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The increase in population and industrialization leads to an increase in the solid waste year by year. The limited availability, increasing cost and adverse effect of climate change on fossil fuel leads to encouraging the research in the field of finding alternatives for energy sources. The organic fraction of municipal solid waste (OFMSW) can be utilized as a bio-energy source, which reduces the environmental impact and the requirement of landfill areas to dispose of municipal solid waste. Anaerobic digestion is the widely used sustainable approach to treat OFMSW. In recent years, the generation of methane from municipal solid waste has received increasing attention in research. This paper reviews literature published in recent years considering various characteristics of input feedstock parameters like pH, total solids, volatile solids, and water content which affect the digestion quality of the OFMSW and increase the production of methane. A regression model is developed to identify the relationship between methane production and various feedstock parameters. When the chemical compositions of feedstock were used as independent variables, the percentage variation accounted for by the model is low (r2 = 0.63) and also the important observation from the analysis is that the pH of the feedstock influences majorly methane production.

Magnetic nanoparticles are desirable adsorbents because of their unique superparamagnetic nature with the enhanced binding specificity and surface material interaction. The above unique features attract researchers to use it for wider applications. Herein, the study focuses on the amino‐induced silica‐layered magnetic nanoparticles amalgamated with plant‐extracted products of Cynodon dactylon in order to turn them into a potent adsorbing material in a continuous column set up for the elimination of noxiously distributed Cr(VI) ionsin the effluents. The selected plant‐mediated magnetite nanoadsorbent, which was used in the fixed column studies, is optimised with the attributes of inlet concentration, adsorbent bed depth, and flow rate. Thomas, Yoon‐Nelson and bed depth model showed the best experimental fit. Breakthrough adsorption time was reported for the various inlet concentrations of 100, 200 and 300 mg/L, adsorbent bed depths 2, 3 and 4 cm and volumetric flow rates of 4, 5 and 6 mL/min. The breakthrough point evaluated for the optimised attribute of inlet concentration of 100 mg/L, packed adsorbent depth 4 cm and flow rate 4 mL/min was 1400 min and the maximum removal efficiency was 60.6%. A better insight of the adsorption of metal ions for large‐scale industrial effluents is provided.

Industrialization and human activities have led to pollution of ecosystems by metals and dyes, calling for advanced remediation methods. For instance, removal of water pollutants has been recently done using low-cost adsorbents. Here we review adsorbents based on cellulose, zeolites, biochar and nanomaterials. Hybridized nanosorbents show adsorption capacities up to five times higher than single materials, due to the combination of functions such as carboxyl, amino, thiol, hydroxyl, vinyl, metals and phenolics. Integrating metals having high magnetization and superparamagnetic properties improves reusability up to 10 cycles with minimal loss of pollutant removal efficiency.

Aim: The objective of the review paper aims to explore and to provide the insight of various low-cost adsorbents prepared and used in the removal of hazardous dye pollutants from the contaminated industrial effluents. Background: The major untreated discharge from the textile industries constitutes a wide range of organic contaminants with the enhanced concentration of biological oxygen demand and chemical oxygen demand inthe water bodies. Dyes are considered as the major water contaminants and this quest the researchers to adopt various technologies to remove the hazardous dye pollutants from the aquatic environment. Dyes are the chemical compounds that tend to adhere themselves with metal or salts by covalent bond formation or complexes by mechanical retention or physical adsorption so as to impart colours to which it is being applied. Objective: Numerous treatment methodologies which have been applied to the degradation of dyes. The current study has been focused on the distinct low cost and cost-effective adsorbents used in the removal of various dye pollutants. Also, the application of nanoparticles in the removal of the hazardous dye pollutants had received great interest because of its size and high reactive nature. Methods: The treatment technologies used in the removal of dye pollutants from wastewater have been listed as adsorption, coagulation, electrocoagulation, flocculation, membrane filtration, oxidation and biological treatment. Results: The complex structure of the dyes causes a great harmful impact on the aquatic environment. Though numerous treatment technologies have been applied, adsorption has been preferred by various researchers because of its cost-effective nature. Conclusion: The various adsorbents are used in the removal of cationic, anionic and non-ionic dyes. The different types of adsorbent from agricultural waste, activated carbons, nanomaterials and biomaterials have been discussed with the advantages and limitations.

