What Is A Sewage Treatment Plant (STP) And How Does It Work?

Polluted wastewater is now a concern for the entire world. It impacts the aquatic ecosystem and hampers the quality of natural resources. In this regard, sewage wastewater treatment plants play a vital role in resolving this fatal concern. It uses various microbes to remove contamination from wastewater.

In this comprehensive guide, we will look into the various aspects of sewage wastewater treatment plants such as definitions, and working while covering the environmental benefits of treating wastewater.

A] What Is Sewage Treatment And What Waste Does Sewage Contain?

Sewage treatment is a process to remove contamination or micropollutants from the sewage wastewater. It generates effluent and sludge by treating the sewage wastewater. However, sewage contains various wastes from household toilets, baths, showers, kitchens, sinks, etc. 

Sewage also contains chemical waste, heavy metals, pharmaceutical waste, and oil and grease. After treating and removing these wastes, liquid effluent is disposed of into groundwater or the natural environment and sludge is used for agriculture and electricity needs. 

B] Understanding Sewage Wastewater Treatment Plants (STP) 

A sewage wastewater treatment plant is a place to treat the sewage wastewater.  It purifies wastewater by decomposing and removing contaminants from the sewage water with the help of microbes. Sewage treatment plants circulate air to improve the oxygen supply to promote the microorganism’s growth. 

The huge amount of microbes feed on contamination or micropollutants and avail clean and disposable effluent into the main water source. The treatment produces liquid effluent and sludge. 

C] Working Procedure Of Sewage Wastewater Treatment Plants (STP) 

1. Preliminary Treatment

In this initial treatment process, large solid particles are filtered out through the initial screening process. The sewage water is forced into the sedimentation tanks to settle down the large and heavy particles of grit, sand, and debris. The removal of large particles further prevents downstream equipment damage. 

However, sewage wastewater goes under manual screening where large objects such as sticks, rags, plastics, and other solid materials are physically removed using grates or screens. After the screening, wastewater passes through a grit chamber where heavier particles like sand, gravel, or grit settle down. The main motive of this process is to remove the large solid particles from wastewater.

2. Primary Treatment

In this treatment step, the wastewater enters the primary treatment phase, where suspended solids are further removed through sedimentation and settling processes. The wastewater is held in large tanks known as primary clarifiers. It allows gravity to settle down suspended solids from the liquid. 

As the wastewater moves slowly through the clarifier, solid particles settle to the bottom as sludge and clear water rise to the surface. The accumulated sludge goes for further processes such as anaerobic digestion or dewatering before disposal or reuse. Primary treatment significantly reduces the concentration of suspended solids and organic contaminants in the wastewater.

3. Secondary Treatment

Secondary treatment focuses on the removal of dissolved organic pollutants and pathogens through biological processes. The activated sludge process or biological aerated filter (BAF) is the most common method used in secondary wastewater treatment. In this process, microorganisms break down organic pollutants in the wastewater into simpler, stable substances through aerobic digestion in the presence of oxygen. 

The wastewater is oxygenated to promote microbial growth to speed up the process and improve the quality of sewage water treatment. The secondary treatment significantly reduced levels of organic pollutants and pathogens, making it suitable for further treatment or discharge into mainstream water supplies.

4. Tertiary Treatment Of Sewage

Tertiary treatment is the final stage of wastewater treatment, where advanced processes are employed to further purify the water before discharge or reuse. The common methods used in tertiary treatment are filtration, chemical treatment, and advanced oxidation processes (AOPs) such as ozonation or ultraviolet (UV) irradiation. 

Filtration techniques like sand filtration or membrane filtration help remove remaining suspended solids and microorganisms from the wastewater. Chemical substances like chlorine or chlorine dioxide are applied to ensure the removal of residual contaminants and pathogens. Tertiary treatment improves the quality of the treated wastewater. It also helps to meet the specific regulatory standards for safe discharge into the environment. 

D] Environmental Benefits of Sewage Wastewater Treatment Plants (STP) 

1. Environmental Protection

Untreated sewage water contains various pollutant substrates. These pollutants can harm the ecosystem of the mainstream water system if released untreated. Treating wastewater saves the environment from harmful micropollutants and protects the aquatic ecosystem from harsh wastewater contaminations. STP water treatment significantly removes the polluting content from water, which promotes water and environmental safety.

2. Reusable Water Source 

Wastewater is the best option to counter the scarcity of freshwater as wastewater can be used in various non-potable applications such as irrigation, industrial supply, and certain household uses. Treatment plants like WTP and STP remove the pollutants from wastewater and restore the fresh-water-like quality. Treating wastewater alleviates the pressure on freshwater sources, promoting sustainable water management practices. 

3. Protection of Aquatic Ecosystems

Aquatic ecosystems are very much impacted by untreated wastewater. The wastewater contamination hampers the optimal oxygen supply to aquatic life and thus causes an imbalance in the aquatic ecosystem.  Wastewater treatment plants are designed to remove the dissolved pollutants before releasing them into mainstream water. As a result, the STP treated water saves the aquatic ecosystem from being hampered.

4. Compliance with Regulations

Sewage and wastewater treatment plants play a vital role in adhering to environmental compliances as they follow strict guidelines towards the discharge water quality controls. These strict regulation saves the aquatic system from being hampered and promptly protect the natural resources from being contaminated.

Conclusion 

Sewage wastewater treatment plants play a vital role in safeguarding aquatic ecosystems and protecting the environment from contamination. It removes contamination from wastewater to avail it for reuse purposes. However, these treatment plants often need electricity to operate and regulate maintenance for smooth operations, so choosing what fits your requirements and budget is crucial.
 
PureBact is a leading biological wastewater treatment solution in India that provides a wide range of sustainable solutions to remove contamination from industrial wastewater. Contact us today to know more!