Abstract: The article deals with the possibilities of microwave energy utilization in the hygienization of sewage sludge. It presents the evaluation of the destruction effectiveness of selected microorganisms existing in sewage sludge as a result of microwave heating. Additionally, it describes the influence of the microwave energy dose on the selected physical-chemical indexes of sludge and on its structure. The tests were conducted on secondary sludge and anaerobically digested sludge. Sewage sludge was heated with the microwave dose from 0.6 kJ/g up to 24 kJ/g of sewage. The frequency of microwaves was 2450 MHz. It was proven that microwaves could be applied to the hygienization of sewage sludge. They should be considered a highly efficient method of heating up sludge to the temperature of its pasteurization. During microwave heating, microorganisms existing in sludge are destroyed. The most sensitive ones are Salmonella and Coli bacteria, whereas thermophilic bacteria and Clostridium demonstrate significant resistance to microwaves.
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