Yamuna's Froth: India's Pollution Crisis

The Yamuna River in Delhi, India, is known for its severe pollution, with toxic foam often forming on its surface. This froth is a result of high levels of untreated sewage, industrial waste, and chemical pollutants entering the river. The release of detergents and chemicals reduces the surface tension of the water, leading to the formation of froth. The river receives billions of litres of sewage daily, with a significant portion left untreated, contributing to the high pollution levels. The dry season further exacerbates the issue, as the decreased water flow rate creates stagnant conditions conducive to froth accumulation. The presence of filamentous bacteria and organic matter from decomposing vegetation also plays a role in stabilising the froth. The Yamuna's poor condition has sparked concerns about its impact on devotees who traditionally bathe in its waters.

Untreated sewage from Delhi, Haryana and Uttar Pradesh

The Yamuna River in Delhi, India, is a vital water source for the city's residents. However, it has been plagued by severe pollution, with the problem of frothing becoming increasingly prevalent during the post-monsoon months. One of the primary contributors to this issue is the discharge of untreated sewage from Delhi, Haryana, and Uttar Pradesh.

Delhi, the capital of India, faces a significant challenge with its water supply due to the presence of untreated sewage in the Yamuna River. The river receives an immense volume of sewage daily, with only a fraction of it being treated. According to reports, Delhi's treatment plants can handle up to 72% of the sewage generated per day, but even this treated sewage is not always reused efficiently, further exacerbating the problem. The Delhi Jal Board has accused the BJP-led Haryana government of deliberately dumping untreated sewage and industrial waste into the Yamuna, endangering the health of Delhi's residents. This allegation has sparked political debates and legal threats.

Haryana, a state neighboring Delhi, has been accused of contributing to the Yamuna River's pollution by releasing untreated sewage and industrial waste. Delhi Chief Minister Atishi termed this action as "water terrorism," claiming that it was an attempt to sabotage Delhi's water supply and influence the assembly elections. Haryana's chief minister denied these allegations and threatened legal action against Atishi for her statements. Despite the political disputes, the presence of phosphates and surfactants in the untreated sewage from Haryana is a significant factor in the frothing of the Yamuna River.

Uttar Pradesh, another state that borders Delhi, has also been implicated in the issue of untreated sewage affecting the Yamuna River. While there have been accusations against the state's government, the primary concern lies in the need to upgrade sewage treatment plants (STPs) to effectively treat wastewater. The Delhi government has acknowledged that upgrading STPs in Uttar Pradesh, along with those in Delhi and Haryana, is crucial to reducing the problem of foaming in the Yamuna River. This process, however, is expected to take several years due to various challenges, including financial constraints and the impact of the COVID-19 lockdown.

The issue of untreated sewage from Delhi, Haryana, and Uttar Pradesh polluting the Yamuna River is a complex one, involving political disputes, environmental concerns, and the health risks posed to the residents of these states. While there have been efforts to address the problem, such as the Delhi Jal Board's efforts to stop contaminated water from entering Delhi, the long-term solution lies in upgrading sewage treatment plants and improving the reuse of treated sewage to reduce the demand for raw water from sources like the Yamuna River.

Industrial waste and effluents

The River Yamuna is one of the most polluted rivers in India. Its quality has been severely affected by the rapid expansion of industrialization and urbanization. The river receives an influx of untreated industrial waste and effluents, including sludge, wastewater, disinfectants, and their by-product contaminants. These are discharged directly into the river or onto the surrounding land, surface water, and groundwater along the river banks through drains without proper treatment.

The industrial belt is mainly situated along the north-eastern part of the state along the Yamuna, and the wastes from these industries enter the river, affecting its water quality. The river receives about 44 million litres of industrial effluents daily, and this has had devastating effects on the river's health and harvest. The discharge of untreated domestic and industrial effluents has led to the river being categorized as fit only for restricted use.

The river's pollution is further exacerbated by the presence of heavy metals, with iron (Fe) being the most abundant and exceeding the limit set by regulatory bodies. High amounts of heavy metals in water can cause adverse health effects such as reduced growth and development, cancer, organ damage, and nervous system damage. The biochemical oxygen demand (BOD) load has also increased significantly between 1980 and 2005, indicating the river's deteriorating health.

The Yamuna also faces plastic pollution, with single-use plastics and other waste items such as flip-flops and paper products ending up in the river through open drains. During the dry season, the decreased water flow rate creates stagnant conditions that facilitate the accumulation of froth. The combination of untreated sewage, industrial waste, and organic matter provides the perfect environment for filamentous bacteria to thrive and stabilize the froth with surfactant molecules.

