GROWTH OF SALMONELLA SPP AND VIBRIO-CHOLERAE IN RECONDITIONED WASTE-WATER

Many food-processing plants are looking to increase the use of recondi tioned water beyond the currently approved uses for initial cleaning ( vegetables) and scalding water (meat and poultry). The preliminary sur vey showed that the reconditioned water from a local meat plant could support bacterial growth. The growth potential of Salmonella spp. and Vibrio cholerae (starting level of 3 to 4 log CFU/ml) in the reconditi oned wastewater from this plant (with and without added thiosulfate) w as studied at temperatures from 5 to 42 degrees C. Bioassays for the a ssimilable organic carbon and coliform growth response suggest that th is reconditioned water contained sufficient nutrients to support bacte rial growth. Both pathogens grew in the unchlorinated reconditioned an d chlorinated reconditioned water containing 10 mg of sodium thiosulfa te per mi to neutralize the residual chlorine. Cell counts declined ra pidly in chlorinated water without thiosulfate. Tile results of this s tudy emphasized the importance of maintaining residual chlorine levels (0.2 mg/liter) in both reconditioned and potable waters to prevent pa thogen growth.