Álvaro Pun, Jesús Valimaña-Traverso, Maria Ángeles García et al.

Environmental Science and Ecotechnology • 2024

50% of pharmaceuticals and 25% of herbicides used worldwide are chiral. Each enantiomer has a unique toxicity and biodegradation profile, affecting differently to organisms. Chirality plays a key role in the behavior of these emerging contaminants (ECs) in terms of their pharmacological or herbicidal activity, but this peculiarity is often overlooked in environmental research. The complexity of chiral ECs is underestimated, as the varying sensitivity of biological systems to enantiomers is rarely considered. Biofilters can promote the activity of specific microbial communities, facilitating the degradation of ECs, due to the greater interaction between water and microorganisms and their compact design. Here, we show that an electroactive biofilter can alter the chirality of drugs and herbicides in wastewater treatment, impacting their removal and toxicity. The electrochemical biofilter (BioeF) removed 80% of pharmaceuticals and 50-75% of herbicides, outperforming the conventional filter (ConF). BioeF also showed greater chiral alterations and lower ecotoxicity. This work provides the first evidence of a relationship between changes in contaminant chirality and detoxification capacity, enhanced by electroactive systems. The increased microbial activity observed in the BioeF suggests that bioelectrochemical systems offer a valuable advance for ECs removal and ecotoxicity reduction, addressing the environmental challenge posed by ECs.

Baoshan Wang, Xiaojie Chen, Gang Wen et al.

Water Research • 2025

G.N. Nikhil, Pathi Suman, S. Venkata Mohan et al.

Chemical Engineering Journal • 2017

Rufis Fregue Tiegam Tagne, Xiaobin Dong, Solomon Gabche Anagho et al.

Environment Development and Sustainability • 2021

Abstract The use of fossil fuels in modern economies has been a success because of the low cost of fossil resources. However, the depletion of fossil reserves, the increase in waste production and global warming concerns have led to increased research on the production of biofuels from renewable resources. Waste production is steadily increasing in quantity and constantly changing in quality, creating enormous risks for the environment and, consequently, for the health of the population. This situation is much more worrying in developing countries, in particular because of the considerable delay in the field of the conversion and recovery of biomaterials, due to their difficulty in approaching the problem in a way that fits their context. The composition of such wastes and residues, rich in organic matter, allows their conversion via biochemical mechanisms, thus constituting an effective solution to address the environmental problems of their disposal. Anaerobic digestion remains a valuable and effective technology for transforming these biomaterials into biogas. The present review focuses on technologies, challenges and areas of application of biogas, especially in China and some African countries, in order to promote the large-scale use of biogas for electricity generation and biofuels. Results point out that China is more used to this technology, while African countries still rely on traditional and less advanced technologies, thus hampering the potential derived from the large availability of biomaterials. Both realities, however, share similar backgrounds about the dimension of the biogas plants and their non-commercial purposes, even if China is recently shifting toward the adoption of a different model. These considerations are used in the article to open an interesting new scenario of political alternatives which may provide a way out from poverty and economic dependence, within the framework of a wider circularity.

Saikat Banerjee, B.S. Naveen Prasad, Selvaraju Sivamani

Journal of Energy and Power Technology • 2022

Biogas is an alternative to gaseous biofuels and is produced by the decomposition of biomass from substances such as animal waste, sewage sludge, and industrial effluents. Biogas is composed of methane, carbon dioxide, nitrogen, hydrogen, hydrogen sulfide, and oxygen. The anaerobic production of biogas can be made cheaper by designing a high throughput reactor and operating procedures. The parameters such as substrate type, particle size, temperature, pH, carbon/nitrogen (C/N) ratio, and inoculum concentration play a major role in the design of reactors to produce biogas. Multistage systems, batch, continuous one-stage systems, and continuous two-stage systems are the types of digesters used in the industry for biogas production. A comprehensive review of reactor design for biogas production is presented in the manuscript.

Yun Qi, Xingyu Chen, Zhan Hu et al.

International Journal of Environmental Research and Public Health • 2019

In recent years, the algae-bacteria symbiotic system has played a significant role in the sustainable development of wastewater treatment. With the continuous expansion of research outputs, publications related to wastewater treatment via algal-bacterial consortia appear to be on the rise. Based on SCI-EXPANDED database, this study investigated the research activities and tendencies of algae-bacteria symbiotic wastewater treatment technology by bibliometric method from 1998 to 2017. The results indicated that environmental sciences and ecology was the most productive subject categories, followed by engineering. Bioresource Technology was the most prominent journal in this field with considerable academic influence. China (146), USA (139) and Spain (76) had the largest amount of publications. Among them, USA was in a leading position in international cooperation, with the highest h-index (67) in 79 countries/territories. The cooperation between China and USA was the closest. The cooperative publishing rate of the Chinese Academy of Sciences was 83.33%, but most of them were in cooperation with domestic institutions, while international cooperation was relatively limited. Methane production, biofuel production, and extracellular polymeric substance were future focal frontiers of research, and this field had gradually become a multi-perspective and inter-disciplinary approach combining biological, environmental and energy technologies.

Hanna Breunig, Ling Jin, Alastair Robinson et al.

