ABSTRACT
While anaerobic digestion is a reliable method that treats the waste and produces renewable biomethane fuel, the necessary sludge in liquid form is difficult to handle due to the constant biogas generation. Therefore, this study investigates the possibility of convective air drying, namely heat pump and hot air circulation oven as preservation methods for anaerobic microbial sludge. Drying was conducted at various temperatures, ranging from 22 to 70°C. The study found that heat pump drying at 22°C resulted in highest chemical oxygen demand removal of 55.3% as well as the least log reduction in methanogens and anaerobes at 1.4 and 2.4, respectively.