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The potential of native as well as acid/alkali pre-treated paddy straw was investigated as inducer substrate for Aspergillus terreus mediated cellulase and xylanase production. The cellulose, hemicellulose and lignin contents of native straw were found to be 25.94%, 17.64% and 15.82%, respectively. However, in the acid/alkali treated straw, cellulose content substantially increased to 48.09%, whereas hemicellulose and lignin contents were reported to be particularly low (11.72%, 5.08%, respectively). The FTIR spectra of native and pre-treated paddy straw further supported the variation in their chemical constituents. A. terreus repertoires were cultivated on native and treated paddy straw under solid state fermentation (SSF) and liquid fermentation (LF) conditions. The LF cultures showed higher cellulase and xylanase activities (Filter Paper cellulase: 45.33 U/L, Carboxymethyl cellulase: 104.75 U/L, β-glucosidase 80.44 U/L, Avicelase: 22.72 U/L and Xylanase: 623.69 U/L) than the respective SSF cultures. Significantly high activities of exoglucanases and endoglucanases were obtained when native straw was used as the growth substrate. The scanning electron micrographs of native and treated straw exhibited disintegration after being subjected to biological treatments, confirming the hyphal adhered growth and production of hydrolysing secretomes by the fungus. Cultivation of A. terreus on native paddy straw in LF culture system resulted in better enzyme production, and holds promise for further optimization. [ABSTRACT FROM AUTHOR]

This paper aims to study dark fermentation (DF) in an upflow anaerobic sludge blanket (UASB) reactor during 20 cycles operating at different hydraulic retention times (HRTs) of 3, 9, and 12 h using substrate wastewater from the food industry and granular inoculum sludge from a treatment plant as codigestion to explore the relationship between substrates, metabolites, and microorganisms to increase the biohydrogen (BioH2) yield. Operation conditions were constant pH 5.50 ± 0.50, T = 35 °C and a carbon-to-nitrogen (C/N) ratio of 30. It is noteworthy that DF with HRT = 9 h obtained the highest yields of organic matter degradation, and BioH2 in biogas (~60%) was attributed to the adjustment of pH and the codigestion buffer capacity. During DF with HRT = 9, the reactor was 11 times more productive with regards to HRT = 3 h, resulting in its performance with a better yield mean (6.22 mmol H2 g COD−1) and productivity (0.35 LH2 L−1 d) than other HRTs with lower records of 0.42 mmol H2 g COD−1 and 0.05 LH2 L−1 d, respectively. The high abundance of native populations (Lactobacillus and Lactococcus) and intrinsic inoculum (Citrobacter) led to the highest BioH2 production. Most of the production of acetic acid ~590 mg L−1 and butyric acid ~450 mg L−1 confirmed that BioH2 is mainly produced by acetic and butyric metabolic routes, and a direct relation with the percentage of retention of total suspended solids was also found, supporting the biodegradation capacity of the process. [ABSTRACT FROM AUTHOR]

Burning corncob for energy requirements caused a huge waste of biomass resources and serious environment pollution. Herein, this study provided a high-value utilization strategy for corncob. Corncob was first pretreated by hydrothermal process. The collected hydrolysates were converted into furfural by a recyclable solid acid with a yield of 52.35%. The pretreated solid was disintegrated into fibers by disc grinding. When corncob fiber addition is below 15%, the ring crush index, tear index, and tensile strength index of the prepared handsheets increased by 1.43 N·m/g, 0.43 mN·m2/g, and 4.66 N·m/g, respectively, compared with that using pure softwood fibers. Besides, corncob fibers were hydrophilically modified with aminosulfonic acid. Water retention value of paper with the modified fiber addition increased by 48.35%. Therefore, this study provided a method of corncob utilization toward two purposes: furfural production and papermaking. [ABSTRACT FROM AUTHOR]

Pleurotus pulmonarius is an economically important edible mushroom well known for the production of several lignocellulolytic enzymes, including polyphenol oxidase (PPO), EC 1.14.18.1. This enzyme can oxidize and hydrolyze phenolic compounds directly associated with the organoleptic and nutritional properties of foods. Thus, the aim of this paper is to produce and characterize the PPO of P. pulmonarius 21 (CCB21). The fungus was able to produce PPO using peach-palm waste and cocoa bean shell as substrates under solid-state fermentation (SSF) in 5 days of cultivation at 90% humidity (3066 ± 232 U/gds). PPO was partially purified with 60% ammonium sulfate and showed a purification rate of 2.1 times and a yield of 53.92%. The enzyme showed an optimum temperature above 45 °C, an optimum pH in the range of 5.5 to 6.5, and proved quite stable, maintaining 86–88% of its activity for up to 120 min under these conditions. PPO had reduced activity in the presence of β-mercaptoethanol, while EDTA, SDS, Al3+, Cu4+, Li4+, and Mg2+ ions increased their activity. The enzyme presented a Vmax of 4166.65 U/min and a Km of 4.16 mM for pyrocatechol. The results obtained suggest that, due to its thermostability and little influence in the presence of ions and reagents tested, the PPO of P. pulmonarius CCB21 can be an alternative for application in different biotechnological and industrial processes. [ABSTRACT FROM AUTHOR]

