Is Reverse Osmosis the solution to your water quality problems?

Pilot testing may be the only way to answer this question. Over the past year, FOX Engineering assisted the Iowa communities of Grimes, Washington and State Center with pilot testing of reverse osmosis (RO) systems to determine whether this technology is a feasible option for providing their communities with safe, clean, drinking water.

What is a pilot study? A pilot study involves the use of small scale equipment designed to simulate the performance of full-scale systems. Pilot equipment is typically installed at the site where full-scale equipment would be installed so that site specific conditions can be evaluated. The studies are typically conducted over a period of 90 days but may require up to a year to complete, depending on the conditions being tested and variations in source water.

Why complete an RO pilot study?  One major reason is to determine whether RO membrane filtration can effectively produce the desired water quality.  Pilot testing provides the data needed to establish design parameters of the full-scale systems such as RO feed pressure, membrane flux rate, and recovery rates. Other key information obtained includes required pretreatment and post treatment of the water, the fouling and scaling potential of the membranes, estimated cleaning frequency, and the ideal blend ratio of RO treated water (permeate) and untreated water to produce the desired water quality. Additionally, pilot testing of RO equipment is required to meet regulatory requirements.

Grimes RO Pilot Unit

Grimes RO Pilot Unit

What’s involved? The first step in the pilot study process is selecting the pilot equipment. FOX Engineering assisted the cities in evaluating pilot system proposals from several manufacturers. Once the pilot system manufacturer is selected, a Pilot Protocol must be developed; this is a written plan or procedure for performing the study.  It outlines goals and objectives for the study, describes equipment to be tested, how the equipment will be installed and operated, what parameters will be sampled and the frequency they will be sampled at, startup and shutdown procedures, and reporting requirements once the pilot study is complete. Since the day-to-day operation of the pilot unit is typically performed by city staff, FOX works closely with them to develop these pilot protocols and coordinated submittal to and approval of the plans by DNR.  At completion of the pilot study, operational data and water quality analysis are reviewed and recommendations for design of the full-scale system are provided by the pilot manufacturer.  The results of the pilot study are used to develop a pilot study report which is submitted to the Iowa DNR for review and approval before design of the full-scale pilot systems can begin.

What are the benefits of Pilot Testing? Pilot testing provides many benefits at a fairly minimal cost, typically less than one percent of the project cost.  Since pilot studies are performed on site using real world conditions, full scale system performance is better predicted which significantly reduces the risk of full scale equipment not performing as desired. Pilot testing also provides an accurate means of determining the on-going costs associated with operation of the equipment, chemical usage, cleaning frequencies, and replacement interval of the membrane elements.  Another benefit of pilot testing is that city staff have the opportunity to operate the pilot equipment and gain valuable hands-on training prior to installation of the full scale units.

Washington RO Pilot - End View

Washington RO Pilot – End View

Washington RO Pilot - Side View

Washington RO Pilot – Side View

FOX Engineering is an environmental engineering firm based in Ames, Iowa. We specialize in water and wastewater solutions for our diverse municipal and industrial clients. Our work varies in size and scope and can be found throughout the Midwest and beyond.