Utilization and Management of Bioresources

The utilization of biogenetic waste and residues draws more and more attention worldwide, driven by the fight against climate change and the efforts to save greenhouse gas emissions. Biodegradable waste and residuals already contribute to energy supply and are used in new biorefinery concepts. The potential of remaining available wastes and residues is compared to the small energy crop potential but important for climate protection goals. In total 98.4 million tons dry mass represent the technical potential that means it is available for utilization in Germany. 30.9 million tons of this technical potential is currently not in use. The biogas sector in Germany is highly developed but has to be further developed as well as the other bioenergy sectors to fulfil the future tasks. The German energy transition has yet not reached its ambitious goals; the process stagnated in certain areas. Biomass and waste biomass must contribute to development a bioeconomy by the combined material and energy utilization in biorefineries and contribute to the energy transition in combination with the other renewable energies. Examples for enhanced energetically utilization of biowaste as well as biorefinery concepts are described.

This article presents a comprehensive comparative assessment of the reaction conditions employed in the heterogeneous and homogeneous catalytic hydrolysis of waste lignocellulosic biomass (WLB) for the production of fermentable sugar (FS) for its subsequent conversion to renewable bioethanol. The effects of catalyst type and reaction conditions on the selectivity of FS in catalytic hydrolysis of low-cost WLB have been meticulously assessed. Moreover, representative radar plots demonstrating FS (substrate for bioethanol) yield in both homogeneous and heterogeneous catalytic protocols have been elucidated. An intensive global attention has recently been paid for the improvement of catalytic technologies pertaining to efficient pretreatment and hydrolysis for conversion of WLB to FS. Cellulose [(C₆H₁₀O₅) _n ], the foremost component in WLB materials, is a biodegradable polymer of simple carbohydrates, consisting of β (1, 4)-linkage of d-glucose units, which can be depolymerized to FS for the subsequent sustainable synthesis of renewable biofuels. In this article, a critical assessment of the production of FS through catalytic pretreatment and subsequent hydrolysis of WLB resources has been elucidated. The abundant presence of low-cost WLB and their potential application for synthesis of FS (d-glucose) and other derivatives (xylose) for subsequent bioethanol, biobutanol, bio-H₂ production can provide an economically sustainable and environmentally benign avenue to mitigate energy crisis and global climate change.

The rampant increase in municipal solid waste (MSW) accumulations has largely contributed to the exacerbating scenario of the environment. The lack of efficient waste processing technologies to mitigate accumulation has led to a large influx of waste into environment causing multiple damages to nature. Failure of developing efficient mechanisms to degrade polythene which constitutes a major fraction of the MSW has also been a hindrance. Scientists across the globe are trying to develop efficient methods of converting waste to energy which can help us resolve energy crisis and reduce solid waste accumulations. Although a plethora of technologies are coming up, their potential to intake unsegregated waste is limited and hence their applications are restricted. Polythene being the most stable component of MSW remains practically unaffected for decades. It is well known that polythene on combustion produces CO₂ and other gases which are responsible for air pollution. The prospects of utilizing this released CO₂ in fuel production are being investigated in this research. Microalgae has been considered as a potential candidate for biofuel production owing to their invasiveness, high CO₂ sequestering potential, and high lipid content. In this study, the growth of microalgae using polythene combustion gas as the CO₂ source was investigated.

Bioprocess optimization can enhance the CO₂ sequestration kinetics and hence cause high oil content. The whole system comprises of an aqua-separation unit to segregate MSW, an anaerobic digester for degrading organic waste, a fermentor to process lignocellulosic waste coupled with the polythene decomposition, and a waste gas bioprocess unit. This can serve the process of utilizing almost all the components of MSW for energy production and hence impart a carbon reduction advantage to the system.

