Introduction
For any industry, residential complex, or infrastructure project, installing a Sewage Treatment Plant (STP) or Water Treatment Plant (WTP) is just the beginning. The real challenge starts with operating the system efficiently over the long term.
Many plant owners face a common issue — high operational expenditure (OPEX) due to poor design, inefficient equipment, and improper system management.
Reducing OPEX is not just about cutting costs — it’s about optimizing performance, energy efficiency, and long-term reliability.
This article explains practical and engineering-based strategies to reduce OPEX in STP and WTP systems.
What is OPEX in STP / WTP Systems?
Operational expenditure (OPEX) includes:
- Electricity consumption
- Chemical usage
- Manpower cost
- Maintenance and repairs
- Sludge handling and disposal
Among these, energy and chemical consumption contribute the most to recurring costs.
1. Optimize Aeration System (Major Cost Factor)
In most STPs, aeration accounts for 50–60% of total power consumption.
Common Issues:
- Oversized blowers
- Continuous operation without control
- Inefficient diffuser systems
Solutions:
✔ Use energy-efficient blowers
✔ Install DO (Dissolved Oxygen) based control systems
✔ Optimize air distribution network
✔ Use fine bubble diffusers for better oxygen transfer
👉 Proper aeration design alone can reduce OPEX significantly.
2. Select the Right Treatment Technology
Choosing the wrong process leads to high operational costs throughout the plant life.
Example:
- MBR → High OPEX (membrane cleaning, replacement)
- SBR → Moderate OPEX (automation required)
- MBBR → Balanced OPEX and performance
Recommendation:
Select technology based on:
- Flow variation
- Available land
- Power availability
- Operator skill
👉 Right selection = long-term savings.
3. Efficient Pump Selection and Operation
Pumps are another major energy-consuming component.
Common Mistakes:
- Oversized pumps
- Continuous running without need
- No automation
Solutions:
✔ Use properly sized pumps
✔ Install VFD (Variable Frequency Drive)
✔ Use level-based automation
✔ Reduce unnecessary recirculation
4. Minimize Chemical Consumption
In WTPs and some STPs, chemicals like:
- Alum
- PAC
- Chlorine
- Polymers
are used extensively.
Optimization Strategies:
✔ Conduct jar testing before dosing
✔ Use automated dosing systems
✔ Avoid overdosing
✔ Monitor water quality regularly
👉 Controlled dosing reduces both cost and operational issues.
5. Improve Hydraulic Design
Poor hydraulic design leads to:
- Extra pumping
- Energy loss
- Inefficient flow
Good Design Practices:
✔ Gravity-based flow wherever possible
✔ Minimize head losses
✔ Proper pipe sizing
✔ Efficient layout planning
👉 Good hydraulic design reduces energy consumption permanently.
6. Reduce Sludge Handling Cost
Sludge management is often ignored but contributes to OPEX.
Optimization:
✔ Reduce excess sludge generation through process control
✔ Use efficient dewatering systems
✔ Plan sludge reuse (if possible)
7. Automation and Monitoring
Manual operation leads to:
- Energy wastage
- Human error
- Inconsistent performance
Smart Solutions:
✔ SCADA systems
✔ Sensor-based monitoring (DO, pH, flow)
✔ Automated control systems
👉 Automation improves efficiency and reduces long-term cost.
8. Regular Maintenance and Preventive Checks
Ignoring maintenance leads to:
- Equipment failure
- High repair cost
- System downtime
Best Practices:
✔ Scheduled maintenance
✔ Periodic inspection
✔ Timely replacement of worn-out parts
9. Design for Actual Load, Not Just Future Load
Many systems are overdesigned, leading to:
- Higher capital cost
- Higher OPEX
Solution:
✔ Design modular systems
✔ Expand when required
Conclusion
Reducing OPEX in STP and WTP systems is not achieved by one single factor — it is the result of proper engineering design, optimized equipment selection, and efficient operation.
The biggest mistake most projects make is focusing only on initial cost (CAPEX) while ignoring long-term operational costs.
At Shivay Projects, the focus is always on designing systems that are not only compliant but also cost-efficient and sustainable in long-term operation.
Frequently Asked questions
OPEX (Operating Expenditure) includes the day-to-day costs of running a treatment plant, such as electricity, chemicals, manpower, maintenance, and consumables.
The biggest contributors to operating costs are power consumption, chemical usage, equipment efficiency, maintenance requirements, and sludge handling processes.
Energy costs can be reduced by using energy-efficient pumps and blowers, installing VFDs, optimizing process design, and implementing automation for better operational control.
Yes. Automation systems such as PLC and SCADA help optimize equipment operation, reduce manual intervention, improve monitoring, and minimize energy and chemical wastage.
A combination of proper system design, energy-efficient equipment, preventive maintenance, automation, and optimized chemical dosing provides the greatest reduction in long-term operating costs.
Need Support in Optimizing Your STP / WTP?
If you are facing high operational costs or planning a new system, a properly engineered design can make a significant difference.
📩 Connect with Shivay Projects to optimize your water and wastewater systems for better performance and lower OPEX.