Environmental Science & Technology • 2017

Food waste makes up approximately 15% of municipal solid waste generated in the United States, and 95% of food waste is ultimately landfilled. Its bioavailable carbon and nutrient content makes it a major contributor to landfill methane emissions, but also presents an important opportunity for energy recovery. This paper presents the first detailed analysis of monthly food waste generation in California at a county level, and its potential contribution to the state's energy production. Scenarios that rely on excess capacity at existing anaerobic digester (AD) and solid biomass combustion facilities, and alternatives that allow for new facility construction, are developed and modeled. Potential monthly electricity generation from the conversion of gross food waste using a combination of AD and combustion varies from 420 to 700 MW, averaging 530 MW. At least 66% of gross high moisture solids and 23% of gross low moisture solids can be treated using existing county infrastructure, and this fraction increases to 99% of high moisture solids and 55% of low moisture solids if waste can be shipped anywhere within the state. Biogas flaring practices at AD facilities can reduce potential energy production by 10 to 40%.

Domagoj Talapko, Jasminka Talapko, Ivan Erić et al.

Energies • 2023

Hydrogen is widely considered as the fuel of the future. Due to the challenges present during hydrogen production using conventional processes and technologies, additional methods must be considered, like the use of microorganisms. One of the most promising technologies is dark fermentation, a process where microorganisms are utilized to produce hydrogen from biomass. The paper provides a comprehensive overview of the biological processes of hydrogen production, specifically emphasizing the dark fermentation process. This kind of fermentation involves bacteria, such as Clostridium and Enterobacterium, to produce hydrogen from organic waste. Synthetic microbial consortia are also discussed for hydrogen production from different types of biomasses, including lignocellulosic biomass, which includes all biomass composed of lignin and (hemi)cellulose, sugar-rich waste waters, and others. The use of genetic engineering to improve the fermentation properties of selected microorganisms is also considered. Finally, the paper covers the important aspect of hydrogen management, including storage, transport, and economics.

Sheetal Kishor Parakh, Zinong Tian, Jonathan Zhi En Wong et al.

Fermentation • 2023

Concerns about rising energy demand, fossil fuel depletion, and global warming have increased interest in developing and utilizing alternate renewable energy sources. Among the available renewable resources, microalgae biomass, a third-generation feedstock, is promising for energy production due to its rich biochemical composition, metabolic elasticity, and ability to produce numerous bioenergy products, including biomethane, biohydrogen, and bioethanol. However, the true potential of microalgae biomass in the future bioenergy economy is yet to be realized. This review provides a comprehensive overview of various biochemical conversion processes (anaerobic digestion, direct biophotolysis, indirect biophotolysis, photo fermentation, dark fermentation, microalgae-catalyzed photo fermentation, microalgae-catalyzed dark fermentation, and traditional alcoholic fermentation by ethanologenic microorganisms) that could be adapted to transform microalgae biomass into different bioenergy products. Recent advances in biochemical conversion processes are compiled and critically analyzed, and their limitations in terms of process viability, efficacy, scalability, and economic and environmental sustainability are highlighted. Based on the current research stage and technological development, biomethane production from anaerobic digestion and bioethanol production from traditional fermentation are identified as promising methods for the future commercialization of microalgae-based bioenergy. However, significant challenges to these technologies’ commercialization remain, including the high microalgae production costs and low energy recovery efficiency. Future research should focus on reducing microalgae production costs, developing an integrated biorefinery approach, and effectively utilizing artificial intelligence tools for process optimization and scale-up to solve the current challenges and accelerate the development of microalgae-based bioenergy.

Shu Takahashi, Morio Miyahara, Atsushi Kouzuma et al.

Bioresources and Bioprocessing • 2016

The results suggest that rice bran is a feasible fuel by itself for generating electricity in MFCs.

Piotr Świątczak, Agnieszka Cydzik‐Kwiatkowska, Paulina Rusanowska

Archives of Environmental Protection • 2017

Abstract Anaerobic digestion is an important technology for the bio-based economy. The stability of the process is crucial for its successful implementation and depends on the structure and functional stability of the microbial community. In this study, the total microbial community was analyzed during mesophilic fermentation of sewage sludge in full-scale digesters. The digesters operated at 34–35°C, and a mixture of primary and excess sludge at a ratio of 2:1 was added to the digesters at 550 m 3 /d, for a sludge load of 0.054 m 3 /(m 3 ·d). The amount and composition of biogas were determined. The microbial structure of the biomass from the digesters was investigated with use of next-generation sequencing. The percentage of methanogens in the biomass reached 21%, resulting in high quality biogas (over 61% methane content). The abundance of syntrophic bacteria was 4.47%, and stable methane production occurred at a Methanomicrobia to Synergistia ratio of 4.6:1.0. The two most numerous genera of methanogens (about 11% total) were Methanosaeta and Methanolinea , indicating that, at the low substrate loading in the digester, the acetoclastic and hydrogenotrophic paths of methane production were equally important. The high abundance of the order Bacteroidetes , including the class Cytophagia (11.6% of all sequences), indicated the high potential of the biomass for efficient degradation of lignocellulitic substances, and for degradation of protein and amino acids to acetate and ammonia. This study sheds light on the ecology of microbial groups that are involved in mesophilic fermentation in mature, stably-performing microbiota in full-scale reactors fed with sewage sludge under low substrate loading.

Omprakash Sarkar, J. Annie Modestra, Ulrika Rova et al.