Biomass saccharification has assumed a significant importance in the context of the modern-day energy crisis and climate change scenarios. Waste biomass, which can constitute a significant portion of solid wastes, can be converted into value-added chemicals like ethanol by this process. The present investigation deals with the development of a solid acid catalyst for biomass saccharification using coconut shell, a cheap and abundant raw material, which has not been explored previously in this field. Coconut shell has been carbonised with zinc chloride at 723 K for 1 h to produce activated carbon which has been sulphonated with conc. H₂SO₄ (98%) at 403 K for 16 h to develop the solid acid catalyst. The catalyst has been characterised by scanning electron micrography, X-ray diffraction, FTIR spectroscopy and nitrogen adsorption. The X-ray diffraction studies have shown a graphene sheet content of 39% in the catalyst, while the FTIR spectra show the presence of SO₃H, phenolic OH and COOH groups. The specific surface area measured by nitrogen adsorption was 10.162 m²/g. The catalyst has been used to hydrolyse pretreated sawdust from Acacia nilotica heartwood as well as microcrystalline cellulose under experimental conditions specified by central composite design. The yields of total reducing sugars in the hydrolysates have been analysed by UV spectrophotometry, and the produced sugars were identified by HPLC.Glucose constituted almost all of the produced sugars with negligible amounts of galactose being formed. The maximum sugar yield was 91% for pretreated sawdust and 93% for microcrystalline cellulose, indicating the excellent catalytic property of the catalyst. The results indicate the suitability of coconut shell as a source for developing biomass saccharification catalysts, as well as the efficacy of such a catalyst in the saccharification process.

Acrylics and polyolefins are widely used synthetic plastics in daily consumer products which are non-biodegradable in nature. An accumulation of these solid wastes in the environment poses ecological threats and requires novel management techniques. Researchers have now focussed their work on developing novel biodegradable polymer materials and isolating and identifying microorganisms which have the potential to degrade these polymeric materials. Isolating and identifying these microorganisms having potential to degrade polymers and polymer composites are required for developing newer biotechnological techniques for management of these solid wastes in the environment. The present work studies the biodegradation behaviour of PMMA and micro-/nano-cellulose-reinforced PMMA (polymethyl methacrylate) composites in pond water. The weight loss data revealed improved biodegradability in cellulose-reinforced PMMA composites in comparison to the synthetic PMMA. Scanning electron microscopy (SEM) images revealed effective biodegradability of the composites in pond water. The microorganism (fungus) was isolated, and its biodegradation behaviour was studied.

Stubbles of rice varieties Mahsuri (Taichung 65/Mayang Ebos 6080/2) and Ranjit (Pankaj x Mahsuri) were treated after harvest of the crop by spraying microbial inoculums – laboratory culture of cellulose degrading microorganism (CDM) or yogurt (commercial) or mixture of CDM and yogurt with glyphosate (0.205% solution in water) either with sugar or without sugar for in situ decomposition. Microbial inoculums were also sprayed with glyphosate and urea, and the treatments were compared with control plots, viz., untreated, water spray, and glyphosate spray. At the end of the fourth month, Mahsuri showed faster decomposition than Ranjit with corresponding decreases in dry biomass and percent organic carbon of the stubbles following treatment with CDM culture or yogurt with glyphosate solution. Addition of sugar to the spray mixture was not significant. The reduction in dry biomass and organic carbon in stubble was up to 61.1 and 45.3% in Mahsuri and up to 47.1 and 46.4% in Ranjit, respectively, after 4 months of the treatments. Significant increase in diversity of weeds in terms of number of species was observed in plots with higher stubble decomposition.

Agro-food processing industries are major contributors of wastes in most developing countries. With Nigeria leading in cassava food production, little attention has been paid to provide a sustainable and profit-oriented solution to the problem of solid waste resulting from cassava processing industries.

Considering the global effort to promote sustainability in the areas of food production, processing and waste management and also the need for resource recovery and utilisation to enhance cassava food value chain, this study assessed the quality and amount of waste in selected cassava industries with regard to cassava production rates and current waste management practices (from six randomly selected cassava industries) in Ibadan Nigeria. The potentials and various options for cassava waste utilisation were explored.

Six cassava production sites were randomly selected for the purpose of this study. Information gathered through personal field observations and key informant interviews showed that between 1.5 and 3 tons of solid (peels and pulp) waste and between 3 and 6 m³ of liquid wastes were generated daily during cassava processing from a daily supply of between 6 and 8 tons of cassava tubers. Between 25 and 37% of solid wastes usually result from production of cassava tubers with only 25% of the total available waste being utilised as livestock feed.