Aim: The review paper aims to explore the effect of plant extracts on nanomaterial adsorbent for the removal of toxic metals present in industrial effluents. Background: Water plays a major role in the sustainability of human life and its existence. Rapid industrialization and urbanization lead to an increase in the pollution and accumulation of hazardous substances which causes the degradation of the aquatic ecosystem. Heavy metals are considered to be a major threat to the environment. Among various metals, the International Union of Pure applied chemistry (IUPAC) has characterized heavy metals based on their intensity of toxicity and hazardous effects. Nanoparticles, due to their unique properties of particle size, exist in the range between 1- 100nm, which represents the possibility to introduce modified chemical groups on their surface functioning as capping agents. Nanoparticles with the increased surface area have specified functional groups which induce the capability of the catalytic reduction reaction and their optical characteristics impact the industrial, agricultural and environmental sectors. Objective: Magnetic nanoparticles incorporated with the enzymes and metallic sites have been widely used in both the synthesis of bio valuable products as well as in the degradation of many hazardous substances like dyes, phenolic compounds, etc. Also, they are used in the removal of metal ions present in wastewater. Methods: Superparamagnetic support nanomaterials (SPIONs) are prepared using the compounds of Fe, Cu, Ni, Mn and Mg for the distinct and unique characteristics of reusability. These metallic nanomaterials are coated with distinct materials like mesoporous and amorphous silica, polyvinyl alcohol and pyrrolidine, polyethylene glycol, polystyrene, chitosan, dextran, starch, gelatin, polystyrene, polyacrylic acid, and polymethyl methacrylate to enhance the stability of the nanomaterials. Results: In comparison to the different nanomaterials, metal oxide NPs possess increased stability, magnetic inertness, optical and electrical properties. Nanomaterials that are used in the medical applications are also used as the adsorbents to remove heavy metals from the industrial wastewater. The presence of polyphenolic compounds and flavonoids makes the plant extracts effective antimicrobial agents that impact pathogens. Moreover, these plant extracts, coupled with other nanomaterials, play a significant role in the removal of toxic pollutants from the environment. Conclusion: Polyphenolic compounds present in plant extract function as natural reducing agents; hence, integrating plant extract with metal/metal oxide nanoparticles proves to be efficient in comparison with the catalysts synthesized by using other chemical methods. These surface modified nanocatalysts tend to possess enhanced stability and specific reactivity in the system and are used in the elimination of organic and inorganic pollutants in the industrial wastewater.

Organic acids such as citric acid, itaconic acid and oxalic acid synthesised by Aspergillus niveus were used for the bioleaching of metals from waste printed circuit boards. Bioleaching of valuable metals was performed in one‐step, two‐steps and spent medium approaches using A. niveus. In the absence of waste printed circuit boards (WPCBs), the dry cell weight of A. niveus was higher when compared with the presence of WPCBs. Variations in the dry cell weight were observed for the presence of different particle sizes. The increase in itaconic acid and oxalic acid synthesis was found at a reduced particle size (60–80 mesh) and reached the maximum titre of itaconic acid (22.35 ± 0.87 mM) and oxalic acid (12.75 ± 0.54 mM) in 12 days during the two‐step bioleaching. The maximum recovery of 75.66% Zn, 73.58% Ni and 80.25% Cu from WPCBs was achieved in 15 days in two‐step leaching with particle sizes of the mesh being 60–80.

