Project Background & Challenges

Contract wastewater operators Alliance Water Resources (AWR) for the City of Bowling Green, MO desired to reduce overall operating costs at the facility. The existing positive displacement blowers, jet aeration system and motive mixing pumps were targeted for energy and operation evaluation and potential upgrade. To achieve these goals, the city looked to AWR and to Environmental Dynamics Inc. (EDI) for answers.

The EDI Answer

AWR partnered with EDI to reduce the plant’s current energy consumption over 40%. AWR and EDI analyzed the existing jet aeration system against an EDI advanced technology Fixed-Grid, Fine Bubble Membrane aeration system for the two existing aeration basins. The energy savings of the EDI fine bubble system and corresponding return on investment looked very attractive. AWR applied for, and obtained, an energy efficiency grant from the local electrical company to help pay for the conversion. This grant contributed 5¢/KWH saved over the first 12 months to incentivize energy saving conversion.

EDI replaced the plant’s jet aeration system with 96 FlexAir® Panel fine-bubble diffusers in each of the plant’s aeration basins. The increased oxygen transfer capabilities of the fine bubble system compared to the jet aeration system resulted in a reduced overall airflow requirement. The blowers were also outfitted with variable frequency drives (VFDs) linked to dissolved oxygen meters, which allows for efficient pacing of the blowers to meet plant loading dynamics.

“We were very pleased with EDI’s work,” Daniel Gummersheimer, Division Manager for Alliance Water Resources said. “From the proposal to the installation, there were no hiccups. Their design and products worked perfectly from the first time we turned the blowers on. Everything went very smoothly.”

With AWR’s improvements to the plant’s current blowers and EDI’s advanced technology fine-bubble aeration system in place, electric consumption dropped by over 40 percent per month on average. Before the upgrade, monthly energy consumption for the plant averaged 117,480kWh. After the project was complete, the plant’s monthly energy consumption on average measured only 68,394kWh. The city achieved a payback on the investment well before their three-year projection.

Note: Typical Energy Savings of 30% to 50% for EDI Advanced Technology Diffuser Aeration over Jet Aeration

Upgraded System Electricity Usage

Baseline: 15 Months Before Improvement

Average kW hours/month: 117,490
Average $/month: $6,215.11

FlexAir Data: 20 Months After Improvement

Average kW hours/month: 68,394
Average $/month: $4,910.28
20 Month Electricity Savings: $26,096.45

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