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Many operating parameters of ultrafiltration (UF) are playing a crucial role when using a polyethersulfone membrane to separate xylose reductase (XR) enzyme from reaction mixtures during xylitol synthesis. The present study focuses on the separation of XR enzyme using a cross-flow ultrafiltration (UF) membrane. The filtration process was analyzed using the three effective variables such as filtration time, cross-flow velocity (CFV), and the transmembrane pressure (TMP), which were ranging from 0 to 100 min, 0.52 to 1.2 cm/s and 1-1.6 bar, respectively. Then, using the resistance in series model, the hydraulic resistance for alkali chemical cleaning during XR separation was estimated. During separation, increased TMP showed a positive-flux effect as a driving force, however, fouling and polarized layer were more prominent under higher TMP. Increased CFV, on the other hand, was found more efficient in fouling control. In terms of the membrane cleaning techniques, an alkaline solution containing 0.1 M sodium hydroxide was shown to be the most effective substance in removing foulants from the membrane surface in this investigation. Cleaning with an alkaline solution resulted in a maximum flux recovery of 93% for xylose reductase separation. This work may serve as a useful guide to better understand the optimization parameters during XR separation and alleviating UF membrane fouling induced during XR separation.

The first hypothetical hydrogen (H2) production from biological means was proposed in the early of nineteenth century. However, the biological H2 production technology did not received much attention until the anticipation of H2 production was practically reported through anaerobic digestion of cellulose using microbes present in the ruminant tract in 1930s. Later on, subsequent development on fermentative H2 production has been reported by researchers employing advanced technologies to the fermentative systems. The present review is envisioned to provide a technological devolvement’s towards fermentative H2 production from the late nineteenth to the present twenty-first century. The major technological aspects associated with H2 production through the fermentative process such as genetic engineering, nanomaterial implementations, immobilization techniques, and reactor configuration developments were highlighted in this review.

This study aims to investigate the effect of the ultrasonic, microwave, and combined ultrasonic-microwave pretreatment of palm oil mill effluent (POME) sludge before fermentation to analyze hydrogen (H2) production and chemical oxygen demand (COD) removal efficiency in batch fermentation. Experimental results showed that the pretreatment of sludge (ultrasonication, microwave, and ultrasonication-microwave pretreatment) had positively influence the H2 production and COD removal efficiency during fermentation as compared to control one (without any pretreatment). Combined ultrasonication-microwave pretreatment of POME sludge was shown to be more effective for increasing both H2 production and COD removal from POME with the highest cumulative H2 and COD removal efficiency of 4080 mL H2/L-POME and 75.56%, respectively. The improvement observed for cumulative H2 production and COD removal was 12.14% and 21.42%, respectively, compared to the control one. These observations concluded that the POME sludge pretreatment with ultrasonication-microwave irradiation could be an effective strategy for improved treatment of POME with simultaneous production of H2.

Ultrasound-assisted-extraction (UAE) and statistical optimization of significant process parameters for high methoxy pectin (HMP) from Hylocereus polyrhizus peels (HPP) were examined and functional properties and proximate chemical characteristics were evaluated in the present study. Statistically, the maximum yield of HMP of 31.4% with a 56.10% degree of esterification (DE) was achieved by a quadratic polynomial equation and regression analysis of 88% and 86%, respectively. The optimal observed conditions for UAE of HMP were; agitation 250 rpm, extraction temperature 65ᵒC, extraction time at 70 min, extraction solvent with pH value of 2 and LSR of 12:1 (v/w). The proximate characteristics showed 17.93% of mannose, 7.65% of rhamnose, 44.34% of galacturonic acid, 2.8% of glucose, 27.32% of galactose with 79.8% purity of the total sugar extracted from HPP. Conclusively, that the extracted HMP from HPP using UAE possesses a high yield of pectin with a significant lower extraction temperature.

