As metabolic intermediates, volatile fatty acids (VFAs) can be recovered by separation and purification and contribute to the economy. It was necessary, however, to investigate the optimization of liquid–liquid extraction (LLE) in this study because of the technical difficulties encountered during the recovery of VFAs. For this reason, the organic solvents diethyl ether, trioctylamine, and toluene were investigated as LLE solvents to extract VFAs from Baker’s yeast industry effluent, which contains high levels of organic matter. An optimal pH value of 3 was determined by a pH scan performed between pH 2.5 and pH 7.5. Principal component analysis (PCA) was used to determine the effects of organic solvents and pH on extraction efficiency. The extraction efficiency was evaluated using the optimal pH and multi-stage extraction experiments. In a three-stage extraction, diethyl ether recovered 82% of the VFAs, making it a promising organic solvent for extracting VFAs from anaerobic fermentation broth. PCA revealed that an opposite correlation between VFA recovery and pH for each organic solvent. Based on the results of the cost analysis, it was determined that the costs of recovering VFAs were reduced by 90% per kilogram.

"Solid waste can contain large amounts of plastic; most are not biodegradable. For this reason, the disposal of waste plastics is a critical issue for society and sustainable life. It is important to note that solid waste landfills are the most common method for disposing plastics. Nowadays, energy recovery from waste plastics is gaining importance due to the energy production potential of waste plastics. Thermal methods such as incineration, gasification and pyrolysis can be used to obtain energy from plastic waste, but the conversion of plastic waste into liquid fuels, including diesel and gasoline, is also being researched. Although these methods reduce the environmental impact of plastic waste and provide alternative energy sources, the recovery of high-value-added products in parallel with energy generation is also important to minimize emissions, ensure adequate waste treatment, and promote environmental sustainability. As an example, the burning potential of polystyrene, which comprises 22 percent of waste plastics, is compatible with the circular economy concept while simultaneously reducing petroleum fuel consumption by recycling high value-added materials such as polycarbonate and polyamide.. Through the use of polymer recycling in conjunction with energy recovery from waste plastics, environmentally friendly, cost-effective waste management can be achieved."

A significant increase in atmospheric greenhouse gases over the last century has led to the development of several methods and technologies to remove carbon dioxide (CO2). Microorganisms produce carbonate minerals through the natural mineralization of CO2; however, the feasibility of this process remains in research. This work aimed to study the cultivation of different microalgae under alkaline pH to maintain their potential for carbon mitigation. According to the results, the highest carbonic anhydrase activity has been reached (4.64 mg/g) for Chlamydomonas reinhardtii at a pH of 10. C. reinhardtii, at a pH of 9.5, yielded the highest chlorophyll content (23.58 mg/g), while Spirulina at a pH of 8.5 produced the highest biomass (882.9 mg/L). Also, a positive correlation existed between pH and lipid content for C. reinhardtii. Spirulina, however, exhibits the opposite effect. According to a principal component analysis, there is an opposite relationship between pH and carbonic anhydrase (CA) activity for C. reinhardtii and filamentous-type cyanobacteria from Salda Lake. The following order of the suitability of the microalgae species for high carbon capture is determined by the Analytic hierarchy process method: Spirulina> C. reinhardtii > Chlorella vulgaris > Coccus-type cyanobacteria > Filamentous-type cyanobacteria from Salda Lake. Additionally, this study provided important results regarding the cyanobacteria species isolated from an alkaline lake, Lake Salda. This would contribute to future studies of carbon capture and carbon mitigation mechanisms.

