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An 8-MGD water reclamation system in Northern California was experiencing membrane fouling that was increasing the required feed pressure to produce water. A membrane autopsy showed that the fouling was caused by silica scale. Membrane Cleaning Chemicals Results - Train One & Three The system consisted of three trains, each designed to produce 1850 gpm of permeate at a feed pressure of 145 psi. When the required feed pressure to produce 1850 gpm increased by over 27%, Train 1 and Train 3 were cleaned using an ammonium bifluoride (ABF) based cleaner. The ABF based cleaner performed well, decreasing feed pressures...

Ultrafiltration System Optimized at Cincinnati Zoo The Cincinnati Zoo uses an ultrafiltration system (UF) to treat storm water. The reclaimed water is collected from fourteen acres of the park, including parking lots, animal exhibit yards, rooftop drains and walking-path storm drains. These combined sources run through a straining basin to a 300,000-gallon retention tank system. From there, the water is pumped from a wet well to the UF system, producing irrigation water and makeup water for various animal exhibits. These include underwater viewing of Polar Bears and Sea Lions, as well as moats for Lions, Cheetahs and African, Painted Dogs....

American Water Chemicals® (AWC) recently received a tail end nanofiltration membrane for autopsy from a client who was experiencing issues with disinfection byproducts in their finished water.  Water testing had confirmed that the NF membranes were not rejecting the high organics in their feed water, and the client was concerned that the membranes (which were in use for less than a year) were not performing per the manufacturer’s claims.When our engineers cut open the membrane, the first thing that caught their attention was that the membrane leaves were “pouching”. In other words, they had a “ravioli” like appearance (see Fig....

One of the most common questions asked by RO plant operators is: “What antiscalant do we need to control high levels of silica in RO systems?” There are many misguided beliefs on how to control silica. Some people recommend operating at a pH of 8, (the point of lowest solubility for amorphous silica) because they’ve heard that silica is more soluble at higher pH. Many others have stories about how they operated successfully with water that had 300 ppm silica by using one silica antiscalant or another. But few realize that silica scaling is dependent on many factors that include...