Have you ever thought about where water is going from the drain? The truth is that from every sink, water travels a journey to the sewage water treatment plant. As STP is where wastewater gets recycled into usable and clean water. This treatment prevents water pollution and protects aquatic life and biodiversity. As this treated water is further used in many activities, such as irrigation and industrial purposes, and by products, which are known as sludge, are used as fertilizer or biogas fuel. 

What is a sewage treatment plant, and how does it work?

A sewage treatment plant is designed to remove contaminants from wastewater, which is generated from households and industries. The primary goal is to convert sewage into clean water with sludge, which can be returned to the environment.

STP works on the basic principle that consists of physical, biological, and chemical processes to treat sewage in stages:

• Primary treatment: This step consists of removing large debris and heavy waste material using sedimentation, which results in partially clarified water and raw sludge.

• Secondary treatment: In this step, the resultant is pumped with oxygen, which will encourage aerobic bacteria to consume organic pollutants, and then water is separated from activated sludge. 

• Tertiary Treatment: The final step, where filtration, disinfection, and nutrient removal processes are followed to create effluent free to discharge.

• Sludge treatment: This is an optional process where anaerobic bacteria are used to break down sludge and produce biogas for energy, and the remaining byproduct is used as fertilizer.

This method of waste management helps you to reduce pollution and sludge management and reduce waste products that are going to get released into the ecosystem. As our environment is protected and public health is not harmed in this process to protect our ecosystem.

Key Components of a Sewage Treatment Plant

A sewage treatment plant consists of many units that will remove waste products from sewage and protect the environment. Now, let me tell you about 5 components with their roles.

• Screening Unit: This unit consists of bar screens, mechanical screens, and grit chambers to physically remove heavy particles from sewage. This will prevent clogging and reduce non-biodegradable waste from going into subsequent stages.

• Sedimentation Tanks: It consists of two processes, which are primary and secondary sedimentation, which separate solids and organic matter from sewage using biological treatment that settles biomass in tanks.

• Aeration Tanks: In these tanks, air is pumped to supply oxygen for microbes to grow to consume CO₂, water, and biomass, which will help in the conversion of harmful waste into harmless products and sludge.

• Sludge treatment units: In this place, sludge is stabilized using the process of heating and creating biogas or using them as fertilizers. This will minimize greenhouse gas or pollution.

• Disinfection System: This is the final unit, where chemical activities such as chlorination, UV radiation, and ozonation are used to ensure that effluent is safe to release. This helps in preventing waterborne diseases like typhoid or cholera.

Types of Sewage Treatment Plants

• Activated Sludge Process: is a method where aerobic microorganisms break organic matter in wastewater. This process is used effectively for large-scale treatment and produces reusable sludge and biogas.

• Sequencing Batch Reactor: This treatment system is a batch where all stages occur in a single tank. There are many advantages, such as compact design, flexible operation, and low sludge production. This method is commonly used in small communities, resorts, and industries.

• Membrane Bioreactor: This method combines biological treatment with ultrafiltration to achieve high-quality effluent. This method removes 99% of pathogens and solids, which creates an ideal for water reuse. This type of plant is used in urban areas with space constraints and small industries.

• Constructed Wetlands: is a natural or engineered system that uses plants and soil to treat wastewater. This is a low-energy and operational-cost unit that enhances biodiversity and aesthetics. As this type of product is used in rural or decentralized communities.

Sewage treatment technology and principles

Sewage relies on a combination of biological, chemical, and physical processes to remove waste products from wastelands. As these processes ultimately transform sewage into safe effluent and byproducts.

• Biological processes: This process consists of microorganisms breaking organic pollutants into harmless products like CO₂ and water. There are many technologies, such as the activated sludge process, trickling filters, anaerobic digestion, and membrane bioreactors, used in this process to convert harmful substances into stable compounds.

• Chemical processes: This process uses chemical reactions to neutralize, precipitate, or disinfect contaminants. There are disinfection processes such as chlorination, ozonation, and UV radiation used in the tanks to eliminate pathogens and toxic chemicals.

• Physical processes: This process removes solids and particulate matter through mechanical or gravitational means. Screening, sedimentation, and filtration are used to prevent damage to protect equipment and reduce big solid products from the sewage.

Wastewater treatment vs. sewage treatment

There are subtle differences between wastewater treatment and sewage treatment; otherwise, let me tell you that sewage treatment is a subset of wastewater treatment. Now let me tell you about some differences:

• Wastewater treatment is used in the industrial and agriculture industries, while sewage treatment is only used in domestic and municipal sewage.

• Wastewater treatment creates ultra-pure water, which can be used in industries, while sewage treatment produces biogas and effluents (released in water).

• For instance, sewage treatment can be used in residential areas, while wastewater treatment treats sewage and factory effluent. 

Advantages of Sewage Treatment Plants

• Environmental Protection: Sewage treatment plants help to reduce water pollution, prevent eutrophication, and protect biodiversity by maintaining oxygen levels and reducing toxicity.

• Public Health Benefits: Sewage treatment Plants eliminate diseases such as cholera and typhoid. As it also ensures clean water for drinking, bathing, and irrigation.

• Technological uses: There are a wide variety of ranges from large-scale activated sludge plants to compact systems like membrane bioreactors (MBRs). There is a highly adaptable advantage to treating varying sewage volumes and pollutants.

Conclusion

Sewage treatment plants are essential for our ecosystem because they are used to treat wastewater that can harm the environment. Biofuel is also produced, which can be used to harness energy through sewage treatment plants. Additionally, compact units like membrane bioreactors, offered by Oxymotec, can be used in your own compact area to meet specific goals.