New factor (quality of temperature) affecting directly the biogas production and solved by solar heating models

Abstract

This research focuses on a new parameter that can directly affect the biogas production. The study was carried out in two groups under two different temperature conditions. The first group, outside the door (allow the digester temperature to change according to ambient temperature), and the second is in the control room that support the digester to keep the temperature in balance without fluctuation, however there is no source of heating. Each group has three digesters with different total solid (TS) i.e, 6, 8 and 10% TS. The result shows that the average of the temperatures inside the digesters of the outdoor group (first group) was 29.39°C (52.2°C maximum, and 12°C minimum) compared with the control room group (second group), which was 25.7°C (30°C maximum, and 20°C minimum). However, the temperature in the first group was higher, but biogas production of the second group was more constant and higher. This phenomenon is due to the gas production been significantly affected by variations of temperature inside the digester during the daytime in the first group. This problem could explain the reason of changing the biogas production in biogas digester that does not use any heat source (lagoon, underground digester, etc.). As the temperature decreases sharply, the gas production also decreases sharply. Accordingly, it is difficult to generate large amounts of gas with stable performance without keeping the temperature inside the digesters in balance throughout the whole fermentation days, even though there is no heating source. Therefore, we recommended one of three solar heating models that is able to keep it in balance temperature and, therefore increase the performance of fermentation without daily additional costs.