Indian mines could be paying a terrible cost for their success and growth!
Mining is a sector that is closely connected to India’s economic growth as well as infrastructure development. As the nation’s infrastructure and exports grow, the mining industry is witnessing considerable growth. For instance, iron ore exports from India were worth US$ 2.23 billion in 2021, growing by 21% compared to the previous year.
However, mining remains one of the largest consumers of water in the industry. In developed countries such as the US, a mine could easily use around 1,140 million gallons of water per day!
The cost of this water use by mines could however be very high.
India is currently facing an ever-growing water shortage. According to government data, the per capita availability of water in India is falling rapidly, down from 5000 Cu.m in 1950 to around 1500 Cu.m in 2020. If it declines further to around 1,000-1,100 Cu.m, then India could be declared a water-stressed country.
The tricky situation between mining and water
It is not just the heavy use of water, but also the way mines procure water that creates a problem. Most mining operations directly draw the groundwater or procure it from rivers, streams, and lakes. However, many times, mines use water in arid or semi-arid areas where water is scarce. In such conditions, environmental regulations are forcing mines to become more sustainable by reducing and optimizing their water use.
In the case of many mining sites, water needs to be pumped away from the mining site. This could also reduce the levels of groundwater, deplete surface water or cause pollution to local rivers.
Characteristics of mining wastewater
Mines use water for a number of processes including mineral processing, dust suppression, slurry transport, and employees’ needs. Streams coming from draining mining areas are often very acidic and contain high concentrations of dissolved metals with little aquatic life. Both localized and dispersed metal pollution cause environmental damage because metals are non-biodegradable.
Unlike some organic pesticides, metals cannot be broken down into less harmful components in the environment. Electron transfer reactions that are connected with oxygen can lead to the production of toxic oxyradicals, a toxicity mechanism now known to be of considerable importance in both animals and plants. Some oxyradicals, such as superoxide anion (O2-) and hydroxyl radical (OH-), can cause serious cellular damage.
6 parameters in mining wastewater are regularly monitored
- pH
- Total suspended solids
- Total dissolved solids
- Biological Oxygen Demand
- Chemical Oxygen Demand
- Oil and grease.
Treatment of wastewater in mining
Traditionally, wastewater from mining has been treated using a range of various methods. First, the pH level of the mining wastewater is adjusted so that the metals will form insoluble precipitates. Various flocculants and coagulants are added to mining water to bind the particles into larger clumps, which then settle down in sedimentation tanks. After this, the process water will head for advanced filtration.
ZLD system
Mines are mostly situated in areas that already face water scarcity. Hence, they need extremely efficient water recovery measures. ZLD systems are best suited for this purpose. While other systems focus on removing contaminants from wastewater, ZLD recovers up to 95%of water from the contaminants, reducing them into a solid cake for disposal. ZLD faces the toughest filtration process of all wastewater treatment processes because the challenge in recovery rises with the increasing concentration of water.
Due to the compulsive demand for high efficiency, zero liquid discharge system costs might entail a high initial investment. However, it significantly lowers the volume of waste, and thus drastically cuts the waste management costs over a period of time.
Explore the working of ZLD plants in detail
RO systems
ZLD plants for wastewater treatment in mining must often work in combination with reverse osmosis systems. After passing through the ZLD system, the water is often passed through RO systems to further improve its quality.
The RO system filters out the chlorine and sediment from process water using a prefilter. Next, it passes the water forcefully through semipermeable membranes to remove dissolved solids. The RO system is often made up of a mix of filters to filter specific materials. A typical RO system could comprise of
- Sediment filters that remove dust, dirt, and rust
- Carbon filters that remove volatile organic compounds and odor
- Semi-permeable membranes that remove up to 98% of dissolved solids
The RO system is capable of removing metallic contaminants and salts, but cannot filter out bacteria. Additionally, bacteria can grow on the membranes and can enter the water that exits through the RO system. Hence, the water that exits the RO system is often put through UV disinfection to obtain near drinking-quality water.
Conclusion
The treatment of wastewater arising from mines is vital from the viewpoint of environmental compliance. Mining water must be carefully treated to has to prevent the pollution of water and soil due to acid or alkaline leaching of heavy metals. Wastewater treatment plants in mining must deliver high efficiency and consistent performance amidst harsh working. Working closely with an expert in wastewater treatment could ensure that a mine has a rightly customized, reliable, and durable water treatment solution in place
Inovar works closely with clients to study their wastewater treatment needs and arrive at a solution. From feasibility studies to design, manufacturing, and installation, Inovar provides the complete set of water management services under one roof. For additional cost-saving, all Inovar products are backed by annual maintenance contracts, making everything from installation, operation and maintenance of the wastewater treatment plant easy and cost-effective.
For more information, write to us at sales@inovar.in or talk to us on +91-7028039207/