AWWA MTC69787

This powerpoint presentation begins by providing a brief overview of a reverse osmosis (RO) bench-scale unit and short/long term hydraulic performances. Membrane autopsy, chemical characterization, and bacteria and phytoplankton characterization are presented. Presentation objective is to develop and validate methods for a RO desalination membrane. Dominant groups were identified by sequencing of 16S rRNA genes, and specific DNA probes will be designed. Diversity changes over the membrane surface were monitored by fingerprinting of 16S rRNA genes (SSCP analysis). The dominant organisms responsible for fouling will be enumerated by fluorescent in situ hybridization techniques using specific probes and confocal microscopy. Topics presented include: bacterial diversity and activity; membrane autopsy protocol; methods used to extract nucleic acids prior to PCR amplification; membrane DNA/RNA Extraction and 16S PCR amplification; effect of DNA extraction method on bacterial diversity as monitored by SSCP analysis; and, analysis of bacterial diversity by fluorescent in situ hybridization (CARD-FISH). Presentation conclusions indicate: no significant decrease of RO hydraulic performances, but presence of foulants on RO membranes, mainly bacteria, aluminosilicates and organics (proteins and carbohydrates); additional resistance negligible in comparison with the intrinsic membrane resistance; for long term operation, the biofilm growth provide significant additional resistance due to the decrease in the cake porosity; DNA/RNA extraction methods were satisfactory; first in situ hybridization trial using a general probe on fouled membranes revealed distinct cell morphologies and many clusters of bacteria; and, the enumeration of cells might be difficult due to the intrinsic irregularity of membrane surface. Includes figures.