Industrial wastewater is highly toxic and needs to be treated before being let into large water bodies. They have been treated using various biological and chemical processes. In this study, integrated magnetic nanoparticles (cobalt, ferrous and manganese) are fabricated with the specific amino group on the silica-coated surface layer with the size of 50 nm. The integrated magnetic nanocomposites are combined with the biochar obtained from groundnut shell are used to eradicate copper and lead pollutants in wastewater. Analytical techniques like Fourier transform infrared spectroscopy provides specific entities alike amino, hydroxyl and silica vibrational stretches; scanning electron microscopy gives over nanoadsorbent size around 30–50 nm and the presence of elemental constituents such as cobalt, manganese, ferrous, nitro, and silica was examined by energy dispersive X-ray analysis. High-resolution transmission electron microscopy figures nanoparticle size around 50 nm. Vibrating sample magnetometer determines the superparamagnetic nature of the particle to be around (magnetic saturation)—50 emu/g. Above nanoadsorbent evaluates an enhanced adsorption capacity pursued upon 436.8 mg/g for copper and 318.9 mg/g—lead ions in an optimal conditions (pH 5, temperature 30 °C, associated contact—1 h). Further exploration of zeta potential, kinetics model, two-parameter and three-parameter isotherm pattern evaluates a reaction pattern on nanoadsorbent with metallic interactions. The metal interactive study showed an excellent fit for pseudo-second order, double exponential kinetics and Langmuir–Freundlich isothermal pattern. The thermodynamic system exhibits a spontaneous and exothermic reaction process. Adsorbent possesses an excellent reusable capacity, where it could be reused for 10 continuous cycles upon the consecutive acid washes.

Immobilised magnetic nanoparticles are extensively used owing to their superparamagnetic nature, surface interaction, and binding specificity with the appropriate portentous substances. The present research focuses on the development of a portentous, robust carrier, which integrates the silica-coated amino-functionalised magnetic nanoparticle (AF-MnP) with the plant extracts of Cynodon dactylon (L1) and Muraya koenigii (L2) for the stable and enhanced removal of hazardous hexavalent chromium pollutant in the wastewater. Vibrating sample magnetometer (M s – 45 emu/g) determines the superparamagnetic properties; Fourier-transform infrared spectroscopy determines the presence of functional groups such as NH2, Si–O–Si, C=C; high-resolution transmission electron microscopy, field emission scanning electron microscope and energy-dispersive X-ray spectroscopy determine the size of the green adsorbents in the range of 20 nm and the presence of elements such as Fe, N, and Si determines the efficacy of the synthesised silica-coated AF-MnP. The AF-MnP-L1 shows the maximum adsorption capacity of 34.7 mg/g of sorbent calculated from the Langmuir isotherm model and the process follows pseudo-second-order kinetics. After treatment, the adsorbents can be easily separated from the solution in the presence of an external magnetic field and are reused for nine cycles after acid treatment with the minimal loss of adsorption efficiency.

Dyes and pigments utilized for colouring purposes by textile industries play a pivotal role in the accumulation of numerous toxic substances in an aquatic environment. This provokes a keen interest in the environmentalist in developing a novel sorbent material that could remove the organic pollutants from the waste effluent. In the current study, Lemna minor, a duckweed plant, acts as the low cost, eco-friendlier sorbent to remove the toxic acid blue 113 dye from the effluents. The characteristic traits of the dried biosorbent were analysed by scanning electron microscope to analyse the porous and rough exterior surface, Fourier transform infrared spectroscopy reveal the presence of specific entities such as amine, hydroxyl, carboxyl and alkyl groups and gas chromatography and mass spectroscopy for the presence of numerous polyphenolic compounds. Optimization was done by response surface methodology to study their potential in the adsorption capacity of the adsorbent. The removal efficiency of 98.5% was attained in the batch study at optimized parameters of contact time (40 min), pH (4.0), temperature (40 °C) and concentration of sorbent (1 g). The reaction mechanism was evaluated with the kinetics and isotherm studies. Kinetics study includes pseudo-first-order, pseudo-second-order, Elovich and intra-particle diffusion, and the isotherm study includes Langmuir, Freundlich, Langmuir–Freundlich and Temkin isotherm models. The system follows the pseudo-second-order kinetics model, Langmuir and Langmuir–Freundlich isotherm model with the maximum sorption capacity of 395.7 mg/g. Thermodynamic studies were evaluated to determine the spontaneous and endothermic nature of the reaction.

