Use of DAF for treatment of spent filter backwash water

摘要

Pilot testing of dissolved air flotation as a means of treating filter backwash water has been carried out at a number of water treatment plants in the US. It is estimated that around half of the water filtration plants in the US currently recycle spent filter backwash water and other streams (such as thickener overflow, dewatering filtrate and centrate) back to the head of the plant. Of those plants that recycle, less than half currently treat this stream. Many utilities are seeking to treat this stream to ensure maximum protection of public health as well as to optimise their treatment processes, but some have site constraints that make traditional settling facilities difficult to install. In the US, there has only been limited testing on a pilot scale of high-rate processes such as dissolved air flotation (DAF). FB Leopold has undertaken four pilot demonstrations for this application.