The objective of this study was to obtain two types of fuels, i.e., bioethanol and biogas, in a sequential combination of biochemical processes from lignocellulosic biomass (corn straw). Waste from the agricultural sector containing lignocellulose structures was used to obtain bioethanol, while the post-fermentation (cellulose stillage) residue obtained from ethanol fermentation was a raw material for the production of high-power biogas in the methane fermentation process. The studies on obtaining ethanol from lignocellulosic substrate were based on the simultaneous saccharification and fermentation (SSF) method, which is a simultaneous hydrolysis of enzymatic cellulose and fermentation of the obtained sugars. Saccharomyces cerevisiae (D-2) in the form of yeast cream was used for bioethanol production. The yeast strain D-2 originated from the collection of the Institute of Agricultural and Food Biotechnology. Volatile compounds identified in the distillates were measured using gas chromatography with flame ionization detector (GC-FID). CH4 and CO2 contained in the biogas were analyzed using a gas chromatograph in isothermal conditions, equipped with thermal conductivity detector (katharometer) with incandescent fiber. Our results show that simultaneous saccharification and fermentation enables production of bioethanol from agricultural residues with management of cellulose stillage in the methane fermentation process.

The aim of this research is to examine the effect of lignocellulosic biomass detoxification on the efficiency of the methane fermentation process. Both for corn straw and rye straw, the methane yield was expressed per volume of fermentation medium and per mass of volatile solids (VS) added. Lignocellulosic biomass was subjected of thermo-chemical and enzymatic sequential pretreatments. It was found that methane yield was higher by 22% when using the detoxification process. In these variants, CH₄ yield was 18.86 L/L for corn straw and 17.69 L/L for rye straw; while methane yield expressed per mass of VS added was 0.31 m³/kg VS for corn straw and 0.29 m³/kg VS for rye straw. The inclusion of a detoxification step in pretreatments of biomass lignocellulosic increases the degree of organic substance decomposition and enhances methane yield. The results show that a two-step pretreatment, alkaline/enzymatic with a detoxification process, is necessary for the effective generation of high methane concentration biogas.

In this study, two types of fermentation methods: SSF and consolidation SHF/SSF were used for production of acetone-butanol-ethanol (ABE) from corn straw as a feedstock. Clostridium acetobutylicum DSM1731 was used as the fermenting organism. Corn straw was thermochemically pretreated and then hydrolyzed using three types of enzymes. The impact has been investigated on the effect of mineral compounds supplementation ((NH₄)₂SO₄, MgSO₄, (NH₄)₃PO₄) on ABE productivity and butanol content. From the SSF, where mineral salts were supplemented into the fermentation medium, it was found that the maximum ABE and butanol concentrations were 28.35 g/L and 24.03 g/L, respectively, corresponding to a productivities of 0.295 g/L/h (ABE) and 0.250 g/L/h (butanol). In the consolidation SHF/SSF method with mineral compounds supplementation, the maximum ABE and butanol concentrations were 31.35 g/L and 28.64 g/L, respectively, corresponding to productivities of 0.327 g/L/h (ABE) and 0.298 g/L/h (butanol). Compared to control samples, mineral salts supplementation had a positive effect on cellular metabolic activities, leading to an earlier initiation of the solventogenesis stage. In supplemented samples, an increase in the rate of ABE fermentation by Clostridium was observed.

The objective of this study was to evaluate the effect of pretreatment and different technological conditions on the course of ABE fermentation of rye straw (RS) and the composition of volatile compounds in the distillates obtained. The highest concentration of ABE and butanol was obtained from the fermentation of pretreated rye straw by alkaline hydrolysis followed by detoxification and enzymatic hydrolysis. After 72 h of fermentation, the maximum butanol concentration, productivity, and yield from RS were 16.11 g/L, 0.224 g/L/h, and 0.402 g/g, respectively. Three different methods to produce butanol were tested: the two-step process (SHF), the simultaneous process (SSF), and simultaneous saccharification with ABE fermentation (consolidation SHF/SSF). The SHF/SSF process observed that ABE concentration (21.28 g/L) was higher than in the SSF (20.03 g/L) and lower compared with the SHF (22.21 g/L). The effect of the detoxification process and various ABE fermentation technologies on the composition of volatile compounds formed during fermentation and distillation were analyzed.

This study investigated the ability of bacterial strains to neutralize odorous substances from cattle slurry (CS). The research was performed to develop a microbial preparation for the deodorization of CS. Among the strains of bacteria (Bacillus and Pseudomonas) isolated from natural environments, those with the highest ammonia and hydrogen sulfide reduction were selected, and the bacterial consortium was prepared. The biopreparation reduced ammonia by 98% in the unshaken culture and 100% in the aeration culture, after 10 days of incubation (compared to the initial sample). Complete elimination of hydrogen sulfide was noted on day 6 of the deodorization process for both cultures. The microbiological supplementation also had a positive effect on the chemical composition of the slurry, increasing its fertilizer value. The addition of biopreparation to the slurry resulted in a reduced loss of ammonium ions and increased nitrogen concentration by 29%. It was found that the use of the microbial consortium also increased the availability of potassium and phosphorus, which can be used in agricultural production. Nitrogen retention by microorganisms in the slurry increases its organic value and leads to a reduction in the use of mineral fertilizers.