Water: Pollutant Or Pure?

Water is an essential resource for all living beings and is crucial for social and economic development, energy production, and adaptation to climate change. However, water pollution, or aquatic pollution, is a significant global issue, with the United Nations (UN) reporting that one in three people worldwide is affected by it. Water pollution is the contamination of water bodies, including lakes, rivers, oceans, and groundwater, which negatively impacts their use. It is primarily caused by human activities, such as industrial and agricultural processes, sewage discharges, and urban runoff. These activities introduce various contaminants, including toxic waste, petroleum, heavy metals, pesticides, plastics, and disease-causing microorganisms, into water sources, rendering them unsafe for human consumption and disrupting aquatic ecosystems.

Water pollution sources

Water pollution is the contamination of water bodies, which negatively impacts their uses. Water pollution is usually the result of human activities. Water bodies include lakes, rivers, oceans, aquifers, reservoirs, and groundwater. Water pollution occurs when contaminants mix with these water bodies. These contaminants can come from four main sources: sewage discharges, industrial activities, agricultural activities, and urban runoff, including stormwater.

Sewage Discharges

Sewage discharges, also known as wastewater, are one of the primary sources of water pollution. This includes water from sinks, showers, and toilets, as well as commercial, industrial, and agricultural activities. More than 80% of the world's wastewater flows back into the environment without proper treatment, contributing to water pollution. Inadequately treated wastewater can contain nutrients, pathogens, suspended solids, and organic fecal matter, including bacteria, viruses, and parasitic worms.

Industrial Activities

Industrial activities are a significant source of water pollution, releasing toxic chemicals, heavy metals, and industrial waste products into water bodies. This includes discharges from manufacturers, refineries, and other facilities. The chemical, pharmaceutical, pulp and paper, dye, and textile industries are known to generate wastewater containing organic and inorganic pollutants. Additionally, the use of water as a coolant by power plants and industrial manufacturers can cause thermal pollution, leading to changes in water temperature.

Agricultural Activities

Agricultural activities, including farming and livestock production, are major contributors to water pollution. They are the biggest consumers of global freshwater resources, using about 70% of the earth's surface water supplies. Agricultural runoff, which occurs when rainfall washes fertilizers, pesticides, and animal waste from farms into waterways, is a significant issue. This type of runoff is a leading cause of water degradation and a major source of contamination in rivers, streams, wetlands, lakes, estuaries, and groundwater.

Urban Runoff and Stormwater

Urban runoff and stormwater are other significant sources of water pollution. This occurs when rainfall washes pollutants such as road salts, oil, grease, chemicals, and debris from impermeable surfaces into waterways. Stormwater runoff can also carry sediments and silt from construction sites, logging practices, and land clearing activities, contributing to water pollution.

Water pollution causes

Water pollution is the contamination of water bodies, which negatively impacts their uses. Water pollution is usually a result of human activities. Water bodies that are polluted include lakes, rivers, oceans, aquifers, reservoirs, and groundwater. Water pollution occurs when contaminants mix with these water bodies.

There are four main sources of water pollution: sewage discharges, industrial activities, agricultural activities, and urban runoff, including stormwater. Water pollution may affect either surface water or groundwater. This form of pollution can lead to many problems, such as the degradation of aquatic ecosystems and the spread of water-borne diseases when people use polluted water for drinking or irrigation. Water pollution also reduces the ecosystem services that clean water provides, such as drinking water.

Sources of water pollution are either point sources or non-point sources. Point sources have one identifiable cause, such as a storm drain, a wastewater treatment plant, or an oil spill. Non-point sources are more diffuse and may include agricultural or stormwater runoff or debris blown into waterways from the land. Non-point source pollution is the leading cause of water pollution in US waters, but it is difficult to regulate because there is no single, identifiable culprit.

Water pollution can also be caused by transboundary pollution, which occurs when contaminated water from one country spills into the waters of another. This can be due to a disaster, such as an oil spill, or the slow, downriver creep of industrial, agricultural, or municipal discharge.

Some specific causes of water pollution include:

• Oil spills and leaks: While often accidental, they are a major cause of water pollution. Leaks and spills are often caused by oil drilling operations in the ocean or ships that transport oil.
• Chemical and pesticide use in agriculture: When it rains, these chemicals mix with rainwater, which then flows into rivers and streams that filter into the ocean, causing further water pollution.
• Rising temperatures due to global warming: This can cause changes in the temperature of freshwater systems and affect water quality.
• Nutrient pollution: Excess nitrogen and phosphorus in water or air can cause algal blooms, a toxic soup of blue-green algae that can be harmful to people and wildlife.
• Inadequately treated wastewater: This can convey nutrients, pathogens, suspended solids, and organic fecal matter into water bodies.
• Heavy metals and other inorganic pollutants: These non-biodegradable substances can pose threats to aquatic flora and fauna and public health.

