Biological Water Pollution: Understanding The Impactful Changes

Water pollution is a pressing global issue that affects people in both wealthy and poor countries. It is caused by the continuous development of industry, which has resulted in huge amounts of wastewater. Biological water pollution occurs when sewage, agricultural waste, ballast water, and other biological pollutants are released into water bodies, causing negative consequences for flora, fauna, and humans. These biological pollutants can include pathogenic microorganisms such as bacteria, viruses, and parasites, which can enter water supplies and cause various illnesses. Additionally, fertilizers and sewage can cause an increase in the growth of aquatic plants and bacteria, reducing the oxygen levels in the water and leading to the death of many aquatic organisms. The presence of invasive species transported through ballast water can also have an impact on indigenous communities. The deterioration of water quality caused by biological pollution has far-reaching effects, damaging the environment, health conditions, and the global economy.

Sewage and agricultural waste

Sewage Pollution

Sewage pollution is a widespread issue, with contamination hotspots found in terrestrial, aquatic, and marine systems, including coral reefs, salt marshes, and fish-rich river systems. It poses risks to both human health and biodiversity. Untreated or poorly treated sewage releases high concentrations of nutrients, pathogens, endocrine disruptors, heavy metals, and pharmaceuticals into natural ecosystems. These contaminants can have detrimental effects on the health of aquatic organisms and ecosystems, leading to declining ecosystem health and biodiversity loss.

The global sanitation crisis demands urgent attention, and new sewage management solutions are emerging. For example, innovations like waste-free toilets and resource recovery processes can generate fuel and drinking water. However, addressing this complex issue requires cross-sector collaboration between conservationists and the human health sector to develop innovative and efficient solutions.

Agricultural Waste

The agricultural sector is the largest user of water and wastewater globally, accounting for approximately 70% of water usage. With increasing water scarcity, wastewater is increasingly utilized for irrigation, especially in water-stressed regions. While this practice helps meet food security and water scarcity challenges, it also carries significant health risks. Agricultural workers and their families are vulnerable to direct contact with contaminated soil and water, and the use of untreated wastewater can lead to water-related diseases.

The complex drivers of wastewater use in agriculture require a delicate balance between reducing health risks and ensuring food security. It is essential to thoroughly examine the health challenges and exposure pathways associated with wastewater contaminants to develop effective risk mitigation strategies. Additionally, changing climate conditions and farming practices can further impact exposure to wastewater, underscoring the need for ongoing research and adaptation.

Ballast water from ships

Water pollution is an important environmental problem that endangers the health of millions of people worldwide. Biological pollution of water refers to the contamination of water with various biological materials, such as plants, animals, viruses, bacteria, and other microorganisms. This can include non-native and exotic species that can have detrimental effects on aquatic ecosystems, human health, and the economy.

The main issue with ballast water is that it can introduce non-native and exotic species into new ecosystems. These species can become invasive and cause extensive ecological, economic, and human health issues. For example, ballast water has been implicated in the spread of cholera, with a form of the disease, Vibrio cholerae, arriving in Peru via ballast water in 1991 and killing more than 10,000 people over the next three years. Other invasive species spread by ballast water include zebra mussels, wakame (an edible seaweed native to East Asia), and the comb jellyfish.

To address the environmental impact of ballast water, the International Maritime Organization (IMO) adopted the "International Convention for the Control and Management of Ships' Ballast Water and Sediments" in 2004. This convention aims to minimize the uptake of organisms and sediments during ballasting and requires ships to implement a ballast water management plan. The IMO has also listed the ten most unwanted species that can be transferred through ballast water. Additionally, technologies such as adsorption and biological approaches using microbes have been effective in removing disinfection by-products from ballast water before discharge, reducing potential environmental pollution.

The management of ballast water is crucial to mitigating the spread of invasive species and minimizing ecological, economic, and health risks associated with biological pollution in water.

Industrial and drainage runoff

One of the major sources of industrial runoff pollution is the release of untreated or inadequately treated industrial wastewater into water bodies. Industrial activities often generate large volumes of wastewater containing chemicals, heavy metals, and other toxic substances. If this wastewater is not properly treated before discharge, it can introduce harmful pollutants into aquatic ecosystems, leading to water contamination.

Drainage runoff, on the other hand, primarily refers to urban stormwater runoff. As rainwater flows across roofs, driveways, parking lots, and paved streets, it picks up a range of pollutants, including fertilizer, oil, pesticides, dirt, bacteria, and debris from construction sites. This polluted stormwater then makes its way through storm drains and ditches, eventually reaching streams, rivers, lakes, and oceans.

