Coal mining has turned Meghalaya’s rivers acidic. Can humble algae revive them?

In February, the public water supply schemes in East Jaintia Hills, Meghalaya’s coal mining hub, were tested for acid content. The results were startling. Of the 37 schemes operating under the state’s public health engineering department, 26 were found to be too acidic for human consumption.

“This is water that people use for drinking,” said BP Katakey, the retired judge heading the National Green Tribunal-appointed panel, which recommended the test. “We told them to stop supplying immediately until the quality of the water improves.”

What mining ban?

The high levels of acidity in the water could be linked to coal mining in the state, which is done entirely using the rat-hole technique, where small, narrow tunnels are dug to allow miners to enter and extract coal.

In 2014, the National Green Tribunal had banned coal mining in Meghalaya. The ban was on the basis of a petition by a student outfit in neighbouring Assam, which claimed that acidic drainage from mining sites upstream in Meghalaya’s Jaintia Hills was poisoning their rivers.

The ban, however, has been ineffectual, by all local accounts. When 15 miners were trapped in a flooded illegal rat-hole mine at Kasan, in the East Jaintia Hills, in December, it confirmed what the residents of Meghalaya always knew – coal mining never quite stopped in the Jaintia Hills.

Now with the test results pointing towards an impending public health crisis, the green-court appointed panel is turning its attention towards reviving the rivers in the area, even as efforts to enforce a blanket ban on coal mining itself have been futile.

Algae to the rescue

As it turns out, Jaintia Hills’s saviour could be humble algae.

“We had written to a company based in Delhi asking for help,” explained Katakey. “They asked us to send water samples. After they treated them with algae, the pH levels of the water samples rose up to permissible limits.”

The pH value is a measure of acidic content in a substance – a higher value indicates low levels of acidity.

Scroll.in has reviewed the results of the lab tests the company submitted to the panel. According to the company’s report, it introduced a “customised consortium of micro-green algae” to three water samples collected from separate places in the Jaintia Hills. The pH value went up significantly in each case after the algae treatment.

The retired judge said the committee has sent some additional queries to the company. “We want to know whether they have undertaken any pilot project on the field for treatment of acidic water earlier and what were its results,” said Katakey. “Also, we want some more details about costs and impact on the environment.”

The company in question, Trinity Impex International, claimed it could replicate its success in Jaintia Hills’ acid mining drainage-affected rivers. Its past experiences, however, have been limited to treating smaller drains infected by industrial effluents.

Sukhdev Singh, the company’s chief executive officer, however, refused to divulge the species of algae with which his company used to treat the water samples.

Past efforts

Yet, this is not the first time that an algae-based cure for Jaintia Hills has been mooted. In 2011, two Shillong-based scientists reported the existence of Microspora quadrata, an alga that grew luxuriantly in the “streams affected by acid mine drainage caused by unscientific coal mining in Jaintia Hills”. The scientists contended that the alga could absorb heavy metals responsible for high acidity in river streams.

But the government at that time – when coal mining was still legal and a major source of revenue for the state government – paid little attention to the discovery. “Some people from the government came then once, but did not follow up,” said Papiya Ramanujan, one of the scientists. “We just did scientific work in the laboratory, but did not do any practical implementation.”

Ramanujan said that the alga used by Trinity Impex International appeared to be different from the one she and her colleague had discovered. “Though they have not revealed the name, it appears to be a micro algae-consortium,” she said. “The alga we found was filamentous.”

The scientist had a word of caution about introducing foreign micro algae to the acidic streams in Jaintia Hills. “It has to be able to survive and grow in very low pH conditions,” she said. “Very few organisms can survive like the alga we discovered, which grew luxuriantly there and fully covered the water.”

Besides, there was also the problem of disposing the biomass after it collected the heavy metals, she pointed out. “You have to burn it very carefully, so that again the heavy metal does not go back to soil,” she said.

Trinity Impex International’s Singh, however, insisted that his company had the technology to deal with these problems. “It is all about finding the correct type of algae,” he said.

For Jaintia Hills, there is very little choice but to bank on algae to bail them out. Currently, limestone slabs have been placed on riverbeds to neutralise acidity – an arrangement that Katakey said could not be a long-term fix. “This will lead to more limestone mining and affect the environment in other ways,” he said. “The algae-based solution looks encouraging on the basis of the initial lab results.”