Microbiological and physico-chemical composition of sewage sludge derived from the food industry / Skład mikrobiologiczny i fizykochemiczny osadów ściekowych pochodzących z przemysłu spożywczego

The aim of the study was to analyze the microbiological and physico-chemical composition of sewage sludge from the food industry. The research material was dewatered sewage sludge with and without lime, derived from the water and drink production plant in the Opole region, obtained for testing in March 2013. Physico-chemical analysis included the determination of: pH, temperature of sludge, sedimentation properties, the dry weight, mineral substances, biogenic elements and heavy metals. Microbiological evaluation included quantitative and qualitative determination of mesophilic, psychrophilic and potentially pathogenic microorganisms. Sewage sludge with and without lime characterized similar physico-chemical parameters. However, the addition of lime to the sludge led to a change in ratios of different groups of microorganisms. In the sludge with lime, we observed reduction in the number of mesophilic bacteria and yeast, and total inhibition of psychrophilic bacteria and fungi. Knowledge of the physico-chemical parameters and microbiological composition of the sewage sludge is needed to determine the directions of their development