Pulsed electric field: An emerging pretreatment technology in a biogas production.

This review focuses on current status of pulsed electric field (PEF) technology and its implementation in biogas production. First, basic principles of PEF and a schematic overview of typical PEF processing system were provided. Thereafter, lab- and pilot-scale PEF pretreatments of sludge with subsequent anaerobic digestion (AD) were provided. Furthermore, PEF technology, as an emerging technology for the lignocellulose (LC) pretreatment in biogas production which is still predominantly used at lab-scale, was outlined. Eventually, conclusion together with future perspectives and challenges were outlined.

Natural Communities of Microalgae and Cyanobacteria from Eutrophicated Waters as Potential Co-substrates for Small-scale Biogas Production.

The purpose of this study was to determine the biogas potential of biomass produced by microbiotic communities developed under natural conditions in freshwater systems such as ponds incorporated into agricultural landscapes. Natural communities of microalgae were collected from a small eutrophicated pond where dominant species were euglenoids (Lepocinclis species). Cyanobacterial communities dominated by Lyngbya species were taken from a domestic aquarium and cultivated under makeshift conditions. Experiments were done using dairy cow manure (DCM) for codigestion with natural communities of microalgae (MDM) and cyanobacteria (CDM) and conducted during 42 days in thermophilic regime. The total biogas yields were 421.40 and 383.34 mL/g volatile solids (VS), while the average methane contents were 63.97 and 64.06% for MDM and CDM, respectively. Our results indicate that the natural communities of microalgae and cyanobacteria used in this study possess the potential for biogas production, which is, in comparison with particular algal and cyanobacterial strains cultivated under strictly controlled cultivation conditions, more promising. Therefore, this study aims to motivate further investigations into the diverse natural communities of microalgae and cyanobacteria and pretreatments that are environmentally friendly and cost-effective and will eventually enhance small-scale biogas production on agricultural farms.

Electroporation of harvest residues for enhanced biogas production in anaerobic co-digestion with dairy cow manure.

The aim of this research was to develop a method for pretreatment of lignocellulose (LC) substrates (harvest residues (HR)) via electroporation (EP) for the purpose of improving the biogas production process. In addition, pretreated LC substrates were analyzed by scanning electron microscopy (SEM) and the energy balance of the total process was calculated. After the conducted pretreatment and anaerobic co-digestion with dairy cow manure (DCM), the statistical data analysis showed statistically significant differences in biogas and/or methane yield for all three LC substrates and their fractions. It was concluded that, after the pretreatment of LC substrates via EP, it is possible to improve the anaerobic co-digestion process and to achieve positive energy balance of the total process.

Thermal Pretreatment of Harvest Residues and Their Use in Anaerobic Co-digestion with Dairy Cow Manure.

Several batch experiments were conducted on the anaerobic co-digestion of dairy cow manure (DCM) with three harvest residues (HR) (soybean straw, sunflower stalks, and corn stover). The influence of thermal pretreatment of HR on biogas production was investigated, where the HR were thermally pretreated at two different temperatures: T = 121 °C and T = 175 °C, during t = 30 and t = 90 min, respectively. All anaerobic co-digestion batch experiments were performed simultaneously under thermophilic regime, at T = 55 °C. Biogas and methane yields were significantly improved in experiments performed with corn stover thermally pretreated at 175 °C for 30 min (491.37 cm3/g VS and 306.96 cm3/g VS, respectively), if compared to experiments performed with untreated corn stover. The highest VS and COD removal rates were also observed in the same group of experiments and were 34.5 and 50.1%, respectively. The highest biogas and methane yields with soybean straw (418.93 cm3/g VS and 261.44 cm3/g VS, respectively) were obtained when soybean straw pretreated at 121 °C during 90 min. The highest biogas and methane yields with sunflower stalk (393.28 cm3/g VS and 245.02 cm3/g VS, respectively) were obtained when sunflower stalk was pretreated at 121 °C during 90 min.