Magnetic nanoparticles owing to their superparamagnetic behaviour and specific reactive sites are facilitated to regenerate and reuse. Our present study determines the cointegration of the plant extracts of Cynodon dactylon and Muraya koenigii with the magnetic nanoparticle coated with silica layer and surface engineered with a specific amine group. The cointegrated magnetic nano adsorbent is characterized for its analytical feature and batch studies are performed to remove zinc (Zn(2+)) copper (Cu(2+)) metal ions. Fourier transform infrared spectroscopy reveals the presence of functional entities such as NH(2), Si-O-Si, C=C. The size of the cointegrated nano adsorbent (12–30 nm) was confirmed by field emission scanning electron microscopy whereas, a high-resolution transmission electron microscope affirms the nanosize of the particle constituted around 20 nm. Energy dispersive x-ray analysis confirms the presence of elements like Fe, N, Si and was confirmed by X-ray diffraction analysis and vibrating sample magnetometer affirms the superparamagnetic nature with the high magnetic saturation value (M(s) – 30 emug(−1)). The cointegrated nano adsorbent reveals the maximum adsorption capacity of Zn(2+) as 78.24 mg.g(−1) and Cu(2+) as 81.76 mg.g(−1) of the adsorbent under the optimized conditions of contact time 45 min, pH 6.0 and temperature 35 °C. Kinetics such as pseudo-first-order, pseudo-second-order, Elovich, intraparticle diffusion and isotherm studies like Langmuir, Freundlich, Dubinin-Radushkevich and Temkin were performed to understand the mechanism of interaction between the nanoadsorbent and metal ions. The reaction system follows the pseudo-second-order kinetics and Langmuir isotherm model for both the Cu(2+) and Zn(2+) metal ions. To determine the reusing capacity of the cointegrated nanoadsorbent, the adsorption efficiency was studied for continuous twelve cycles with 80% recovery after subsequent acid treatment. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s40201-021-00696-9.

Immobilized magnetic particles are substantially used in several applications, due to their superparamagnetic nature and specific binding capacity with the appropriate support molecules. The presen...

The present study focuses on the measurement of metabolic heat profile for the proteolytic activity by the Aspergillus tamarii. Here, agricultural by-products like wheat bran, cottonseed meal, soya flour and skimmed milk were utilized to maximize the enzyme expression. The study revealed that the maximum heat release (69.5 kJ/L) was dominantly from the oxidative breakdown of the nitrogen source i.e. the cottonseed. A distinguishable growth and non-growth enzyme expression phases of A. tamarii could be identified from the metabolic heat profiles. A maximum enzyme expression of 1.511 U/mL was obtained with a 1% supply of nitrogen source. Metabolic heat production rates were correlated to fungal protease secretion for the first time.

Heavy metals are considered to be the widespread contaminants in our ecosystem. Industrialization, modernization, and urbanization are extensively important for the increase in the release of these pollutants that are seriously considered as a major threat to the environment. The International Union of Pure and Applied Chemistry has named certain metals to be toxic based on their hazardous nature and the intensity of their toxicity when exposed to the flora and fauna in the ecosystem. Numerous metals including As, Ba, Be, Cu, Cr, Co, Ni, Zn, Mn, Pb, Cd, and Hg are registered as toxic pollutants, which alter the regular mechanism of the genetic system causing a mutation in numerous organisms that prevail in our environment. This results in adverse health issues that cause several medical complications and death. Natural zeolites are extensively concentrated in the removal of these hazardous toxic metal pollutants owing to their distinct physical and chemical properties. These are crystalline structural particles hydrated with a certain quantity of aluminosilicates linked by oxygen molecules. They also contain numerous elements such as calcium, sodium, barium, potassium, strontium, and magnesium. These natural zeolites are used as the potential adsorbent in the removal of various metal pollutants through electrostatic interactions between them. Natural zeolites are also modified through ion exchange and their removal capacity depends on the exchange of cations, particle selectivity, and kinetics behavior between the pollutants and the adsorbent molecules. Natural zeolites are considered as effective adsorbents based on their easy availability, low cost, high surface area, and high electric field density.

