Sewage's Impact: Water Pollution And Contamination

Water pollution is a critical issue that jeopardizes both human health and natural ecosystems. Sewage pollution, in particular, poses a significant threat to water sources, as it introduces a range of harmful contaminants. Sewage is water-carried waste, including human waste, household chemicals, personal hygiene products, pharmaceuticals, and industrial wastewater. When sewage enters rivers, streams, and oceans, it can have detrimental effects on the environment and human health. In this paragraph, we will explore the impact of sewage pollution on water sources and the potential consequences of this environmental crisis.

Sewage can enter water sources due to leaking or flooding

In addition to leaks, flooding events can also cause sewage to enter water sources. Heavy rainfall can exceed the capacity of sewage systems, resulting in overflow and the discharge of untreated or partially treated sewage into nearby rivers and waterways. This issue is exacerbated by outdated infrastructure, particularly in older cities where sewage networks cannot handle the increased volume of water during heavy rainfall. Combined sewer systems, which mix stormwater runoff with wastewater from households and industries, are especially vulnerable to overflow during heavy rain.

The impact of sewage pollution on water quality is severe. Sewage discharge introduces bacteria, viruses, heavy metals, and chemicals into waterways, reducing water quality and endangering wildlife, plants, and human health. High nutrient levels from sewage can lead to eutrophication, causing algal blooms and oxygen depletion, which can result in fish kills and harm aquatic life. Sewage pollution also affects the breeding and feeding patterns of various species, leading to population decline and potential ecosystem collapse.

Furthermore, sewage contamination poses a significant threat to human health. Contact with or ingestion of contaminated water can lead to various diseases, including gastrointestinal illnesses, skin infections, respiratory problems, hepatitis, and gastroenteritis. Young children, the elderly, and individuals with pre-existing health conditions are particularly vulnerable to the harmful effects of sewage-contaminated water.

To mitigate the impact of sewage pollution, it is crucial to invest in infrastructure upgrades, improve treatment technologies, and enforce stricter regulations on wastewater treatment plants. Collaboration between water companies, government agencies, and communities is essential to ensure proper sewage management and protect water sources from contamination.

Untreated sewage contains harmful bacteria and viruses

Bacteria

• Salmonella: This bacterium can cause salmonellosis, typhoid, and paratyphoid. Symptoms include watery or bloody diarrhea, abdominal cramps, nausea, vomiting, and fever.
• Escherichia coli (E. coli): This bacterium can lead to gastrointestinal infections such as diarrhea, dysentery, and gastroenteritis. Some strains of E. coli are pathogenic and can cause more severe illnesses.
• Shigella: This bacterium is responsible for bacillary dysentery, characterized by bloody diarrhea, fever, and stomach cramps.
• Yersinia: Yersiniosis, caused by this bacterium, results in symptoms such as abdominal pain, diarrhea, rash, and joint pain.
• Leptospira: Leptospirosis, caused by this bacterium, can lead to kidney damage, meningitis, liver failure, and respiratory distress if left untreated.

Viruses

• Hepatitis A: This virus causes a liver disease with symptoms like jaundice, fatigue, abdominal pain, nausea, diarrhea, and fever.
• Rotavirus: This virus is one of the causes of viral gastroenteritis, often referred to as the "stomach flu," with symptoms such as watery diarrhea, vomiting, headache, fever, and abdominal cramps.
• Adenoviruses: These viruses are another cause of viral gastroenteritis and can lead to severe diarrhea, vomiting, and abdominal pain.
• Noroviruses: Noroviruses are highly contagious and can cause acute gastroenteritis with severe diarrhea and vomiting.
• Astroviruses: These viruses are also associated with viral gastroenteritis and can result in watery diarrhea and vomiting.

It is important to note that while some people infected with these bacteria and viruses may exhibit no symptoms, they can still spread the pathogens to others. Therefore, it is crucial to treat sewage properly and take precautions when working with or being exposed to untreated sewage to prevent the spread of these harmful bacteria and viruses.

Sewage can cause algal blooms, which can be harmful to wildlife

Sewage is a major contributor to water pollution. It can contaminate rivers, reservoirs, lakes, and seas, degrading water quality and making it toxic to both humans and the environment.

