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The inefficient food processing and food leftover management strategies often lead to the wastage of untapped carbohydrate-rich feedstocks. The conversion of these feedstocks into bioethanol can mitigate the emission of greenhouse gases (GHGs) while providing a sustainable and eco-friendly method for disposing of food wastes. In light of the above, the current review scrutinizes various types of food wastes (homogeneous and heterogeneous) and pretreatment methods (physical, chemical, physicochemical, and biological) for their valorization into bioethanol. The main constraints to commercial production of food-waste-derived bioethanol, that is, the requirement for sterilization and collection of feedstocks, are also discussed. The former issue can be addressed by developing an optimized solid-state fermentation process. Employing selective conditions to enrich bioethanol-producing microorganisms can increase the feasibility of this process configuration while inhibiting ethanol-consuming strains. The feedstock collection issue can be minimized by determining the hot spots that are in the vicinity of the large food processing sites.

This study reviews the innovations and optimizations in biogas production from the biological perspective reported by recently published patents and research works. The proposed biological strategies can be categorized into three different groups, i.e., upstream, mainstream, and downstream approaches. In the first part of this review, upstream strategies, including pretreatments by fungal, microbial consortium, and enzymatic as well as some other biological methods including microaeration, composting, ensiling, and genetic and metabolic engineering are discussed in detail. The impacts of upstream strategies on biogas production as well as their potentials in further improving the biogas industry are comprehensively scrutinized. Despite their promising impacts on biogas production, such biological innovations are time-consuming and require extra equipment and facilities that should be addressed in future studies. Overall, most information on biogas production has been generated through lab-scale investigations and not by commercial plants, undermining the commercial value of these data for the right decision-making. Pilot data would be necessary for techno-economic analyses with acceptable accuracies. Therefore, the future efforts should be directed toward providing the missing data for re-engineering designs, calculations, and life cycle assessment (LCA) of the newly designed biogas plants.

It is obvious that Iran agricultural industry, unlike Brazil and USA, cannot afford to provide conventional biomass, i.e. sugary or starchy biomass for bioethanol production, mainly due to climatic and geographic conditions. With some exception of date (fruit), first-generation ethanol production triggers food vs. fuel debates in Iran and put nation to hunger. Agricultural products including apple, barley, carrot, corn, grape, orange, potato, rice, sugar beet, sugarcane, and wheat are consumed domestically, exported, or even lost because of poor harvesting and processing conditions such as transportation or packaging. These products may alone generate 21.56 million ton per annum green wastes upon processing in the food industry. Every year about 5.4 billion liters of bioethanol can be produced by establishing second-generation ethanol plants next to the food processing sectors. Seventy-seven-percent of this amount of bioethanol can easily support 5% ethanol (E5) policy to phase out the consumption of 4.2 billion liters methyl tert-butyl ether (MTBE) for raising the octane number of gasoline in the country. If more comprehensive policy is adopted, larger quantities of lignocellulosic feedstocks can be gathered from agro as well as forestry practices. Second-generation bioethanol technology can help Iran to tackle air pollution in its big cities and to address the adverse effects of MTBE on its populations and ecosystem. The other advantages are improvement of fuel security, mitigation of climate change, and development of economy. The motivation can be created through passing a framework policy to cut fossil fuel subsidies, to mandate bioethanol blends in gasoline, and to impose carbon taxes. Development of coherent socially and environmentally relevant strategies and facilitation of investment in bioethanol industry are also necessary.

Environmental deterioration, global climate change, and consequent increases in pollution-related health problems among populations have been attributed to growing consumption of fossil fuels in particular by the transportation sector. Hence, replacing these energy carriers, also known as major contributors of greenhouse gas emissions, with biofuels have been regarded as a solution to mitigate the above-mentioned challenges. On the other hand, efforts have been put into limiting the utilization of edible feedstocks for biofuels production, i.e., first generation biofuels, by promoting higher generations of these eco-friendly alternatives. In light of that, the present review is aimed at comprehensively assessing the role and importance of microorganisms such as bacteria and yeasts as catalysts for sustainable production of liquid biofuels including bioethanol, biomethanol, biobutanol, bio-ammonia, biokerosene, and bioglycerol. Various aspects of these biofuels, i.e., background, chemical synthesis, microbial production (including exploitation of wild and metabolically-engineered species), and product recovery as well as the derivatives produced from these biofuels which are used as fuel additives are thoroughly covered and critically discussed. Furthermore, the industrial features of these green liquid fuels including the industrial practices reported in the literature and the challenges faced as well as possible approaches to enhance these practices are presented.