Fermentation • 2023

Anaerobic digestion (AD) is an environmentally friendly process for recovering low-carbon energy from the breakdown of organic substrates. In recent years, AD has undergone a major paradigm shift, and now the technology is not only considered as a “waste treatment” method and is instead viewed as a key enabler of the future “circular economy” with its potential for resource recovery (low-carbon energy, safe water, and nutrients). Currently, waste-derived biogas from AD is the most affordable and scalable source of renewable energy. Biomethane (upgraded biogas) can serve as a significant renewable and dispatchable energy source for combating the problem of global warming. Acidogenesis, an intermediate step of AD, can produce molecular hydrogen (H2) along with green chemicals/platform chemicals. The use of low-carbon hydrogen as a clean energy source is on the rise throughout the world, and is currently considered a potential alternative energy source that can contribute to the transition to a carbon-neutral future. In order to determine the future trade routes for hydrogen, nations are developing hydrogen policies, and various agreements. Hydrogen produced by biological routes has been found to be suitable due to its potential as a green energy source that is carbon neutral for the developing “Hydrogen Economy”. Recently, hydrogen blended with methane to a specific proportion and known as biohythane/hydrogen-enriched compressed natural gas (HCNG) has emerged as a promising clean fuel that can substantially contribute to an integrated net-zero energy system. This review provides an overview of the current state of fermentative hydrogen and methane production from biogenic waste/wastewater in a biorefinery approach and its utilization in the context of energy transition. The limitations and economic viability of the process, which are crucial challenges associated with biohydrogen/biomethane production, are discussed, along with its utilization.

Ojima Z. Wada, Annette Shoba Vincent, Hamish R. Mackey

Reviews in Environmental Science and Bio/Technology • 2022

Abstract Large-scale production of single-cell protein (SCP) has the potential not only to solve some of the food insecurity and water scarcity crises that plague a significant portion of our world today but also holds the promise to reduce the cost associated with the treatment of industrial and agricultural wastewater. Resource recovery of SCP from organic waste by microbes like yeast and microalgae is commonly documented. However, recently, a class of phototrophic bacteria, purple non-sulphur bacteria (PNSB), has emerged as a favourable option in terms of both wastewater treatment and resource recovery. PNSB are metabolically versatile and tolerant to a wide range of conditions, hence their ability to thrive in diverse waste streams. Besides its rich protein content, PNSB contains other nutritionally valuable bioproducts like carotenoids, coenzyme Q10, 5-aminolevulinic acid, and pantothenic acid. Recent evidence also indicates that PNSB-based aquafeed enhances growth and boosts immunity in certain aquaculture trials. It does not possess the same toxicity as most gram-negative bacteria due to its comparatively less potent lipopolysaccharide composition. With diverse promising prospects of PNSB-based SCP, it is critical to extensively examine the landscape from a holistic standpoint, highlighting the potential challenges large-scale SCP production may pose. Thus, this review explores the comparative advantages of utilizing PNSB for SCP production, essential components of PNSB-based SCP processing, and possible environmental and economic gains associated with the process. Current challenges with PNSB-based SCP production and future outlooks are also examined.

Rodica Mariana Niculescu, Adrian Clenci, Victor Iorga-Simăn

Energies • 2019

The use of alternative fuels contributes to the lowering of the carbon footprint of the internal combustion engine. Biofuels are the most important kinds of alternative fuels. Currently, thanks to the new manufacturing processes of biofuels, there is potential to decrease greenhouse gas (GHG) emissions, compared to fossil fuels, on a well-to-wheel basis. Amongst the most prominent alternative fuels to be used in mixtures/blends with fossil fuels in internal combustion (IC) engines are biodiesel, bioethanol, and biomethanol. With this perspective, considerable attention has been given to biodiesel and petroleum diesel fuel blends in compression ignition (CI) engines. Many studies have been conducted to assess the impacts of biodiesel use on engine operation. The addition of alcohols such as methanol and ethanol is also practised in biodiesel–diesel blends, due to their miscibility with the pure biodiesel. Alcohols improve the physico-chemical properties of biodiesel–diesel blends, which lead to improved CI engine operation. This review paper discusses some results of recent studies on biodiesel, bioethanol, and biomethanol production, their physicochemical properties, and also, on the influence of the use of diesel–biodiesel–alcohols blends in CI engines: combustion characteristics, performance, and emissions.

Erdem Çarşanba, Séraphim Papanikolaou, Patrick Fickers et al.

Microorganisms • 2020

Oleaginous microorganisms, such as Yarrowia lipolytica , accumulate lipids that can have interesting applications in food biotechnology or the synthesis of biodiesel. Y. lipolytica yeast can have many advantages such as wide substrate range usage and robustness to extreme conditions, while under several culture conditions it can produce high lipid productivity. Based on this assumption, in this study, 12 different Yarrowia lipolytica strains were used to investigate microbial lipid production using a glucose-based medium under nitrogen-limited conditions in shake-flask cultivations. Twelve wild-type or mutant strains of Yarrowia lipolytica which were newly isolated or belonged to official culture collections were tested, and moderate lipid quantities (up to 1.30 g/L) were produced; in many instances, nitrogen limitation led to citric acid production in the medium. Lipids were mainly composed of C16 and C18 fatty acids. Most of the fatty acids of the microbial lipid were unsaturated and corresponded mainly to oleic, palmitic and linoleic acids. Linolenic acid (C18:3) was produced in significant quantities (between 10% and 20%, wt/wt of dry cell weight (DCW)) by strains H917 and Po1dL.

Rebecca Gmoser, Rikard Fristedt, Karin Larsson et al.

