Duration of the thermophilic composting of sewage sludge and vegetable waste in terms of three different technologies

Abstract

Thermophilic stage during composting process is characterized by natural rise of temperature and high rate of organic matter biodegradation, due to high rate of microbial activity. This stage is very important for elimination of pathogenic microorganisms and is characterized by high rate of oxygen demand. After this stage, starts ripening stage, a period of low microbial activity and low need of aeration. So, the period of thermophilic stage has consequences in the size of composting facilities and biological reactors which has direct relation with total coast of the process. This paper presents results of monitoring of similar mixtures of sewage sludge and plant residues during composting process using the windrow system, static pile system and biological reactor system, and period of each thermophilic stage. In windrow system thermophilic stage had around 90 days of duration , and in the static pile ( aerated) the thermophilic stage was 20 days and around 8 days in the biological reator.