Effects of High Temperature & Pressure Pretreatment Process on Methane Production from Cyanobacteria

Abstract

In this study, Desertifilum tharense cyanobacteria, which has energy generation potential, was firstly isolated from the water sources from Denizli/Turkey, the culture-specific parameters were identified, characterization analyses were performed, and the production in photoreactors under laboratory conditions was performed. D. tharense cyanobacterium was subjected to a high temperature–pressure pretreatment process (HTPP) to increase methane production efficiency, and the pretreatment process was optimized for methane production. D. tharense had a total carbon (C) content of 50.2% and total organic carbon content (TOC) of 48.9%. The biochemical methane potential (BMP) of the raw D. tharense sample was measured as 261.8 mL methane (CH4) per gram of volatile solids (VS). In order to investigate the effects of HTPP and to determine the optimum process conditions, Central Composite Design (CCD) approach-based Response Surface Methodology (RSM) was used. BMP values of the samples treated with HTTP were measured in the range of 201.5–235 mLCH4 gVS−1 and lower than the raw sample. These results revealed that the HTPP is not suitable for the production of biofuel methane from D. tharense. The optimization of the HTPP was carried out by Design Expert software. For maximum BMP production, the software proposed a reaction temperature of 200 °C and a reaction time of 20 min as optimum conditions. With the proposed model, it was estimated that 227.1 mLCH4 g VS−1 methane could be produced under these conditions, and 211.4 mLCH4 g VS−1 methane was produced in the validation experiment. It was determined that D. tharense cyanobacterium could be used as a suitable biomass source for methane production. However, it was not necessary to use the HTTP as a pretreatment process prior to the methane production.