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To date, microwave radiation has been successfully used to support the chemical hydrolysis of organic substrates in the laboratory. There is a lack of studies on large-scale plants that would provide the basis for a reliable evaluation of this technology. The aim of the research was to determine the effectiveness of using microwave radiation to support the acidic and alkaline thermohydrolysis of lignocellulosic biomass prior to anaerobic digestion on a semi-industrial scale. Regardless of the pretreatment options, similar concentrations of dissolved organic compounds were observed, ranging from 99.0 ± 2.5 g/L to 115.0 ± 3.0 in the case of COD and from 33.9 ± 0.92 g/L to 38.2 ± 1.41 g/L for TOC. However, these values were more than twice as high as the values for the substrate without pretreatment. The degree of solubilisation was similar and ranged between 20 and 28% for both monitored indicators. The highest anaerobic digestion effects, ranging from 99 to 102 LCH4/kgFM, were achieved using a combined process consisting of 20 min of microwave heating, 0.10–0.20 g HCl/gTS dose, and alkaline thermohydrolysis. For the control sample, the value was only 78 LCH4/kgFM; for the other variants, it was between 79 and 94 LCH4/kgFM. The highest net energy gain of 3.51 kWh was achieved in the combined alkaline thermohydrolysis with NaOH doses between 0.10 and 0.20 g/gTS. The use of a prototype at the 5th technology readiness level made it possible to demonstrate that the strong technological effects of the thermohydrolysis process, as demonstrated in laboratory tests to date, do not allow for positive energy balance in most cases. This fact considerably limits the practical application of this type of solution.

Perform pretreatment is crucial particularly in the case of the use of hard-degradable biomass, the biochemical susceptibility to degradation, for example, alcoholic fermentation is limited. Biomass disintegration processes lead to the destruction of compact structures and release of the organic substance to the phase dissolved in a resultant increase in the concentration of dissolved easily degradable organic substances. Effective pretreatment should meet several criteria, including ensuring the separation of lignin from cellulose, to increase the share of amorphous cellulose, provide a higher porosity substrates, eliminate waste sugars limit formation of inhibitors, minimize energy costs. The aim of this paper is to show the possibilities of using electromagnetic microwave radiation for pre-treatment plant biomass before the fermentation process of alcohol and comparison of the effectiveness of the described method with other commonly used techniques of pre-treatment. The substrate subjected to microwave treatment has a fast rate of hydrolysis and a high content of glucose in the hydrolyzate, which increases the efficiency of the production of bioethanol.

Research to date has mainly focused on the properties and efficiency of the production of selected, individual types of biofuels from microalgae biomass. There are not enough studies investigating the efficiency of the production of all energy sources synthesised by these microorganisms in a single technological cycle. The aim of this research was to determine the possibilities and efficiency of the production of hydrogen, bio-oil, and methane in the continuous cycle of processing T. subcordiformis microalgae biomass. This study showed it was feasible to produce these three energy carriers, but the production protocol adopted was not necessarily valuable from the energy gain standpoint. The production of bio-oil was found to be the least viable process, as bio-oil energy value was only 1.3 kWh/MgTS. The most valuable single process for microalgae biomass conversion turned out to be methane fermentation. The highest specific gross energy gain was found after applying a protocol combining biomass production, hydrogen biosynthesis, and subsequent methane production from T. subcordiformis biomass, which yielded a total value of 1891.4 kWh/MgTS. The direct methane fermentation of T. subcordiformis biomass enabled energy production at 1769.8 kWh/MgTS.

One of the most effective technologies involving the use of lignocellulosic biomass is the production of biofuels, including methane-rich biogas. In order to increase the amount of gas produced, it is necessary to optimize the fermentation process, for example, by substrate pretreatment. The present study aimed to analyze the coupled effects of microwave radiation and the following acids: phosphoric(V) acid (H3PO4), hydrochloric acid (HCl), and sulfuric(VI) acid (H2SO4), on the destruction of a lignocellulosic complex of maize silage biomass and its susceptibility to anaerobic degradation in the methane fermentation process. The study compared the effects of plant biomass (maize silage) disintegration using microwave and conventional heating; the criterion differentiating experimental variants was the dose of acid used, i.e., 10% H3PO4, 10% HCl, and 10% H2SO4 in doses of 0.02, 0.05, 0.10, 0.20, and 0.40 g/gTS. Microwave heating caused a higher biogas production in the case of all acids tested (HCl, H2SO4, H3PO4). The highest biogas volume, exceeding 1800 L/kgVS, was produced in the variant with HCl used at a dose of 0.4 g/gTS.

