What Is Domestic Sewage & How Does It Work

Domestic Sewage Management

Most of the environmental problems are associated with domestic sewage and due to improper handling of wastewater. Do you also know that wastewater, when not treated properly, could lead to water body pollution and could eventually lead to the death of marine life? Well, that is the case if there are no proper measures in place to treat wastewater. A wastewater treatment system helps store, treat, and provide clean water, which helps protect the environment. So, if you are wondering how this is done and what domestic sewage is, here is a detailed guide regarding the same.

What is domestic sewage?

Before we learn more about wastewater treatment, let’s examine domestic sewage and how it is formed. Domestic sewage is much more than just water; it consists of anything that goes down the drains of your house. This includes soaps, hair, bits of food, and anything else that gets flushed down. It is also filled with organic materials and plant nutrients, which tend to rot as they flow.

The soap content in domestic sewage might also sometimes contain harmful chemicals, which tend to affect the health of underwater life. When this sewage water enters a stream or lake, microorganisms often decompose the organic materials.  

Domestic sewage treatment process

The domestic sewage treatment process mainly consists of four steps: three major stages and a preliminary treatment step. These steps are essential to ensure proper cleaning of water before it is released. Here are the steps that need to be followed to complete the domestic sewage treatment process.

Preliminary Treatment: Screening and Grit Removal

The primary treatment stage consists of screening and grit removal, during which almost 40 to 60 per cent of the suspended solids are removed. Large objects, such as stones, sticks, etc., are mainly removed in this stage since they can damage the tank inlets. The grit chamber is also present, where wastewater flow is slowed down, and grit is allowed to fall to the bottom of the tank and is removed from there.

 Primary Treatment: Sedimentation 

Once the preliminary treatment stage is completed, the water is allowed to undergo sedimentation. In this stage, all the sinking and floating contaminants are removed. The partially treated water from this stage is passed onto the secondary stage.

 Secondary Treatment: Biological Processing

The secondary treatment stage consists of biological wastewater treatment. In this section, about 90 per cent of the organic matter is removed. This stage uses an activated sludge process where dissolved oxygen is present and promotes biological floc that removes organic matter. The activated sludge that consists of bacteria is continually re-circulated back to the aeration tank, which helps increase the organic decomposition. Bacteria attack hence dissolves the finely suspended solids and removes them, which couldn’t be done in the first stage. The water is now taken to the settling tanks, where the sludge tends to settle again. Here, the water is about 90 to 95 per cent free of all sorts of contaminants.

Tertiary Treatment: Advanced Purification

When the water from the secondary stage is not acceptable for usage, it is further advanced to the third stage. The third stage consists of advanced purification, where the fine particles and suspended matter are removed. The water at this stage will be almost free from any sort of chemical or harmful substances, which can be reused, recycled, or even released back into the environment.

What are the Benefits of Domestic Wastewater Treatment?

Wastewater treatment does not only mean that you are removing harmful chemicals and leaving them back into the environment, but you are also ensuring that this water is made suitable for use more than once. In such a way, you do not waste water; instead, you keep on reusing it by purifying it. This also means that water pollution control is being maintained. While this is one of the benefits of domestic wastewater treatment there is a few other benefits of domestic wastewater treatment.  

Less expensive

If they are maintained properly, wastewater systems can last up to 15 years in terms of workability. They also provide a very cost-effective solution for treating water while keeping unwanted bacteria away. Various financial assistance is also available to help you purchase or maintain a domestic septic system.

 Waste reduction

Modern-day septic systems use less water. No excess water needs to be treated right after one load of laundry or one use of the toilet, making it easy to treat water immediately and filter it naturally.

Prevents potential illness

Multiple illness-causing bacteria are present in domestic sewage and need to be treated. Wastewater treatment of water released from urban drainage systems can kill these bacteria. This also prevents the illness-causing bacteria from reaching plants and farm animals, which helps protect the environment.

Faster solids decomposition

Modern septic systems consist of aerobic systems that help break down the solids present much faster. Therefore, blockages become less of an issue, and fewer solids contaminate the water.

Methods of Sewage Treatment Plant

While sewage treatment plants help purify the water for further usage, there are multiple ways in which this can be achieved. Here are a few such methodologies of sewage water treatment that help in sewage pollutants treatment:

Physical Treatment

The name itself indicates that a physical process is involved in removing small and large floating suspended solids. This is done by two processes, filtration and sedimentation. Firstly, the suspended particles are removed by filtration. The filtrated solution is then kept in open tanks, and the impurities in it are left to settle down.

Biological Treatment

In the biological method, the human waste or the degrading waste present in the wastewater is treated with the help of microbes and bacteria that convert the sewage waste into various other products called sludge.

Chemical Treatment

In this method, chemicals are involved in treating the wastewater and sterilizing it so that it does not transmit disease or infection.

Sludge Treatment

Sludge treatment mainly involves microorganisms that feed on the organic matter present in domestic sewage water. This process converts the water into a purified solution. The solution is further provided with lots of oxygen to meet the microorganisms’ demands.

Future Trends in Domestic Sewage Management

With climate change and high population growth, there has been an increasing demand for wastewater treatment. To meet the growing demand for water in this world, it has become essential to focus on technologies that help with domestic sewage management. Here are the five trends that are going to dominate the industry of domestic sewage treatment.

  1. Wastewater processing

Technologies such as adsorption/biosorption, advanced oxidation processes, and even anaerobic remedies are helping reduce pollutants and maintain high-quality water.

2. Digital water management

    Digitalization has now been adopted in water treatment, where AI and IoT sensors help enhance water quality. Technologies like blockchain, 5G, and even cloud technologies are helping with data security for water management solutions.

    3. Flood prevention

      Advances in flood prevention have also got multiple improved device designs, forecasting, monitoring, and catastrophe modelling.

      4. Innovative materials

        Material science is also contributing significantly to water management by offering innovative materials, such as membranes, to ensure high water quality.

        5. Desalination

          Desalination is also an evolving trend, with a focus on reducing costs and environmental impact. The main motive is extracting salt from seawater, and renewable energy and biomimicry are used to achieve this.


          How does domestic sewage cause water pollution?

          Domestic sewage consists of bacteria and organic waste that decomposes over time. If left open into streams or lakes, it could lead to water pollution.

          What is the difference between domestic sewage and sullage?

          Domestic sewage is all the organic waste from any household, including faeces and urine. Sullage, on the other hand, is wastewater that does not consist of human excreta but of every waste apart from it.

          What are the harmful effects of domestic sewage?

          Since domestic sewage contains many pathogen microbes, these tend to cause illnesses such as polio, typhoid, or even cholera.

          What are the domestic sewage pollutants?

          There is a wide variety of domestic sewage pollutants, including biowastes, detergents, oil and grease, kitchen waste, salts, pathogens, heavy metals, and even soluble particulate matter.

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