PETALING JAYA: Leachate from solid waste landfills poses a serious risk to human health, experts say, especially when landfills are near raw water supply areas that serve as drinking water sources.
“The leachate can seep into groundwater and into nearby rivers, carrying pollutants such as ammonia,” said Universiti Teknologi Malaysia water expert Prof Dr Maketab Mohamed.
He said researchers had recorded high amounts of ammonia in leachate from dumpsites, ranging from 150mg to as high as 350mg per litre.
By comparison, the Health Ministry’s Drinking Water Surveillance Programme states that the recommended ammonia level in raw water should be 1.5mg/litre.
Prof Maketab explained that the Simpang Renggam landfill accepted waste not just from the local populace, but from other areas as far away as Batu Pahat, where the solid waste site was closed years ago.
The landfill had been identified last week as the source of pollution into Ulu Sungai Benut after a bund at the storage pond collapsed.
“The landfill is about 12km upstream from the river, and since it’s a pretty rural area, a small township with oil palm plantations, the source of ammonia pollution can only be the landfill,” he said.
According to Association of Water and Energy Research Malaysia president S. Piarapakaran, ammonia has featured increasingly as a leachate pollutant in recent years.
“As pollution increases, this is becoming more and more frequent, and luckily we test frequently for ammonia at water treatment plants.
“The problem is that once you catch ammonia in the water, the treatment plant needs to be shut down and the water cleaned, resulting in water disruptions,” said Piarapakaran.
In the case of Simpang Renggam, there were 23,000 water accounts in the area, which translated to nearly 150,000 people affected by the ammonia leachate.
Piarapakaran explained that even with sanitary landfills, where the sites are prepared by lining the ground with high-density polymer sheets to prevent leachate filtering through, the main issue was enforcement and regulation.
Another issue, he said, was “pollution loading” as more rural to urban migration took place, resulting in the amount of solid waste generated increasing exponentially: “More solid waste filling up the landfill means more leachate.”
Food waste comprises the largest segment of waste, resulting in millions spent to treat the landfills which emit greenhouse gases and toxic leachate as the food decays.
Piarapakaran also pointed out that e-waste management was lacking, leading to people just dumping old batteries, phones and computers along with other solid waste destined for landfills.
“From there, you have heavy metals such as cadmium and other toxic metals going into the groundwater too,” he said.
Prof Maketab added that conventional water treatment could not totally remove heavy metals from raw water sources.
Minister: Leachate contamination must be addressed