• Energy Research

Abstract This work investigated the improvement of ethanol production by engineered ethanologenic Escherichia coli to express the hemoglobin from the bacterium Vitreoscilla (VHb). Ethanologenic E. coli strain FBR5 and FBR5 transformed with the VHb gene in two constructs (strains TS3 and TS4) were grown in cheese whey (CW) medium at small and large scales, at both high and low aeration, or with whey powder (WP) or sugar beet molasses hydrolysate (SBMH) media at large scale and low aeration. Culture pH, cell growth, VHb levels, and ethanol production were evaluated after 48 h. VHb expression in TS3 and TS4 enhanced their ethanol production in CW (21–419%), in WP (17–362%), or in SBMH (48–118%) media. This work extends the findings that “VHb technology” may be useful for improving the production of ethanol from waste and byproducts of various sources.

This study describes an efficient and reusable process for ethanol production from medium containing whey powder, using alginate immobilized ethanologenic E. coli strains either expressing (TS3) or not expressing (FBR5) Vitreoscilla hemoglobin. Reuseabilities of the FBR5 and TS3 strains were investigated regarding their ethanol production capacities over the course of 15 successive 96-h batch fermentations. The ethanol production was fairly stable over the entire duration of the experiment, with strain TS3 maintaining a substantial advantage over strain FBR5. Storage of both strains in 2 different solutions for up to 60 d resulted in only a modest loss of ethanol production, with strain TS3 consistently outperforming strain FBR5 by a substantial amount. Strains stored for 15 or 30 d maintained their abilities to produce ethanol without dimunition over the course of 8 successive batch fermentations; again strain TS3 maintained a substantial advantage over strain FBR5 throughout the entire experiment. Thus, immobilization is a useful strategy to maintain the advantage in ethanol productivity afforded by expression of Vitreoscilla hemoglobin over long periods of time and large numbers of repeated batch fermentations, including, as in this case, using media with food processing wastes as the carbon source.

A high load of inorganics in raw lignocellulosic biomass is known to inhibit the yield of bio-oil and alter the chemical reactions during fast pyrolysis of biomass. In this study, palm kernel shell (PKS), an agricultural residue from palm oil production, and two other woody biomass samples (mahogany (MAH) sawdust and iroko (IRO) sawdust) were pretreated with distilled water or an acidic solution (either acetic, formic, hydrochloric (HCl) or sulfuric acid (H2SO4)) before fast pyrolysis in order to investigate its effect on the primary products and pyrolysis reaction pathways. The raw and pretreated PKS, MAH and IRO were pyrolysed at 600 °C and 5 s with a micro-pyrolyser connected to a gas chromatograph–mass spectrometer/flame ionisation detector (GC-MS/FID). Of the leaching solutions, HCl was the most effective in removing inorganics from the biomass and enhancing the primary pyrolysis product formed compared to the organic acids (acetic and formic acid). The production of levoglucosan was greatly improved for all pretreated biomasses when compared to the original biomass but especially after HCl pretreatment. Additionally, the relative content of the saccharides was maximised after pretreatment with H2SO4, which was due to the increased production of levoglucosenone. The relative content of the saccharides increased by over 70%. This increase may have occurred due to a possible reaction catalysed by the remaining acid in the biomass. The production of furans, especially furfural, was increased for all pretreatments but most noticeable when H2SO4 was used. However, the relative content of acids and ketones was generally reduced for PKS, MAH and IRO across all leaching solutions. The relative content of the phenol-type compound decreased to a large extent during pyrolysis after acid pretreatment, which may be attributed to dehydration and demethoxylation reactions. This study shows that the production of valuable chemicals could be promoted by pretreatment with different acid solutions.