Phosphates and surfactants in detergents

Phosphates are one of the essential nutrients contributing to eutrophication, and detergents are a significant source of phosphate discharged into the environment. Eutrophication is the enrichment of phosphorus in lakes, reservoirs, and coastal waters, which can lead to an increase in harmful algae blooms, hypoxia, and loss of aquatic biodiversity. Since the 1960s, scientists have recognized that phosphates in water cause eutrophication, and by the 1970s, it was established that high phosphate levels in water were a consequence of pollution.

Phosphorus is a non-renewable material with a finite supply on Earth, and due to the rapid growth of the manufacturing industry, phosphorus contamination has become a global concern. About 5% of the total phosphate mined worldwide is used in detergents, predominantly in the form of pentasodium triphosphate (PSTP). Phosphates are used in detergents because of their ability to form strong complexes with calcium and magnesium ions, dispersing dirt in the washing solution.

However, phosphates can cause ecological damage and are often discharged with wastewaters into surface waters. As a result, there have been increasing calls for a reduction or ban on the use of phosphates in detergents. Several countries have already banned or partially banned phosphates in detergents due to pollution concerns.

Surfactants are another common ingredient in detergents and are known to reduce the surface tension of water, facilitating the formation and persistence of bubbles. When released into rivers, these surfactants can lead to the formation of froth, as seen in the Yamuna River in India. The froth on the Yamuna River is primarily attributed to high levels of pollutants and untreated sewage entering the river, with detergents containing phosphates and surfactants being significant contributors.

Volatile organic pollutants

The Yamuna River in Delhi, India, is known for its severe pollution, with the city dumping about 58% of its waste into the river. This includes a significant amount of untreated sewage, industrial effluents, and agricultural runoff. The river receives over 3.5 billion litres of sewage daily, of which only about 35-40% is treated.

This high level of pollution leads to the infamous frothing that occurs during the post-monsoon months and the onset of winter. The dry season's reduced water flow rate creates stagnant conditions, providing a perfect environment for the accumulation of froth. The untreated sewage and industrial waste contain high levels of phosphates, detergents, and surfactants, which reduce the surface tension of the water, facilitating the formation and persistence of bubbles.

The organic matter in the froth, including volatile organic compounds, can partition between the water and air. This process is influenced by the water's temperature, humidity, and organic composition. The movement of these volatile compounds into the air poses additional risks to air quality, particularly in urban areas with heavy pollution like Delhi.

The release of volatile organic gases and semi-volatile organic compounds from the froth has raised concerns among experts. Professor Sachchida Nand Tripathi, an expert from the Indian Institute of Technology, Kanpur, warned that the froth's organic matter releases volatile gases directly into the atmosphere, posing a danger to air quality. He recommended increasing wastewater treatment capacity and ensuring no untreated waste enters the river to combat the frothing issue.

Water hyacinth and biomass

Water hyacinth, or Eichhornia crassipes, is a fast-growing, perennial aquatic weed. In favourable conditions, an individual water hyacinth can produce 140 million daughter plants annually, covering 1.40 km2 of water with 28,000 tons of fresh biomass. Water hyacinth has been labelled as the world's most noxious and dreadful aquatic invasive weed. It has caused many environmental problems in Asia, affecting livelihoods by decreasing fish populations, impeding recreation and navigation, clogging irrigation systems, and causing flooding.

Water hyacinth biomass (WHB) has a high combined cellulose and hemicellulose content (58.6%) and a low lignin content compared to other types of biomass. This composition makes it a good source of bioenergy production. An efficient alkali pretreatment technology for WHB has been developed, and the enzymatic hydrolysis of WHB to reducing sugars has been investigated. With favourable conditions, the cellulose conversion rate can reach almost 100%.

Water hyacinth can be converted into biochar through physiochemical processes such as pyrolysis, gasification, or hydrothermal carbonization. Biochar has many potential uses, including soil amendment, pollution abatement, carbon sequestration, and wastewater treatment.

The froth in the Yamuna River in Delhi, India, is caused by high levels of pollution, specifically untreated sewage and industrial and domestic effluents. The river receives over 3.5 billion litres of sewage each day, but only 35-40% is treated. The untreated sewage contains phosphates and surfactants, which reduce the surface tension of the water, leading to the formation of froth. The presence of filamentous bacteria also contributes to the froth, as they release surfactant molecules that stabilise the foam. The foam is more stable in cooler winter temperatures, so froth formation intensifies after the monsoon season.

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