The effect of physicochemical treatment on pectin yield, degree of esterification, along with the kinetics and thermodynamics characteristics was investigated in the present study. Several extraction parameters were observed to have impacted the yield and degree of esterification significantly, and the best extraction condition was as follows: agitation rate of 250 rpm, temperature of 70 °C, extraction time of 120 min, pH 2, and liquid to solid ratio of 10 v/w which has resulted in 28.20% of pectin yield, with DE (degree of esterification) of 57.00%. A theoretical model which describes the extractability, dissolution and degradation rate of pectin to predict the maximal yield at the maximal time was established to study the extraction kinetics of pectin from HPP. The kinetic analysis from Panchev's model shows the extraction rate was found highest at LSR 10 with ymax 30.85%. The calculated activation energy for pectin dissolution and degradation was found to be 4.532 kJ/mol and 28.054 kJ/mol, respectively. The thermodynamic study has suggested that the process was endothermic, spontaneous and reversible. These results suggest that the physical and chemical treatment applied could be an efficient technique for the extraction of pectin from Hylocereus polyrhizus peels.

The present study has enabled to establish an appropriate kinetic and operational condition for hydrogen production using ultrasonicated palm oil mill effluent (POME). The kinetic analysis was performed corresponds to cumulative hydrogen (H2) production by varying substrate-inoculum ratio (COD/VS) from 0.2 to 0.6. The maximum H2 production potential (P) of 448 mL H2 with lag-time (ρ) of 8.2 h and H2 production rate (Rm) of 14.62 mL H2 h−1 was achieved using the substrate-inoculum ratio of 0.6. However, the Rm of 17.979 mL H2 h−1 with the ρ of 16.84 h, which is almost double than the substrate-inoculum ratio of 0.6 was observed at a substrate-inoculum ratio of 0.4. Furthermore, response surface methodology (RSM), including experimental design, regression analysis, was successfully applied to achieved optimum substrate-inoculum ratio and initial pH for biological H2 production from ultrasonicated POME. The maximum yield of 0.416 L H2/g-CODremoval was observed at the optimum conditions of substrate-inoculum ratio of 0.5 and an initial pH of 5.0. The linear, quadratic and interactive effect of substrate-inoculum ratio and initial pH on H2 yield were significant.

Biomass can be a sustainable choice for bioenergy production worldwide. Biohydrogen production using fermentative conversion of biomass has gained great interest during the last decade. Besides being an efficient transportation fuel, biohydrogen can also be also be a low-carbon source of heat and electricity. Microbes assisted conversion (bioconversion) can be take place either in presence or absence of light. This is called photo-fermentation or dark-fermentation respectively. This review provides an overview of approaches of fermentative hydrogen production. This includes: dark, photo and integrated fermentative modes of hydrogen production; the molecular basis behind its production and diverse range of its applicability industrially. Mechanistic understanding of the metabolic pathways involved in biomass-based fermentative hydrogen production are also reviewed. Keywords: Hydrogen, Biomass, Fermentation, Dark and photo fermentation

The impact of nickel and cobalt oxide nanoparticles (NPs) additive to palm oil mill effluent (POME) on hydrogen production was investigated using different Ni/Co oxide NPs-ratio. The Ni/Co oxide NPs-ratio of 1:0, 3:1, 1:1, 1:3 and 0:1 was added in batch mode operation. Experimental results suggested the H2 production dependency on the Ni/Co oxide NPs-ratio. The Ni/Co oxide NPs-ratio of 3:1 had better performance with the cumulative H2 and H2 production rate of 2844 mLH2 and 45 mL H2/h, respectively. This increased by ~37% and ~14, respectively in compared with the controlled one. The maximum CODremoval efficiency of 74% was observed at 3:1, which accounted for ~45% increment. These results suggested the improved performance of Bio-H2 can be fulfilled by additive of proper Ni/Co oxide NPs-ratio to the POME.

As a renewable energy carrier, hydrogen gains international recognition, with the ability to substitute fossil fuels. A state-of-the-art technology called a microbial electrolysis cell (MEC) can produce viable, clean hydrogen energy and also treat wastewater using various renewable carbon sources. The key substrates tested include wastewater, fermentable, and nonfermentable organic effluents. This chapter mainly discuss the scientific fundamentals of MEC technology, including its operating principles, thermodynamics, and electron transfer mechanisms. This chapter also discusses the nutrient, heavy metal removal, and integrated technologies used for higher hydrogen production.