In recent years especially during COVID-19, the increased usage of antiviral drugs has led to increased interest in monitoring their presence in wastewater worldwide. In this study, it was examined the occurrence, fate and environmental risks of favipiravir which is used for COVID-19 treatment in two wastewater treatment plants (WWTPs) with different treatment processes in Istanbul, Turkey. Favipiravir was measured in WWTPs influent samples, effluent samples and sludge samples with maximum concentrations of 97 mu g/L, 64.11 mu g/L and 182.47 mu g/g, respectively. Favipiravir had removal efficiency below 55 % for both WWTPs. Mass balance analysis showed that favipiravir removal in WWTPs mainly attributed to biodegradation/biotransformation. Statistical analysis revealed a significant correlation between favipiravir concentration and COVID-19 incidence in Istanbul. The microbial distribution analysis indicated that comparison of collected COVID-19 pandemic sludge and postpandemic period sludge samples, a noteworthy reduction in the Chloroflexi and Actinobacteriota phyla at the phylum level was observed. Environmental risk assessment using risk quotients ranged from 168 to 704, indicating that the presence of this antiviral drug posed significant ecological risks to aquatic organisms. The study concluded that WWTPs were releasing antiviral drugs into the environment, thereby posing risks to both the

This study employs several approaches to enhance environmental sustainability: First, algal biomass (with 52.5% protein content) was converted into value-added products. Second, residual algal biomass from protein extraction and pigment extraction and raw algal biomass were used to manufacture bioplastics. Third, radiation shielding performance of bioplastics has been investigated. As an alternative to plastics originated from petroleum-based raw materials, environmentally friendly bioplastics were derived from residual algae biomass after extraction. The gamma-ray radiation shielding properties of the produced bioplastic have been investigated using WinXCOM theoretical calculation and GEANT4 Monte Carlo (MC) simulation. Fast neutron shielding performance of the considered materials also evaluated with help of theoretical calculation and the same MC simulation. The produced bioplastics are similar to ones with commercially available PLA polymer. Sample 1 was found to be better gamma-ray attenuator while Sample 2 has the highest value of the effective neutron removal cross section. Additionally, the boron addition has resulted in lower water absorption capacity in the prepared samples. Using algae to produce more than one product as a raw material source will be an effective step toward sustainable life, and they could be an alternative gamma-ray shielding material to existing commercial polymers.

Nitrogen stress can influence microalgae’s growth characteristics, and microalgae grown in nitrogen-deficient conditions may produce higher or lower levels of biotechnological products as a result of metabolic changes. In photoautotrophic and heterotrophic cultures, nitrogen limitation has been proven effective in promoting lipid accumulation. In spite of this, no study has demonstrated a significant correlation between lipid content and other biotechnological products such as bioactive compounds (BACs). This research examines a strategy for lipid accumulation as well as the potential production of BACs with antibacterial properties in parallel with that strategy. This concept involved the treatment of the microalga Auxenochlorella protothecoides with low and high concentrations of ammonium (NH 4 + ). This particular experiment reached a maximum lipid content of 59.5% using a 0.8 mM NH 4 + concentration, resulting in the yellowing of the chlorophyll levels. Agar diffusion assays were conducted to determine the antibacterial activity of different extracts derived from the biomass when stressed with different levels of nitrogen. Algal extracts prepared by a variety of solvents showed different levels of antibacterial activity against representative strains of both gram-negative ( Escherichia coli ) and gram-positive ( Staphylococcus aureus ) bacteria. Among the extracts tested, 500 mg/L ethyl acetate extract had the greatest antibacterial activity against Escherichia coli . In order to identify the components responsible for the extract’s antibacterial activity, fatty acid methyl ester (FAME) analysis was performed. It has been suggested that the lipid fraction may be a valuable indicator of these activities since some lipid components are known to possess antimicrobial properties. In this regard, it was found that the amount of polyunsaturated fatty acid (PUFA) significantly decreased by 53.4% under the conditions with the highest antibacterial activity observed.

