- India’s dairy business produces over 2.5 occasions extra wastewater than the milk it processes, posing a significant however underreported environmental danger.
- Pure coagulants supply an natural various to traditional chemical therapies of wastewater.
- Specialists stress the necessity for sustainable, reusable, and eco-friendly strategies to handle dairy wastewater amid rising water shortage.
India has been the world chief in milk manufacturing since 1998, at the moment accounting for almost 25% of world output. In 2024 alone, the nation produced over 239 million tonnes of milk. Whereas the dairy sector performs a significant function in India’s economic system and rural livelihoods, a lesser-known and underreported consequence is the huge quantity of wastewater it generates, a big however neglected environmental problem.
Research present the amount of wastewater produced by the sector is about 2.5 occasions better than the quantity of milk processed. A big quantity of wastewater can also be produced whereas processing uncooked milk into client objects equivalent to yoghurt, butter, and cheese. Though conventional wastewater therapies, which contain using chemical substances, have been used for many years, their value and environmental affect have been a trigger for concern.
A brand new examine revealed in Environmental Monitoring and Evaluation proposes pure coagulants as an eco-friendly various. “There’s an rising demand for water the world over, so it’s essential to search out methods to wash wastewater in a means that helps ecosystem well being and reduces air pollution,” says Lipsa Mishra, lead creator of the examine and assistant professor, MIT World Peace College.
Enter pure coagulants
Of their examine, Mishra and her staff used Carica papaya seeds, Citrus limetta peels (candy lemon), and Moringa oleifera (drumstick) in powder kind as pure coagulants. Papaya seeds can connect to particles in water and sink to the underside. Citrus limetta peels can get well vital vitamins for recycling or reuse, whereas additionally bettering water high quality, the examine explains.
Importantly, Moringa oleifera’s antibacterial properties assist inhibit bacterial development in water, bettering water high quality and decreasing the danger of waterborne illnesses. Pure coagulants additionally contribute to sustaining pH stability of water and reducing biochemical oxygen demand (BOD), chemical oxygen demand (COD), and turbidity ranges, Mishra and colleagues be aware within the examine. As an illustration, Moringa oleifera prevents oxygen loss from microbial breakdown and helps decrease biochemical oxygen demand or BOD, which is important to take care of wholesome aquatic habitats.
Biochemical oxygen demand (BOD) and chemical oxygen demand (COD) are important parameters for assessing natural air pollution in wastewater. BOD measures the oxygen required by microorganisms to decompose biodegradable matter, whereas COD quantifies the whole oxygen wanted to chemically oxidise each biodegradable and non-biodegradable compounds, the examine explains. Excessive ranges of COD and BOD can suffocate aquatic life, as microorganisms quickly eat oxygen whereas breaking down natural compounds, resulting in oxygen depletion.
“After we get rid of dairy wastewater into water our bodies with out remedy, it causes eutrophication, and marine life and aquatic vegetation can’t maintain themselves in such an atmosphere as a result of lack of dissolved oxygen,” says Pragyan Das, assistant professor, Odisha College of Expertise and Analysis. Das can also be the creator of a 2022 examine Dairy wastewater and its potential for waste administration.
Wastewater disposed in water our bodies with out remedy may result in dangerous algal blooms that additional deplete oxygen ranges and inhibit aquatic plant development. Furthermore, poisonous compounds like detergents and sanitisers in untreated dairy wastewater pose threats to aquatic ecosystems, the examine elaborates.
Among the many varied dairy merchandise, a 2016 examine discovered that candy whey was essentially the most polluting dairy effluent. Its biochemical composition is wealthy in natural matter (lactose, protein, phosphorus, nitrates, and nitrogen) and is 60 to 80 occasions extra polluting than home sewage.
Though the improper remedy of dairy wastewater is linked to excessive environmental dangers, it typically doesn’t obtain the identical consideration as different industries. “Industries equivalent to textiles, prescription drugs, coal mining, metal vegetation, and others launch extra seen hazardous pollution or heavy metals. In consequence, there are sometimes extra discussions about these in comparison with dairy wastewater,” notes Mishra.
The examine confirmed that Citrus limetta peels achieved a 93.8% elimination effectivity for BOD, whereas Carica papaya seeds and Moringa oleifera exhibited vital effectivity in turbidity and whole dissolved solids (TDS) elimination, reaching values of 94% and 68%, respectively. “Comparatively, alum was in a position to take away over 99% of turbidity however with excessive chemical sludge. Nonetheless, papaya seeds, lemon peels, and drumstick powder confirmed over 93% effectivity with biodegradable sludge. Lemon peels carried out the perfect in BOD elimination with virtually 94%,” Mishra elaborates.