The recovery of this huge amount of waste resource in terms of animal feed, biomass for energy production and biosolids from spent slurry has the potential to increase the cassava food value chain significantly.

In most developing countries, rapid economic growth and industrialization have transformed its landscape with significant effects on the environment. One major effect of this urbanization is the increase in waste generated and is more evident in developing nations since the capacity of these cities to collect, process or reuse and dispose solid waste is limited and is not sustainable. Disposing waste on land has been the most common and cheapest way of disposing it. But due to the uncontrolled dumping, the land has reached its carrying capacity which eventually affects the environment and its visual quality. Moreover, the quality of the wastes which has the potential for reuse in productive purposes is not considered.

In this paper, land (vacant land, open dumps/landfills) is considered as specific example case of urban landscapes which can be conserved and transformed to a productive space where organic fraction of the urban waste is processed and used for landscape development simultaneously. In addition to organic waste management the productive urban landscapes also contribute to a range of functions like food or non-food/ornamental crops for personal consumption or marketing purposes, nutrient recycling, biodiversity and visual quality that benefits the community. It also emphasizes the role of urban planners and landscape architects in ensuring that, when neighbourhood level plans are made and zoning is done, appropriate area is earmarked for such productive task, based on the number of household and the quantity of waste generated within an urban area. Thus, the paper explores the possibility of integrating the proposed facility into the urban fabric so that it is a multifunctional and a sustainable component which can be applied flexibly providing benefits to the people/community.

The growing demand for cooking fuel and non-reliable supply of commercial cooking fuel has become a major concern in recent years. In this context, biogas, a clean and renewable energy source, can be a supplement to non-renewable conventional cooking fuel. In India, small-sized biogas plants have been prevalent in domestic sectors with mixed degree of success. However, the application of community-sized biogas plants is very limited. In case of residential institute like Tezpur University, Assam, India, considering the huge amount of food waste generated, conversion of kitchen waste into useful cooking gas (biogas) through anaerobic digestion can be a better option to supplement the elevated requirement of LPG. In this work, feasibility study of renewable energy-based cooking system (biogas plant, size 50 m³), implemented in one of the hostels of Tezpur University, is thoroughly examined from commissioning to operational stage, in order to assess the barriers and carriers of such renewable energy technology. A study investigated the performance of the installed plant, feedstock characteristics, composition and economic assessment of biogas-fuelled cooking at Tezpur University campus. Performance analysis and economic assessment of the 50 m³ biomethanation plant showed that it can be a viable option for utilization of the food waste generated in educational institutions through production of clean cooking fuel. However, proper monitoring of feeding rate and quality is critical for smooth performance of the biogas system.

According to some reports, the amount of fecal sludge (FS) that is also known as septic tank sludge or septage in urban areas of Vietnam is relatively high. It can be up to hundreds of tons per year in some big cities (Hanoi Urban Environment. The situation and solutions of management, collection and treatment of fecal sludge, International Conference on Management of sludge from the drainage system and sanitation (FS3 – 2015) – Proceedings sludge management in Vietnam opportunity to improve, pp 25–27, 2015). Therefore, the management and treatment of septic tank are an urgent problem currently. Ingredients of fecal sludge such as total nitrogen (TN), total phosphorus (TP), and alkalinity are high, but the ratio of C/N is often lower (Montangero A, Strauss M, Fecal sludge treatment, Eawag/Sandec, 2004; Klingel F et al, Fecal Sludge Management in Developing Countries, Eawag/Sandec, 2002; Thai et al, Fecal sludge management from the sanitation, Science and Technology Publishing, Hanoi, 2013). So, the anaerobic co-digestion fecal sludge with other organic wastes with C/N higher can recover biogas. This study was conducted with experiment model in mesophilic fermentation conditions during 40 days in the solid waste laboratory of National University of Civil Engineering. Fecal sludge (FS) and organic waste (OW) have mixed with the ratios of 4:1, 3:1, and 2:1 by weight in three parallel models. Experimental results showed that at ratio of 3:1, it yielded higher biogas production with 514.33 Nl/kgVS of feed. Also the ratio and parameters of process such as the change of its height, temperature, pH, and COD are consistent with anaerobic digestion process, and the amount of fecal sludge treated is high relatively.

