Method and apparatus are provided for treating and removing particulate matter from fluid or treating and removing fluid from a recoverable particulate matter from fluid circulating into, through and out of an industrial operation, and for washing a disposable cartridge filter used therein. The influent fluid is maintained at a flow rate such that the differential pressure across the cartridge filter is no greater than 10 psi to prevent the buildup of non-porous filter cake. A pressure detecting mechanism and method is also provided to detect the amount of deposited particulate matter inside the cartridge filter, so that an operator can determine whether the cartridge filter should be taken out to remove or recycle the deposited particulate matter.