Rapid growth and high carbon-fixation properties make microalgal biomass a preferred source of energy-production technologies, particularly biodiesel and bioethanol, as well as nutritional supplements and pharmaceuticals. Today, microalgal biofuel technology, which is continuing to be developed as a surrogate for fossil-fuel technology, is the focus of constant research and development, especially regarding biomass yield and lipid production. Single stressors on microalgae have been commonly examined for efficient biofuel production; however, the synergetic effects of stressors on the lipid and biomass productivity of microalgae might lead to enhanced lipid properties. In addition, considering more than one parameter might be time-consuming; thus, many models, such as the surface-response methodology, can enable significant optimization of microalgal productivity economically. As well as multiple stressors, adaptive stressors considered in “adaptive laboratory evolution” could provide robust strains that alter low lipid yields. Although the field has progressed substantially in recent years, much about microalgae, their biological potential, how to efficiently utilize them, and their metabolic responses to various stressors remain unknown. Using an extensive review of recent developments in single-stress strategies, combined-stress strategies, and adaptive stress strategies, this paper gives an overview of recent developments in microalgal biofuel production under stress conditions. Further, it has also been suggested that an integrated microalgal biorefinery that also produces high-value chemicals alongside biofuel might significantly enhance its economic feasibility. It is expected that this document will provide an understanding of how to develop commercially viable microalgae strains for biofuel applications, taking several types of stress into consideration.

Mutagenesis in microbial strains might result in robust strains with enhanced biofuel properties. Besides that, oleaginous microalgae, Auxenochlorella sp. with enhanced biomass and lipid content, can be a strong candidate for biodiesel production. In this context, a chemical mutagen called ethyl methane sulfonate (EMS) was screened at different concentrations. Considering that a lower survival rate can result in a higher mutation rate, an EMS concentration of 0.25M with 13 mins exposure time was selected as the optimum mutation condition. An acetyl-coenzyme A carboxylase (ACCase) inhibitor herbicide, tralkoxydim, was used as a selective environment to choose the mutant strains. Using an ACCase inhibitor herbicide would maintain a more desirable mutant strain that had the enhanced characteristics of biodiesel. Multi-scale comparisons between selected mutant strains and a wild strain revealed that by the time there was a remarkable decrease of 12.6% in the lipid content of the wild strain under the addition of Tralkoxydim (34.8%) compared to 39.8% in wild type, the lipid contents of the mutant strains remained higher. A remarkable increase by 1.50-fold and 1.33-fold in biodiesel fuel properties for Tralkoxydim-treated strains emphasizes that the ACCase synthesis pathway for lipid production is influenced by the stress factor that reaches the European biodiesel standards.

Since Yarrowia lipolytica, an oily yeast, contains many valuable products as biomass, to increase its widespread use, it is very important to develop a sustainable production model. In this study, the production of high acid hydrolysate from sawdust biomass, which is produced in very high amounts in our environment, and the effect of these products on the growth efficiency of Yarrowia lipolytica were investigated. A preliminary statistical analysis was carried out to assess sugar production from sawdust by hydrolysis, which estimated 85% of total sugar recovery (TSR) using 96 g of sawdust, while TSR at the highest sawdust was as high as 79%. There was a higher loss in the recovery of C5 sugars with acid and time. This study revealed that Y. lipolytica could grow with high biomass yields in varying hydrolysate concentrations, approaching yields achieved in synthetic glucose media. The maximum biomass obtained was 13 and 26 g in batch and airlift operations, respectively, using organic nutrients. Biomass and lipid yields from kinetic modeling provided a close approximation to the experimental yields performed on an airlift reactor. It was found that Y. lipolytica biomass cultivated on sawdust hydrolysates had significant lipid and protein compositions, as high as 29 and 38%, respectively.

Müsilaj oluşumu, çeşitli biyolojik ve hidrolojik etkileşimleri içeren çok karmaşık bir olgudur. Müsilaj oluşumuna elverişli koşullar oşinografik değişimlerle gözlenebilirken, ortamda bulunan bakteriyel ve fitoplanktona dayalı aktiviteler de müsilaj oluşumunda etkin rol oynar. 17. yüzyıldan beri farklı denizlerde ve ekosistemlerde gözlenmiş müsilajın, mikrobiyal yapısı ve şekli de farklıdır. Bu durumu, müsilaj oluşumunun çoğunlukla taksona özgü olması ve kalınlığının ile dokusunun ise çevresel faktörlerden etkilenmesi ile açıklamak mümkündür. Müsilaj araştırmalarında baskın tür olarak çoğunlukla fitoplankterler karşımıza çıkmaktadır. Özellikle, ortamdaki yüksek organik madde miktarı ve nutrient miktarları, fitoplankton oluşumu ve mikroçevre oluşumunu tetiklemektedir ve suyun sıcaklık, akışkanlık, türbidite gibi bazı özellikleri müsilaj üretimini artırıcı etki göstermektedir. Bu derlemede, öncelikle çözünmüş organik madde (ÇOM) ve mikrobiyal popülasyonun agregat oluşturarak nasıl müsilaja dönüştüğünden bahsedilmiştir. Sonrasında, mikrobiyal ekoloji incelemelerinde müsilajın yapısında karşılaşılmış canlı grupları anlatılmıştır. Müsilaj bölgelerinde gözlenen baskın türler, vaka bilgileri ile detaylı olarak anlatıldıktan sonra, müsilaj oluşumu sonucu yaşamı olumsuz etkilenen canlılardan bazı örnekler verilmiştir.

