Sewage treatment is the process of removing contaminants from wastewater & flat sewage, both runoff (effluents) & domestic. It includes a physical, chemical, and biological process to remove physical, chemical, and biological contaminants.
Its objective is to produce treated effluent and soil waste or sludge suitable for discharge or re-use back into the sewage plant.
Introduction: Types of sewage treatment plants:
1. A sewage treatment plant, also known as a wastewater treatment plant, is a facility that treats wastewater and sewage.
2. The wastewater and sewage are treated to remove pollutants and to make the water safe for release back into the environment.
3. Wastewater treatment plants come in a variety of sizes and can be used to treat wastewater from residential, commercial, or industrial sources.
The main goals of wastewater treatment plants are:
Wastewater treatment plants can be constructed on-site or they can be constructed in conjunction with a municipal sewage system. This is because the facilities will be located close to where the wastewater originates. However, they can be designed to treat wastewater from many locations.
Wastewater treatment plants are operated by a public entity, usually the municipality where they are located.
How they work:
- Primary Treatment
- Secondary treatment
- Tertiary treatment
PRIMARY TREATMENT
Screen chamber:-
Screening is the primary unit operation that most wastewater treatment plants encounter. A screen is a barrier with uniformly sized apertures that are used to retain particulates found in influent wastewater that might otherwise harm equipment or prevent treatment units from operating properly.
The screen’s primary function is to remove course items from the flow stream. Cleaning of bar screens is normally done by hand, while mechanical cleaning devices are sometimes available.
These cleaning devices are rakes that sweep the entire screen regularly, removing the solids for processing or disposal. Hand-cleaned racks are commonly arranged at a 45-degree inclination to the horizontal to maximize the cleaning surface and make raking activities easier.
Collection Tank or Equalization Tank:-
The Sewage water from the bar screen chamber is entered into the Equalization tank by gravity which provides consistent flow and loading to a biological process that is important to maintain optimal treatment. By maintaining significant flow fluctuations, Equalization (EQ) Basins are designed to deliver constant influent flow to downstream processes.
Due to the additional retention time, aeration and homogeneous mixing are required to prevent the raw wastewater from becoming septic and to maintain solids in the suspension then the water pumped to the Aeration basin by raw water pumps
SECONDARY TREATMENT
Aeration Tank:
The Moving Aerobic Bio-Reactor is provided with a state-of-the-art’ diffused aeration system using Fine Bubble Membrane Diffuser. In this system, aeration is affected by employing porous diffusers installed at the bottom of the tank.
In the aeration process oxygen transfer takes place by molecular diffusion through the terrace film between air and liquid and increases in proportion to the interface area for a given flow, The surface area increases, and the rise velocity of the bubbles decreases with the number of bubbles. This factor contributes to the higher oxygen transfer capacity of diffused aeration systems.
The Moving Bed Bio Reactor is filled with high-quality self-supporting cylindrical-shaped made of polypropylene. Bacterial growth shall be generated by providing compressed air in Bio-Reactors (MBBR) and getting attached to the PP media to form a fixed film which reduces 98% reduction of BOD, COD, and organic pollutants.
TERTIARY Or FINAL TREATMENT
This treatment is called the final or advanced treatment and consists of removing the organic load left after secondary treatment for the removal of nutrients from sewage and particularly to kill the pathogenic bacteria.
Secondary sewage treatment plant effluents contain both nitrogen (N) and phosphorus (P). All fertilizers contain nitrogen and phosphorus. Plant growth in receiving waters may be enhanced when excess levels of N and P are dumped, resulting in algae growth in the water body receiving such waste. Algae growth may be stimulated causing blooms that are toxic to fish life as well as aesthetically unpleasing.
Secondary treated effluent also contains residual, mixed, and colloidal elements that may need to be removed before the treated effluent may be reused or disposed of.
The goal of tertiary treatment is to provide the last treatment stage to improve effluent quality before it is released to the receiving environment, such as the sea, river, lake, or ground, or to improve the treated water quality to the point where it can be reused. This phase eliminates organic material, SS, nutrients, pathogens, and heavy metals, among other contaminants.
In Short, the wastewater treatment process begins with screening to remove large objects such as rags, sticks, and bottles. The wastewater then flows into a grit chamber where the heavier particles settle out and are removed. The wastewater then flows into a sedimentation tank where the organic material settles out and is removed.
This leaves behind a clarified liquid that is discharged from the plant.
Advantages and disadvantages:
A plant that cleans the water using a network of tanks and filters is one of the most frequent sewage treatment technologies. The plant treats the wastewater by removing sediment, debris, and pollutants. The water is then disinfected before it is released back into the environment.
There are several advantages to using a sewage treatment plant. The plant can remove large amounts of sediment and debris from the wastewater. And will remove many pollutants, including bacteria and viruses from the source water. The plant can also disinfect the water before being released into the environment.
There are also several disadvantages to using a sewage treatment plant. The plant can be expensive to operate and maintain. The plant can also take up a lot of space. The water is also treated somewhat differently in many states.
Some states use membrane filters to remove particles, bacteria, and sediment from the water. Other states use chemical processes to remove these substances.
Conclusion.
The wastewater generated by residential, commercial, and industrial sources needs careful treatment and disinfection before being released back into the environment. A sewage treatment plant is responsible for removing pollutants and debris from the wastewater to protect public health and the environment.
The plant also needs to ensure that the water meets all regulatory requirements before being discharged into a water body.
We take on projects such as sewage treatment plant design, installation, testing, commissioning, and maintenance.
(Note: This article is for illustrative purposes only and does not imply an endorsement of any specific product or company. It’s essential to research and evaluate options based on your specific needs and requirements.)