Landfills in Dhaka have now become a major polluter as they contaminate surface and ground waters with toxic liquid matter, reveals a study on contamination of surface and ground waters at landfill sites.
Heavy metals were also found in samples of the crops cultivated near those landfills, according to the study published in 'Applied Water Science' recently.
The study, for the first time, calculated the leachate pollution index (LPI) for landfill sites.
Leachate is a term for the liquid pollution generated from a landfill's waste pile. Such liquid contains harmful chemicals that can cause cancer and other serious health issues.
The study reviewed the status of leachate pollution potential of four major landfill sites namely Amin Bazar, Matuail, Mogla Bazar, and Rowfabad.
Dr Fahmida Parvin and Prof Dr Shafi M Tareq conducted the study.
Dr Shafi M Tareq, who teaches environmental sciences at Jahangirnagar University, told the FE that source segregation waste, especially hazardous waste can improve the situation.
"Dhaka's landfills are not engineered or sanitary landfills. These can hardly be called dumping grounds. An engineered landfill must have several protection layers so that toxic liquid cannot be absorbed by dumping grounds or leached to groundwater."
"We can separate household waste in source segregation like composting for organic waste; recycling for electronic, paper and plastic waste; and solidification or stabilisation for hazardous waste," he added.
The study suggested that landfills should be constructed with synthetic membranes and other possible engineering materials to prevent heavy metals and other toxic materials from escaping into soil and groundwater.
Faulty and non-engineered landfills have also been contaminating food grains and intake of contaminated food items could develop cancer in human body.
The human health risk index for toxic heavy metals in different vegetables and rice grains in those landfill areas showed high health risk for lead, cadmium, nickel and manganese.
Prof Tareq said, "Household waste also pollutes the landfill soil and surrounding agricultural land. We have found the presence of heavy metals in agricultural products."
Amin Bazar landfill has also displaced thousands of people destroying their livelihood and biodiversity, said environmental experts.
Shahriar Hossain, secretary general of Environment and Social Development Organization (ESDO) said, "A variety of fishes was found in Amin Bazar wetland in 1990s. Some 20 million people who depended on wetlands for their livelihood lost their habitat soon after it turned into a landfill."
Waste management is yet to see any major change, he said, adding that Amin Bazar landfill is now the only source of methane gas in Bangladesh because of its faulty management.
He also suggested a zero-waste management system. "Of the total household waste, 60-65 per cent is organic waste which is biodegradable."
Absence of a central or properly-designed waste management system in Bangladesh worsened the situation further destroying biodiversity, both experts said.
The waste-to-energy project has been approached by the government as an alternative but if 'we fail to manage massive activities, then it would be reversed for us. We don't have skilled manpower or engineering experience to operate such costly and technology-based project, they fear.
DNCC CEO Md Selim Reza said they do not deal with household waste. "We mainly dump collected waste into landfills from Secondary Transfer Station (STS)."
Source segregation is usually done in secondary station or STS process, he said, adding that existing landfills in the city are causing environmental pollution. "We are in the process of acquiring land to set up some modern landfills in the city."
He added: "We also think of revising waste collection and source segregation. We are working on a policy to introduce engineered landfill."
"Waste generation is rising with time. Necessary work for acquisition of 40 acres of additional land along Amin Bazar landfill has almost been completed."
About the waste-to-power project, he said, "We will analyse the cost of investment. If we can launch the waste-to-energy project, it will bring a major change in the city's waste management."
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