Technologies for removal of antibiotic resistant bacteria and antibiotic resistance genes from sewage sludge

Excessive use of antibiotics in addressing both human and animal ailments lead to their discharge to the environment. This facilitates increased exposure of microbes to antibiotics and the spread of Antibiotic Resistant Genes (ARGs) in soil, groundwater, surface water and sediments. One such exposure, especially of bacteria to antibiotics at very high concentration is prevalent in effluent water and sludge from wastewater treatment plants (WWTPs). Thus, WWTPs are considered major hotspots for dissemination of ARGs. To combat this spread, several secondary and tertiary treatment methods both for wastewater and sludge alike are incorporated in the process flow of the WWTPs. These technologies include various hygienization and disinfection processes for the elimination of pathogens as well as the antibiotic resistant organisms. In this Ph.D. project, we will test the effectiveness of technologies for sanitation of sewage sludge in terms of their ability to remove antibiotic resistance. The technologies studied include: 1) Thermal treatment processes, 2) Chemical treatment, and other 3) Additional treatment processes. For all technologies, process conditions will be sought to ensure the removal of antibiotic resistant bacteria (ARB) and ARGs. As test sludges, sludges from thermophilic and mesophilic anaerobic stabilization, sludges after aerobic stabilization, sludges from fat separators, and wastes exported to wastewater treatment plants will be studied. Further, we will look to quantify the efficiency of removal of ARB and ARGs that enter the environment through the application of sewage sludge in agriculture. The aim of the project is to propose parameters of sludge disinfection processes that safely ensure the removal of ARB and ARGs so that sludge can be used as fertilizer.