Bioengineered • 2020

By-products from the food sector with a high load of organic matter present both a waste-handling problem related to expenses and to the environment, yet also an opportunity. This study aims to increase the value of stale bread and brewers spent grain (BSG) by re-introducing these residues to the food production chain by converting them to new protein-enriched products using the edible filamentous fungi Neurospora intermedia and Rhizopusoryzae . After 6 days of solid state fermentation (at 35°C, with a95% relative humidity and moisture content of 40% in the substrate) on stale bread, a nutrient-rich fungal-fermented product was produced. The total protein content, as analyzed by total amino acids, increased from 16.5% in stale sourdough bread to 21.1% (on dry weight basis) in the final product with an improved relative ratio of essential amino acids. An increase in dietary fiber, minerals (Cu, Fe, Zn) and vitamin E, as well as an addition of vitamin D2 (0.89 µg/g dry weight sample) was obtained compared with untreated stale bread. Furthermore, addition of BSG to the sourdough bread with the aim to improve textural changes after fermentation showed promising outcomes. Cultivation of N. intermedia or R. oryzae on stale sourdough bread mixed with 6.5% or 11.8% BSG, respectively, resulted in fungal-fermented products with similar textural properties to a commercial soybean burger. Bioconversion of stale bread and BSG by fungal solid state fermentation to produce a nutrient-enriched food product was confirmed to be a successful way to minimize food waste and protein shortage.

Liliana Pampillón-González, Nadia L. Ortiz‐Cornejo, Marco Luna‐Guido et al.

Microbial Physiology • 2017

Biogas production from animal waste is an economically viable way to reduce environmental pollution and produce valuable products, i.e., methane and a nutrient-rich organic waste product. An anaerobic digestion reactor for biogas production from pig waste was sampled at the entrance, middle (digestion chamber), and exit of a digester, while the bacterial and archaeal community structure was studied by 16S rRNA gene metagenomics. The number of bacterial operational taxonomic units (OTU)-97% was 3-7 times larger than that of archaeal ones. Bacteria and Archaea found in feces of animals (e.g., Clostridiaceae, Lachnospiraceae, Ruminococcaceae, Methanosarcina, Methanolobus, Methanosaeta, and Methanospirillum) dominated the entrance of the digester. The digestion chamber was dominated by anaerobic sugar-fermenting OP9 bacteria and the syntrophic bacteria Candidatus Cloacamonas (Waste Water of Evry 1; WWE1). The methanogens dominant in the digestion chamber were the acetoclastic Methanosaeta and the hydrogenothrophic Methanoculleus and Methanospirillum. Similar bacterial and archaeal groups that dominated in the middle of the digestion chamber were found in the waste that left the digester. Predicted functions associated with degradation of xenobiotic compounds were significantly different between the sampling locations. The microbial community found in an anaerobic digestion reactor loaded with pig manure contained microorganisms with biochemical capacities related to the 4 phases of methane production.

Tábita Veiga Dias Rodrigues, Thalita D. Amore, Erika Carvalho Teixeira et al.

Food Technology and Biotechnology • 2019

Carotenoids are natural pigments that can be produced through biotechnological processes. However, the costs are relatively high and can be minimized by using lower-cost substrates as alternative nutrient sources. The fed-batch fermentation is one of the techniques used to obtain a high biomass concentration and/or maximum production. Thus, the aim of this work is to produce carotenoids in batch and fed-batch fermentation with the yeast Rhodotorula mucilaginosa CCT 7688 using agroindustrial byproducts in the culture medium. Carotenoid production was increased using experimental designs, which modified the concentration of the agroindustrial medium. In batch production the highest concentrations of total carotenoids (1248.5 μg/L) and biomass (7.9 g/L) were obtained in the medium containing 70 g/L sugar cane molasses and 3.4 g/L corn steep liquor at 25 °C and 180 rpm in 168 h, demonstrating an increase of 17% when compared to the standard yeast malt medium (1200 μg/L). In the fed-batch production, different feeding strategies were tested with 30 g/L sugar cane molasses and 6.5 g/L corn steep liquor, reaching a total carotenoid production of 3726 μg/L and biomass concentration of 16 g/L. Therefore, the strategy of the fed-batch process resulted in an increase in the carotenoid production of approx. 400% compared to that in the batch process (740.3 μg/L). Thus, the R. mucilaginosa strain has the potential to produce carotenoids in agroindustrial medium.

Ram Chandra, Vineet Kumar

Frontiers in Microbiology • 2017

Sugarcane-molasses-based post-methanated distillery waste is well known for its toxicity, causing adverse effects on aquatic flora and fauna. Here, it has been demonstrated that there is an abundant mixture of androgenic and mutagenic compounds both in distillery sludge and leachate. Gas chromatography-mass spectrometry (GC-MS) analysis showed dodecanoic acid, octadecanoic acid, n -pentadecanoic acid, hexadecanoic acid, β-sitosterol, stigmasterol, β-sitosterol trimethyl ether, heptacosane, dotriacontane, lanosta-8, 24-dien-3-one, 1-methylene-3-methyl butanol, 1-phenyl-1-propanol, 5-methyl-2-(1-methylethyl) cyclohexanol, and 2-ethylthio-10-hydroxy-9-methoxy-1,4 anthraquinone as major organic pollutants along with heavy metals (all mg kg -1 ): Fe (2403), Zn (210.15), Mn (126.30, Cu (73.62), Cr (21.825), Pb (16.33) and Ni (13.425). In a simultaneous analysis of bacterial communities using the restriction fragment length polymorphism (RFLP) method the dominance of Bacillus sp. followed by Enterococcus sp. as autochthonous bacterial communities growing in this extremely toxic environment was shown, indicating a primary community for bioremediation. A toxicity evaluation showed a reduction of toxicity in degraded samples of sludge and leachate, confirming the role of autochthonous bacterial communities in the bioremediation of distillery waste in situ .

