BONITA SPRINGS RO ENERGY OPTIMIZATION PROJECT: AN INTEGRATED MEMBRANE, ENERGY RECOVERY AND CONTROL APPROACH TO SAVING POWER COST

摘要

The Bonita Springs Utilities (BSU) RO WTP is a 6 mgd facility that treats brackish aquifer wellwater. After more than eight years of service, the existing membrane elements were reaching theend of their useful life and BSU was looking to improve energy efficiency and operability of theRO facility. CH2M HILL conducted an upgrades study, design and construction project thatoptimized membrane replacement, new energy recovery devices (ERDs), potential trainexpansion and overall wellfield and RO train control. The upgrades project completed in July of2012 is projected to save BSU more than $150,000 annually and provide options for low-costfuture expansion.The study compared several ERD, membrane element, and membrane train expansioncombinations. The analysis resulted in a membrane element specification that considered notonly purchase cost, but also life-cycle cost when operating with the new ERD at current andpotential future feed water quality and train capacity.The existing treatment facility including wellfield, membrane feed pumps, and RO system weremodeled to better understand how proposed ERD and membrane choices, along with expansionoptions and control system changes would impact overall treatment facility energy consumption.The model was used to optimize overall membrane system efficiency both at current and futurefeed water quality and treatment capacity.This paper describes the comprehensive evaluation process and how a life-cycle cost evaluationapproach was used to select a replacement membrane and energy recovery device that wouldmaximize annual energy savings over the anticipated life of the membrane elements.