What is Treated in an STP?

Key pollutants in sewage that our PSTP removes

BOD

Biochemical Oxygen Demand

Measure of organic matter that consumes oxygen. High BOD kills aquatic life and indicates heavy organic pollution. Our STP achieves BOD output <20 mg/L.

COD

Chemical Oxygen Demand

Measures all oxidizable organic carbon. Unlike BOD, COD captures non-biodegradable compounds. Our process achieves >85% COD removal.

TSS

Total Suspended Solids

All particles suspended in water. Causes turbidity and carries pathogens. Our tertiary filtration reduces TSS to <30 mg/L.

pH

pH Control

Sewage pH varies widely. We maintain neutral pH (6.5–8.5) in treated water — safe for reuse in gardening and flushing.

PSTP Process Description

Complete treatment train from raw sewage to reusable water

1

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Influent sewage passes through a bar screen to remove large objects (cans, rags, sticks, plastic packets). This protects downstream equipment.

2

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First stage of PSTP is an oxygen-depleted zone where solids settle and scum floats. Anaerobic bacteria break down organic matter — no aeration energy needed.

3

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Denitrification occurs here — nitrates converted to nitrogen gas. Reduces total nitrogen in treated water. Critical for meeting discharge norms.

4

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Moving Bed Biofilm Reactor (MBBR) — plastic carriers provide high surface area for biofilm. Aerobic bacteria rapidly degrade remaining BOD/COD. Core of the PSTP.

5

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Secondary settling tank separates biological sludge from treated water. Clarified effluent moves to tertiary treatment.

6

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Pressure Sand Filter + Activated Carbon Filter remove TSS, colour, odour. Final chlorination disinfects treated water. Output: BOD <20, TSS <30 mg/L.

Process Flow Diagram

Packaged STP (PSTP) — Plant Gallery

Packaged STP Vessel — Containerized Unit

PSTP Internal Process Components

Advanced Option

Ozone Based STP

For applications requiring superior disinfection and odour control, Headwheel offers Ozone-based STP. Ozone is the most powerful oxidant available — it disinfects, decolourizes, and eliminates odour without forming harmful chlorination by-products.