Olga N. Tsolcha, V. Patrinou, Christina Ν. Economou et al.

Water • 2021

Biofuels produced from photosynthetic microorganisms such as microalgae and cyanobacteria could potentially replace fossil fuels as they offer several advantages over fuels produced from lignocellulosic biomass. In this study, energy production potential in the form of bioethanol was examined using different biomasses derived from the growth of a cyanobacteria-based microbial consortium on a chemical medium and on agro-industrial wastewaters (i.e., dairy wastewater, winery wastewater and mixed winery–raisin effluent) supplemented with a raisin residue extract. The possibility of recovering fermentable sugars from a microbial biomass dominated by the filamentous cyanobacterium Leptolynbgya sp. was demonstrated. Of the different acid hydrolysis conditions tested, the best results were obtained with sulfuric acid 2.5 N for 120 min using dried biomass from dairy wastewater and mixed winery–raisin wastewaters. After optimizing sugar release from the microbial biomass by applying acid hydrolysis, alcoholic fermentation was performed using the yeast Saccharomyces cerevisiae. Raisin residue extract was added to the treated biomass broth in all experiments to enhance ethanol production. Results showed that up to 85.9% of the theoretical ethanol yield was achieved, indicating the potential use of cyanobacteria-based biomass in combination with a raisin residue extract as feedstock for bioethanol production.

Anisha Priya, Avinash Alagumalai, D. Balaji et al.

RSC Sustainability • 2023

Utilizing waste streams to produce bio-based products has the potential to promote a circular economy. In addition, by incorporating biowaste into the circular economy, the production of sustainable bioproducts and bioenergy can be enhanced.

B. Saenz de Miera, A.S. Oliveira, J.A. Baeza et al.

Journal of Cleaner Production • 2019

Alok Patel, Fabio Mikes, Saskja Bühler et al.

Molecules • 2018

Brewers' spent grain (BSG) accounts for 85% of the total amount of by-products generated by the brewing industries. BSG is a lignocellulosic biomass that is rich in proteins, lipids, minerals, and vitamins. In the present study, BSG was subjected to pretreatment by two different methods (microwave assisted alkaline pretreatment and organosolv) and was evaluated for the liberation of glucose and xylose during enzymatic saccharification trials. The highest amount of glucose (46.45 ± 1.43 g/L) and xylose (25.15 ± 1.36 g/L) were observed after enzymatic saccharification of the organosolv pretreated BSG. The glucose and xylose yield for the microwave assisted alkaline pretreated BSG were 34.86 ± 1.27 g/L and 16.54 ± 2.1 g/L, respectively. The hydrolysates from the organosolv pretreated BSG were used as substrate for the cultivation of the oleaginous yeast Rhodosporidium toruloides, aiming to produce microbial lipids. The yeast synthesized as high as 18.44 ± 0.96 g/L of cell dry weight and 10.41 ± 0.34 g/L lipids (lipid content of 56.45 ± 0.76%) when cultivated on BSG hydrolysate with a C/N ratio of 500. The cell dry weight, total lipid concentration and lipid content were higher compared to the results obtained when grown on synthetic media containing glucose, xylose or mixture of glucose and xylose. To the best of our knowledge, this is the first report using hydrolysates of organosolv pretreated BSG for the growth and lipid production of oleaginous yeast in literature. The lipid profile of this oleaginous yeast showed similar fatty acid contents to vegetable oils, which can result in good biodiesel properties of the produced biodiesel.

Víctor Martin-Dominguez, Juliana Estevez, Francisco de Borja Ojembarrena et al.

Fermentation • 2018

The increasing scarcity of fossil raw materials, together with the need to develop new processes and technology based on renewable sources, and the need to dispose of an increasing amount of biomass-derived waste, have boosted the concept of biorefineries. Both 1G and 2G biorefineries are focused on the obtention of biofuels, chemicals, materials, food and feed from biomass, a renewable resource. Fumaric acid, and most compounds involved in the Kreb cycle, are considered key platform chemicals, not only for being acidulants and additives in the food industry, but also for their prospective use as monomers. This review is focused on the biotechnological processes based on fungi, mainly of the Rhizopus genus, whose main product is fumaric acid, on the process conditions, the bioreactors and modes of operation and on the purification of the acid once it is produced.

Izabela Wysocka, Jacek Gębicki, Jacek Namieśnik

Environmental Science and Pollution Research • 2019

There is an increasing number of citizens' complaints about odor nuisance due to production or service activity. High social awareness imposes pressure on entrepreneurs and service providers forcing them to undertake effective steps aimed at minimization of the effects of their activity, also with respect to emission of malodorous substances. The article presents information about various technologies used for gas deodorization. Known solutions can be included into two groups: technologies offering prevention of emissions, and methodological solutions that enable removal of malodorous substances from the stream of emitted gases. It is obvious that the selection of deodorization technologies is conditioned by many factors, and it should be preceded by an in-depth analysis of possibilities and limitations offered by various solutions. The aim of the article is presentation of the available gas deodorization technologies as to facilitate the potential investors with selection of the method of malodorous gases emission limitation, suitable for particular conditions.

