Agricultural Runoff: The Second Largest Water Polluter

Water pollution is a serious issue, with unsafe water killing more people annually than war and other forms of violence combined. The fashion industry is the second-largest water polluter, after agriculture. The fashion industry has a huge water footprint, consuming 79 billion cubic meters of water per year, and producing around 20% of global wastewater. This is largely due to the dyeing of clothes with toxic chemicals, and the release of fibres and dyes into wastewater when washing clothes.

The Fashion Industry is the Second Largest Water Polluter in the World

Fashion industry

Water is an essential resource for all living beings and is crucial for social and economic development. However, water pollution is a pressing issue that is endangering the health of millions worldwide. The fashion industry is the second-largest water polluter globally, after agriculture. The fashion industry's water pollution is driven by several factors, including the use of natural fibres like cotton, synthetic fabrics, and the dyeing process.

Cotton is the most widely used natural fabric in the fashion industry, and its production has a significant impact on the global water crisis. Cotton farming requires large amounts of water for irrigation and treatment, leading to the depletion of local freshwater and groundwater resources. To meet the high demand for cotton, farmers often use pesticides and fertilisers, which contaminate water sources through runoff, posing threats to local biodiversity and human health.

The production of synthetic fabrics also contributes to water pollution. The process releases pollutants such as lead, arsenic, and benzene into water sources. Additionally, the washing of synthetic clothing contributes to the release of microplastic fibres, which end up in sewage systems and local waterways, eventually reaching the ocean. These microplastics pose a serious threat to marine life, with estimates suggesting that up to 700 species could face extinction due to plastic pollution.

The dyeing process in the fashion industry is another major source of water pollution. Dyeing releases colourants and harmful chemicals into wastewater, contributing to over 20% of global industrial water pollution. The fast fashion business model, which mass-produces trendy clothing at low costs, exacerbates the issue by promoting frequent washing, leading to the accumulation of microplastics in the oceans.

While some companies have acknowledged their role in water pollution and implemented measures to reduce water use and contamination, public awareness of the climate crisis has pressured the majority of retailers to adopt more sustainable practices. Consumers are also encouraged to play a role in reducing the fashion industry's water pollution by shifting towards long-term use of quality garments, repairing or donating older items, and purchasing second-hand clothing.

Sewage and wastewater treatment

Wastewater treatment, also known as sewage treatment, aims to remove these contaminants and produce an effluent that can be safely discharged into the environment or reused. This process is crucial as nature can only cope with small amounts of water waste and pollution. Without treatment, the billions of gallons of wastewater and sewage produced daily would overwhelm natural systems and contaminate water sources.

There are two main types of sewage systems: decentralized (on-site treatment) and centralized (municipal treatment plants). Decentralized systems treat sewage close to where it is created, using septic tanks or other on-site facilities. Centralized systems, on the other hand, collect and transport sewage through a network of pipes and pump stations to a municipal treatment plant.

The treatment process typically involves primary and secondary stages, with advanced treatment including a tertiary stage. Primary treatment removes about 60% of suspended solids and involves aerating the wastewater to restore oxygen levels. Secondary treatment removes more than 90% of suspended solids. Tertiary treatment, or advanced treatment, includes polishing processes and nutrient removal.

In many cities, combined sewer systems collect rainwater runoff, domestic sewage, and industrial wastewater in the same pipes. During high precipitation, these systems can experience overflow events, releasing untreated sewage directly into water bodies, posing a serious threat to public health and the environment.

The fashion industry, particularly fast fashion, has been identified as the second-largest water polluter after agriculture. The production and use of clothing contribute to water pollution through the release of chemicals, pesticides, fertilizers, and plastic microfibers into sewage systems and waterways.

Microplastics

The presence of microplastics in water has raised concerns about their potential health risks. Research has found that up to 83% of tap water worldwide contains microplastic fibers, and these have been detected even in bottled water. The ingestion of microplastics has been associated with harmful effects in animals, and it is estimated that up to 700 species could go extinct due to plastic pollution.

To address the issue of microplastics in water, efforts are being made to develop filters that can reduce plastic pollution from laundry wastewater, as synthetic textiles are a common source of microplastics in indoor environments. Additionally, there is a growing number of companies choosing to produce clothing to high ethical standards, reducing the environmental impact of the fashion industry, which is the second-largest water polluter after agriculture.

Oil spills

The consequences of oil spills are far-reaching and long-lasting. They harm ocean life in two primary ways: fouling or oiling, and the reduction of dissolved oxygen in the water. Fouling or oiling occurs when oil physically harms a plant or animal. For example, oil can coat a bird's wings, rendering it unable to fly, or it can strip away the insulating properties of a sea otter's fur, leaving the animal vulnerable to hypothermia. Ingesting oil can also be toxic to affected animals. Additionally, oil spills can damage plant life, such as saltwater marshes and mangroves, and have significant negative impacts on tourism, commerce, and utilities that rely on seawater.

The economic and ecological costs of oil spills are substantial. The cleanup and recovery processes are laborious and expensive, and the damage to ecosystems and economies can persist for decades. When oil spills occur, response teams employ various techniques to contain and remove the oil. These include using floating booms, skimming, sorbents, and chemical surfactants to manage the spill and mitigate its impacts.

Eutrophication

In China, eutrophication has affected many lakes, including Taihu Lake, Chaohu Lake, and Xuanwu Lake. The problem is expected to worsen, with predictions suggesting that by 2030, all urban lakes and most medium-sized lakes in China's urban-rural fringe areas may suffer from eutrophication.

The basic cause of eutrophication is an imbalance in the load of nitrogen and phosphorus with respect to silica. While nutrient enrichment is a necessary factor, it is not sufficient on its own to cause eutrophication. The complex mechanisms of eutrophication, including the absorption and release of contaminants in sediments and the excessive production of algae and cyanobacteria, require further study to develop effective prevention and remediation strategies.

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