The consequences of industrial and drainage runoff pollution are far-reaching. It can lead to the destruction of biodiversity, as aquatic ecosystems are disrupted and the proliferation of certain species, such as phytoplankton in lakes, is triggered. Contamination of the food chain can occur, posing risks to both human and animal health. Additionally, the economic impact of deteriorating water quality cannot be overlooked, as it can stall economic growth and exacerbate poverty in affected regions.

To mitigate the impacts of industrial and drainage runoff, several strategies can be employed. Firstly, implementing responsible land management practices, reducing chemical use in agriculture, and promoting sustainable farming methods can minimize the presence of pollutants at the source. Secondly, improving urban planning by incorporating green infrastructure, such as permeable surfaces, rain gardens, and green roofs, can help reduce the volume of surface runoff and mitigate its harmful effects. Additionally, proper waste disposal and the development of circular economies in industries can significantly reduce the release of contaminants into waterways.

Pathogenic microorganisms

Water pollution is a pressing issue that affects both wealthy and poor countries, with one in every three people on the planet lacking access to clean and safe drinking water. The contamination of water resources by pathogenic bacteria is a major concern for global water quality. Pathogenic microorganisms, such as bacteria, viruses, and protozoa, can cause waterborne diseases and infections, impacting human health and well-being.

Ingestion of water contaminated with feces is associated with the greatest microbial risks. Waterborne pathogens can lead to severe and mild to moderate infections, resulting in thousands of deaths annually. Some common bacterial diseases transmitted through water include cholera, typhoid fever, and bacillary dysentery. Additionally, Cryptosporidium, Giardia lamblia, Legionella, and Escherichia coli are microorganisms that have been associated with water contamination and related illnesses.

The presence of pathogenic microorganisms in water can have far-reaching consequences. It can lead to the destruction of biodiversity, contamination of the food chain, and economic impacts. The proliferation of phytoplankton in lakes, known as eutrophication, is one of the outcomes of water pollution. Moreover, ballast water from ships can introduce invasive species, such as killer algae, zebra mussels, and comb jellyfish, which can colonize new environments and disrupt indigenous communities.

To address the issue of pathogenic microorganisms in water, there is a growing emphasis on field-scale studies and the development of new models to predict and control waterborne pathogen levels. Integrating knowledge from hydrology, microbiology, and ecology can enhance our understanding of pollution levels and potential causes, enabling the formulation of long-term strategies to improve water quality and safeguard public health.

Purification and disinfection

Water purification is a critical process that involves removing various physical, chemical, and biological contaminants to produce water suitable for specific purposes, such as human consumption, medical, and industrial applications. The purification process aims to eliminate undesirable chemicals, suspended solids, gases, and biological contaminants like bacteria, parasites, algae, and viruses. Here is an overview of the purification and disinfection processes employed to address biological pollution in water:

Storage and Natural Biological Purification:

Water from rivers can be stored in bankside reservoirs for periods ranging from days to months, allowing natural biological purification to occur. This process is particularly important for water treatment using slow sand filters. Storage reservoirs also help maintain water supply during short droughts or transitory pollution incidents.

Pre-chlorination:

In the past, many water treatment plants used pre-chlorination, where incoming water was chlorinated to minimize the growth of fouling organisms in pipes and tanks. However, due to potential adverse effects, this practice has been largely discontinued.

Slow Sand Filters:

Slow sand filters are used when there is sufficient land and space. These filters rely on biological treatment processes rather than physical filtration. They are carefully constructed with graded layers of sand and gravel, with the coarsest material at the bottom and the finest sand at the top. Treated water is conveyed away for disinfection through drains at the base. An effective slow sand filter can remain in service for extended periods, producing water with very low nutrient levels, which allows for safe distribution with minimal disinfectant levels.

Biologically Activated Carbon (BAC):

BAC has been traditionally used as a polishing treatment in drinking water purification. However, it has gained prominence due to its ability to address challenges posed by changes in natural organic matter (NOM) composition, including increased NOM concentration and higher levels of hydrophilic compounds and trace organic pollutants. BAC can effectively remove these contaminants, improve downstream processes when used as a pre-treatment, and reduce disinfection by-products.

Granular Activated Carbon (GAC):

GAC is commonly used in aqueous solutions and adsorption columns for water treatment. It is highly effective in removing water pollutants such as heavy metals, pharmaceuticals, pesticides, natural organic matter, disinfection by-products, and microplastics. However, commercial GAC is costly and derived from non-renewable sources, leading to a search for alternative renewable materials.

Disinfection:

Disinfection is a crucial step in water purification, aiming to reduce the presence of biological pollutants like bacteria, protozoa, and viruses. While complete removal of these microorganisms is not feasible, global health organizations like the WHO and EPA have established strict guidelines for minimum allowed microbial limits. Disinfectants like chlorine, bromine, and iodine are used, with chlorine being highly effective against Escherichia coli. Iodine is often used in portable water purification, while bromine is common in swimming pool disinfection.

Frequently asked questions