Lokeshwar Puri, Yulin Hu, G.F. Naterer

Frontiers in Fuels • 2024

In the face of environmental challenges (e.g., dramatically increasing greenhouse gas emissions and climate change), it is utmost of importance to sustainable energy systems. Biomass consisting of agricultural and forest waste, municipal solid waste, and aquatics, has been identified as alternative and promising fuel sources. Thermochemical conversion approaches like pyrolysis can turn various types of biomass into three valuable product streams, namely, bio-oil, biochar, and syngas. To date, past review articles have considered the major operating parameters of kinetics, chemistry, and the application of pyrolysis products. However, ash content is one of the key biomass components that lacks investigation on its influence during biomass pyrolysis with respect to products yield and properties. This review article examines: i) the ash content and composition in different types of biomass; ii) effects of ash content on catalytic pathway and biomass thermal degradation; iii) ash related problems in the thermal degradation of biomass; and iv) available deashing techniques for biomass. The review aims to provide new understandings and insights regarding the effects of ash content and composition on biomass pyrolysis.

Gunjan Singh, Sweta Sinha, K. K. Bandyopadhyay et al.

Microbial Cell Factories • 2018

Upon publication of this article [1], the authors realized that one of the coauthor name was accedentally deleted during the review process and not presented in the original version of the article. The coauthor Dr. Ram Prasad should be listed as fifth author. The corrected author group is published with this erratum.

Matevž Zupančič, Valerija Možic, Matic Može et al.

Sustainability • 2022

Growing world population and increasing population density are leading to increasing waste production with biological waste amounting to several billion tonnes annually. Together with the increasing need for renewable energy sources, waste-to-biogas conversion as a prime example of waste-to-energy technology represents a facile way of solving two problems simultaneously. This review aims to address the recent progress in the field of waste-to-biogas technology, which is lately facing intensive research and development, and present the current status of this waste treatment method both in technological and legislative terms. The first part provides an overview of waste and waste management issues. This is followed by a detailed description of applicable waste-to-energy (WtE) technologies and their current implementation in selected European countries. Moreover, national energy and climate plans (NECPs) of selected EU Member States are reviewed and compared with a focus on implementation of WtE technologies. In a further section, biogas production from waste around the world is reviewed and compared country wise. Finally, an outlook into the future of WtE technologies is provided alongside the conclusions based upon the reviewed data.

Christy E. Manyi-Loh, Ryk Lues

Fermentation • 2023

Modern society is characterised by its outstanding capacity to generate waste. Lignocellulosic biomass is most abundant in nature and is biorenewable and contains energy sources formed via biological photosynthesis from the available atmospheric carbon dioxide, water, and sunlight. It is composed of cellulose, hemicellulose, and lignin, constituting a complex polymer. The traditional disposal of these types of waste is associated with several environmental and public health effects; however, they could be harnessed to produce several value-added products and clean energy. Moreover, the increase in population and industrialisation have caused current energy resources to be continuously exploited, resulting in the depletion of global fuel reservoirs. The overexploitation of resources has caused negative environmental effects such as climate change, exacerbating global greenhouse gas emissions. In the quest to meet the world’s future energy needs and adequate management of these types of waste, the anaerobic digestion of lignocellulosic biomass has remained the focus, attracting great interest as a sustainable alternative to fossil carbon resources. However, substrate characteristics offer recalcitrance to the process, which negatively impacts the methane yield. Nevertheless, the biodigestibility of these substrates can be enhanced through chemical, physical, and biological pretreatment methods, leading to improvement in biogas yields. Furthermore, the co-digestion of these substrates with other types and adding specific nutrients as trace elements or inoculum will help to adjust substrate characteristics to a level appropriate for efficient anaerobic digestion and increased biogas yield.

Liuwei Wang, Jiayu Deng, Xiaodong Yang et al.

Carbon Research • 2023

Abstract Carbon neutrality by the mid-twenty-first century is a grand challenge requiring technological innovations. Biochar, a traditional soil amendment which has been used for fertility improvement and contaminant remediation, has revealed new vitality in this context. In this review we highlight the huge potential of biochar application in different fields to mitigate as high as 2.56 × 10 9 t CO 2 e total greenhouse gas (GHG) emissions per year, accounting for 5.0% of the global GHG emissions. Soil applications of biochar as either a controlled-release fertilizer or an immobilization agent offer improved soil health while simultaneously suppressing the emissions of CH 4 and N 2 O. Non-soil applications of biochar also contribute to carbon neutrality in unique ways. Firstly, biochar application as a ruminant feed decreases CH 4 emissions via physical sorption and enhanced activities of methanotrophs. Secondly, biochar can be used as a green catalyst for biorefinery. Besides, biochar as an additive to Portland cement and low impact development (LID) infrastructure lowers the carbon footprint and builds resilience to climate change. Furthermore, biochar can be used as novel batteries and supercapacitors for energy storage purposes. Finally, the high CO 2 adsorption capacity makes it possible for biochar being used as a sorbent for carbon capture, utilization, and storage (CCUS). We advocate that future research should further explore the effectiveness of biochar systems for climate change mitigation in large scale applications, and assess the economic and social viability of local biochar systems to combat climate change. Graphical Abstract

Annika Vaksmaa, Mike S. M. Jetten, Katharina F. Ettwig et al.