This is a prime time to develop and implement the "waste to energy" projects across the globe to attain a sustainable environment. Anaerobic digestion (AD) has attracted the scientific community due to its simplicity and easiness to handle, and has the potential to utilize any kind of organic waste to produce a mixture of combustible gases, i.e., biogas and digested slurry, which has further applications in agriculture, solid biofuels, and purification. The process, in turn, reduces the local waste and helps in recycling in a manner that reduces greenhouse gas (GHG) emission, conserves the resources, and establishes a circular economy in the time of undetermined future for the production of energy and safe disposal of the waste. However, the conventional processes encounter with the low biogas yield and long retention time, which discourage the developers. To enhance biogas yield and quality, the momentum of research has increased towards implementation of advanced techniques for development of efficient processes. The present article summarizes the effect of different operational parameters on AD and impact of advanced techniques for enhanced biomethane/biogas. The article further covers the life cycle assessment (LCA) and techno-economic aspect (TCA) of the AD process. This will provide the comparison of different advanced techniques in terms of biomethane/biogas yield. [ABSTRACT FROM AUTHOR]

A growing paddy crop produces large quantities of parboiled rice mill wastewater (PRMWW), which contains several organic and inorganic compounds and nutrients (nitrogen and phosphate). Discharges of the rice industry's wastewater pose a substantial threat to aquatic bodies and the surrounding environment, so an eco-friendly treatment plan is necessary. Parboiling stands out among grain-processing methods due to its numerous nutritional and physical advantages. Fewer literatures have only mentioned about the severity of the organic rich liquid effluents generated after parboiling process. Generating renewable energy from anaerobic digestion (AD) is one of the most environmentally friendly technologies to address the growing energy demands. This study is intended to give a systematic and critical review of the parboiling process, solid and liquid fractions of wastes generated, and various treatment options, with special emphasis on scope of application of AD for treating PRMWW along with energy recovery. The study explains various glitches in the AD processes of PRMWW for biogas generation and also recommends co-digesting PBMWW with other carbonaceous organic substrates for improved digestibility, and to reduce the inhibitions caused by lack of alkalinity, acid accumulation, and pH imbalance. To this end, this literature review seeks to provide a broad overview of knowledge to laypeople, entrepreneurs, and researchers. [ABSTRACT FROM AUTHOR]

Hydrothermal carbonization (HTC) of dairy manure digestate (DMD) was explored in this study. Response surface methodology was used to investigate the influence of temperature, time, and DMD pH on hydrochar properties. Hydrochar obtained in the study exhibited higher heating value (HHV) in the range of 17.5–20.6 MJ kg−1, with energy and hydrochar yields 45.8–72.4% and 57.6–80.1%, respectively. It was demonstrated that temperature was the most significant factor. At higher temperature, the HHV of hydrochar was higher while both energy and hydrochar yields were lower. In particular, hydrochar obtained at temperature ≥ 260 °C had HHV ≥ 20.0 MJ kg−1, which was close to that of lignite and implied its potential as fuel. To gain insights about the fate of various elements during HTC and facilitate overall evaluation of hydrochar, a wide range of elements (30 in total, including macro- and micro-nutrients, as well as heavy metals) was analyzed. Hydrochar had carbon to nitrogen (C/N) ratio between 10 and 12, which was in the suitable range for nutrient availability as soil amendment. Half of the elements remained in the hydrochar, while most of Na, K, and half of S leached into process water, especially at temperature ≥ 260 °C, thus combusting hydrochar can potentially alleviate the slagging and fouling problems associated with direct combustion of dried DMD. The study provided insights for further rational utilization of DMD hydrochar, and integration of HTC into existing on-farm anaerobic digestion was a promising option for reduction disposal of DMD. [ABSTRACT FROM AUTHOR]

Biochar shows great potential for enhancing anaerobic digestion (AD); however, the key factors for this remain unknown. This study evaluated the effects of pyrolysis temperature, porosity, and specific surface area (SSA) on the performance enhancement of biochar. The results showed that pyrolysis temperature played an essential role in enhancing the performance of biochar. The addition of cow manure biochar pyrolyzed at 400 °C (NFC-400) and mushroom bran biochar pyrolyzed at 550 °C (JKC-550) increased methane production by 81.30% and 77.59%, respectively, compared with that by the control. Therefore, NFC-400 showed increased gas production, while JKC-550 showed a shorter fermentation period. The SSA and porosity of biochar positively correlated with the pyrolysis temperature but not with biogas production, which indicated that their influence on AD performance enhancement by biochar was not critical. [ABSTRACT FROM AUTHOR]