Anaerobic Digestate (AD) is a desirable and significant nutrient source for microalgal growth. It can be utilized as a part of the circular economy in the generation of high-value-added products. Dual-mode cultivation with AD as a substrate can be an efficient strategy to enhance the algal biomass and produce high-quality biodiesel. As dilution is required to prevent growth inhibition, in this study, growth optimization was initially carried out to figure out the best dilution ratio of AD, which corresponded to a wide range of 0 to 2,000 mg NH4-N/L concentrations. The Bold's basal medium with triple nitrate (3NBBM) that supplemented AD at 4 % dilution resulted in the highest biomass (2290 mg center dot L-1). After maintaining the highest biomass-producing condition, stressors such as sodium chloride (NaCl) and ferric chloride (FeCl3) have also been searched to increase lipid production. The lipid content has increased by 1.8-fold as a result of the stress (at 20 g center dot L-1 NaCl and 0.1 mg center dot L-1 FeCl3). At those stress conditions, the saturated fatty acid concentrations were around 33 % of the total fatty acid methyl esters (FAME). In addition, compliance with the biodiesel standards has also been ensured at 0.1 mg center dot L-1 FeCl3. The combination of AD with nutrients and salt stressors, like NaCl and FeCl3, within the concept of dual-mode cultivation, could be a viable strategy to produce sustainable, high-quality biodiesel with a high proportion of algal biomass and could be integrated into microalgae production facilities.

Inadequate global fossil fuel reserves have forced researchers to investigate alternative fuel sources, and oleaginous microorganisms have attracted attention with their potential. Since high lipid production yield is an important criterion for suitable fuel production, in this study an oleaginous yeast, Yarrowia lipolytica, was selected and the lipid and biomass productivity under molasses (M20) substrate and nutrient supplementation was investigated. The effect of phosphorus as dipotassium hydrogen phosphate (K2HPO4), magnesium as magnesium sulphate (MgSO4), and yeast extract supplementation to molasses (M20) were evaluated individually and in combination. In addition, two quadratic models, using Box-Wilson central composite design, were used to correlate the phosphorus, magnesium and yeast extract concentrations that would achieve the highest biomass and lipid productivity. The study has shown that molasses (M20) supplemented with 336 mg/L K2HPO4, 0.17 g/L MgSO4 and 4.54 g/L yeast extract had the highest biomass productivity (80.7 mg/L/hour) and the highest lipid productivity (28.3 mg/L/hour). These productivity results were 1.44-fold and 2.42-fold higher than those of yeast extract-peptone-dextrose (YPD) broth, respectively. With enhanced biomass and lipid productivity, Yarrowia lipolytica can thus be used effectively in the fermentation industry.

Biogas is produced with an anaerobic method, which involves live digestionof biomass in an oxygen-free environment. The second part of our book givesinformation about algae technology of the anaerobic process, which produces biogas bya biological process using animal fertilizers, food waste, and bioenergy products. Ingeneral, biogas can be used to produce heat and electricity, and its addition to thenatural gas network is even considered as a vehicle fuel. It consists of 30-40% CO2 ascontent, 45-65% CH4. Conversion of CH4, which is 20 times more harmful than CO2 asa greenhouse gas, into energy is essential for the protection of environmental impact. Inthis sense, the burning of biogas emerges as a greenhouse gas reduction strategy.

