ABSTRACT
Various sources of antibiotic-contaminated wastewater, including hospitals, households, and pharmaceutical manufacturing facilities, can discharge antibiotic-resistant genes (ARGs) into sewage sludge. Antibiotic overuse results in many antibiotic-resistant bacteria (ARB) and ARGs. Transduction, conjugation, and transformation are all methods of horizontal gene transfer for transferring ARGs between bacteria. Wastewater treatment plants (WWTPs) are important sources and sinks of ARGs, as well as players in their generation, treatment, and distribution. This chapter summarizes the ARGs types, concentrations, and factors in WWTPs, investigates the sources of ARGs in wastewater, compares the removal efficiencies of different treatment processes on ARGs, and analyses the potential risks of ARGs accumulation in the effluent, sludge, and air emission. Culture-independent molecular biology techniques are widely used to detect AB resistance in sludge. The presence, as well as identification of ARGs in microbes, is frequently based on genetic information taken from samples. Thus, to detect ARGs using culture-independent molecular biology techniques, RNA and/or DNA were extracted from sludge samples using extraction kits, i.e. RNeasy Mini Kit for RNA and Fast DNA™ Spin Kit for DNA. Because RNA is unstable, the RNA extracted is usually synthesized into cDNA and then used for ARG detection via RT-qPCR, metagenomics, or DNA microarray. To minimize the spread of antibiotic resistance, water treatment, antibiotic use, and sludge management practices must all be improved. This chapter systematically summarizes and compares the fate of ARGs due to various sludge digestion strategies and in combination with relevant pretreatment technologies and additives.
