This research aims to study the degree and duration of the thermophilic phase by changing the available carbon source to reduce the period of composting within a fully equipped reactor with a controllable stirring and ventilation unit and its impact on the quality of the produced compost. The first stage analysis of raw materials used physically and chemically. Then determined the need for nitrogen supplements and the appropriate particle size of the nutrient.
Initially, the experiment contained six treatments obtained by mixing agricultural plant residues (pepper and broccoli) with cow manure in different mixing ratios: 95:5, 90:10, 85:15, 60:40, 50:50 and 10:90 respectively. Then from the resulting data of the first experiment, the mixing ratios of 50:50 and 60:40 were chosen as the best ratios that showed the highest temperatures, then other parameters were added to them, which are (20 ml used oil and 20% compost as inoculum).
The addition of used oil (50:50) resulted in the record of the highest temperature of 59°C and the thermophilic phase lasted for 5 days. However, with ratios (60:40) recorded 56°C and the thermophilic phase lasted for 4 days and the composting process was completed within 18 days. While when the inoculum was added with (50:50) ratios, the temperature reached 52.7°C and with (60:40) it reached 51°c and the compost was completed ripening after 25 days from the beginning of the experiment.