East China Municipal Wastewater Plant VFD Energy-Saving Retrofit Case | 42% Power Reduction

Project Overview

This project targets a large-scale municipal wastewater treatment plant in East China with a daily processing capacity of 50,000 m³. For long-term operation, the plant’s core energy-consuming equipment—aeration blowers and lift pumps—adopted traditional fixed-speed operation mode. Subject to manual empirical regulation, the equipment suffered from high energy consumption, poor process stability, loud operating noise and frequent maintenance problems, resulting in high operational costs and unstable effluent quality.

To solve the above pain points fundamentally, the plant launched an energy-saving and efficiency upgrade project. AnyHz provided a full set of FST-650L series VFD closed-loop intelligent speed regulation solutions for blowers and pump groups, realizing on-demand intelligent operation of core water treatment equipment, achieving significant energy-saving effects and process optimization upgrades.

Original Operational Pain Points

Before the retrofit, the plant was equipped with 4 sets of 75 kW aeration blowers and 6 sets of 37 kW lift pumps, with an annual power consumption of up to 2.8 million kWh. The traditional fixed-speed operation mode brought multiple operational bottlenecks restricting efficient and low-cost operation:

• Coarse aeration control & poor water stability: Aeration volume relied entirely on manual experience adjustment, with large dissolved oxygen (DO) fluctuation (±1.5 mg/L). The unstable oxygen environment interfered with nitrification and denitrification biological reactions, leading to fluctuating effluent water quality.
• Serious energy waste: Lift pumps and blowers ran at fixed speed for 24 hours long-term, lacking linkage adjustment with actual water volume and tank water level. Throttling loss and no-load high-load operation caused massive invalid power consumption.
• High noise & poor working environment: Fixed-speed full-load continuous operation led to equipment noise as high as 85 dB, causing noise interference to on-site operators and the surrounding environment.
• Frequent maintenance & high operating costs: Frequent mechanical impact and electrical stress caused by frequent start-stop and fixed-speed operation accelerated equipment aging. The maintenance cycle was only 3 months, with high manpower and spare parts costs.

Customized VFD Intelligent Retrofit Solution

Aiming at the pain points of fixed-speed operation and manual coarse regulation of the plant’s core equipment, AnyHz adopted the FST-650L series special industrial VFD as the core, matching online detection sensors and centralized HMI monitoring system, to build a closed-loop automatic speed regulation system integrating real-time monitoring, intelligent adjustment and centralized management.

1. Aeration Blower Intelligent Closed-Loop Control

Equipped with 4 sets of AnyHz FST-650L-075G/090P VFDs for the original 75 kW aeration blowers. The VFDs are connected with online DO analyzers installed in biological tanks in real time, forming a closed-loop oxygen supply control system. The system automatically adjusts the blower operating frequency according to the real-time DO value of the biochemical tank, abandoning the traditional fixed-frequency full-load operation mode, realizing on-demand oxygen supply, effectively avoiding excessive aeration and insufficient aeration problems.

2. Lift Pump Group Water Level Linkage Speed Regulation

Equipped with 6 sets of AnyHz FST-650L-037G/045P VFDs for 37 kW lift pump groups. The VFDs collect real-time wet-well water level signals to realize automatic stepless speed regulation of pumps. When the water level is low, the pump speed is automatically reduced to avoid throttling loss and redundant head waste; when the water level rises, the speed is smoothly increased to ensure stable water lifting capacity. The soft start-stop function eliminates instantaneous current impact and mechanical vibration of equipment.

3. Centralized HMI Monitoring System

Configured with a 7-inch HMI touch screen, realizing centralized visual monitoring of all retrofitted VFD equipment. Operators can view real-time operating parameters such as VFD operating status, frequency, current, voltage on site, and quickly check alarm information and interlock status. The system supports data trend viewing and abnormal early warning, which greatly facilitates daily operation management and equipment troubleshooting.

Project Operation Results & Data Verification

After the completion of the retrofit, the plant’s core operating indicators have been comprehensively optimized, with prominent energy-saving benefits, greatly improved process stability, reduced operating noise and maintenance costs, and a short investment payback cycle, achieving a perfect balance of energy saving, efficiency improvement and stable operation.

In terms of process operation, the aeration system has realized intelligent closed-loop feedback regulation, completely getting rid of the limitations of manual experience adjustment. The precise and stable dissolved oxygen environment effectively optimizes the biochemical reaction process and significantly improves effluent quality stability. The smooth speed regulation of lift pumps eliminates frequent start-stop impact, reduces electrical and mechanical equipment wear and tear, and greatly improves the overall operational reliability of the system.

Customer Feedback

"After the AnyHz VFD retrofit, our plant’s power consumption and operating costs dropped significantly. The aeration system runs very stably all year round, and the effluent quality is more stable than before. Most importantly, the FST-650L series VFDs adapt well to the humid and dusty working environment of sewage plants, with zero operating failures in more than a year of continuous operation, and the product reliability is very trustworthy."

— Equipment Section Chief, East China Municipal Wastewater Treatment Plant

Project Core Value & Applicable Scenarios

Core Value

This project successfully upgrades the traditional fixed-speed and manually operated high-energy-consuming equipment of municipal sewage plants to closed-loop intelligent demand-based speed control mode. Relying on AnyHz FST-650L VFD’s stable speed regulation performance and perfect signal linkage control capability, it solves the industry pain points of high energy consumption, poor stability, high noise and frequent maintenance of aeration blowers and lift pumps. It realizes multiple benefits of energy saving and cost reduction, process optimization, environmental improvement and maintenance simplification for sewage plant operation.

Applicable Scenarios

This solution is widely applicable to energy-saving intelligent retrofits of various water treatment equipment in municipal sewage plants and industrial wastewater treatment stations, includingaeration blowers, lift pumps, return sludge pumps, dosing pumps and other 24/7 continuous operating equipment. It is especially suitable for working conditions with fluctuating water volume and air volume demand, humid and dusty on-site environments, and high requirements for equipment stability and continuous operation.

Consult & Customize Similar Solutions

AnyHz focuses on VFD energy-saving retrofits and intelligent control system solutions for the water treatment industry. With rich on-site project experience and mature product solutions, we help various sewage plants reduce operating costs, optimize production processes and realize intelligent and low-carbon operation.Contact us now to get a free project energy-saving assessment and customized VFD retrofit solution!