Applied Microbiology and Biotechnology • 2017

The nitrogen and methane cycles are important biogeochemical processes. Recently, 'Candidatus Methanoperedens nitroreducens,' archaea that catalyze nitrate-dependent anaerobic oxidation of methane (AOM), were enriched, and their genomes were analyzed. Diagnostic molecular tools for the sensitive detection of 'Candidatus M. nitroreducens' are not yet available. Here, we report the design of two novel mcrA primer combinations that specifically target the alpha sub-unit of the methyl-coenzyme M reductase (mcrA) gene of 'Candidatus M. nitroreducens'. The first primer pair produces a fragment of 186-bp that can be used to quantify 'Candidatus M. nitroreducens' cells, whereas the second primer pair yields an 1191-bp amplicon that is with sufficient length and well suited for more detailed phylogenetic analyses. Six different environmental samples were evaluated with the new qPCR primer pair, and the abundances were compared with those determined using primers for the 16S rRNA gene. The qPCR results indicated that the number of copies of the 'Candidatus M. nitroreducens' mcrA gene was highest in rice field soil, with 5.6 ± 0.8 × 10 6 copies g -1 wet weight, whereas Indonesian river sediment had only 4.6 ± 2.7 × 10 2 copies g -1 wet weight. In addition to freshwater environments, sequences were also detected in marine sediment of the North Sea, which contained approximately 2.5 ± 0.7 × 10 4 copies g -1 wet weight. Phylogenetic analysis revealed that the amplified 1191-bp mcrA gene sequences from the different environments all clustered together with available genome sequences of mcrA from known 'Candidatus M. nitroreducens' archaea. Taken together, these results demonstrate the validity and utility of the new primers for the quantitative and sensitive detection of the mcrA gene sequences of these important nitrate-dependent AOM archaea. Furthermore, the newly obtained mcrA sequences will contribute to greater phylogenetic resolution of 'Candidatus M. nitroreducens' sequences, which have been only poorly captured by general methanogenic mcrA primers.

Ganna I. Kulichkova, Tetiana S. Ivanova, Mihael Köttner et al.

The Open Agriculture Journal • 2020

Introduction: Nowadays, organic waste utilization and replacement of fossil energy sources with their renewable alternatives pose a challenging problem both for industrially developed and developing countries. Anaerobic digestion of organic biomass into biogas is considered an efficient technology for bioenergy production. Over the period from 2009 to 2018, the global biogas production capacities have more than doubled and are continuing to grow. The composition and the amount of biogas depend strongly on the type of the substrate. Various types of feedstock can be used for the production of biogas such as animal wastes, agricultural residues, and dedicated energy crops. Objective: To review biogas production potentials of energy crops and plant processing raw materials. Results: In the background of historical development and present state, the paper reviews the potential of different plant raw materials to be utilized for biogas production purposes. The potential of energy crops, agricultural residues, and wastes for biogas production is analyzed. International projects concerning energy crops grown on marginal lands are presented and commented on in the article. The approach of implementing crop rotation systems for industrial energy crop cultivation is described and recommended as beneficial for various purposes. The anaerobic degradability of biomass constituents, optimal process parameters, and biomass treatment for biogas production are discussed. C/N ration and lignocelluloses content in the substrate are considered among the most decisive parameters for AD and methane production. Various concepts of biogas bioreactor technologies have been studied depending on the substrate type. Conclusion: Plant feedstock may play a decisive role in biogas production as a renewable energy source. To avoid GHG release into the atmosphere, biogas facilities should be built within the closest vicinities to the places of existing garbage dumps, and waste management practice involving organic fraction separation in households and in the industry should be applied. Construction of biogas facilities is beneficial for environmental, economic, and social reasons.

Aliyu Salihu, Md. Zahangir Alam

Journal of Applied Sciences • 2016

During biogas production, the rate-determining step for the conversion of complex organic matter is the hydrolysis. Different pretreatment methods aid in facilitating the anaerobic digestion by increasing the rate of organic matter hydrolysis. This in effect results in enhanced production of biogas and aids in waste stabilization as well as disposal. This review gives an overview of the methods used in pretreating organic wastes including mechanical, thermal, chemical and biological. In addition, hybrid method (physico-chemical) involving more than one technology has been useful in enhancing waste solubilization and anaerobic digestion. Thus, economic analysis including the cost of operation and the benefits derived in form of biogas, waste minimization and treatment should be considered during the selection of any pretreatment methods for large scale application.

Aleta Duque, Cristina Álvarez, Pablo Doménech et al.

Processes • 2021

The production of so-called advanced bioethanol offers several advantages compared to traditional bioethanol production processes in terms of sustainability criteria. This includes, for instance, the use of nonfood crops or residual biomass as raw material and a higher potential for reducing greenhouse gas emissions. The present review focuses on the recent progress related to the production of advanced bioethanol, (i) highlighting current results from using novel biomass sources such as the organic fraction of municipal solid waste and certain industrial residues (e.g., residues from the paper, food, and beverage industries); (ii) describing new developments in pretreatment technologies for the fractionation and conversion of lignocellulosic biomass, such as the bioextrusion process or the use of novel ionic liquids; (iii) listing the use of new enzyme catalysts and microbial strains during saccharification and fermentation processes. Furthermore, the most promising biorefinery approaches that will contribute to the cost-competitiveness of advanced bioethanol production processes are also discussed, focusing on innovative technologies and applications that can contribute to achieve a more sustainable and effective utilization of all biomass fractions. Special attention is given to integrated strategies such as lignocellulose-based biorefineries for the simultaneous production of bioethanol and other high added value bioproducts.

George Z. Kyzas, K. A. Matis

Processes • 2019

In today’s world of environmental strain, wastewater treatment has become a, more or less, conventional application of flotation—as for instance, in the oil, food, or chemical industries, and in potable water treatment. In this paper, different flotation methods (such as ion, adsorbing colloid, and adsorptive flotation, including biosorption) and techniques will be reviewed; and, in order to explain them further, several applications of these from the laboratory (General and Inorganic Chemical Technology) at Aristotle University of Thessaloniki, Greece (AUTh) will be presented and analyzed, with the main focus on sustainability. The application of flotation as a separation process, when applied in pollution control or during water treatment, was often criticized due to the possible toxicity of the applied collectors; however, the use of biosurfactants may alleviate this concern and enhance its further acceptability.

