Background: Wastewater treatment is aimed at removing impurities present in wastewater in the form of floating material, suspended solids, biodegradable organics and elimination of pathogens., but there needs to be regular monitoring to see working capability and overall efficiency.
Methods: Microbiological examination of samples was conducted as promptly as possible (within 24 hours) after collection or were stored at 4°C in a refrigerator until use. A multiple tube fermentation technique or Most Probable Number (MPN) technique (APHA, 1998) was used to determine bacterial indicators as Total Coliforms (TC), Faecal Coliforms (FC) and Faecal Streptococci (FS) according to standard methods as described in APHA (1998). Student t-test and Chi-square tests were used to compare the data.
Conclusions: In order to assess the microbial evaluation and effect of season on Hazratbal sewage treatment plant, a study was carried out during 2010-2011. The results showed significant (p<0.05) differences in total coliform between wastewater (raw) and treated wastewater (final) from the sewage treatment plant. The comparison of percentage efficiency rate of the treatment plant showed significant differences among different microbial parameters. Removal efficiency rate was greater in Faecal Coliform (72.33%) and least for Faecal Streptococci (38.70%). The results showed significant variation among different seasons (p<0.05). It seems from the data that season play an important role in predicting the efficiency of this sewage treatment plant. The greater efficiency rate was observed in summer and autumn months and least in winters. Finally it was concluded that although Hazratbal sewage treatment plant succeeded in removing some pathogens from the influents, but it is little less than the required and efficiency rate did not reach to the level of national and international standards and as such discharge of effluent from this sewage treatment plant into the lake is not suitable.
Keywords: Microbial evaluation; faecal coliform; faecal streptococci; total coliforms