Microbiological study of water-softener resins

Microbial identification using effluents backflushed from exhausted urban and rural tank resins and cleaned resins containing the sulfonated copolymer of styrene and divinylbenzene (SDB) were completed, along with microbial assessment of the concentrated stock salt brine. Forty-four different bacterial and fungal genera were identified. Extensive biochemical and animal virulence tests completed on one of the six bacterial salt brine isolates indicated a pathogenic staphylococcal strain. The retention of Staphylococcus aureus, a Flavobacterium sp, and Escherichia coli B bacteriophage was demonstrated both by using the nonexhausted sodium-regenerated resin and by using the same resin exchanged with different mono-, di-, and trivalent cations. Effluent counts completed after bacterial seepage through the resins indicated the Pb(++) exchanged resin removed 55% of the bacteria; Na(+), Fe(++), and Al(+++) removed 31 to 36% and Ca(++) and Cu(++) removed about 10 to 15%. Seventy per cent or more of the bacteriophage was removed by Fe(++), Cu(++), and Al(+++), whereas the Ca(++) and Na(++) cations removed 25 to 31%. Over a 77-day period, nonsterile tap water was passed through bacterial seeded and uninoculated SDB (Na) resin columns. Effluent and resin elution counts demonstrated the growth and survival of 2 different bacteria per column. Increased bacterial retention, survival, and multiplication occurred concomitantly with accumulation of organic and inorganic materials and the Ca(++) and Mg(++) cations from the tap water. Furthermore, microbial elution from resin particles taken from column depths of 1, 8, and 16 cm indicated a bacterial diminution with increasing depths.