Sewage can cause algal blooms, which are a rapid increase in the density of algae in an aquatic system. These blooms can be harmful when they produce toxins (poisons) that make people and animals sick. Sewage contains high levels of nutrients, particularly nitrogen and phosphorus, which help these harmful algal blooms grow. When sewage washes into lakes, rivers, or oceans, it can trigger an algal bloom if the right combination of temperature, sunlight, and low flow is present.

The toxins produced by these algal blooms can affect wildlife in several ways. Firstly, animals can get sick or even die within hours of coming into contact with or ingesting the contaminated water. Additionally, dense blooms can block sunlight from reaching underwater plants, disrupting the ecosystem and causing some plants to die. When a bloom dies off, the decay process can also reduce oxygen levels in the water, suffocating other living organisms. Furthermore, algal blooms can release harmful gases like methane and hydrogen sulfide, which can be dangerous to people and animals.

The impact of sewage on algal blooms highlights the importance of proper sewage management and the need to address this issue to protect both human health and the environment.

Wastewater treatment plants can struggle with excess stormwater

Wastewater treatment plants can indeed struggle with excess stormwater. This is especially true in areas with combined sewer systems, where stormwater and sewage share the same pipes. During heavy rainfall or snowmelt, some wastewater systems are designed to occasionally overflow, discharging untreated sewage directly into nearby streams, rivers, or other bodies of water. This is known as a combined sewer overflow (CSO) and is common in many cities across the globe.

The issue of excess stormwater is further exacerbated by outdated and aging infrastructure. In the US, the average age of underground wastewater pipes is 45 years, with some pipes being nearly 200 years old. As a result, wastewater treatment plants may become overwhelmed, leading to the release of untreated wastewater into the environment.

Urbanization and population growth also contribute to the problem. As cities expand, more impervious surfaces, such as concrete and asphalt, are created, increasing the amount of stormwater that surges into sewers. This, in turn, can lead to sewer overflows and the contamination of nearby water bodies.

Climate change is another factor that impacts wastewater treatment plants. In areas with combined sewer systems, heavy rainfall or flooding can cause excess stormwater to flood the plant, forcing operators to release a mixture of untreated wastewater and floodwaters into the surrounding environment.

To mitigate the impact of excess stormwater, some districts are exploring green infrastructure solutions, such as rain gardens, pervious pavement, rain barrels, and green roofs. These techniques help to slow down and infiltrate stormwater, reducing the burden on treatment plants and allowing natural systems to filter out pollutants.

Treated sewage can still contain microplastics

Sewage treatment plants (STPs) are considered a significant source of microplastics in freshwater systems. These microplastics can eventually reach the oceans via river flows. Microplastics are plastic particles smaller than 5mm in size. They are formed by the breakdown of larger plastic products through various weathering processes.

The occurrence of microplastics in STP influents and effluents is expressed based on the number concentration. The reported number concentrations in STP influents range from 15.1 to 640 L-1, while in effluents, it varies from not detectable to 65 L-1. The removal efficiency of STPs is generally high, ranging from 98.3% to 99.9%. However, the high removal efficiency of microplastics by STPs does not eliminate the risk of environmental contamination.

Microplastics in STPs are predominantly composed of thermoplastics such as polyethylene and polypropylene, as well as polyester. The relative abundance of these materials corresponds to their reported production volumes. Polyester fibres, commonly found in garments, are a significant source of microplastics in sewage water.

The morphology of microplastics in STPs is dominated by fibres, followed by flakes and fragments. This indicates that microplastics entering STPs are primarily synthetic fibres and fragmented secondary microplastics. Less common forms include films, pellets, and foams.

The concentration of microplastics in sewage sludge from STPs varies across different regions. Studies have reported concentrations ranging from 129 ± 17 MP particles per gram of dry weight in Iran to 6077 MP/kg ds in Norway. The average concentration of microplastics in Chinese STPs was found to be higher than in freshwater sediments by one to two orders of magnitude.

The use of sewage sludge in agriculture is a growing concern as it can introduce microplastics into the soil ecosystem.

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