Effects of water pollution

Water pollution has far-reaching consequences for the environment and human health. When water bodies like lakes, rivers, and oceans are contaminated, the natural balance of aquatic ecosystems is disrupted, leading to a cascade of negative impacts.

Firstly, water pollution harms aquatic life and biodiversity. Contaminants such as heavy metals, toxic chemicals, and oil spills destroy habitats and kill organisms, from bacteria and viruses to fish and other wildlife. This, in turn, impacts the quality of water available for human use, as contaminated water sources can carry harmful substances that pose serious health risks.

The consumption of polluted water or exposure through swimming can lead to various diseases and illnesses. Waterborne diseases, such as cholera, are prevalent in areas with water pollution, and poor sanitation and unsafe drinking water contribute to high rates of diarrhoeal diseases, particularly in children. More than 50 kinds of diseases have been linked to poor drinking water quality, including gastrointestinal issues, respiratory problems, skin infections, and even cancer.

In addition to direct health impacts, water pollution also affects industries that rely on good water quality, such as agriculture and recreation. The natural processes that support aquatic ecosystems are disrupted, reducing the ecosystem services they can provide, such as drinking water for humans and habitats for aquatic life.

The sources of water pollution are varied and include industrial activities, agricultural runoff, poor waste disposal, and sewage treatment plants. These sources introduce contaminants such as toxic substances, oils, metals, plastics, pesticides, and industrial waste products into water bodies, degrading water quality and rendering it unsafe for human and environmental use.

Addressing water pollution requires a combination of infrastructure improvements, management plans, and legislation that holds polluters accountable. Without action, the challenges posed by water pollution will only increase as global demand for freshwater continues to grow.

Water treatment methods

Water is easily polluted as toxic substances from farms, towns, and factories readily dissolve and mix with it. Water pollution is the contamination of water bodies, including lakes, rivers, oceans, aquifers, reservoirs, and groundwater, and it has a negative impact on their uses.

Filtration

Filtration is a basic but effective method of removing contaminants from water. It involves passing water through a fine mesh or filter that captures particles larger than a certain size. There are two main types of filtration: depth filtration and surface filtration. Depth filtration can remove a range of particle sizes, while surface filtration is more efficient for targeting specific particle sizes. Bag filters are a type of depth filtration that can successfully capture sediment, debris, and larger contaminants.

Adsorption

Adsorption is a process where contaminants are attracted to and retained by a solid material, such as activated carbon. This method is highly effective for removing organic compounds, certain chemicals, heavy metals, and pollutants like chlorine, chloramine, and pesticides. Adsorption on natural materials like zeolites has gained interest due to its ability to form complexes with metal ions.

Membrane Separation

Membrane separation is a widely used technique, especially for treating wastewater with high concentrations of heavy metals. It involves forcing water through a semi-permeable membrane to remove dissolved contaminants such as salts, ions, and organics. This method is versatile and used in both residential and industrial settings.

Chemical and Biological Processes

Various chemical and biological processes are employed to treat wastewater from different industries, including chemical, biological, food, pharmaceutical, and textile. The choice of method depends on the type, nature, and concentration of contaminants. For example, the photo-Fenton process is used for dye removal, while electro-Fenton is an emerging process for safe electro-generation of H2O2.

Reverse Osmosis

Reverse osmosis is a specific type of membrane filtration where water is de-mineralised or de-ionised by being forced under pressure through a semi-permeable membrane. It can remove a wide range of dissolved contaminants and is used in both residential and industrial settings.

Ion Exchange

Ion exchange is a process where undesirable ions in water are exchanged for harmless ones. It is typically done using a resin bed and is effective for removing specific contaminants like heavy metals, hardness, and nitrates.

Hybrid Systems

Hybrid systems combine two or more treatment methods to improve energy and treatment efficiencies. For example, the AC/MBR system integrates membrane separation, biological activity, and adsorption for comprehensive pollutant removal.

Water pollution prevention

Water is not a pollutant, but it is easily polluted by toxic substances from farms, towns, and factories. Water pollution is the contamination of water bodies, which negatively impacts their use. It is usually the result of human activities.

• Using water-efficient toilets or placing a brick or container in the toilet tank to reduce water use per flush.
• Running the dishwasher or washing machine only with a full load to conserve water and electricity.
• Using phosphate-free, biodegradable soaps and detergents and minimizing the use of bleach.
• Reducing the use of pesticides, herbicides, and fertilizers, and never disposing of these chemicals, motor oil, or other automotive fluids into sewer systems.
• Washing your car less often or using a car wash that recycles water.
• Using porous pavement, such as gravel, instead of asphalt to allow rainwater to recharge groundwater supplies.
• Using drought-tolerant plants and grasses for landscaping and reducing grass-covered areas.
• Watering plants and grass in the evening or early morning to minimize evaporation.

These practices can help to reduce water pollution and conserve water resources.

Frequently asked questions