A Change in Filter Control Almost Doubles Filtered Water Production per Filter Run

Comparison of variable flow rate operation vs. traditional constant rate was performed at the A battery filters over two time periods (from September to November 2010) and (from January to March 2011). Results show that operation at variable flow rate increased volume of the filtrate per filter run on average by about 70% during first testing period and by about 75% during the second testing period. Filtered effluent quality under variable flow rate operation was very good and remained less than 2NTU at all times. It was on average about 0.57NTU which is significantly less than Title 22 requirement. Volume of backwash water per backwash has not been increased for the variable flow rate operation. Based on these results it can be concluded that implementation of variable flow rate operation may lead to an increased capacity of filters discharging to the Bay by 60%–70%, reduction of energy and chemical usage for backwash by 41%–43%.