Chromium Remediation Project
Kanpur
Kanpur is the ninth-largest city in India, and one of its most severely polluted. Its eastern districts feature about 350 industrial leather tanneries, many of which discharge untreated waste into local ground water sources and the Ganges River. These pollutants include toxic levels of heavy metal contaminants such as chromium, mercury, and arsenic. Chromium is popular in the tanning industry because it makes leather goods stronger. The hexavalent chromium in tanning waste is known to cause cancer, liver failure, kidney damage, and premature dementia.
Noraiakheda is a settlement of 30,000 people within Kanpur that has developed on top of a plume of chromium VI, which is emitted in toxic sludge from an old chemical plant that had supported the region’s tanneries. The sludge is a source of pollution and a danger to human health. Flammable methane trapped inside the sludge catches fire during the hot summer months, thus releasing harmful toxins into the air. Summer heat and winds also distribute dust particles from the sludge, which contain chromium and other toxins that are harmful when inhaled. The chromium from the sludge leaks into the river, subsoil, and ground water, the primary sources of drinking water for the surrounding community. A 1997 study conducted by the Central Pollution Control Board on the ground water quality in Kanpur revealed chromium VI concentrations of 6.2 mg/L; the Indian government places the maximum allowable level for public consumption at 0.05 mg/L.
Project Strategies
Highly toxic chromium VI can be converted to a less harmful chromium III by introducing an electrondonating chemical that will cause a reduction reaction. In addition to being safer for human exposure, the newly created chromium III also binds more easily with subsurface sediments to keep it out of the water supply. Though proven in laboratories and at other work sites, this technique had never been used in India. Blacksmith Institute initiated a two-pronged approach aimed at both chemically neutralizing the chromium and warning locals of the hazards. For the awareness-raising campaign, Blacksmith supported Ecofriends, a local environmental NGO in Kanpur. For chemical remediation of the chromium, Blacksmith worked with Ecocycle/GZA (engineering consultants who could supply some of the needed materials) and the Central Pollution Control Board in order to undertake the first such project in India. Other collaborators included the Industrial Toxicology Research Center, Indian Institute of Technology- Kanpur, and National Geophysical Research Institute.
As part of the remediation, Blacksmith and its partners dug four new wells in a portion of the contaminated ground water system. One of the wells was an injection well used to introduce the electron donor chemical, and the other three were water quality monitoring stations that would test for 16 health criteria, including heavy metal concentrations. Once baseline samples had been taken, the chemical was added through the injection well and then the monitoring sites were subsequently sampled multiple times.
Outcomes and Follow-Up
The intervention from Blacksmith and Ecofriends succeeded in installing two new submersible water pumps that would supply the Noraiakheda area with safe, potable drinking water. The chemical remediation was also successful, with levels of chromium VI dropping at all the test sites, sometimes to undetectable levels.
Blacksmith has now proven that its techniques for chemically treating toxic chromium will work in Indian sites. The next step will be to expand implementation throughout broader areas as needed. GZA has prepared an action plan for largerscale remediation throughout Kanpur, which is expected to cost $2-4 million.
