Unistar Aquatech is a leading sewage treatment plant, we are committed to helping industries, residential societies, municipalities, and commercial facilities understand the importance of efficient wastewater management. We design STPs that are energy-efficient, easy to maintain, and fully compliant with pollution control board guidelines. One of the simplest ways to understand the treatment process is through a flowchart sewage treatment plant process. These diagrams visually explain how sewage enters the system, gets treated, and finally leaves as clean, reusable water.
An STP is a structured system designed to treat wastewater from bathrooms, kitchens, washing areas, and industries so that it becomes environmentally safe. With rising water scarcity, the treated water can be reused for gardening, flushing, cooling towers, and construction activities.
Importance of Flow Diagrams in STP
A diagram of sewage treatment plant gives a quick snapshot of the entire process. It shows how wastewater flows from one tank to another, undergoes various biological and mechanical treatments, and finally becomes clean enough for reuse or discharge.
These diagrams help in:
- Understanding plant design and workflow
- Troubleshooting operational issues
- Training plant operators
- Demonstrating compliance during inspections
- Planning space and equipment needs
At Unistar Aquatech, we often create customized diagrams for clients to help them visualize their STP system better.
Also Read : The Difference Between SBR vs MBR vs MBBR Sewage Treatment Plants
Step-by-Step Sewage Treatment Process: Explained Through Flow Diagram Stages
Let’s break down the typical flowchart sewage treatment plant process into simple, user-friendly steps. Each stage plays a crucial role in transforming sewage into treated water.
1. Screening and Bar Racks
The sewage first enters the screening chamber. Here, large solid waste—like plastic, cloth, sticks, and sanitary items—is removed. This prevents blockages in downstream equipment.
2. Grit Removal / Oil and Grease Trap
After screening, the wastewater passes through a grit chamber. Sand, soil, and small stones settle at the bottom. In some designs, there is also an oil and grease separator.
3. Equalization Tank
In this tank, incoming sewage water is collected and mixed to balance the flow and load. A blower is used to prevent foul smell and sludge settlement at the bottom.
4. Primary Treatment / Sedimentation Tank
Heavier suspended solids settle at the bottom as sludge while lighter particles rise to the surface. This reduces the load on the biological treatment process.
5. Biological Treatment (Secondary Treatment)
This is the heart of the treatment process. STPs commonly use:
- MBBR (Moving Bed Biofilm Reactor)
- SBR (Sequencing Batch Reactor)
- MBR (Membrane Bioreactor)
Microorganisms break down organic matter in sewage. Aeration blowers provide oxygen that helps bacteria grow and consume pollutants.
6. Secondary Clarifier
Here, treated water flows into a clarifier where remaining sludge settles at the bottom. The clear water at the top moves to the next stage.
7. Tertiary Treatment (Advanced Cleaning)
To ensure the water meets standards, tertiary treatment is applied. This may include:
- Pressure sand filter (PSF)
- Activated carbon filter (ACF)
- Chlorination or UV disinfection
This step removes color, odor, fine particles, and harmful microorganisms.
8. Treated Water Tank
The clean water from tertiary treatment flows into a storage tank. This water, known as STP water, is safe for various non-drinking purposes like gardening, flushing, and cooling towers.
9. Sludge Handling System
Settled sludge from various tanks is pumped to a sludge drying bed or filter press. After drying, it becomes a soil-like material that can be safely disposed of.
A flowchart sewage treatment plant process offers a clear understanding of how wastewater is collected, treated, purified, and reused. With increasing environmental concerns and water shortages, STPs have become essential for every modern building and industry. Unistar Aquatech continues to provide innovative, reliable, and user-friendly sewage treatment solutions backed by simple diagrams, strong engineering, and real-world experience.