The sidestreams produced during fish processing end in a separation tank where the resulting fractions follow biogas production or wastewater treatment. These streams can alternatively be used for production of protein-rich fungal biomass for e.g. fish feed applications, a product in increasing demand. These streams and upper streams originated during fish processing were used in this study for production of biomass using the edible filamentous fungus Rhizopus oryzae. The COD of the streams varied between 11 and 54 kg/m3 and, after fungal conversion of organic matter into protein-rich biomass and separation, a reduction of 34-69% was achieved. The stream origin had an effect on the final production and composition of the fungal biomass: 480 kg of biomass containing 33% protein per ton of COD were produced after cultivation in the separation tank streams, while 220 kg of biomass containing 62% protein per ton of COD were produced in upper sidestreams with lower amounts of suspended solids. Changing the initial pH (6.1-6.5) to 5.0 had a negative influence on the amount of biomass produced while medium supplementation had no influence. Thus, fish processing sidestreams can be diverted from biogas production and wastewater treatment to the production of protein-rich biomass for feed applications.

Les matériaux lignocellulosiques sont des ressources précieuses dans les technologies de bioprocédés d'aujourd' hui ; cependant, leur récalcitrance est un obstacle majeur dans l'industrie en ce qui concerne leur conversion en produits microbiens. À cette fin, dans cette étude, la synthèse des liquides ioniques (IL), sa fonction dans l'hydrolyse des matériaux lignocellulosiques, sa biochimie et ses éventuels effets toxiques ont été étudiés. En outre, la bioconversion des matériaux lignocellulosiques prétraités avec des liquides ioniques en biocarburants (bioéthanol, biobutanol, biogaz et hydrogène) et diverses substances biochimiques est discutée en détail. Pour cela, l'accent est mis sur le potentiel des IL pour l'intégration industrielle et l'utilisation dans les réacteurs à grande échelle. Les IL offrent des avantages significatifs en raison de leur potentiel de facilité d'utilisation et de leurs caractéristiques telles que la récupération et la réutilisation après prétraitement. Cependant, il existe des problèmes économiques et techniques qui doivent être résolus pour développer les IL dans les systèmes industriels et augmenter leur potentiel d'utilisation. Pour surmonter ces problèmes et la facilité d'utilisation des technologies IL dans l'industrie, des analyses techno-économiques ont été examinées et comparées aux processus traditionnels. Los materiales lignocelulósicos son recursos valiosos en las tecnologías de bioprocesos actuales; sin embargo, su recalcitrancia es una barrera importante en la industria con respecto a su conversión en productos microbianos. Para ello, en este estudio se investigó la síntesis de líquidos iónicos (ILs), su función en la hidrólisis de materiales lignocelulósicos, su bioquímica y posibles efectos tóxicos. Además, se analiza en detalle la bioconversión de materiales lignocelulósicos pretratados con líquidos iónicos en biocombustibles (bioetanol, biobutanol, biogás e hidrógeno) y diversos bioquímicos. Para ello, la atención se centra en el potencial de las IL para la integración industrial y el uso en reactores a gran escala. Los IL ofrecen ventajas significativas debido a su potencial de facilidad de uso y sus características como la recuperación y la reutilización después del pretratamiento. Sin embargo, existen problemas económicos y técnicos que deben resolverse para expandir las IL en los sistemas industriales y aumentar su potencial de uso. Para superar estos problemas y la usabilidad de las tecnologías de IL en la industria, se han examinado y comparado los análisis tecnoeconómicos con los procesos tradicionales. Lignocellulosic materials are valuable resources in today's bioprocess technologies; however, their recalcitrance is a major barrier in industry regarding their conversion to microbial products. For this purpose, in this study, the synthesis of ionic liquids (ILs), its function in the hydrolysis of lignocellulosic materials, its biochemistry and possible toxic effects were investigated. In addition, the bioconversion of lignocellulosic materials pretreated with ionic liquids to biofuels (bioethanol, biobutanol, biogas and hydrogen) and various biochemicals is discussed in detail. For this, the focus is on the potential of ILs for industrial integration and use in large-scale reactors. ILs offer significant advantages due to their potential for ease of use and their features such as recovery and reuse after pretreatment. However, there are economic and technical problems that need to be solved to expand ILs in industrial systems and increase their use potential. To overcome these problems and the usability of ILs technologies in industry, techno-economic analyses has been examined and compared with traditional processes. تعد المواد الليجنوسليلوزية موارد قيمة في تقنيات العمليات الحيوية اليوم ؛ ومع ذلك، فإن عنادها يمثل حاجزًا رئيسيًا في الصناعة فيما يتعلق بتحويلها إلى منتجات ميكروبية. لهذا الغرض، في هذه الدراسة، تم التحقيق في تخليق السوائل الأيونية (ILs)، ووظيفتها في التحلل المائي للمواد الليجنوسليلوزية، والكيمياء الحيوية والآثار السامة المحتملة. بالإضافة إلى ذلك، تتم مناقشة التحويل الحيوي للمواد الليجنوسليلوزية المعالجة مسبقًا بالسوائل الأيونية إلى وقود حيوي (الإيثانول الحيوي والبيوتانول الحيوي والغاز الحيوي والهيدروجين) والعديد من المواد الكيميائية الحيوية بالتفصيل. لهذا، ينصب التركيز على إمكانات ILs للتكامل الصناعي والاستخدام في المفاعلات واسعة النطاق. توفر ILs مزايا كبيرة بسبب قدرتها على سهولة الاستخدام وميزاتها مثل التعافي وإعادة الاستخدام بعد المعالجة المسبقة. ومع ذلك، هناك مشاكل اقتصادية وتقنية تحتاج إلى حل لتوسيع نطاق ILs في الأنظمة الصناعية وزيادة إمكانات استخدامها. للتغلب على هذه المشاكل وقابلية استخدام تقنيات ILS في الصناعة، تم فحص التحليلات التقنية والاقتصادية ومقارنتها بالعمليات التقليدية.