Water is a basic requirement in process industries such as pharmaceutical, textile, tannery, and pesticides industries. These industries generate a large amount of wastewater that is colored, and has high Chemical Oxygen Demand (COD) and Biochemical Oxygen Demand (BOD). Various treatment techniques such as chemical methods and biological methods have been adopted to treat wastewater. Advanced oxidation processes (AOPs) have gained immense importance in recent years as it completely mineralizes the emerging and nondegradable organic pollutants into carbon dioxide and water at feasible ambient reaction conditions. Photocatalysis is an AOP that uses visible and ultraviolet (UV) light in the presence of a catalyst and completely degrades the organic pollutant. Semiconductor materials are widely used as a photocatalyst and it can be used for the UV and visible region based on their bandgap energy. Extensive research was performed over the past few years in the development of a catalyst for the degradation of nondegradable organic pollutant as well as the design of a photocatalytic reactor to minimize photon transfer and mass transfer limitations. This chapter concentrates on various photocatalytic methods, wastewater from textile, pharmaceutical and tannery industries and their treatment methods, factors affecting photocatalytic degradation and photocatalytic reactors used for the treatment of said industrial wastewater.

Nanotechnology is a novel branch of science and technology that has been used in various fields of science and engineering as it has unique features at the nanoscale. This novel technology aims at producing atoms and molecules in various sizes and shapes at the nanoscale that have modified novel properties and functionality, rather than atoms or molecules as a whole. the consumption of high energy levels and the usage of chemicals that have negative impacts on the environment are the major disadvantages of physical and chemical methods. Thus biosynthesis, an alternative synthesis method, has been established. Using the biological method, plant extracts and microbes can be utilized to produce nanoparticles. This chapter emphasizes the techniques involved in nanoparticle synthesis, characterization, and its application in biofuel and bioenergy for environmental sustainability.

Immobilization of magnetic nanoparticles and enzymes with the aid of chemicals and metals as their major support is extensively used in numerous applications, owing to their superparamagnetic nature, surface interaction, alteration, and binding specificity with the appropriate proteinaceous substances. The metal nanoparticles are widely accepted as the antioxidants, and their prevalent usage inadvertently releases toxic metals that contribute as a major threat to our environment. This leads to the development of the integrated biocatalyst that acts as the robust carrier in the removal of hazardous pollutants in the wastewater. Heavy metals are considered to be a major threat to our environment due to industrialization and urbanization.

Immobilised magnetic nanoparticles are extensively used owing to their superparamagnetic nature, surface interaction, and binding specificity with the appropriate portentous substances. The present research focuses on the development of a portentous, robust carrier, which integrates the silica‐coated amino‐functionalised magnetic nanoparticle (AF‐MnP) with the plant extracts of Cynodon dactylon (L1) and Muraya koenigii (L2) for the stable and enhanced removal of hazardous hexavalent chromium pollutant in the wastewater. Vibrating sample magnetometer (M (s) – 45 emu/g) determines the superparamagnetic properties; Fourier‐transform infrared spectroscopy determines the presence of functional groups such as NH(2), Si–O–Si, C=C; high‐resolution transmission electron microscopy, field emission scanning electron microscope and energy‐dispersive X‐ray spectroscopy determine the size of the green adsorbents in the range of 20 nm and the presence of elements such as Fe, N, and Si determines the efficacy of the synthesised silica‐coated AF‐MnP. The AF‐MnP‐L1 shows the maximum adsorption capacity of 34.7 mg/g of sorbent calculated from the Langmuir isotherm model and the process follows pseudo‐second‐order kinetics. After treatment, the adsorbents can be easily separated from the solution in the presence of an external magnetic field and are reused for nine cycles after acid treatment with the minimal loss of adsorption efficiency.

