating a greater contamination threat. The LPI also provides a means to analyze trends from landfill monitoring during operation and post-closure, as well as a comparative tool for developing leachate treatment facilities at landfills within the same area.
Leachate treatment facilitation requires permeable reactive barriers (multibarriers), which stop the flow of contaminants and subsequently remediate them. The two main processes that occur through these multibarriers are immobilization of contaminants and transformation. Immobilization occurs through precipitation of contaminants out of the leachate, into the barrier. With transformation, the leachate contaminants become transformed into less harmful or toxic forms. Multibarriers utilize either reactive materials such as or zerovalent iron or indirect material application like peat moss, which serve to enhance microbial activity so that treatment may occur physically, chemically, or biologically.
In determining LPI, Bhalla et al. focused on five significant leachate pollutant variables, pH, TDS (Total Dissolved Solids), BOD5 (Biological Oxygen Demand), COD (Chemical Oxygen Demand), and Chloride in assessing treatment efficiency of leachate collected from the Ludhiana City, Punjab (India) Jamalpur landfill site. The amount of dissolved oxygen required by organisms in a certain body of water over a period of time at a specific temperature can be described as biological oxygen demand. Similarly, chemical oxygen demand quantifies the amount of organic compounds present in a body of water.
Given these leachate parameters, the authors could assess proxies for indicators such as toxicity and overall amount of pollution in the leachate. The landfill site studied does not have a leachate collection or treatment system, base liner, or landfill cover, meaning that all leachate from the landfill eventually reaches the surrounding environment. Furthermore, the landfill does not have a waste compaction process to help eliminate odors, vermin, litter, or surface water infiltration. By assessing leachate through the LPI both before and after implementation of the permeable reactive barrier, the authors could determine whether the barrier could serve as a low-cost method for treating leachate effectively.
The landfill site spans 25 acres with an average depth of 810 ft. In January 2012,The authors collected samples from a number of sites at the landfill at the bottom of solid waste heaps to ensure a comprehensive assessment of landfill leachate. Using standard methods for examination of water and wastewater from the American Public Health Association, the authors tested the landfill leachate. Although the LPI contains eighteen leachate parameters, this study utilized five available parameters: pH, TDS, BOD5, COD, and Chloride. Each pollutant has a weighted value based on the significance level of the pollutant, thus indicating the relative importance of the variable to overall leachate pollution potential. The authors then established a connection between leachate pollution and concentration of the parameter using sub-index curves. To calculate the LPI, the relative weights and the sub-index value of each pollutant variable were summed.
Bhalla et al. concluded that the LPI of the Jamalpur landfill site before treatment was 26.45, while the standards for inland surface water per Municipal Solid Waste Management and Handling Rules in India should not exceed a LPI of 7.378. However, after utilizing the permeable reactive barrier, the LPI was reduced to 7.03. These findings suggest that the multibarrier could serve as an attractive leachate pollution remediation system in India and other developing countries.
Barjinder Bhalla, M.S. Saini, M.K. Jha. 2014. Assessment of Municipal Solid Waste Landfill Leachate Treatment Efficiency by Leachate Pollution Index. International Journal of Innovative Research in Science, Engineering and Technology 3, 8447—8454.