AWWA MTC61193

The Clark County Water Reclamation District (CCWRD) is investigating new wastewater technologies for improving overall plant performance and as an alternative for installation in remote reclamation facilities to provide unrestricted reclaimed water. One such technology is the Membrane Bioreactor (MBR) which combines activated sludge treatment with a membrane liquid-solid separation process. The membrane component using low-pressure membranes such as microfiltration (MF) or ultrafiltration (UF) takes the place of clarification and tertiary filtration found in conventional treatment plants. The use of membranes is of particular interest for expansion of the Central Plant and as a means of increasing effluent quality to meet the ever-tightening standards for discharge into the Las Vegas Wash. An MBR facility at the Central Plant would not be able to take advantage of the small footprint for such facilities since design is currently progressing to construct facilities that will provide full secondary treatment for the ultimate flow to the Central Plant. Membranes in an ultrafiltration configuration would allow the Central Plant to produce an effluent of higher quality than currently possible with the existing filtration and disinfection facilities. CCWRD conducted studies using microfilter (MF) and ultrafilter (UF) membranes and pilot systems provided by several leading manufacturers in the membrane industry. The pilot studies evaluated the use of the membranes on aeration basin mixed liquor (MBR configuration) and clarifier effluent (UF configuration). The paper lists various areas of research needed to evaluate the viability of the membrane process for effluent quality improvement and water reclamation, and for ensuring successful design and operation of planned facilities. Includes figures.