Proteolytic enzymes are one of the significant commercially manufactured enzymes. The manufacture of extracellular alkaline protease by

Chemical recycling of polyethylene terephthalate, known as PET, has been the subject of increased interest as a valuable feedstock for different chemical processes. In the present work, an attempt has been made to depolymerize PET to yield Terephthalic acid (TPA) and ethylene glycol (EG). This process leads to the complete depolymerization of PET to its monomers, carried out by the chemical recycling of PET waste in the reactor and 92% conversion of PET will be obtained at 90 degrees Celsius. Chemical recycling of post-consumer waste PET bottles via alkaline hydrolysis. At the end, complete conversion of the PET wastes into terephthalic acid is obtained. The important objective of this research work is to eliminate or reduce PET plastic wastes and converted completely into value-added products for additives. The operational parameters such as time, temperature and amounts of ethylene glycol and catalysts are varied to achieve greater efficiency of the reaction.

Organic acids are considered to be the third-largest entity among the other chemical substitutes. The worldwide market rate was projected to be US$6.55 billion, and it was expected to reach about US$9.29 billion by 2021. These compounds have proven to be used in the numerous applications as additives in the food industries and due to their major demand as the feedstocks in the chemical industries. These compounds are also used as the silages in the perspective of drinking water. Organic acids could be produced through chemical and microbiological processes. But fermentation is considered as the major phenomena in the commercial large-scale production of numerous organic acids. Mostly genetically engineered strains could produce the high yield of organic acids using alternate residues from the chemical feedstocks. The choice of raw material and microbial sources is considered as the major significant factor for the enhanced productivity and yield, especially in the large-scale production. Mainly solid-state fermentation with renewable source as the feedstock was preferred because of the economic factor of low cost and easy availability. Citric acid is considerably produced in large quantities among the other acids with 1.6 million tons, whereas acetic acid and lactic acid constitute to be the second and third place in the productivity of various organic acids. These organic acids are extensively found to be used in the numerous applications of food industries, dairy products, and pharmaceuticals and also in the production of various components like inks, plastics, lacquers, etc.; they play a prominent role as a chelating agent in the removal of various metal pollutants from soil. The cost of the petrochemical derivatives tends to increase the usage and provokes the strong interest toward the agricultural by-products to be used as the major feedstock in the numerous organic acid production. These agricultural by-products are considered to be both renewable and economically cheap material as the feedstock to be easily consumed by numerous microorganisms in the commercial and large-scale production of various organic acids.

In this study, Carbon Cloth (CC) and Graphite Rod (GR) were used as electrodes in the Microbial Fuel Cell (MFC) to notably reduce the COD level and produce the electricity. By varying the distance between the electrodes, electricity production will improve. Two values of distance between electrodes i.e. 40 cm and 60 cm were assessed for finding the efficiency of electricity production in the process. Both electrodes showed COD reduction: 82 % for CC and 76% for GR, and power outputs of 530±18 mW m−2 and 455±20 mW m−2 respectively. The present study reveals that electricity production depends on the distance between the electrodes.

Proteolytic enzymes are one of the significant commercially manufactured enzymes. The manufacture of extracellular alkaline protease by Aspergillus tamarii MTCC5152 was explored using several agricultural by-products as substrates viz., cottonseed meal, wheat bran, skimmed milk and soya flour in submerged fermentation, were found to be efficient for enzyme production and commercially significant. Response surface methodology (RSM) is a statistics-based experimental design, sourced to explore the impact of physical parameters on the manufacture of protease from A. tamarii in a batch stirred tank bioreactor (STBR). The four substantial variables (pH, temperature, inoculum size, and agitation) were carefully chosen for optimization analyses and the statistical pattern was created using a central composite design and the quadratic model has been developed. The optimum conditions for protease production (1.51 U mL−1) where: pH 6.4, temperature 27 °C, inoculum size 2.6%, and agitation 327 rpm. The analysis revealed that the anticipated values were in accord with trial data with a correlation coefficient of 0.969.