In this review article, discuss the many ways utilized by the dairy sector to treat pollutants, emphasizing their influence on the quality and efficiency with which contamination is removed. It focuses on biotechnology possibilities for valorizing dairy waste in particular. The findings revealed that dairy waste may be treated using physicochemical, biological, and biotechnological techniques. Notably, this article highlighted the possibility of dairy waste being used as a feedstock not only for the generation of biogas, bioethanol, biohydrogen, microbial fuel cells, lactic acid, and fumaric acid via microbial technology but also for the production of biooil and biochar by pyrolysis. In addition, this article critically evaluates the many treatment techniques available for recovering energy and materials from dairy waste, their combinations, and implementation prospects. Valorization of dairy waste streams presents an opportunity to extend the dairy industry's presence in the fermented functional beverage sector.

Discovering eco-friendly alternatives to synthetic chemicals has become an increasingly popular area of research. Natural products are now in the spotlight for their potential use as replacements for synthetic chemicals. To maximize the benefits of these natural products, it is important to use efficient extraction methods, especially from agroindustrial waste. Olive oil mill wastewater (OOMW) is a byproduct of the olive oil production process and is considered a pollutant; however, OOMW contains a wide range of phenolic compounds that have proven antimicrobial properties. This study investigates the extraction of these compounds from OOMW, with the aim of determining their potential antimicrobial activities against several bacterial strains and fungi, including Bacillus spizizenii, Bacillus cereus, Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa, Klebsiella aerogenes, Streptococcus uberis, Enterococcus faecalis, and Candida albicans. The OOMW extracts (OEs) were prepared by using three different solvents: ethyl acetate, ethanol, and methanol. The highest total phenolic contents (4.03 g, GAE/L) and the strongest antibacterial activity were obtained with methanol extraction. All OEs showed no antifungal activity against C. albicans. OEs, particularly methanol extracts of OOMW, can be used as bioactive substances in various industries as nutraceuticals and food ingredients, respectively.

This review focuses on a holistic view of biochar, production from feedstock's, engineering production strategies, its applications and future prospects. This article reveals a systematic emphasis on the continuation and development of biochar and its production methods such as Physical engineering, chemical and bio-engineering techniques. In addition, biochar alternatives such as nutrient formations and surface area made it a promising cheap source of carbon-based products such as anaerobic digestion, gasification, and pyrolysis, commercially available wastewater treatment, carbons, energy storage, microbial fuel cell electrodes, and super-capacitors repair have been reviewed. This paper also covers the knowledge blanks of strategies and ideas for the future in the field of engineering biochar production techniques and application as well as expand the technology used in the circular bio-economy.