The present study embarked on investigating the photo-fermentative bio-H2 production kinetics and statistical optimization of operational parameters using immobilized inoculum from dark fermented palm oil mill effluent (DPOME). The statistical optimized values of initial pH, inoculum-substrate percentage (ISP), and light intensity were achieved by implicating the central composite design (CCD) under response surface methodology (RSM). The kinetic evaluation was conducted in terms of H2-yield with ISP ranged from 10 to 30%. The highest H2 production potential (P) and rate (Rmax) of 30.59 ml.H2/g-CODremoved and 0.514 ml h−1 respectively were achieved with reported lag phase (ρ) value of 32 h by using 20% of ISP. However, an observed Rmax of 0.746 with a ρ value of 39 h was attained at ISP of 15%. The quadratic model developed by using CCD was observed to display the significance value of < 00.5 of probability error. Additionally, observed values of correlation coefficient (R2), adequate precision (AP), and coefficient of variance (CV) for acquired H2-yield were 0.9219, 12.076, and 11.24 ml.H2/g-CODremoved, respectively. Under optimal conditions values (initial pH, 6.0; ISP, 20%; and light intensity, 350% W/m2), H2 yield of 147 ml.H2/g-CODremoved was achieved from DPOME, while reducing the COD value by 78 percentage. This statistical model is suggested to possess the regression, interaction, and quadratic terms as significant, so it can be deemed acceptable in terms of its achievable reproducibility.

In an era of electronics, recovering the precious metal such as gold from ever increasing piles of electronic-wastes and metal-ion infested soil has become one of the prime concerns for researchers worldwide. Biological mining is an attractive, economical and non-hazardous to recover gold from the low-grade auriferous ore containing waste or soil. This review represents the recent major biological gold retrieval methods used to bio-mine gold. The biomining methods discussed in this review include, bioleaching, bio-oxidation, bio-precipitation, bio-flotation, bio-flocculation, bio-sorption, bio-reduction, bio-electrometallurgical technologies and bioaccumulation. The mechanism of gold biorecovery by microbes is explained in detail to explore its intracellular mechanistic, which help it withstand high concentrations of gold without causing any fatal consequences. Major challenges and future opportunities associated with each method and how they will dictate the fate of gold bio-metallurgy from metal wastes or metal infested soil bioremediation in the coming future are also discussed. With the help of concurrent advancements in high-throughput technologies, the gold bio-exploratory methods will speed up our ways to ensure maximum gold retrieval out of such low-grade ores containing sources, while keeping the gold mining clean and more sustainable.

Present 21st century world has started facing several challenges (such as waste management, bioresource scarcity, food/and energy security, climate change, global warming and health risks) as a heavy price of reckless usage/or exploitation of natural resource. In such a scenario, the implementation of circular economy model (based on use, produce, consume, waste recovery/or recycling, sharing, leasing, reusing, repairing, renovating, refurbishing and using waste feedstock to produce secondary products) emerged as the best sustainable option than linear economy model (based on use, produce, consume and waste discard). Inculcation of circularity in every aspect of our life (behavior, livelihood, economy, infrastructure) can help us in attaining long-term goals of sustainability and harmonizing human existence on planet Earth. Recent technological advancements have assisted in creating sustainable methods (incineration, pyrolysis, composting, anaerobic digestion) for treating or recycling the enormous solid waste, thereby enhancing valuable product recovery (such as heavy metals, biogases, bioelectricity, feedstock). So, it is necessary to develop more efficient sustainable waste-to-energy technologies capable of reutilizing solid wastes and helping to safeguard the environment from waste generated hazards. This chapter deals with sustainable ways to incorporate solid wastes into the circular loop of circular economy model. This chapter will present practical solutions for solid waste recycling and for fully realizing the potential of solid waste in circular economy in terms of more revenues.

