Leachate spill in Aravalis: activists write to Haryana rights body

Subject : Environment

Section: Pollution

Context:

A group of environmental activists has written to the Haryana Human Rights Commission (HHRC) drawing its attention to the alarming levels of toxic pollutants caused by leachate spilling over to the Aravalis from the Bandhwari landfill site in Gurugram.

Details:

A Haryana State Pollution Control Board laboratory report has been quoted which pointed to the high presence of toxic substances, such as fluoride and chloride, in the Aravalis due to the leachate spill.
While chloride is harmful for human consumption, the high level of fluoride could damage the bones of humans and animals.
The leachate collecting in the mining pit was close to the underground aquifers and led to the contamination of groundwater.

Leachate:

Leachate is a widely used term in the environmental sciences where it has the specific meaning of a liquid that has dissolved or entrained environmentally harmful substances that may then enter the environment. It is most commonly used in the context of landfilling of putrescible or industrial waste.
In the narrow environmental context, leachate is therefore any liquid material that drains from land or stockpiled material and contains significantly elevated concentrations of undesirable material derived from the material that it has passed through.

Properties of leachate:

In older landfills and those with no membrane between the waste and the underlying geology, leachate is free to leave the waste and flow directly into the groundwater.
In such cases, high concentrations of leachate are often found in nearby springs and flushes.
As leachate first emerges it can be black in colour, anoxic, and possibly effervescent, with dissolved and entrained gases.
As it becomes oxygenated it tends to turn brown or yellow because of the presence of iron salts in solution and in suspension.
It also quickly develops a bacterial flora often comprising substantial growths of Sphaerotilus natans.

Leachate treatment process

Treatment Type	Target of Removal	Remark
Treatment Type	Target of Removal	Remark
1. Leachate Transfer
Co-Treatment	Suspended solid	Excess biomass and nutrients
Recycling	Improve leachate quality	Least expensive and low efficiency
2. Biological Processes
Aerobic Processes	Suspended solid	Hamper by refractory compound and excess biomass
Anaerobic Processes	Suspended solid	Hamper by refractory compound, long time and biogas
3. Physicochemical Processes
Coagulation / Flocculation	Heavy metals, suspended solids	High sludge production and subsequent disposal
Chemical Precipitation	Heavy metals, NH3-N	Requires further disposal due to sludge generation
Adsorption	Organic compounds	Carbon fouling can be a problem and granulated activated carbon adsorption is costly
Oxidation	Organic compounds	Residual O3
Stripping	NH3-N	Requires other equipment for air pollution control
Ion Exchange	Dissolved compounds, cations/anions	Used as a polishing step after biological treatment and treatment cost is high
4. Membrane Filtration
Microfiltration	Suspended solids	Used after metal precipitation
Ultrafiltration	High molecular weight compounds	Costly and limited applicability due to membrane fouling
Nanofiltration	Sulfate salts, hardness ions	Costly and requires lower pressure than reverse osmosis
Reverse Osmosis	Organic and inorganic compounds	Costly and extensive pre-treatment is required prior to RO3.

About Aravallis:

The Aravalli Range (also spelled Aravali) is a mountain range in Northwestern India.
It runs approximately 670 km (430 mi) in a southwest direction, starting near Delhi, passing through southern Haryana and Rajasthan, and ending in Gujarat.
The highest peak is Guru Shikhar at 1,722 metres (5,650 ft). Guru Shikhar is a peak in the Arbuda Mountains of Rajasthan. It is 15 km from Mount Abu.
Three major rivers and their tributaries flow from the Aravalli, namely Banas and Sahibi Rivers which are tributaries of Yamuna, as well as the Luni River which flows into the Rann of Kutch.
The Aravalli Range is arguably the oldest geological feature on Earth, having its origin in the Proterozoic era.
The Aravalli Range is rich in natural resources and serves as a check to the growth of the western desert.