ERD comparison tool developed by WateReuse project
A tool to allow engineers to evaluate commercially available energy-recovery devices (ERDs) for reverse-osmosis (RO) systems has been developed under a research project funded by the WateReuse Research Foundation.The tool will be demonstrated in a webcast to be presented by the CH2M Hill engineers who developed it on 14 March 2013.
ERDs at seawater RO plants can typically achieve a payback period of less than three years. However, for source waters of lower salinity, including brackish waters and wastewater effluents, the residual energy in the RO concentrate stream is significantly lower and the value of an ERD is consequently less.
At lower salinities, a case-by-case analysis must be performed to determine whether or not the use of an ERD is beneficial. Analysis must also be performed to determine which specific device is most beneficial, since multiple ERDs are available, each with different efficiencies and system costs.
In the foundation's study, Selecting the Best Energy Recovery Device for Reverse Osmosis Plants (WRF-08-14), conducted for the WateReuse Research Foundation, CH2M Hill performed a literature review of ERDs and their use in RO systems treating the full range of impaired water supplies: seawater, brackish groundwater, brackish surface water and wastewater.
Based on typical municipal requirements, the project developed an Excel-based model that integrates mass-balance based RO projection software, energy-recovery calculations and life-cycle cost estimates into a comprehensive, user-friendly tool. The tool permits utilities, engineers and plant operating staff to evaluate the applicability of a range of commercially available ERDs and to determine if one or more of these devices would be cost effective to incorporate into a new or existing RO facility.
The webcast will provide a technical overview of the five ERDs that were included in the tool and will offer a demonstration of the tool. The information presented will be useful to any utility that currently operates an RO plant not utilizing energy recovery or is considering implementing RO as a treatment process going forward.
The presenters will be Tyler Nading, a process engineer with four years of experience in water treatment with CH2M Hill, and Steve Alt, chemical engineer and membrane and desalination technologist in CH2M Hill's San Diego office.