Biological hydrogen production through photo-fermentative process using dark fermented palm oil effluent (DPOME) is a cost effective and environmentally benign process. In this study, effect of various factors like light intensity, agitation rate and dilution of DPOME on the hydrogen productivity of Rhodopseudomanas palustris were investigated using batch system. Investigation methods like response surface methodology (RSM) and Box-Behnken design were employed to investigate the optimum conditions for enhanced photo-fermentative hydrogen production. The regression analysis suggested that hydrogen yield was well fitted by a quadratic polynomial equation (R2 = 0.92). The hydrogen production was investigated by varying the intensity levels of these three independent variables, in which all have significant influences on hydrogen yield. The set of 19 experimental runs were conducted to optimize these variables. The highest hydrogen yield of 3.07 ± 0.66 H2 yield mol-H2/mol-acetate was obtained under the optimum condition of light intensity 250 W/m2, agitation rate 200 rpm, and 30% dilution of DPOME. The experimentally obtained hydrogen yield found out to be in a good agreement with predicted yield which was about 2.80 mol-H2/mol-acetate. In short, results suggest that experimental strategy using RSM approach along with Box-Behnken design can be a promising approach to achieve enhanced biological hydrogen production.

The world is now seeking sources of renewable energy that are both economical and environmentally friendly. Purified biogas is one essential source of renewable energy that can act as a substitute for fossil fuels. Anaerobic digestion has been recognised as a biochemical method of biogas generation that can convert organic compounds into a sustainable source of energy. Anaerobic co-digestion, AcoD is considered a pragmatic method to resolve the difficulties related to substrate properties and system optimisation in single-substrate digestion processes. The present manuscript studied the research prospects and challenges of anaerobic co-digestion, and the contributions of different methods in biogas generation studies. With the increased use of anaerobic co-digestion, the complexity of the process also increases. Several mathematical models had been established to optimise the anaerobic co-digestion technique. The biological methane potential test is a preferred technique for measuring the biodegradability and decomposition rate of organic substances. Furthermore, various additives are now used to maximise methane production. The improvement and optimisation processes of biogas production still need to be investigated in greater detail. In developing countries like Malaysia, biogas production may be more economically feasible if the latest simulation and characterisation methods are used at the industrial scale. Finally, this review describes a design and development framework to incorporate various aspects to enhance biogas production.

The aim of this work was to evaluate the comparative performance of hybrid metal oxide nanorods i.e. MnCo2O4 nanorods (MCON) and single metal oxide nanorods i.e. Co3O4 nanorods (CON) as oxygen reduction catalyst in microbial fuel cells (MFC). Compared to the single metal oxide, the hybrid MCON exhibited a higher BET surface area and provided additional positively charged ions, i.e., Co2+/Co3+ and Mn3+/Mn4+ on its surfaces, which increased the electro-conductivity of the cathode and improved the oxygen reduction kinetics significantly, achieved an io of 6.01 A/m2 that was 12.4% higher than CON. Moreover, the porous architecture of MCON facilitated the diffusion of electrolyte, reactants and electrons during the oxygen reduction, suggested by lower diffusion (Rd), activation (Ract) and ohmic resistance (Rohm) values. This enhanced oxygen reduction by MCON boosted the power generation in MFC, achieving a maximum power density of 587 mW/m2 that was ∼29% higher than CON.

In the present study, hydrogen production from palm oil mill effluent (POME) was investigated with the incorporation of nanoparticles (NPs) comprising of nickel (NiO) and cobalt oxides (CoO). The NPs of NiO and CoO were prepared using hydrothermal method and were further applied to analyse, their effect on hydrogen production. The results demonstrated that, a maxima volumetric hydrogen production rate of 21 ml H2/L-POME/h with the hydrogen yield of 0.563 L H2/g-CODremoved was obtained with 1.5 mg/L concentration of NiO NPs. On the other hand, the addition of CoO NPs produced maximum volumetric hydrogen production rate of 18 ml H2/L-POME/h with a hydrogen yield of 0.487 L H2/g-CODremoved with 1.0 mg/L of CoO NPs. Results showed that addition of optimal concentration of NiO and CoO NPs to the POME enhances the hydrogen yield by 1.51 and 1.67 fold respectively. Besides, this addition of NiO and CoO enhanced the COD removal efficiency by 15 and 10% respectively as compared to an un-additive NPs POME. The toxicity of NPs was also tested using bacterial viability test, which revealed that application of 3.0 mg/L of NiO and CoO NPs to modified Luria-Bertani (LB) medium had 63% and 83% reduction in bacterial cell growth. The results concluded that supplementation of NiO and CoO NPs under an optimal range to the wastewater can improve the hydrogen productivity.