The cost of lipid production per biomass is an important factor for the expansion of the microalgal biorefinery industry. Some stressors and regulatory molecules, such as salicylic acid (SA), abscisic acid (ABA), indole-3-butyric acid (IBA), and carbendazim (CARB), can stimulate microalgal biomass and lipid quality, as well as improve their properties, by lowering unsaturated fatty acids, stimulating cell division and development, or causing oxidative stress. This study focused on identifying a microalgal growth condition that is compatible with enhanced lipid and biomass yields and high biodiesel quality while being highly resistant to stressors. Many carbon sources, such as glycerol (GLY), remain unclear as to how hormones and other stressors may stimulate growth under photoheterotrophic conditions, and GLY, also a regulator of fatty acid metabolism and hormone cross-talk, might enhance lipid accumulation under supplementation with phytohormones, fungicides, or even organic solvents. In addition, two organic solvents, three phytohormones, and one fungicide were evaluated, which are considered stressors to increase lipid productivity and the lipid quality of microalgae. Among the six stressors, 108 µM SA and 2.5 µM ABA combined with 8.4 g/L GLY resulted in the highest lipid productivity for Auxenochlorella protothecoides. In addition, supplementation with CARB concentrations of 260 µM and 1040 µM, ABA concentrations between 10 and 40 µM, and an SA concentration of 360 µM to GLY-modified Blue‒Green (BG11) medium provided lipid productivity to satisfy biodiesel standards. As a general statement, organic solvents, plant hormones, and fungicides at various concentrations in combination with GLY can enhance microalgal biomass productivity and lipid quality by promoting microalgal-based biodiesel.

Microbial lipid production by oleaginous yeast applying Food Waste (FW) could be a sustainable alternative for fossil fuels. This study was conducted with the aim of increase cell growth and lipid accumulation of Yarrowia lipolytica under nitrogen deficiency condition. Two-stage batch strategy was conducted using Fermented Food Waste (FFW) at initial stage and three different carbon sources (i.e., glucose, glycerol and potassium acetate) at second stage along with different COD/TKN ratios (i.e., 75, 100, 125, 150 and 175). High lipid content of 42.2 ± 1.72

Health problems and reduced treatment effectiveness due to antimicrobial resistance have become important global problems and are important factors that negatively affect life expectancy. Antimicrobial photodynamic therapy (APDT) is constantly evolving and can minimize this antimicrobial resistance problem. Reactive oxygen species produced when nontoxic photosensitizers are exposed to light are the main functional components of APDT responsible for microbial destruction; therefore, APDT has a broad spectrum of target pathogens, such as bacteria, fungi, and viruses. Various photosensitizers, including natural extracts, compounds, and their synthetic derivatives, are being investigated. The main limitations, such as weak antimicrobial activity against Gram-negative bacteria, solubility, specificity, and cost, encourage the exploration of new photosensitizer candidates. Many additional methods, such as cell surface engineering, cotreatment with membrane-damaging agents, nanotechnology, computational simulation, and sonodynamic therapy, are also being investigated to develop novel APDT methods with improved properties. In this review, we summarize APDT research, focusing on natural photosensitizers used in in vitro and in vivo experimental models. In addition, we describe the limitations observed for natural photosensitizers and the methods developed to counter those limitations with emerging technologies.

It is known that environmental problems in our world and life are mostly caused by fossil fuel consumption. Issues such as global climate change, seasonal warming and narrowing of cooling periods have started to affect our daily life negatively in the world. This book chapter is intended to provide a methodical solution to these problems. In the recent COVID-19 outbreak, the spread of a virus infected by a bat species in a way that threatens human life also reveals that we do not exist in the world, that is, different living species from us are a determining factor in our lives. Like the famous physicist Einstein's word above. Life cycle assessment (LCA) became popular in the early nineties. This technique was initially considered as a direct marketing tool used during the environmental impact assessment of the whole production or the comparison of the two production stages. In the following periods, it was understood that the more effective results of this method were put forward not only as a marketing tool. Therefore, LCA application is important because it can be applied to all production methods. Especially in recent years, this method has started to be expressed as a critical method in environmental policies. The concept of integrated product policy is a prime example of this. Not only the European Union but also China and the United States are developing strategies that support this method as an important key. The attractiveness of this method is increasing day by day as the world's top 500 companies conduct sustainability reporting in their operations, especially in terms of LCA. In this study, firstly, we showed about fossil fuel power plants, and then we gave information about algae technology about the retention of flue gas in the atmosphere and lastly, the life cycle assessment for energy systems was evaluated to make flue gas to be less harmful to the environment. © 2021 by Nova Science Publishers, Inc. All rights reserved.

