Water clarity is improved 50 to 85 percent, depending upon raw water conditions. Clarified water then enters the tri-media depth filter tank and flows downward. University studies have demonstrated that on cold water with less than 1 NTU, this process was also capable of 99 percent Giardia removal. Post-chlorination is used for disinfection purposes on these applications requiring a safe drinking water supply. When the filter effluent quality is no longer satisfactory, or the headloss through the equipment increases by 5 to 10 psi, it is time to recondition the Multi-Tech filtration system.
Water is directed upflow through the filter backwash the bed.
This backwash water passes into the clarifier tank in series and is then used for backwashing the clarifier. The backwash water from the filter passes through an eductor which can draw air. After a few minutes of backwashing with water only, the eductor valve is opened to allow air scouring of the clarifier bed. The air valve is closed to continue the upflow cycle and displace any accumulated air. The entire upflow cycles typically operates for 10 minutes.