The discharge of palm oil mill effluent (POME) on arable land causes large amounts of environmental distress due to its high concentration of phenolic compounds and chemical oxygen demand (COD). The approach of simultaneous microbial oil production and wastewater treatment is an attractive option to combine renewable energy production and environmental resilience. This study aims to produce cost effective microbial lipids using the oleaginous yeast Lipomyces starkeyi through the bioremediation of POME. A moderately dilute solution (50%) of POME showed higher microbial growth and lipid accumulation and offered a significantly higher degree of bioremediation. A lipid content of 21.32% was achieved with 50% POME, whereas the value was 15.14% for 25% POME. Three different techniques including ultrasonic treatment, Fenton's reagent and Fenton's + ultrasonic were employed to extract lipids from microbial biomass, and the maximum lipid concentration was obtained using the Fenton's + ultrasonic treatment. The degree of bioremediation was evaluated by the calculating seed germination index (GI) values. Higher GI values were observed for the 25% and 50% dilutions compared to undiluted (100%) POME. This combined approach can be a potential alternative technology that integrates bioremediation of POME with microbial lipid production.

The potential of methane production in a continuously stirred tank reactor (CSTR) was investigated using dairy manure as inoculum at pH 6.8 and 37 °C temperature in this study. Two identical anaerobic bioreactors namely CSTR1 and CSTR2 filled with palm oil mill effluent (POME) as a carbon source were used. CSTR1 was not added with the inoculum, while CSTR2 was added with dairy manure as inoculum. Both the reactors were allowed to run for 5 days (d) in batch condition at hydraulic retention time (HRT) 10 d. The CSTR2produced 0.85 L/d gas yield and 59% methane content compared to 0.39 L/d gas yield and 20% produced in CSTR1, respectively. A better chemical oxygen demand (COD) reduction percentage of 48% was found in CSTR2 compared to CSTR1 with 33%. The investigation showed that dairy manure as inoculum has a marked influence on the start-up period and the biogas production rate.

In the present study, a new mesophilic bacterial strain, identified as Bacillus anthracis strain PUNAJAN 1 was isolated from palm oil mill effluent (POME) sludge, and tested for its hydrogen production ability. Effect of physico-chemical factors such as temperature, initial pH, nitrogen source and carbon sources were investigated in order to determine the optimal conditions for hydrogen production. The maximum hydrogen yield of 2.42 mol H 2 /mol mannose was obtained at 35 °C and initial pH of 6.5. Yeast and mannose were used as the main carbon and nitrogen sources respectively in the course of the hydrogen production. Apart from synthetic substrate, specific hydrogen production potentials of the strain using POME was calculated and found to be 236 ml H 2 /g chemical oxygen demand (COD). The findings of this study demonstrate that the indigenous strain PUNAJAN 1 could be a potential candidate for hydrogen using POME as substrate.

The influence of water-cement ratio and cement content on the performance of seaweed-modified (Gracilaria Sp.) mortar was investigated in this study. The experiment was performed using seaweed-modified and unmodified mortars with different water-cement ratios. The modified mortars contained different cement percentages ranged between 21%-30%. The water-cement ratio varied from 0.33-0.6. The flexural strengths of unmodified samples responded insignificantly to the change of water-cement proportion or cement rate. Compressive and flexural strengths of the modified mortars were increased with the higher cement proportions. For higher cement portions and low water-cement proportions, the adhesion strength of the modified samples was enhanced under the wet condition. Shrinkage and water absorption of the modified samples increased with growth of cement proportion and constant water-cement ratio. The scientific application of this green technology can make the concrete environment friendly and greatly reduce the carbon-di-oxide emission as well. The commercial application of this technology can contribute to the cost reduction of the production process.

