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McClelland Designs State's First Membrane Bioreactor System


     McClelland Consulting Engineers and the City of Decatur this February completed a $9 million wastewater treatment plant expansion that included a process conversion from a sequencing batch reactor to Arkansas' first membrane bioreactor (MBR) system.

     The progressive design-build project by MCE and Crossland Heavy Contractors increased the design capacity from 2.2 million gallons per day to 3.8 MGD (interim) and 4.6 MGD (ultimate) without increasing the plant's footprint.

     Additional tasks included in the conversion were: influent pump station renovation; installation of rotary rum screen, membrane tanks, pumps, and piping; permeate pumps, tank and piping; new ultraviolet disinfection equipment; a new sludge press; existing wet well expansion; process piping; construction of a new electrical building; and equipment for fine screening, aeration, chemical injection, and biological treatment.

     Innovative approaches included placing MBR tanks atop the existing SBR equalization structure, allowing for siphoning of permeate water, reducing energy consumption, and minimizing plant shutdowns; incorporating VFDs on existing equipment; implementing SCADA in order to fully automate the new plant; and conducting clean water testing before the train shutdown to make the start-up more efficient and effective.

     The project enables Decatur to be in compliance with the Arkansas Department of Environmental Quality under a repermitting of the plant effluent requirements to a stricter and more technologically advanced permit, with the ability to treat up to 4.6 MGD, a 109% increase from the initial capacity, for roughly $4.08/gallon of treatment capacity.

(McClelland Designs State's First Membrane Bioreactor System, Building Arkansas, December 2019, Pg. 11)