Understanding Biological Water Pollution: Causes And Origins

Water is an essential natural resource for all living beings, and it is crucial for social and economic development, energy production, and adaptation to climate change. However, water pollution, caused by biological, chemical, and physical processes, poses a significant threat to this vital resource. Biological water pollution, specifically, is caused by various microorganisms, including bacteria, viruses, algae, and worms, which can lead to waterborne diseases and other health issues in humans and animals. These microorganisms thrive in decaying organic matter, animal wastes, and improperly disposed-of human wastes, and their presence in water indicates contamination. While natural processes like volcanic eruptions contribute to water pollution, most biological water pollution stems from human activities, such as industrial processes, agricultural runoff, and sewage discharges.

Human activities

Water pollution is the contamination of water bodies, which can negatively impact their use. Although natural processes such as volcanic eruptions can cause water pollution, most water pollution is derived from human activities. Water pollution can lead to the degradation of aquatic ecosystems and the spread of water-borne diseases when people use polluted water for drinking or irrigation.

• Sewage discharges: The UN estimates that over 80% of the world's sewage ends up in seas and rivers untreated. This can include human waste from open defecation, sanitation systems, and sewage treatment plants.
• Industrial activities: Many chemicals used in industry, such as chlorinated solvents and petroleum products, can pollute water. For example, MTBE (Methyl-tert-butyl-ether), a gasoline oxygenate, is a water pollutant.
• Agricultural activities: Large animal farms, or concentrated feeding operations (CFOs), are considered potential point sources of pollution due to untreated animal waste entering nearby water bodies. Agricultural runoff can also carry pollutants such as herbicides, pesticides, and fertilizers into water sources.
• Urban runoff: Cities can be sources of non-point source pollution, contributing pollutants such as oil, antifreeze, animal waste, and road salt to water sources.
• Combined sewer systems: During heavy rain, stormwater runoff can exceed sewer capacity, causing untreated sewage to spill directly into surface waters.
• Climate change: Progressive globalization, intensive agriculture, and climate change are among the main causes of new microbial threats in water systems.
• Tourism: Global tourism is another cause of microbial threats in water systems.
• Improper waste disposal: Improper disposal of human and animal wastes can lead to biological water pollution.
• Fertilizers: Fertilizers, including nitrates and phosphates, can be harmful to humans and animals when present in high concentrations in water.

It is important to address these human activities that contribute to biological water pollution to protect aquatic ecosystems and ensure safe drinking water for humans.

Industrial processes

One of the most significant ways in which industries pollute water is through chemical dumping. Industries often release untreated wastewater, which contains harmful chemicals such as nitrates, fluorides, phosphates, and heavy metals, into water bodies. These chemicals can have detrimental effects on aquatic ecosystems and human health. For example, excess nitrogen in water can have carcinogenic properties, leading to cases of methemoglobinemia and cancer. Similarly, fluoride, which is present as fluoride ions in natural waters, can be discharged from industrial processes, leading to health concerns.

In addition to chemical pollution, industries also contribute to biological water pollution through the release of untreated sewage and manure. This introduces high levels of pathogens, such as bacteria, viruses, and parasitic worms, into water bodies. These organisms can cause waterborne diseases in both humans and animals, posing significant risks to public health.

Another indirect way in which industrial processes contribute to biological water pollution is through the use of water as a coolant. This can lead to thermal pollution, which involves changes in water temperature and can have detrimental effects on aquatic life. Furthermore, industrial activities can result in oil spills and the discharge of petroleum products, such as gasoline, diesel fuel, and jet fuel, which can contaminate water bodies and harm aquatic ecosystems.

The pollution caused by industrial processes can have far-reaching consequences, impacting not only the environment but also human health and economic development. It is crucial to address these issues through proper waste treatment, stricter regulations, and the implementation of sustainable practices to mitigate the negative effects of industrial activities on water quality.

Sewage and wastewater

One of the primary sources of sewage and wastewater pollution is the release of untreated sewage into inland waters, rivers, lakes, and seas. This often occurs during heavy rainfall when the capacity of sewage treatment plants is exceeded. Water companies have been criticized for routinely releasing sewage illegally, a practice known as "dry spilling." In 2024, water companies in England discharged raw sewage into seas and rivers for a record 3.61 million hours, with similar issues observed in Scotland, Wales, and Northern Ireland.

The impact of sewage and wastewater pollution is far-reaching. It poses a threat to wildlife and human health, with swimmers at risk of contracting harmful illnesses, including viruses and antimicrobial-resistant bacteria. It also damages natural ecosystems and habitats, such as kelp beds and seagrasses, leading to reduced biodiversity and the ocean's ability to store carbon. Additionally, poor water quality can have economic consequences, stalling economic growth and exacerbating poverty in affected regions.

To address the issue of sewage and wastewater pollution, several measures have been proposed and implemented. The UK government has introduced the Environment Bill, which includes a new duty on water companies to monitor water quality upstream and downstream of storm overflows and sewage disposal works. The bill also aims for an 80% reduction in phosphorus loadings from treated wastewater by 2037. Water companies have committed to reducing phosphorus levels by 50% by 2027. However, weak enforcement of regulations and underfunded environmental agencies have hindered progress in mitigating sewage and wastewater pollution.

The complex nature of sewage and wastewater pollution requires a comprehensive approach to address it effectively. While some efforts have been made, such as infrastructure upgrades and the introduction of legislation, further improvements in waste management, stricter enforcement of regulations, and increased investment in sustainable wastewater treatment technologies are necessary to mitigate the environmental, health, and economic impacts of this type of pollution.

Microorganisms

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

• Escherichia coli
• Burkholderia pseudomallei
• Cryptosporidium parvum
• Giardia lamblia
• Salmonella
• Norovirus
• Schistosoma

The presence of these microorganisms in water is often a result of decaying organic material, animal wastes, and improper disposal of human wastes. Intensive agriculture, poor sanitation procedures, and sewage treatment plants without disinfection steps can also contribute to the presence of pathogenic microorganisms in water.

Natural organic matter (NOM) can also aggravate the growth of microorganisms in water. Additionally, biological toxins, such as cyanobacterial toxins, can be released into water treatment plants due to the presence of specific microorganisms.

Water filtration is an important step in removing or reducing the concentration of microorganisms and other contaminants from water. However, the control of water pollution also requires appropriate infrastructure, management plans, and legislation.

Agricultural activities

Fertilizers, for instance, often contain high levels of nitrogen and phosphorus.

Frequently asked questions