Superparamagnetic nanocomposites integrated with multiple metals, and surface engineered nanoparticles play a vital role in the removal of heavy metals. In the present study, amino-functional silica-coated magnetic nanocomposites with biochar synthesised from Cynodon dactylon plant residues are prepared in a single step reaction process. The synthesised nanocomposites are characterized using various analytical techniques such as FTIR to determine their functional entities, SEM, TEM, EDX and VSM to analyse the size (~50 nm), elements and magnetic nature of the nanocomposites. Characterization reveals that the prepared nanobiochar was coated with silica and a specific amine group. The magnetic saturation value of 50 emu/g confirms the prepared sorbent was superparamagnetic. Kinetics, isotherm and thermodynamics parameters are evaluated to study the metal interaction mechanism with the nanocomposites where the system follows pseudo-second-order kinetics and the four-parameter Fritz Schlunder model for both metal ions. The nanocomposites showed the enhanced adsorption capacity of copper (Cu(II)) ions with 220.4 mg/g and 185.4 mg/g for lead (Pb(II)) ions. The nanocomposites also showed the excessive reusing ability of 15 times with the maximum removal efficiency for Cu(II) and Pb(II) metal ions. Column studies are evaluated to demonstrate the vital performance in the removal of Cu(II) ions and the breakthrough point was inferred for the parameters such as concentration (100–300 mg/L), bed height (1–3 cm) and flow rate (2–4 mL/min). The breakthrough point was attained at 1400 min and the removal efficiency of about 64.58% was obtained.

Superfluous algal biomass hydrolysate and purified glycerol obtained from biodiesel production were utilized for the production of itaconic acid by Aspergillus niveus. The lipid extracted Gracilaria edulis algal biomass residual was subjected to a pretreatment for the enhanced production of itaconic acid. Glycerol acquired from biodiesel production was pretreated and utilized as a substrate for itaconic acid production. The effect of individual and combined substrate concentration on itaconic acid production was investigated. Ultrasonication combined with the acid pretreated algal biomass produces higher itaconic acid due to the higher level of the total carbohydrate content (58.47 ± 2.57% w/v). After 168 h of incubation, A. niveus utilizes algal biomass hydrolysate and purified glycerol as substrate and produced 31.55 ± 1.25 g/L of itaconic acid and the dry cell weight is 18.24 ± 0.23 g/L respectively. Glycerol and algal biomass hydrolysate was a potential substrate for itaconic acid production by fungal species.

The synthesis of extremely stable and active earth abundant electrocatalyst is necessary to minimize the reliance on platinum (Pt) for hydrogen evolution reaction (HER) over broad pH medium which is remaining as a great challenge. Among different ordinary metal based electrocatalysts, nickel sulphide-based material has been recognized as active electrocatalyst due to its more active edge and high stability. Herein, nickel sulphide with nitrogen doped carbon (Ni3S2/NC) composites electrocatalyst have been prepared with different weight contents (Ni3S2/NC10, Ni3S2/NC20, Ni3S2/NC30 and Ni3S2/NC40) of NC via a simple hydrothermal one-step approach to evaluate the HER activity. The morphological and structural properties of the synthesized electrocatalysts were characterized using FTIR, XRD, SEM, HR-TEM and EDAX. The SEM of the synthesized Ni3S2/NC20 composite has shown nanocube like structure. Additionally, the electrochemical behaviour was evaluated over a broad pH medium to assess the HER activity of the synthesized materials. The obtained electrochemical results displayed that the Ni3S2/NC20 composite showed a good activity with the overpotential value of 174, 199 and 249 mV in 0.5 M H2SO4, 1.0 M KOH, and 1.0 M phosphate buffer solution (PBS) at 10 mA cm−2, respectively. This optimized composition exhibited an efficient stability for 1000 cycles and durability for 15 h in broad pH medium. Hence, the chosen Ni3S2/NC20 electrocatalyst will be a less expensive non-Pt based electrocatalyst for efficient HER.