In this study, waste breads have been utilized as the only nutrient source for the production of glucose using Aspergillus niger and subsequently ethanol production from glucose by Saccharomyces cerevisiae. Solid-state fermentation of waste bread by Aspergillus niger resulted in the production of a multienzyme solution containing amylolytic and proteolytic enzymes. The glucoamylase and protease enzymes are then extracted, and enzyme activities were quantified. This crude enzyme extract was used for the hydrolysis of waste bread at 55 °C at 300 rpm. After hydrolysis, the amount of glucose was determined using anthrone colorimetric method, and the free amino nitrogen (FAN) was determined by ninhydrin colorimetric method. The resulting solution contains approximately 145 g/l of glucose. The bread hydrolysate was then further used to produce ethanol having concentration of 54 ± 2 g/l. The result depicts yield of ethanol from glucose, Y_P/S, as 0.37, i.e., a conversion efficiency of 72%. This process is important in the sustainable chemical industry because it converts the waste food into a value-added product like ethanol.

During the study orange peel and pulp waste samples in the ratio of 1:1 were pretreated to acidic and heat treated followed by solid-state and submerged fermentation. Fermented fractions were then subjected to distillation. Distilled fermented fractions were then analyzed by gas chromatography-mass spectrometry (GC-MS). The chromatographic analysis revealed that from Citrus reticulata fruit wastes, biodiesel can be produced, and the highest bioethanol yield (6.0029%) was observed via solid-state fermentation compared to submerged fermentation. Positive and promising results of GC-MS show that Citrus reticulata fruit wastes can be a feasible alternative for efficient bioethanol production.

Bioethanol is a renewable energy source produced from the resources which can be easily replenished. The bioethanol production through fermentation may provide an economically competitive source of energy by its incorporation into gasoline. Production of bioethanol from waste food crops like potatoes could be the better substrate, and the waste produced is also biodegradable. Lack of storage facilities and postharvest losses make potato a promising crop which can be used for production of ethanol. Moreover, the conversion of potato starch into glucose by bakhar is more cost-effective, and fermentation with baker’s yeast Saccharomyces cerevisiae yields maximum amount of ethanol. This process of production of ethanol from waste potato would be promising and economically effective for the production of biofuel, called bioethanol.

Biofuels are a promising long-term renewable energy source having potentials which could address both environmental impacts and security concerns posed by current dependence on petroleum-based fuels. Biodiesel fuel is a renewable energy fuel produced from biological materials or biomass. Development of biodiesel processors is still a novel technology in Nigeria where till date; much works has not been recorded on the development of biodiesel processors. A one-stage nine-flask continuous-batch biodiesel reactor is developed to withhold the heat generated during the reaction of hydrocarbons (vegetable oil), alcohols (methanol or ethanol), and the catalyst (sodium or potassium hydroxide) for biodiesel production. The stages include methoxide tank to mix the methanol; the reactor where the transesterification of the mixtures of vegetable oil, alcohol, and catalyst occur; the settling tower where freshly reacted batch of biodiesel is transferred to free up the reactor; first wash tank for wet washing; second wash tank for dry washing; dry tank to free up the wash tanks for the next batch and also dry the fuel much faster with much better results through heating; glycerin tank where the glycerin from the wash tank is drained; biodiesel tank in which the dry biodiesel is stored; and water tank used in washing the biodiesel.

