Sustainable Low Pressure Reverse Osmosis Concentrate Management - Four Years and Counting

The management and disposal of concentrate is often considered to be the most significant obstacle to the implementation of membrane technology. Faced with the need to manage and dispose of up to 1.0 million gallons per day (mgd) of concentrate generated from a new 4.0-mgd low pressure reverse osmosis (LPRO) expansion of its water treatment plant (WTP), the City of Ormond Beach embarked on a mission to implement an innovative and sustainable method of concentrate management, which consisted of blending the concentrate with treated wastewater at the City's wastewater treatment plant (WWTP). Implementation of this concentrate management strategy allowed the City to reclaim and reuse a traditionally unutilized resource as well as augment its reclaimed water supplies without consuming treatment capacity of the WWTP. The success of this innovative and sustainable concentrate management strategy has been demonstrated throughout the past four years of operation. Analysis and examination of data preceding and succeeding the LPRO expansion revealed the following: ≤ The City's reclaimed water supplies increased by an average of 0.34 mgd following the commissioning of the LPRO expansion. ≤ Approximately 52 percent of the concentrate generated by the LPRO expansion was reused for irrigation purposes. ≤ One-hundred percent of the concentrate is reused during periods of high reclaimed water demand. ≤ The quality of the blended reclaimed water degraded as a result of concentrate blending (increased total dissolved solids, sodium, sulfate, and chloride concentrations); however, no adverse effects to the vegetation or soil structure have been observed.