Bianca Ferrazzo Naspolini, Antônio Carlos de Oliveira Machado, Walter Barreiro Cravo et al.

BioMed Research International • 2017

Vinasse, a residue from bioethanol production containing high organic matter concentration, was used as substrate in submerged fermentation of Pseudomonas aeruginosa PA1 for biosurfactant production. About 2.7 g/L of rhamnolipids was obtained, with surface tension of 29.2 mN/m and critical micelle concentration of 80.3 mg/L. After separation of rhamnolipid and biomass, residual fermentation media were submitted to anaerobic biodegradation in mesophilic conditions. The residual medium derived from fermentation with vinasse diluted to 1 : 1, without addition of nitrogen, C : N 21, and for 168 h, led to 63.2% chemical oxygen demand (COD) removal and 97.6 mL CH 4 /g COD removed . Compared to results obtained with fresh vinasse (73.7% COD removal and 112.4 mL CH 4 /g COD removed ), it could be concluded that both processes can be integrated in order to add value to the residue and obtain energy, reducing production costs and at the same time environmental impacts related to vinasse disposal.

Mehrdad Arshadi, Thomas M. Attard, Rafał Bogel‐Łukasik et al.

Green Chemistry • 2016

The enormous quantity of food wastes discarded annually forces a look into alternatives for this interesting feedstock.

Sandra Imaculada Maintinguer, Carolina Zampol Lázaro, Renan Pachiega et al.

International Journal of Hydrogen Energy • 2017

Hydrogen-producing bacterial strains were isolated from granular sludge from a UASB reactor that treats brewery wastewater. Most of the isolated strains were related to the Enterobacter genus through a phylogenetic analysis of the 16S rRNA sequences. The strains could use various carbon sources (sugars and glycerol) to produce hydrogen. The isolated strain, identified as Enterobacter sp. based on 16S rRNA gene sequencing, produced 6.8 mmol H2 L−1 culture medium when growing on glucose (2.0 g L−1) in anaerobic conditions at 30 °C. The main liquid metabolites were acetic acid (367 mg L−1), methanol (437 mg L−1) and ethanol (1101.26 mg L−1), after 9 h of fermentation. The maximum hydrogen yield of 0.8 mol H2/mol glucose was observed, indicating that Enterobacter sp. isolated from brewery wastewater was an efficient hydrogen-producing bacterium under mesophilic conditions.

Vinayak Laxman Pachapur, Prianka Kutty, Preetika Kuknur Pachapur et al.

Energies • 2019

Hydrogen is an important source of energy and is considered as the future energy carrier post-petroleum era. Nowadays hydrogen production through various methods is being explored and developed to minimize the production costs. Biological hydrogen production has remained an attractive option, highly economical despite low yields. The mixed-culture systems use undefined microbial consortia unlike pure-cultures that use defined microbial species for hydrogen production. This review summarizes mixed-culture system pretreatments such as heat, chemical (acid, alkali), microwave, ultrasound, aeration, and electric current, amongst others, and their combinations to improve the hydrogen yields. The literature representation of pretreatments in mixed-culture systems is as follows: 45–50% heat-treatment, 15–20% chemical, 5–10% microwave, 10–15% combined and 10–15% other treatment. In comparison to pure-culture mixed-culture offers several advantages, such as technical feasibility, minimum inoculum steps, minimum media supplements, ease of operation, and the fact it works on a wide spectrum of low-cost easily available organic wastes for valorization in hydrogen production. In comparison to pure-culture, mixed-culture can eliminate media sterilization (4 h), incubation step (18–36 h), media supplements cost ($4–6 for bioconversion of 1 kg crude glycerol (CG)) and around 10–15 Millijoule (MJ) of energy can be decreased for the single run.

Mohamed Eida, Osama M. Darwesh, Ibrahim A. Matter

Journal of Ecological Engineering • 2018

Local single cell microalgae isolated from a wastewater swamp and identified as Scenedesmus obliquus was used to determine its applicability for utilization of domestic wastewater for biomass and lipid production. Secondary treated domestic wastewater with or without mixing of growth medium was used to cultivate S. obliquus for the biomass and lipid production as a renewable feedstock for biodiesel. S. obliquus showed the highest OD when grown in 100% Bold's basal medium (BBM). S. obliquus utilized 95.2% and 78.5% of P and N contents, respectively, when grown in 25% WW+75% BBM mixture and the utilization efficiency of both elements decreased with the increasing wastewater portion in the mixture. Although the BBM displayed the highest dry biomass and lipid production (25.15% of the cell dry biomass). The lowest values were recorded for the uninoculated wastewater, followed by 100% wastewater enriched with S. obliquus. The obtained data revealed that the lipid classes of S. obliquus differs according to the cultivation medium and conditions. The highest percentage of C16-C18 fatty acids (54.76% from total lipids) were recorded in case of algae cultivated in 100% wastewater, followed by 46.96% in case of 100% BBM medium. These results suggest the utilization of mixtures containing a higher portion of secondary treated wastewater, such as 75% WW+25% BBM or 50% WW+50% BBM, could increase the economical production of the lipid-rich microalgae S. obliquus for biodiesel through saving water and nutrients.