Waste cooking oil (WCO) is considered the most promising biodiesel feedstock despite its drawback of high free fatty acid (FFA). In this study, microwave-assisted transesterification of WCO is carried out in the presence of potassium hydroxide supported on carbonized coconut shell (KOH/CS) catalyst. The effect of reaction temperature on the yield of fatty acid methyl esters (FAME) is studied. Conventional transesterification is also performed for comparison. The results show that reaction temperature of 80 °C is optimum for FAME production. The properties of the produced biodiesel satisfy the criteria according to ASTM D6751. Acid-catalysed esterification of WCO before transesterification leads to higher production of FAME due to reduction of FFA. At 80 °C, reaction time of 40 min, alcohol to oil ratio of 12:1 and 5 wt.% catalyst, a FAME production of 91.3% is achieved. At 65 °C, reaction time of 90 min, alcohol to oil ratio of 12:1 and 5 wt.% catalyst, conventional transesterification results in slightly higher FAME production (92.1%). However, conventional transesterification using WCO without esterification as feedstock yields lower FAME. Pretreatment of feedstock with esterification is found to be more beneficial and applicable in the case of biodiesel production through conventional transesterification, allowing production of FAME with higher yields. This furthermore indicates that although microwave heating decreases the reaction time, it does not necessarily lead to increased FAME. The production of FAME depends on not only the type of transesterification process but also the type of feedstock used. Overall, the proposed methodology allows the use of high FFA content feedstock. However, this will need careful selection of feedstock as well as additional treatment prior to transesterification process; otherwise the yield may be reduced.

Naphthalene an organic pollutant arises from industrial operations and natural events such as forest fires. According to US EPA list of priority pollutants, naphthalene is considered as possible carcinogen due to its low solubility and bioavailability. Degradation of this recalcitrant can be carried out using physical and chemical methods but it leads to various products, most of them are toxic to the environment. Therefore, bioremediation using selected microorganisms remains the most suitable solution to treat such pollutants.

In the present study, bacterial strains utilising naphthalene as sole carbon and energy source were isolated from crude oil-contaminated soil. Out of the eight isolates initially screened, two bacterial isolates S3 and F3 were selected on the basis of their best growth in M9 minimal medium containing naphthalene, as the sole source of carbon. Isolate S3 and F3 were characterised through biochemical, physiological and phylogenetic analysis (16S rRNA) that revealed their significant similarity to Pseudomonas aeruginosa sp. and Enterobacter cloacae sp. The sequence was submitted to NCBI database and the assigned accession numbers were JX254648.1 and JX480546. Isolates S3 and F3 were then utilised for the degradation of naphthalene in oil-contaminated soil, and decrease in 77.77 % and 61.11 % of concentration, respectively, after 7 days of incubation, was observed as determined by HPLC.

Dyes present in water affect the balance of aquatic life as well as human being due to its toxicity. Insufficient sunlight impairs the process of photosynthesis of aquatic plants and phytoplankton, and, thus, they die without having sufficient food. After the death of these plants and animals, the numbers of zooplanktons and other higher organisms present in that aquatic system are automatically reduced. Finally, in this way the aquatic ecosystem loses its balance. The mixing of dye-colored wastewaters into the aquatic ecosystem and, thus, its accumulation in wildlife through food chain can cause many negative ecotoxicological effects and public health hazards.

Congo red dye is a type of azo dye which can cause harmful effects on environment. This present study aims to investigate the degradation of azo dye (Congo red) using bacterial species, Acinetobacter sp., at different variable parameters (pH, temperature, salinity, agitation, dye concentration, and inoculum volume). Optimum pH, temperature, salinity, agitation, dye concentration, and inoculum volume for this study are pH 7, 37 °C, 3 mg/L, 120 rpm., 50 mg/L, and 50 ml/L, respectively, to degrade the Congo red dye by using Acinetobacter sp. Optimum dye decolorization efficiency was found to be 87.89%.

Untreated industrial effluents discharged into the environment pose a serious problem to the soil living organism and human beings also. Almost all the traditional physicochemical methods do not provide effective solutions for the elimination of metals from industrial effluents. Industrial waste soil samples collected from different industrial belts of West Bengal were analyzed for physicochemical and microbiological characteristics. Eighteen arsenic (As)-tolerant bacterial strains were isolated from arsenic-contaminated industrial soil. Among them, three bacterial strains, viz., MsfL2, HsR₂1, and HlR₂11, exhibited higher As resistance capacity and showed 50% relative growth in LB medium incorporated with 1500 μg/ml of arsenate (V) and 200 μg/ml of arsenite (III). Antibiotic susceptibility of the isolates was also done, and results indicate variation with respect to the tested strain. Additionally it was found that the strains were sensitive to gentamycin, tetracycline, and bacitracin. Biochemical analysis and 16S rRNA sequencing were done to identify and determine the phylogeny of the selected arsenic-tolerant strains. Since arsenic-induced stress has often been known to have correlation with osmotic as well as oxidative stress, the selected strains under study might be metabolically adapted to arsenic-induced oxidative and osmotic stress. Physiological test and PCR results indicate that the isolates probably have developed resistance via arsenic reduction mechanism. From all the above facts, it is evident that the selected isolate(s) is promising candidate(s) for arsenic bioremediation in polluted industrial environment.