The aim of this study was to determine the effect of sorption of Basic Red 46 (BR46) dye by lignocellulosic biomass on the susceptibility of the sorbed waste to anaerobic decomposition by anaerobic digestion. The research material used in the experiment consisted of two types of biomass: stalks with leaves and inflorescences after mowing Canadian goldenrod (Solidago canadensis L.) (GB), and rapeseed hulls (RHs) after oil pressing. During the anaerobic decomposition of RHs, 732.30 NmL/gVS and 646.63 NmL/gVS of methane were obtained from the non-sorbed substrate and the plant material after dye sorption, respectively. Similarly, in the variants using Canadian goldenrod, the production was 220.70 NmL/gVS and 183.20 NmL/gVS. The GB sorbent sorbed 34% more BR46 dye than the RH sorbent, which is likely to have resulted in the accumulation of VFA and contributed to the partial inhibition of methane production. In light of the obtained results and the literature data, it is concluded that there is a possibility of effective use of dye sorption waste for methane production.

Hydrogen is an environmentally friendly biofuel which, if widely used, could reduce atmospheric carbon dioxide emissions. The main barrier to the widespread use of hydrogen for power generation is the lack of technologically feasible and—more importantly—cost-effective methods of production and storage. So far, hydrogen has been produced using thermochemical methods (such as gasification, pyrolysis or water electrolysis) and biological methods (most of which involve anaerobic digestion and photofermentation), with conventional fuels, waste or dedicated crop biomass used as a feedstock. Microalgae possess very high photosynthetic efficiency, can rapidly build biomass, and possess other beneficial properties, which is why they are considered to be one of the strongest contenders among biohydrogen production technologies. This review gives an account of present knowledge on microalgal hydrogen production and compares it with the other available biofuel production technologies.

These studies were designed to determine the optimum parameters of respirometric susceptibility test substrates for anaerobic digestion plant for example silage Sida. Biochemical dynamics of organic material determined by measuring blood OxiTop. The experiment was conducted in three series of research, different load measuring cells, the initial charge of organic compounds, a series of I – 5 gd.o.m/l, Series II – 10 gd.o.m/l, Series III – 20 gd.o.m/l. Fermentation was carried out in mesophilic conditions for 20 days in an anaerobic reaction chambers inoculated with activated sludge. Achieved a maximum of 3500 ml of biogas in series III, the least biogas created in Series I, which introduced the smallest load of organic compounds. Based on the results of the biogas production rate was determined in a series I was on y = 365 ml/gd.o.m, in the second series was y = 319 ml/gd.o.m. and the series III y = 278 ml/gd.o.m. Measuring the quality of the resulting biogas pointed to the relationship between the content of methane in the biogas with an initial charge of organic matter introduced into the reaction chamber, the methane content of the biogas ranged from 37% in the third series of up to 48% in the series and the experiment.

The characteristics of excess aerobic granular sludge, related to its structure and chemical composition, limit the efficiency of anaerobic digestion. For this reason, pre-treatment methods and compositions with other organic substrates are used. In earlier work, no attempt was made to intensify the methane fermentation of the excess aerobic granular sludge by adding fatty waste materials. The aim of the research was to determine the effects of co-digestion of pre-hydrodynamically cavitated aerobic granular sludge with waste fats on the efficiency of methane fermentation under mesophilic and thermophilic conditions. The addition of waste fats improved the C/N ratio and increased its value to 19. Under mesophilic conditions, the highest effects were observed when the proportion of volatile solids from waste fats was 25%. The amount of biogas produced increased by 17.85% and CH4 by 19.85% compared to the control. The greatest effects were observed in thermophilic anaerobic digestion at 55 °C, where a 15% waste fat content in volatile solids was ensured. This resulted in the production of 1278.2 ± 40.2 mL/gVS biogas and 889.4 ± 29.7 mL/gVS CH4. The CH4 content of the biogas was 69.6 ± 1.3%. The increase in biogas and CH4 yield compared to pure aerobic granular sludge anaerobic digestion was 34.4% and 40.1%, respectively. An increase in the proportion of waste fats in the substrate had no significant effect on the efficiency of methane fermentation. Strong positive correlations (R2 > 0.9) were observed between biogas and CH4 production and the C/N ratio and VS concentration.