Finding renewable alternative energy resources for fossil fuels substitution has become very vital due to the serious challenges faced by humankind at present such as environmental pollution, greenhouse gas emissions, climate change, crude oil price volatility, and fossil fuels exhaustion. Macroalgae (seaweeds) are fast-growing marine plants, providing several harvests per year without the need for arable land, fertilizer, and fresh water. Various types of ecosystems like coral reefs, mangrove forests, and rocky shores can efficiently host the seaweeds production systems. These characteristics have made them highly suitable feedstocks for third-generation bioethanol production. Iran has a huge potential in renewable energy resources owing to its unique geographical location and climatic features. The country borders with the Caspian Sea in the north and with the Persian Gulf and the Gulf of Oman in the south. Seaweeds farming can also play a key role in mitigating air pollution, increasing employment rate, sustaining fossil fuel resources, bioremediating contaminated water, and improving marine ecosystem in the Persian Gulf and the Gulf of Oman. In the present article, macroalgae diversity, cultivation, and their conversion and upgrading technologies into bioethanol in Iran are scrutinized and discussed. Finally, the potential of Bushehr (the Persian Gulf) and Chabahar (the Gulf of Oman) coastlines for macroalgae cultivation is investigated. These locations receive the annual solar radiation in the range of 1680‒1753 kWh/m2 and the photosynthetically active radiation (PAR) in the range of 2.6‒2.71 GJ/m2/year with 3051‒3311.9 h sunshine per annum. Furthermore, the nutrient-rich and calm water with relatively stable pH, salinity, and temperature make these coasts suitable for macroalgae farming. A potential yield up to 147‒153 t/ha/year can be obtained if proper native/engineered species, well-situated sites, and compatible cultivation techniques are selected.

Agricultural and livestock/slaughterhouse wastes are produced in huge quantities and could be promising sources for electricity generation to partially reduce dependence on fossil-oriented electricity. In light of that, the state of the production for these wastes in different parts of the globe was first presented. Subsequently, various waste-to-energy technologies and their electricity generation feasibility from both environmental and economic perspectives were reviewed. Finally, electricity generation and greenhouse gas (GHG) reduction potentials through anaerobic digestion of the above-mentioned wastes generated in each province of Iran in 2016 were investigated as a case study. Accordingly, Khuzestan province with the highest amount of agro-wastes (7.61 million tons) and Sistan and Baluchestan province with the highest amount of livestock/slaughterhouse wastes (10.69 million tons) had the maximum electricity generation potentials of 82.83 MW and 164.23 MW, respectively. Moreover, the country's total potentials for electricity generation from these wastes was determined at 2848.26 MW. Based on the life cycle assessment (LCA) results, a minimum of 10,693.5 thousand tons CO2eq/yr could be avoided by valorizing these wastes into electricity in Iran. This would be translated into 1.5% reduction of Iran's annual GHG emissions; a promising achievement given Iran's international GHGs reduction commitment. Moreover, if a short-term time horizon would be considered for electricity generation from these wastes, the reduction rate could reach 24,153 thousand tons CO2eq/yr, i.e., 3.39% reduction of Iran's annual GHG emissions. To the best of our knowledge, this is the first report scrutinizing electricity generation potentials from both agricultural and livestock/slaughterhouse wastes in Iran while assessing the consequent GHG emission reduction potentials. The outcomes of the study could assist policy makers with decisions aimed at taking advantage of these resources while the platform introduced pave the way for other researchers to conduct similar studies in different parts of the world.