Global population explosion and food security concerns have resulted in an increased use of toxic pesticides to prevent the cash food crops from pest-infestation or to minimize yield loss. These xenobiotic compounds are known to cause hazardous effect on human health and its inhabiting environment. The current chapter aims to summarize the innate ability of the soil microbial communities to metabolize the toxic pesticide compounds. Microbial-mediated pesticide degradation is a sustainable approach to restore the pesticide-infested environments back to its previous ecologically clean and balanced state. Researches based on the steering effect of various factors on the growth of pesticide biograders (viz. bacteria, fungi, cynobacteria) are only few, and change in the microbial dynamics and associated mechanistics of biodegradation, with changing pesticide type, are yet to be fully understood). However, advent of advanced tools such as genomics, proteomics, transcriptomics, and metabolomics has tremendously helped researchers to gain the basic mechanistic understanding of microbial community dynamics and associated metabolic pathways involved in pesticide biodegradation, in order to make knowledge-based decisions to design better strategies to enhance pesticide degradation potential of microbes by manipulating its metabolic networks using genetic engineering approaches. This chapter will address the current state of the art of researches taking place in the area of microbe-assisted pesticide (xenobiotic compounds) degradation along with the integrative role of omics approaches in microbial-mediated bioremediation.

The aim of this study was to investigate the maximum hydrogen yield as well as the chemical oxygen demand (COD) reduction from palm oil mill effluent (POME) by using two stage sequential dark and photo fermentation. The first stage operation was carried out using Clostridium butyricum LS2, which has the maximum hydrogen yield of 0.784 ml H 2 /ml POME and COD removal of 57%. The dark fermentative effluent was diluted with 50% of tap water (DEPOME-50), for better penetration of light and was subsequently used as substrate to the second stage fermentation using Rhodopseudomonas palustris as hydrogen producer. Hydrogen production was monitored under optimized light illumination of 7 klux, in batch mode. The two-stage fermentation enhanced the total hydrogen yield from 0.784 (dark fermentation) to 3.064 ml H 2 /ml POME (dark/photo-fermentation). Meanwhile, a 93% of total COD removal was also achieved.

Microbial oils are considered as alternative to vegetable oils or animal fats as biodiesel feedstock. Microalgae and oleaginous yeast are the main candidates of microbial oil producers' community. However, biodiesel synthesis from these sources is associated with high cost and process complexity. The traditional transesterification method includes several steps such as biomass drying, cell disruption, oil extraction and solvent recovery. Therefore, direct transesterification or in situ transesterification, which combines all the steps in a single reactor, has been suggested to make the process cost effective. Nevertheless, the process is not applicable for large-scale biodiesel production having some difficulties such as high water content of biomass that makes the reaction rate slower and hurdles of cell disruption makes the efficiency of oil extraction lower. Additionally, it requires high heating energy in the solvent extraction and recovery stage. To resolve these difficulties, this review suggests the application of antimicrobial peptides and high electric fields to foster the microbial cell wall disruption.

In the present study, high-methoxyl pectin (HMP) was extracted from Hylocereus polyrhizus peel's using physico-chemical process. In addition, the hypolipidemic activity of HMP was investigated at different concentration and time corresponding to its adsorption ability. FTIR and contact angle analysis were used to determine the sorbent characterization. A high degree of esterification (63.8%) and the contact angle (95.5°) confirmed hydrophobic nature and resulting bad wetting of the HMP extract, respectively. The methoxyl content in the pectin acted as an affinity-precursor of the pectin towards cholesterol due to its increased hydrophobicity. The maximum equilibrium uptake capacity of cholesterol of 370.5mg/g (0.96mmol/g) was observed by HMP. The experimental data showed good fitting for Freundlich isotherm equation and followed pseudo-first-order kinetic model with a correlation coefficient (R2) of 0.89-0.97 due to physisorption mechanism. Intra-particle model confirmed that the cholesterol sorption rate by HMP was significantly influenced by external mass transfer (surface diffusion) and intra-particle diffusion (diffusion control). It was also revealed that the HMP extracted from Hylocereus polyrhizus peels possess a high affinity towards cholesterol, making it an ideal hypolipidemic agent.

The aim of this work was to evaluate the comparative performance of hybrid metal oxide nanorods i.e. MnCo

Wastewater treatment for water reuse and membrane biofouling control is of significant value to sustainable performance of a membrane bioreactor system. Different treatment techniques have been employed to treat dye wastewater. In recent studies, membrane bioreactor was employed to treat dye wastewater; however, membrane bioreactors are facing biofouling problem. Biofouling (is a process of membrane surface colonization by microbial cells via adhesion and production of extracellular polymeric substances (EPSs)) is almost always a major hitch for membrane bioreactors (MBRs) and membrane systems. Biofouling of membrane reactors results in higher operational expenses and reduced stability and operational performance. In this chapter, biological treatment of membrane biofouling is demonstrated. Furthermore, major causes of biofouling and biological control strategies are discussed. Lastly, conclusions on wastewater treatment and membrane biofouling are presented.