Moreover, plant-based coagulants not solely supply cost-effectiveness but additionally current fewer environmental dangers.
Great amount of waste water
Water is utilized in all processes within the dairy business, together with heating, cooling, and washing. Mishra estimates that round 3,000 litres of wastewater are generated per 1,000 litres of milk processed.
From excessive quantities of natural supplies equivalent to dissolved solids, suspended solids, oil and grease, to detergents and varied chemical substances equivalent to benzene, mercury, zinc, ammonia, and chromium used throughout industrial cleansing, an array of effluents might be present in dairy wastewater. These may cause hurt to marine life if not handled correctly.
“The presence of excessive natural matter results in excessive ranges of BOD and COD, which may deplete oxygen in receiving water our bodies if untreated wastewater is launched. It creates hypoxic situations that threaten aquatic life and disrupt nutrient biking,” says Mishra.
Improper disposal of wastewater on land can result in contamination of groundwater and deterioration of floor water high quality. And if this wastewater is launched into water our bodies, they may turn into breeding grounds for flies and mosquitoes carrying malaria and different illnesses equivalent to dengue fever, yellow fever, and chikungunya.
Dairy wastewater, specifically, might be handled with bodily, chemical and organic strategies. One other generally used technique is constructed wetlands. The big floor space of constructed wetlands facilitates an atmosphere for eradicating pollution equivalent to natural matter, suspended solids, and vitamins. They’re cost-effective and sustainable.
Probably the most extensively used chemical strategies is coagulation. Coagulants equivalent to alum (aluminum sulphate) and ferrous sulphate are conventionally used to deal with dairy wastewater. Nonetheless, the sludge they produce accommodates chemical substances that may hurt water our bodies and ecosystems. To deal with this subject, current analysis has been centered on discovering various coagulants which can be pure, protected for people, biodegradable, and produce minimal sludge.
Therapy of dairy wastewater
A 2024 report by the Centre for Science and Surroundings reveals that lower than one-third of India’s city wastewater and sewage is handled. This implies the remaining flows into rivers, lakes, and land.
Mishra explains that in conventional strategies of water or wastewater remedy, there are three phases: preliminary or main, secondary, and tertiary therapies. In preliminary remedy, solely heavy particles or floating supplies are eliminated. In main remedy, conventionally used coagulants equivalent to alum and ferrous sulphate, that are simply out there out there, are added.
“These coagulants kind sludge that settles on the backside of the tank, which must be handled once more earlier than being launched. Some dairy vegetation simply take away the sludge and get rid of it on the bottom, which contaminates the soil and causes air pollution,” says Mishra.
Das additional provides that chemical coagulants produce giant quantities of sludge which may’t be reused. “The sludge solely accommodates fatty acids, oil, and grease which shouldn’t be getting into the atmosphere. It must be handled once more, however typically that doesn’t occur,” she says.
Nonetheless, as chemical coagulants are nonetheless extensively used, the shift in the direction of pure coagulants is an extended journey. “Alum and ferric chloride are already out there out there on a big scale. To encourage using pure coagulants, there must be extra consciousness, and we require better market availability of those supplies,” Mishra says. She additionally emphasises that pure coagulants require intensive testing earlier than widespread adoption.
The main focus whereas exploring dairy wastewater remedy choices must be on reuse, Das emphasises. “We dwell within the age of water shortage. Dairy wastewater remedy shouldn’t simply use eco-friendly strategies but additionally concentrate on tips on how to make the water reusable. As an illustration, my examine on vermifiltration, wherein earthworms are launched right into a filter mattress to interrupt down natural pollution, confirmed this could possibly be an efficient various. After vermifiltration, the wastewater might be reused for functions equivalent to irrigation,” Das explains.
Nonetheless, each Mishra and Das be aware a scarcity of analysis on dairy wastewater and sustainable remedy choices. “Extra research on how dairy wastewater impacts the atmosphere and the other ways of treating it, notably extra eco-friendly strategies, could possibly be useful for each people and the atmosphere,” says Mishra.
Learn extra: Researchers suggest algae-based resolution for wastewater remedy
Banner picture: Employees unload milk cans at a dairy plant in Dimapur, Nagaland. Picture by ILRI/Stevie Mann by way of Flickr (CC BY-NC-NC 2.0).
