Understanding Key Sources Of Domestic Water Pollution

Water pollution is a critical issue that poses a threat to human health, the environment, and the global economy. One of the major elements of domestic water pollution is sewage, which contains harmful substances such as pathogens, bacteria, viruses, parasites, and putrescible organic matter. Sewage can originate from both human waste and animal waste, and it contaminates water sources through improper disposal or inadequate treatment. These contaminants can lead to the proliferation of harmful algae, depletion of oxygen levels, and the introduction of toxins into the food chain. The impact of sewage pollution extends beyond the immediate ecological consequences, as it also affects sectors like commercial fishing, recreation, and tourism, underscoring the far-reaching implications of water pollution on a global scale.

Industrial waste

The high content of toxic components in industrial wastewater is a significant concern. Even small amounts of heavy metals, such as lead, mercury, cadmium, and zinc, can become toxic when they enter water sources. These metals can cause serious health issues for people who consume contaminated water. Other toxic components in industrial wastewater include aromatic hydrocarbons, phenols, detergents, cyanide, sulfates, chlorides, and phosphates.

Inorganic and organic compounds are also present in industrial wastewater. Organic pollutants, such as putrescible organic matter, deplete the dissolved oxygen content in water, endangering the health of fish and other aquatic organisms. Additionally, organic substances can serve as a breeding ground for harmful bacteria, further contaminating the water.

The impact of industrial waste on water pollution is not limited to chemical and organic pollutants. Dry cleaning fluids and embalming fluids, for example, have contaminated groundwater supplies across the United States. Carcinogenic substances like perchloroethylene (PCE) in dry cleaning fluids and embalming fluids pose serious health risks, leading to stricter regulations for water contamination levels.

While most major industries have treatment facilities for industrial effluents, small-scale industries often lack the necessary resources to invest in pollution control equipment. As a result, their waste can go untreated, contributing to the pollution of water sources. The location of industrial sites near low-income and minority communities further exacerbates the issue, as these communities may not have the political power to fight against the establishment of polluting industries in their areas.

Sewage treatment plants

Role of Sewage Treatment Plants

Treatment Processes

The treatment process in sewage treatment plants typically involves several steps to ensure effective pollutant removal. While the specific processes may vary depending on the plant and local regulations, here are some common steps:

• Screening and Pumping: This initial step involves removing large objects and materials, such as rags, plastics, and grease, from the incoming wastewater. Screening helps prevent damage to pumps and ensures smooth water flow.
• Grit Removal: In this step, fine but heavy materials like sand and gravel are removed from the wastewater. These materials are sent to landfills for disposal.
• Primary Settling: Using large circular tanks called clarifiers, the wastewater is allowed to settle, and the settled material, known as primary sludge, is pumped out from the bottom. Floating debris and grease are skimmed off the top.
• Aeration/Activated Sludge: This step is crucial for biological degradation. Wastewater is aerated to encourage the growth of bacteria that break down organic materials. The pollutants are consumed by microorganisms and transformed into cell tissue, water, and nitrogen.
• Secondary Settling: Treated wastewater is separated from the biology in large secondary clarifier tanks. This step yields an effluent that is typically over 90% treated.
• Filtration: The clarified effluent undergoes further polishing through filtration, using fine media like 10-micron polyester.
• Disinfection: Ultraviolet disinfection is applied to ensure the treated wastewater is free of bacteria. This step kills any remaining bacteria to comply with discharge regulations.
• Oxygen Uptake: If necessary, the treated water is aerated to bring the dissolved oxygen levels up to the required standard.

Challenges and Impact

Despite the presence of sewage treatment plants, water pollution remains a significant challenge. Aging infrastructure, overwhelmed systems, and the complexity of controlling dispersed sources of pollution contribute to the release of untreated wastewater. However, these treatment plants play a vital role in reducing the environmental and health impacts of water pollution, protecting aquatic life, and ensuring safe water resources for human use.

Oil spills

One of the most well-known oil spills was the Deepwater Horizon oil spill in 2010, which released over 4 million barrels of oil into the Gulf of Mexico and had devastating consequences for marine life and the surrounding environment. Oil spills can also occur during routine maintenance, such as bilge pumping, where each discharge of oil and water mixture, while small, can add up to a significant amount of oil pollution over time. This type of pollution is challenging to measure as it is often done illegally.

In addition to large spills, consumer activities account for a significant amount of oil pollution in our seas. This includes oil and gasoline drips from cars and trucks, as well as oil changes, where the average oil change uses almost five litres of oil, enough to contaminate approximately 3.8 million litres of freshwater. Furthermore, industrial and domestic runoff, as well as stormwater runoff, contribute to oil pollution. Oil pollution can also occur naturally, with oil seeping from the ocean floor and eroding sedimentary rocks.

Overall, oil spills are a significant contributor to domestic water pollution, with a range of negative consequences for the environment, wildlife, and human activities.

Fertilizers and pesticides

Additionally, fertilizers and pesticides can enter indoor drains and sewer systems, eventually making their way into groundwater. This is particularly relevant for those who rely on well water, as pesticides and fertilizers can filter through the soil and contaminate the groundwater used for drinking and other domestic purposes. Even wastewater treatment facilities may not entirely remove all pesticide and fertilizer residues, leading to their presence in treated water discharged back into waterways.

The presence of fertilizers and pesticides in water bodies can have significant ecological and health consequences. Nutrient pollution, caused by excess nitrogen and phosphorus, can lead to algal blooms, creating "dead zones" where aquatic life cannot survive due to oxygen depletion. These toxins can also accumulate in the bodies of aquatic organisms, including invertebrates, which are vital to the aquatic food chain. As a result, the consumption of contaminated water or aquatic life can introduce harmful substances into the human body, posing health risks, especially to young children.

To mitigate the impact of fertilizers and pesticides on water pollution, it is essential to follow proper application and disposal procedures. Applying these substances under favourable weather conditions, such as calm weather with low wind speeds, can help prevent their movement into water bodies. Additionally, limiting the use of highly toxic pesticides, such as pyrethroids and organophosphates, or using alternative methods like organic farming practices, can help reduce the risk of water contamination.

Radioactive waste

The treatment of radioactive wastewater is a critical issue in the development of nuclear energy technology. The Fukushima Daiichi nuclear power plant disaster in 2011, for example, resulted in the release of thousands of tons of radioactively contaminated water into the ocean. While the ocean has a significant capacity to dilute radiation, there are concerns about its impact on marine life and humans. Radioactive isotopes have been observed moving up the local food chain, potentially affecting those who consume seafood.

Overall, radioactive waste is a significant contributor to domestic water pollution, and proper treatment and disposal methods are crucial to mitigate its environmental and health impacts. However, it is important to recognize that it is just one of the many elements contributing to the deteriorating water quality worldwide.

Frequently asked questions