The present study investigated the cultivable mesophilic (37 degrees C) and thermophilic (60 degrees C) cellulose-degrading bacterial diversity in a weathered soil-like sample collected from the deep subsurface (1.5 km depth) of the Homestake gold mine in Lead, South Dakota, USA. Chemical characterization of the sample by X-ray fluorescence spectroscopy revealed a high amount of toxic heavy metals such as Cu, Cr, Pb, Ni, and Zn. Molecular community structures were determined by phylogenetic analysis of 16S rRNA gene sequences retrieved from enrichment cultures growing in presence of microcrystalline cellulose as the sole source of carbon. All phylotypes retrieved from enrichment cultures were affiliated to Firmicutes. Cellulose-degrading mesophilic and thermophilic pure cultures belonging to the genera Brevibacillus, Paenibacillus, Bacillus, and Geobacillus were isolated from enrichment cultures, and selected cultures were studied for enzyme activities. For a mesophilic isolate (DUSELG12), the optimum pH and temperature for carboxymethyl cellulase (CMCase) were 5.5 and 55 degrees C, while for a thermophilic isolate (DUSELR7) they were 5.0 and 75 degrees C, respectively. Furthermore, DUSELG12 retained about 40% CMCase activity after incubation at 60 degrees C for 8 h. Most remarkably, thermophilic isolate, DUSELR7 retained 26% CMCase activity at 60 degrees C up to a period of 300 h. Overall, the present work revealed the presence of different cellulose-degrading bacterial lineages in the unique deep subsurface environment of the mine. The results also have strong implications for biological conversion of cellulosic agricultural and forestry wastes to commodity chemicals including sugars.

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In this study we investigated the technical feasibility of convert paper mill sludge into fuel ethanol. This involved the removal of mineral fillers by using either chemical pretreatment or mechanical fractionation to determine their effects on cellulose hydrolysis and fermentation to ethanol. In addition, we studied the effect of cationic polyelectrolyte (as accelerant) addition and hydrogen peroxide pretreatment on enzymatic hydrolysis and fermentation. We present results showing that removing the fillers content (ash and calcium carbonate) from the paper mill sludge increases the enzymatic hydrolysis performance dramatically with higher cellulose conversion at faster rates. The addition of accelerant and hydrogen peroxide pretreatment further improved the hydrolysis yields by 16% and 25% (g glucose / g cellulose), respectively with the de-ashed sludge. The fermentation process of produced sugars achieved up to 95% of the maximum theoretical ethanol yield and higher ethanol productivities within 9h of fermentation.

Within a biorefinery production process, concentrating the sugar-rich hydrolysate stream by evaporation prior to fermentation can enhance the fermentation productivity and reduce downstream product recovery costs. However, fouling of the evaporator surface by soluble and suspended solids within the process steams can become problematic. In this study we analyzed fouling characteristics of an acid pretreated pine wood enzymatic hydrolysate using an annular fouling probe in batch mode at 110, 120, 130, and 140 °C with 0, 10, and 20% total suspended solids based on dry weight/volume. Results showed that the rate of fouling and the induction period for onset of fouling depended strongly on temperature, with a maximum fouling resistance of ∼0.5 m 2 •K/kW experienced at 130 and 140 °C with no suspended solids present. Characterization of the fouling deposits was studied using Fourier transform infrared (FTIR), scanning electron microscopy (SEM), SEM energy dispersive spectroscopy (SEM-EDS), and inductively coupled plasma (ICP) analysis. CaSO 4 was identified as the predominant foulant in the deposits at temperatures >120 °C with 10% total suspended solids. On the basis of the analyses and characterizations, an attempt was made to understand the fouling mechanisms, and fouling reduction techniques were suggested to improve the process efficiencies.

The present paper investigated the technical possibilities of bioethanol production from coffee pulp in a sustainable manner. Coffee pulp is a largely underutilized waste stream and has the potential to become a bioethanol feedstock if processing is economically viable. This study aimed to characterize the chemical composition of coffee pulp with relevance to bioethanol production and to compare results to other bioethanol feedstocks. Based on the total sugar yield, we investigated bioethanol production using AspenPlus simulation software. In the sugar characterization part, total carbohydrates were measured after complete acid hydrolysis of dry pulp, while water-soluble carbohydrates were measured after acid hydrolysis of soxhlet extracted solutions. Moisture, lignin, and ash contents were measured gravimetrically after appropriate heating treatments. The results showed sugar contents, expressed as percentages of dry mass, as follows: 5.8, 5.2, 20.2, 4.2, and 4.7 % for arabinose, galactose, glucose, xylose, and mannose, respectively. Arabinose, galactose, and glucose were the only water-extracted simple sugars, at 1.0, 1.4, and 2.6 % of dry mass, respectively. AspenPlus simulation was based on processing 10,000 ton/day of coffee pulp. The results demonstrated sugar and ethanol yield of 2100 and 1050 ton/day, respectively. This would make annually profit of $0.13 million. The simulation estimated the capital investment cost was about $2 million. In order to satisfy the process economy, the process operation cost must be operated at minimum of $1.87 million annually. The life-cycle analysis showed the net value of energy of the whole process is an economical as well as the balance of CO 2 emission/reduction was on the environmental favor.