Biofuels production is mostly oriented with fermentation process, which requires fermentable sugar as nutrient for microbial growth. Lignocellulosic biomass (LCB) represents the most attractive, low-cost feedstock for biofuel production, it is now arousing great interest. The cellulose that is embedded in the lignin matrix has an insoluble, highly-crystalline structure, so it is difficult to hydrolyze into fermentable sugar or cell protein. On the other hand, microbial lipid has been studying as substitute of plant oils or animal fat to produce biodiesel. It is still a great challenge to extract maximum lipid from microbial cells (yeast, fungi, algae) investing minimum energy. Electroporation (EP) of LCB results a significant increase in cell conductivity and permeability caused due to the application of an external electric field. EP is required to alter the size and structure of the biomass, to reduce the cellulose crystallinity, and increase their porosity as well as chemical composition, so that the hydrolysis of the carbohydrate fraction to monomeric sugars can be achieved rapidly and with greater yields. Furthermore, EP has a great potential to disrupt the microbial cell walls within few seconds to bring out the intracellular materials (lipid) to the solution. Therefore, this study aims to describe the challenges and prospect of application of EP technique in biofuels processing.

The demand and prospect of biogas technology as a renewable energy source in terms of market value have not been adequately addressed. This paper focuses on the status of legal framework and future market situation related to biogas technology in order to facilitate its improvements. Biogas technology, known as biofuel production process through fermentation of biological wastes, is a well-established technique to improve lives, livelihoods, health, and ecosystem. This approach generates a large revenue opportunity that supports the socioeconomic development in rural areas. However, very little initiative has been introduced specially in the developing world to gear up the biogas technology. For more sustainable development of this technology, policy-makers should reform the existing institutional framework by reorganizing subsidies, motivating and attracting investor with flexible financial conditions, liberalizing the management of gas grids, and involving farmers in local projects. Therefore, it is a great challenge to find a proper mode of marketing policy, business models and multi-profit options, and a sustainable financing mechanism. This paper covers the state-of-the-art enlargements and future consequences of the hastily emerging biogas market, starting with a universal viewpoint and going through the market characteristics of Europe, the USA, Africa, and Asia Pacific.

Biogas technology, which converts biological waste into energy, is considered as an excellent tool to improve the lives, livelihoods, health, and ecosystem. The demand and prospect of biogas technology as a renewable energy source in terms of market value have not been adequately addressed, although it offers a large revenue opportunity that supports the socioeconomic development in rural areas. For more sustainable development of this technology, policy-makers should reform the existing institutional framework by reorganizing subsidies, motivating and attracting investors with flexible financial conditions, liberalizing the management of gas grids, and involving farmers in local projects. Therefore, it is a great challenge to find a proper mode of marketing policy, business models, and multi-profit options and a sustainable financing mechanism. This paper covers the state-of-the-art enlargements and future consequences of the hastily emerging biogas market, starting with a universal viewpoint and going through special market characteristics of Europe, USA, Africa, and Asia Pacific.

The catalytic microorganisms oxidise the organic matter to produce electrical energy in microbial fuel cells (MFCs). The microorganisms that can shuttle the electrons exogenously to the electrode surface without utilising artificial mediators are referred as exoelectrogens. The microorganisms produce specific proteins or genes for their inevitable performance towards electricity generation in MFCs. Multiple studies have confirmed the expression of certain genes for outer membrane multiheme cytochromes (e.g. OmcZ), redox-active compounds (e.g. pyocyanin), conductive pili, and their potential roles in the exoelectrogenic activity of various microorganisms, particularly in the members of Geobacteraceae and Shewanellaceae family. This chapter explores the various mechanisms of microorganisms that are advantageous for the technology: biofilm formation, metabolism, electron transfer mechanisms from inside the microorganisms to the electrodes and vice versa.