Itaconic acid production was investigated by using isolated A. japonicas on pretreated Citrullus lanatus rind under solid-state fermentation. The isolated elite fungal strain A. japonicas showed maximum itaconic acid production was identified by using 18 S rRNA sequencing method. Citrullus lanatus rind was collected and pretreated using microwave radiation and its impact on itaconic acid production was investigated. Further, the effect of parameters like incubation period, inoculum percentage, moisture content, several nitrogen sources, nitrogen and KH2PO4 concentration were explored. Pretreated Citrullus lanatus rind exhibited maximum itaconic acid production of 17.68 ± 0.65 g of itaconic acid/kg of CLR. The optimum level of incubation period and inoculum percentage was found to be 192 h and 6% (v/w), respectively. Further, 60% (w/w) of moisture content, 2% (w/w) of peptone and 0.6% (w/w) of KH2PO4 resulted in 21.52 ± 1.87 g itaconic acid/kg of CLR was produced using novel A. japonicas.

Filamentous fungi from the genus Aspergillus are of high importance for the production of organic acids. Itaconic acid (IA) is considered as an important component for the production of synthetic fibers, resin, plastics, rubber, paints, coatings, adhesives, thickeners and binders. Aspergillus niveus MG183809 was isolated from the soil sample (wastewater unit) which was collected from Avadi, Chennai, India. In the present study, itaconic acid was successfully produced by isolated A. niveus by submerged batch fermentation. In the fermentation process, various low-cost substrates like corn starch, wheat flour and sweet potato were used for itaconic acid production. Further, the factor influencing parameters such as substrate concentration and incubation period were optimized. Maximum yield of itaconic acid (15.65 ± 1.75 g/L) was achieved by using A. niveus from corn starch at a concentration of 120 g/L after 168 hr (pH 3.0). And also extraction of itaconic acid from the fermentation was performed with 91.96 ± 1.57 degree of extraction.

Biocalorimetry has proved to be an efficient tool for studying the energetics involved in several biochemical reactions. In this study, biocalorimetry was employed to simultaneously analyze biokinetics and bioenergetics involved during cultivation of a salt tolerant Pseudomonas aeruginosa for the production of alkaline protease. Batch experiments were performed in a bench scale biocalorimeter for alkaline protease production by P. aeruginosa using optimized process conditions. Tessier’s double substrate growth model was found to provide a good fit for the growth of P. aeruginosa in the biocalorimeter, and the biokinetic parameters were estimated. The heat flow profile resulting from metabolic activity of P. aeruginosa was shown to accurately depict both the kinetics of cell growth and protease production. Biokinetic and bioenergetic analysis on the growth of P. aeruginosa revealed that peptone is preferentially used as the substrate for its intracellular activities and glycerol acts as an energy source for its growth metabolism.

The effects of aeration and agitation on metabolic heat, alkaline protease production and morphology for Aspergillus tamarii MTCC5152 are reported in this manuscript. Measurement of metabolic heat has been attempted by the continuous and dynamic heat balance method in a biological real-time reaction calorimeter. At lower agitation intensities, growth-related processes were dominating. As a result the protease activity and the product heat yields were lower than those for 350 and 450 rpm. Although biomass growth was necessary to obtain maximum protease yield, agitation seemed to play a vital role in the protease production process. Energy dissipation per circulation function of the process is also deduced from power input. At optimal conditions, 350 rpm and 1 vvm, the gassed power required was 0.133 W. Pellet morphology and protease production were studied under different aeration and agitation intensities of A. tamarii. Pellet structure was considerably influenced by DO, a higher DO level resulted in denser pellets (1,018.4 kg/m(3)) leading to higher protease activity. Coupling of hydrodynamics and bio-reaction highlighted the complex relationship between energy dissipation, substrate uptake rate and fungal physiology. This study emphasised the potential of biocalorimetry as a reliable monitoring and robust control tool for aerobic fermentation of A. tamarii, using agricultural by-products.