analysis the existence of heterotrophic bacteria in active water desalination plant output of kashan city, iran

abstract aims: one of the consequences of taking ground water into surface is changing its chemical quality, specially increasing the concentration of dissolved salts. this research was performed in order to analyze growth possibility of heterotrophic bacteria in the membrane of active desalination plants in kashan city, iran. instrument & methods: this descriptive cross-sectional study was done on water output of 20 active desalination plants in 2013 in kashan city, iran and 200 specimens of input and output water was randomly extracted from desalination plants. awareness and education level of system operators, filter changing intervals, hpc of input and output water and chlorine concentration of input and output water were measured and recorded. obtained data were analyzed statistically with spss 18 software using one-way anova, chi-square, mcnemar and one-sample t tests. findings: there was a significant relation between the interval time and output hpc level of the plants (p<0.05). the mean number of hpc was decreased from 16.7±24.5cfu/ml in input water to 14.4±23.7cfu/ml in output water which was not significant (p>0.05). the mean concentration of chlorine in samples of 20 desalination plants was 0.76±0.44mg/l in input water and 0.64±0.52mg/l in output water (p>0.05). level of awareness had significant relation with the output water pollution with hpc (p<0.05) but their education level had no such relation (p>0.05). conclusion: the mean level of hpc pollution in output water of desalination plants of kashan city, iran, is much less than who standards.