Sewage Pollution: Understanding Its Causes And Impact

Sewage pollution is a pressing ecological issue that has gained significant attention in recent years, particularly in England. It is primarily caused by a combination of factors, including inadequate or outdated sewage treatment facilities, improper waste disposal, and a lack of proper sanitation infrastructure. The problem is exacerbated by industrial wastewater discharge, heavy rainfall leading to sewer overflow, and the disposal of fats, oils, and grease that clog pipes. Sewage pollution has severe environmental and health impacts, contaminating water bodies, destroying ecosystems, and posing risks of diseases to both humans and wildlife.

Blocked pipes and sewers

Another cause of blocked pipes is the connection of new building sewage systems to existing sewers built for other residential buildings. This can lead to sewer overflow, which is hazardous to human health, potentially causing various diseases. Additionally, contractors may connect drainage from a building to the wrong sewer network, resulting in misconnections and polluting waterways.

The age of the sewage system also plays a role in blockages. Older systems may be more susceptible to breakdowns and overflows, especially when combined with modern urban development. As cities expand, the amount of stormwater surging into sewers increases, exacerbating the problem. This is particularly prevalent in older cities like New York, where approximately 40% of sewers are over 60 years old, and some pipes are nearly 200 years old.

Furthermore, heavy rainfall can overwhelm sewer systems, leading to combined sewer overflows (CSOs). During intense rain, stormwater combines with household sewage, and if the system's capacity is exceeded, raw sewage mixed with stormwater can flow untreated into waterways. This has been a persistent issue in cities like Philadelphia, where billions of gallons of pollution are discharged into local waterways annually.

To mitigate blocked pipes and sewers, proper disposal of substances like fats, oils, and grease is crucial. Additionally, investing in modernizing and expanding sewage treatment infrastructure is essential to cope with increasing volumes of wastewater and stormwater. Implementing green infrastructure projects, such as rain gardens and tree trenches, can also help manage stormwater and reduce the risk of sewer overflows.

Poor sanitation and sewage treatment facilities

Poor sanitation and inadequate sewage treatment facilities are key contributors to sewage pollution. Sanitation is fundamental to public health, development, and survival, yet billions of people are vulnerable to water-related diseases due to limited access to proper sanitation facilities. Poor sanitation increases the risk of disease transmission, with diarrhoeal diseases, intestinal worms, cholera, dysentery, typhoid, schistosomiasis, and polio being common ailments associated with inadequate sanitation. According to the World Health Organization (WHO), 46% of the world's population lacks access to adequate sanitation services, and an estimated 1.7 billion people do not have basic sanitation facilities like private toilets or latrines.

Inadequate sewage treatment infrastructure exacerbates the problem. Many treatment plants are unable to cope with large volumes of sewage and suffer from a lack of maintenance or repairs. In some regions, there may be a complete absence of treatment facilities, as seen in low-income countries where communities may not have access to any sanitation facilities or clean drinking water. This situation leads to the easy contamination of streams and rivers by sewage, causing harmful environmental and health impacts.

Improper waste disposal methods, such as open defecation, further contribute to the issue. Open defecation practices can contaminate land and water sources, increasing the risk of infection for entire communities. Additionally, untreated sewage can contain a variety of harmful chemicals, bacteria, and diseases, including nitrogen, phosphorus, herbicides, pesticides, hormones, medications, and human waste. When released into waterways, these contaminants pose significant threats to both human and aquatic life.

The issue of poor sanitation and sewage treatment is prevalent in various regions, including Latin America and the Caribbean, sub-Saharan Africa and Southern Asia. These areas often suffer from insufficient access to improved sanitation facilities and poor service quality, impacting public health. For example, in Haiti, only 30% of the population had access to improved sanitation in 2004, and human waste disposal is a pressing concern, with a lack of sewage collection services and the illegal dumping of solids into rivers and seas.

Furthermore, sewage systems in developed countries like the UK are also facing challenges. Years of underfunding and deregulation have pushed these systems to crisis points, resulting in the discharge of raw or partially treated sewage into rivers and coastal areas. Climate events, such as heavy rainfall, can also overwhelm sewer systems, leading to overflows and the release of untreated wastewater into natural water bodies.

Industrial wastewater

Sewage pollution is caused by a variety of factors, including improper sewage treatment, blockages, and industrial wastewater.

The type of industry determines the quality and quantity of wastewater generated. For example, mining operations can affect surface and groundwater quality, drinking water supplies, and air quality due to the generation of tailings, waste rock, and wastewater discharges. Shale gas extraction produces large volumes of wastewater, which can contain high concentrations of dissolved solids (salts), naturally occurring radionuclides, metals, and other drilling pollutants.

