Effluent Limitations Guidelines (ELGs), Part IV: Zero Liquid Discharge — Bottom Ash Transport Water

For coal-fired power stations, complying with the US Environmental Protection Agency’s (EPA’s) Effluent Limitations Guidelines (ELGs) is no small task. Oftentimes, an all-out effort to restructure and refine a station’s water balance is required.

To assist stations in establishing a zero liquid discharge configuration for existing bottom ash systems, I’ve authored a comprehensive white paper that provides the guiding steps to ELG compliance—an abstract of the paper is provided below.

Zero Liquid Discharge—Bottom Ash Transport Water

ABSTRACT | One of the major compliance hurdles introduced by the recently finalized Effluent Limitations Guidelines (ELGs) is the establishment of a zero liquid discharge (ZLD) configuration for existing bottom ash systems. Bottom ash management systems vary widely from station to station, but they generally include some or all of the following eight components: source water supply; ash sluice pumps; boiler hopper; clinker grinder; hydrobins/dewatering bins; ash filter ponds; surge/equalization tanks; and recirculation pumps. This white paper, authored by David Weakley II, PE, Assistant Engineering Manager at GAI Consultants, outlines nine steps to serve as a starting point for stations gearing up for ELG compliance. The steps include creating and verifying the station water balance; isolating the ash sluice system; determining a make-up water source to the bottom ash system; completing a hydraulic analysis; eliminating influent flows into the closed-loop system; understanding chemistry issues of a closed-loop system; identifying opportunities for ELG compliant blowdown of the bottom ash system; removing fines; and implementing operator and control changes.

Read the Full White Paper

Stay tuned for more information on ELG compliance and what it means for the coal power industry. For questions or additional information, contact Assistant Engineering Manager David Weakley II, PE at 412.476.2000.

For related information, check out the following blog posts:

Effluent Limitations Guidelines (ELGs), Part I: Compliance Check | December 15, 2015
Effluent Limitations Guidelines (ELGs), Part II: Compliance Resources | February 9, 2016
Effluent Limitations Guidelines (ELGs), Part III: Importance of the Power Station Water Balance | March 8, 2016

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