Diesel engines are preferred over spark ignition counterparts for heavy-duty applications and power generation plants because of their higher efficiency, durability, and productivity. Currently, the research interests have been propelled towards renewable and sustainable diesel fuels such as biodiesel in order to address the environmental and energy security challenges associated with these energy systems. However, the most challenging issue concerning large-scale production of biodiesel is its relatively high cost over fossil-based diesel owing to high feedstock and manufacturing costs. Therefore, cost-effective and eco-friendly biodiesel production technologies should be necessarily developed and continuously improved in order to make this biofuel more competitive vs. its petroleum counterpart. Accordingly, this paper comprehensively reviews biodiesel manufacturing techniques from natural oils and fats using conventional and advanced technologies with an in-depth state-of-the-art focus on the utmost important unit, i.e., transesterification reactor. The effects of the main influential parameters on the transesterification process are first discussed in detail in order to better understand the mechanisms behind each reactor technology. Different transesterification reactors; e.g., tubular/plug-flow reactors, rotating reactors, simultaneous reaction-separation reactors, cavitational reactors, and microwave reactors are then scrutinized from the scientific and practical viewpoints. Merits and limitations of each reactor technology for biodiesel production are highlighted to guide future R&D on this topic. At the end of the paper, the sustainability aspects of biodiesel production are comprehensively discussed by emphasizing on the biorefinery concept utilizing waste-oriented oils.

Human livelihood highly depends on applying different sources of energy whose utilization is associated with air pollution. On the other hand, air pollution may be associated with glioblastoma multiforme (GBM) development. Unlike other environmental causes of cancer (e.g., irradiation), air pollution cannot efficiently be controlled by geographical borders, regulations, and policies. The unavoidable exposure to air pollution can modify cancer incidence and mortality. GBM treatment with chemotherapy or even its surgical removal has proven insufficient (100% recurrence rate; patient’s survival mean of 15 months; 90% fatality within five years) due to glioma infiltrative and migratory capacities. Given the barrage of attention and research investments currently plowed into next-generation cancer therapy, oncolytic viruses are perhaps the most vigorously pursued. Provision of an insight into the current state of the research and future direction is essential for stimulating new ideas with the potentials of filling research gaps. This review manuscript aims to overview types of brain cancer, their burden, and different causative agents. It also describes why air pollution is becoming a concerning factor. The different opinions on the association of air pollution with brain cancer are reviewed. It tries to address the significant controversy in this field by hypothesizing the air-pollution-brain-cancer association via inflammation and atopic conditions. The last section of this review deals with the oncolytic viruses, which have been used in, or are still under clinical trials for GBM treatment. Engineered adenoviruses (i.e., DNX-2401, DNX-2440, CRAd8-S-pk7 loaded Neural stem cells), herpes simplex virus type 1 (i.e., HSV-1 C134, HSV-1 rQNestin34.5v.2, HSV-1 G207, HSV-1 M032), measles virus (i.e., MV-CEA), parvovirus (i.e., ParvOryx), poliovirus (i.e., Poliovirus PVSRIPO), reovirus (i.e., pelareorep), moloney murine leukemia virus (i.e., Toca 511 vector), and vaccinia virus (i.e., vaccinia virus TG6002) as possible life-changing alleviations for GBM have been discussed. To the best of our knowledge, this review is the first review that comprehensively discusses both (i) the negative/positive association of air pollution with GBM; and (ii) the application of oncolytic viruses for GBM, including the most recent advances and clinical trials. It is also the first review that addresses the controversies over air pollution and brain cancer association. We believe that the article will significantly appeal to a broad readership of virologists, oncologists, neurologists, environmentalists, and those who work in the field of (bio)energy. Policymakers may also use it to establish better health policies and regulations about air pollution and (bio)fuels exploration, production, and consumption.

Fossil fuels and chemical pesticides could probably be blamed for future human downfall. Therefore, the global dependence on fossil fuels must be reduced immediately due to climate change, environmental issues, and health complications. The latter two negative effects could also be rendered by chemical pesticides. Among renewable energy alternatives, liquid biofuels have higher compatibility with the current fuel infrastructures and engines (i.e., transportation, storage, and engine systems), and hence, are very promising for transportation sector. Bioethanol, a liquid biofuel, is an ideal gasoline extender and is widely used in many countries in blended form with gasoline at specific ratios to improve fuel characteristics and engine performance. Although the bioethanol production industry has long been operational, finding suitable and sustainable feedstock is still an active field of study. The consumption of food/feed commodities such as sugarcane and corn (i.e., the first-generation bioethanol) has raised food vs. fuel debate. Alternatively, scientists have concentrated on the second-generation bioethanol, which consumes wastes such as lignocelluloses. However, huge amounts of hydrolytic enzymes, particularly cellulases, are required that contribute to high bioethanol production cost. Fungal biocontrol agents are superb producers of these enzymes, while at the same time they could be used as effective biological pesticides for sustainable agriculture. In this chapter, a novel viewpoint is put forward for sustainable direct production of bioethanol from lignocellulose by fungi, which could easily be separated at the end of the process and be exploited as biological control agents. For this purpose, several promising species within Fusarium, Paecilomyces, Pichia, and Trichoderma along with two species including Aspergillus oryzae and Pochonia chlamydosporia are comprehensively evaluated and scrutinized. The characteristics of these fungi could be further improved and harnessed for a dual production of biocontrol agents and bioethanol, improving the economic and environmental feasibilities of lignocellulose-based bioethanol production.