t Wastewater from textile industry is considered one of the major environmental challenges due to the large volume of highly colored, polluted and toxic effluent. This study investigated the treatability of real textile wastewater by pilot-scale anoxic-aerobic Membrane Bioreactor (MBR) system without sludge wasting for an operation period of 100 days. The proposed system was investigated under different Internal Recycle (IR) ratios and the impact of IR ratio on Total Organic Carbon (TOC), Total Nitrogen (TN) and Color removals were examined. Under IR ratios between anoxic and aerobic tanks of 0.0, 0.5 and 2.0, the respective average removal efficiency of TN was 20.9%, 53.4% and 71.7%, whereas average color removal of 81%, 85% and 88%, respectively was noted. The results indicated that increase of recycle ratio from 0.5 to 2.0 enhanced TN removal to about 71% and color removal to above 85%. The IR between anoxic and aerobic tanks has a significant role in TN and color removal due to its effect on the development of bacterial communities. On the other hand, the results indicate over 93% TOC removal, which was independent of IR ratio.t

This study aimed to optimize the growth conditions of the microalgae Auxenochlorella protothecoides to maximize the biomass and lipid content. The pH values and acetate concentrations of a tris-acetate-phosphate medium were varied for a photoheterotrophically grown culture of A. protothecoides. Approximately 23% of the microalgal biomass consisted of saturated fatty acids (SFAs). The highest lipid content (47.8%) was achieved with a medium containing 17 mM acetate at pH 6.2, and a medium containing 50 mM acetate at pH 5.8 resulted in the highest SFA content (43.7%). Surface response methodology was used to analyze the effects of two independent variables, pH (5.8–7.2) and acetate (0–35 mM), on lipid and biomass content. Four quadratic models, using the Box-Wilson central composite design, were proposed to correlate the optimal pH and acetate concentrations that would achieve the maximum biomass and lipid content. The study demonstrated that medium containing 24.4 mM acetate at pH 5.96 resulted in the highest lipid content (47.8%), and resulted in the highest biomass (1537 mg/L). Microalgae growth under these optimized conditions can enhance biomass and lipid productivity and can provide suitable conditions for high-quality biodiesel.

In this study, iron sources and their optimum concentrations for high-quality biodiesel production were determined on Auxenochlorella protothecoides microalgae. Three iron compounds-ferrous sulfate, ferric ethylenediaminetetraacetic acid (EDTA), and ferric chloride-were assessed regarding concentration, specific growth rate, lipid, and lipid quality in relation to fatty acid methyl ester (FAME) composition of microalgal biomass. Auxenochlorella protothecoides demonstrated high resistivity to high concentrations of iron species, still showing an ability to grow in the presence of iron concentrations as high as 21.60 mM. The highest saturated fatty acid (SFA), at 78.5% of FAME, was observed at 1.15 mM ferric chloride, and the highest biomass generation was observed at 1.08 mM ferrous sulfate. In addition, biodiesel and diesel fuel qualities were satisfactory with microalgae cultivated at 0.2 and 14.4 mM ferrous sulfate, 7.19 mM ferric EDTA, and 0.07-21.58 mM ferric chloride concentrations. The former may be more practical, since the use of this iron compound gives the desired result in a broader range. Overall, it can be inferred that high-quality lipid and biodiesel production can be obtained by changing the concentrations and sources of iron compounds. (C) 2020 Elsevier Ltd. All rights reserved.