Coal Power Plant Project: Sustainable FGD Wastewater Treatment

Summary

• Collaborative Water Research: Georgia Power’s Plant Bowen, along with 16 partner organizations, is using the Water Research Center to advance real-world water treatment and conservation technologies tailored for power plants.
• Pilot Project Tackles FGD Wastewater: A two-stage pilot treatment train, developed by WesTech , is designed to meet EPA guidelines by removing solids, metals, and reducing selenium in Flue Gas Desulfurization (FGD) wastewater.
• Flexible Testing for Future Standards: With adaptable equipment and modular configurations, the pilot project allows for testing various operational factors, ensuring it can meet evolving environmental regulations.

The Water Research Center (WRC), a facility established in 2012 at Georgia Power's Plant Bowen, plays a key role in the development and testing of innovative water treatment and conservation technologies.

As the first facility of its kind in the United States, the WRC represents a collaborative effort between the Electric Power Research Institute (EPRI), Southern Research (SR), @Southern Company, its subsidiary Georgia Power, and 14 other utility companies.

To date, the WRC has launched or completed more than 40 test programs across seven distinct focus areas:

1. Overall plant water management
2. Cooling tower and advanced cooling systems
3. Zero Liquid Discharge (ZLD) options
4. Solid landfill water management
5. Carbon Capture and Storage (CCS) technology water issues
6. Moisture recovery
7. Flue Gas Desulfurization (FGD) process wastewater treatment

The WRC shares findings from these test programs with a network of research organizations and utility companies, all working toward the shared goals of water conservation and minimizing wastewater production.

In 2014, Southern Company and WesTech Engineering initiated discussions to facilitate additional testing of FGD wastewater treatment processes. At that time, the EPA was revising its Coal Combustion Residual (CCR) rules to include new standards for coal ash surface impoundments, along with proposed revisions to its Effluent Limit Guidelines (ELGs) for steam electric power plants. These guidelines established federal limits for levels of specific contaminants (arsenic, mercury, selenium, chromium, and others) in wastewater discharged from power plants.

In response to heightened regulatory standards, Southern Company decided to develop a two-part FGD wastewater treatment pilot designed to test biological processes for selenium removal. The pilot required compact equipment capable of adjusting a range of operational factors such as flux rates, retention times, chemical dosages, and varying feedwater types.

Southern Company was already using WesTech’s mobile RapiSand? unit for related testing, making WesTech a natural partner for this new FGD pilot project.

“The customer wanted the ability to easily change process configuration and have two to three different testing options,” said Steve Goldsmith, WesTech’s Lead Project Manager. “The aim was flexibility – test, test, test.”

First Stage of Treatment Removes Solids and Metals, Controls pH

WesTech’s expertise allowed them to meet Southern Company’s challenging requirements by proposing a modular configuration of a physical/chemical treatment system, designed specifically to maximize testing flexibility.

The system WesTech developed served as the first part of a two-stage pilot treatment train, with the overall goal of meeting ELG compliance standards. The initial stage focused on removing solids and metals from the influent wastewater and stabilizing pH levels. To achieve this, WesTech provided primary and secondary clarifiers, reaction tanks, process tanks, pumps, chemical feed skids, and essential instrumentation and control systems.

Water from a holding pond was first routed into an equalization tank before entering the physical/chemical treatment system. Once adjusted, influent water was transferred to a reaction tank where lime was added to balance pH. The water then flowed by gravity into two additional reaction tanks, where ferric chloride and organosulfide were introduced to precipitate metal hydroxides. A polymer was also added to promote flocculation, and the water was subsequently sent to a clarifier for settling and solids removal.

The water was then directed to the second stage of the treatment train, which included a sand filter and a biological treatment system specifically designed to reduce selenium levels.

“It was a pleasure working with WesTech on this project,” said Rebecca Osteen, Research Engineer with Southern Company Services. “Throughout the design and construction of the system, the WesTech team quickly responded to issues and questions and adjusted to both major and minor changes. Their flexibility and expertise were essential to the successful startup of this project.”

For WesTech engineers, contributing to innovative research projects like this brings particular satisfaction.

“We’re glad that our expertise could help Southern Company determine how to better recover water used in the processes of generating electricity,” said Goldsmith.

Related Resources:

– Learn more about WesTech’s wastewater treatment solutions for coal-fired power plants.

Contact:

West: Barron Sawyer WesTech Engineering Call ?? 801-290-5565 [email protected]

Central, incl. Texas: David Stanek , WesTech Engineering Call +?? 801-290-5785 [email protected]