Design, construction, and operation of helical tubular biogas reactor: Dairy manure application example

In this study, a low cost helical tubular biogas reactor (HTBR) was built for the production of biogas from dairy manure. The performance indicators of the HTBR reactor were determined. The data obtained from the HTBR reactor were compared with the continuous stirred tank reactor (CSTR) operated under the same conditions. Trials were carried out at ambient temperature and no heating was performed. In this experiment, two types of reactors were loaded with two different dry matter contents (6% and 8%) and four different organic loading rates (OLR) (2.5, 3.5, 3.3, and 4.6 kg OM/m3 day). Trials lasted 20 days under stable regime. The results on average daily biogas production showed that the values obtained from the CSTR trials were found to be 8.05%, 11.79%, 8.07%, and 10.78% higher than those obtained from the HTBR reactor based on OLR of 2.5, 3.5, 3.3, and 4.6 kg OM/m3 day, respectively. Cumulative methane production in CSTR reactors ranged from 357.86 to 460.56 NL and in HTBR reactor from 318.57 NL to 395.50 NL. The highest methane production in HTBR reactor was obtained with condition of 8% dry matter content with OLR of 4.6 OM/m3. As a result, when CSTR and HBTR reactors operated under similar operating conditions (no heating) were compared in terms of energy production and consumption, it was found that HBTR reactors had no energy expenditure and CSTR reactors had energy consumption due to mixing. It was determined that HTBR type reactors which are considered as low cost design produced less biogas than CSTR type reactors.