Aim: To simplify the recognition of Actinobacteria, at different stages of the growth phase, from a mixed culture to facilitate the isolation of novel strains of these bacteria for drug discovery purposes. Materials & methods: A method was developed based on Gabor transform, and machine learning using k-Nearest Neighbors and Naive Bayes classifier, Logitboost, Bagging and Random Forest to automatically categorize the colonies. Results: A signature pattern was inferred by the model, making the differentiation of identical strains possible. Additionally, higher performance, compared with other classification methods was achieved. Conclusion: This automated approach can contribute to the acceleration of the drug discovery process while it simultaneously can diminish the loss of budget due to the redundancy occurred by the inexperienced researchers.

Anaerobic digestion (AD) of organic wastes is among the most promising approaches used for the simultaneous treatment of various waste streams, environment conservation, and renewable bioenergy generation (biomethane). Among the latest innovations investigated to enhance the overall performance of this process both qualitatively and quantitatively, the application of some nanoparticles (NPs) has attracted a great deal of attention. Typically, the NPs of potential benefit to the AD process could be divided into three groups: (i) zero-valent iron (ZVI) NPs, (ii) metallic and metal oxides NPs, and (iii) carbon-based NPs. The present review focuses on the latest findings reported on the application of these NPs in AD process and presents their various mechanisms of action leading to higher or lower biogas production rates. Among the NPs studies, ZVI NPs could be regarded as the most promising nanomaterials for enhancing biogas production through stabilizing the AD process as well as by stimulating the growth of beneficial microorganisms to the AD process and the enzymes involved. Future research should focus on various attributes of NPs when used as additives in biogas production, including facilitating mixing and pumping operations, enriching the population and diversity of beneficial microorganisms for AD, improving biogas release, and inducing the production and activity of AD-related enzymes. The higher volume of methane-enriched biogas would be translated into higher returns on investment and could therefore, result in further growth of the biogas production industry. Nevertheless, efforts should be devoted to decreasing the price of NPs so that the enhanced biogas and methane production (by over 90%, compared to control) would be more economically justified, facilitating the large-scale application of these compounds. In addition to economic considerations, environmental issues are also regarded as major constraints which should be addressed prior to widespread implementation of NP-augmented AD processes. More specifically, the fate of NPs augmented in AD process should be scrutinized to ensure maximal beneficial impacts while adverse environmental/health consequences are minimized.

A sustainable management of environment and agriculture is crucial to protect soil, water, and air during intensified agriculture practices as well as huge industrial and transportation activities. A promising tool to address these challenges could be the application of biochar, a carbonaceous product of biomass pyrolysis. The efficiency of biochar could be improved through physical, chemical and microbial procedures. Engineered biochar could then be applied for various applications ranging from sustainable agriculture to pollution remediation and catalytic reactions. Biochar engineering allows achieving biochar properties which are optimum for specific applications and/or under specific conditions. This would lead to harnessing the favorable features of biochar and to enhance its efficiency while simultaneously minimizing the existing tradeoffs. This review covers the production and applications of engineered biochar by summarizing great deals of research and knowledge on the field. Unlike previous reviews, herein biochar physical and chemical properties and the factors affecting them (i.e., biomass nature and pyrolysis conditions) have been discussed in detail. Moreover, the contributions of each physical and chemical activation/modification method to improving biochar characteristics with respect to environmental applications have been specifically scrutinized. By providing the state-of-the-art knowledge about engineered biochar production, properties, and applications, this review aims to help research in this field for identification of the culprits that must be addressed in future experiments.