Other industrial processes release water during manufacturing, cleaning, and commercial activities, which can contain various contaminants depending on the industry. These contaminants may include non-biodegradable waste such as heavy metals, pesticides, plastics, and biodegradable compounds like paper, leather, and wool.

Without proper treatment and management strategies, the discharge of industrial wastewater into water bodies can have detrimental environmental and health effects. The toxins released can interfere with aquatic life, leading to the death of aquatic organisms and the disruption of ecosystems. It can also pose significant threats to human health if allowed to enter our waterways untreated.

To address these issues, it is crucial to employ adequate treatment methods, including physical, chemical, and biological processes, to eliminate toxicity and enable water recycling for conservation.

Rain and flooding

Rain and snowmelt can cause sewage pollution in several ways. Firstly, they can increase the amount of stormwater, which can overwhelm wastewater treatment plants and cause them to release untreated sewage into rivers and other waterways. This can happen when the capacity of the treatment plant is exceeded during heavy rainfall, and the ground cannot quickly absorb large amounts of water. This can lead to sewage works being inundated and potential flooding of streets, homes, and open spaces.

Secondly, rain and snowmelt can cause what is known as nonpoint source pollution. As rainfall or snowmelt moves over and through the ground, it picks up and carries pollutants such as fertilizers, pesticides, and animal waste from farms and livestock operations. These pollutants are then washed into waterways, leading to nutrient pollution, which is the number-one threat to water quality worldwide. Nutrient pollution can cause algal blooms, which can be harmful to people and wildlife.

Thirdly, rain and flooding can cause sewage pollution by increasing the amount of stormwater runoff. When rainfall or flooding occurs, stormwater can become polluted and transport environmental toxins to seas and rivers. This can happen when water flows backwards in sewer and stormwater systems, or when it carries pollutants from roads, roofs, driveways, and parking lots into waterways.

Finally, rain and flooding can exacerbate the problem of aging and poorly maintained sewage infrastructure. As urban areas expand, new areas of concrete and asphalt increase the amount of stormwater surging into sewers and the amount of pollution spewing out. This can lead to sewage backing up into buildings and spilling onto streets and parks, and waterways.

To mitigate the impact of rain and flooding on sewage pollution, several measures can be taken. These include:

• Implementing projects that prevent sewage overflows, such as green roofs and permeable pavements.
• Reducing stormwater runoff by soaking up rain and preventing it from flowing into streets and stormwater systems.
• Improving wastewater treatment infrastructure and ensuring proper maintenance and management of these systems.
• Strong notification programs that alert people to the danger of raw sewage and sewage contamination in waterways.

Old and obsolete drainage networks

One of the primary challenges with old drainage networks is their inability to handle the increasing volume of wastewater. Sewers are designed to manage a specific amount of wastewater, and when this capacity is exceeded, it results in sewer overflows and leaks. Heavy rainfall exacerbates this problem, as rainwater seeps into sewers, mixing with wastewater and overwhelming the system. This issue is particularly acute in combined sewer systems, where stormwater and household sewage are combined in the same pipes. When too much stormwater enters the system, it frequently leads to overflows, resulting in the release of raw sewage into lakes, rivers, and coastal waters, causing significant environmental and public health concerns.

The consequences of outdated drainage networks are severe. Sewer overflows can lead to the contamination of waterways, including streams, rivers, and lakes. Untreated human sewage contains harmful bacteria, viruses, and parasites, posing a risk to human health and the environment. It can cause various diseases, including acute viral and bacterial infections such as gastroenteritis, hepatitis, and typhoid. Additionally, the presence of sewage in aquatic environments can disrupt ecosystems, leading to the decline of fish populations and other freshwater organisms.

Furthermore, old drainage networks are prone to blockages, which further contribute to sewage pollution. Fats, oils, and grease (FOG) accumulate and congeal inside drains and sewers, leading to clogs and reducing the diameter of the pipe system. This results in flooding and sewage backing up into homes and public spaces, causing odour pollution and creating unsanitary conditions. Additionally, incorrect plumbing and misconnections, where drainage from a building is connected to the wrong sewer network, can also pollute waterways.

The issue of outdated drainage networks is compounded by poorly planned urban development. As urban areas expand, the increase in impervious surfaces, such as concrete and asphalt, contributes to higher volumes of stormwater rushing into sewers, exacerbating the problem of sewer overflows. Upgrading and modernising sewer systems is crucial to address these issues, but it will require significant investments and time to implement effective solutions.

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