Pyrolysis is the foremost thermal conversion process that can be successfully used to transform biomaterials into a value-added product. The estimated biodegradable portion is prominent and denotes as 60% from total waste generation in Asian developing countries. There have been several studies on exploring the pyrolysis of complex organic fraction of municipal solid waste (MSW) streams as a sustainable MSW management technique. The objective of this research was to evaluate physicochemical characteristics of MSW biochar (MSW-BC) produced from organic MSW to observe its potential for landfill contaminant removal with case studies from Sri Lanka. Biochar was pyrolyzed from the MSW in an onsite pyrolyzer. For physicochemical properties of biochar, pH, point of zero charge, electrical conductivity, proximate analysis, ultimate analysis, heavy metal composition, bioavailable heavy metal composition and BET surface area were acquired. In addition, surface functional groups and structural identification were determined by FTIR analysis and scanning electron microscopy (SEM) analysis, respectively. Adsorption capacities for the pollutants (benzene and toluene) were examined by batch sorption experiments. Furthermore, sorption isotherms were fitted using non-linear models for better understanding of the sorption capacities of the materials. Ultimate analysis data suggested high-temperature pyrolysis of MSW. Further, low values for both H/C and polarity index depict the strongly carbonized and highly aromatic structure in BC. Additionally, FTIR suggested a loss of labile, aliphatic compounds and functional groups during pyrolysis and the formation of more recalcitrant, aromatic constituents, whereas BET and SEM data revealed a well-developed porous structure and surface properties, which indicates MSW-BC to be a potential sorbent. Further, the reported total and bioavailable heavy metal content was low in MSW-BC; hence, it can be easily mixed with compost and used as a fertilizer. At the same time, MSW-BC will potentially be used to remediate heavy metals in the landfill leachate. Therefore, MSW-BC shows high potential to be used as a material to remediate contaminants simultaneously that minimizes MSW volume. Thus, conversion of MSW to BC and chemical and thermal modification of MSW-BC would allow effective engineering to optimize their properties as a potential material in landfill covers and permeable reactive barriers and integrate in leachate treatment techniques.

External supply of plant nutrients is a must to achieve intensification of agricultural sector, thereby meeting food demand of growing global population. However, non-substitutable nutrient like phosphorus (P) with finite natural reserve makes recovery of it a progressively attractive option from alternative waste sources. P recovery method identifies production of P-enriched mineral as mainstream option through technically and economically viable recovery processes. In this context, recovery of struvite (MgNH₄PO_4.6H₂O), an alternative P fertiliser from waste streams of farm, municipal and industrial origin, remains a research focus, as considerable fraction of P ends up in these P sinks. The recovery process creates added benefits of quality control of nutrient-laden waste before environmental disposal and reduction of waste volume. In this study, we evaluate some potential P wastes for struvite recovery, in terms of some compositional parameters (orthophosphate, ammonium, calcium). Among these sources, anaerobically digested waste represents suitable considerations for struvite recovery because of retention of nutrient with increased plant availability. Study assessed the potential of anaerobic digestate of different climatic zones (India and the UK) as prospective P source by determining their chemical composition. Through a range of treatments (acidification and chelating agent), P availability was shown to be elevated, indicating its further enhanced potential recovery.

Waste source composition and the need for their management strategy with a focus to their optimal utilisation are identified as the driving forces for the selection of a waste source for P recovery. A viable struvite recovery process is anticipated to develop a product with enriched value to retain P into the nutrient cycle and can be useful as waste treatment/management method.

Electronic waste is the waste electrical and electronic equipment which is not fit for its original intended use. Out of which printed circuit board (PCB) has approximately ten different metals with it, while the percentage of metals present in PCB differ according to the instruments. The extraction of these metals play a major role because of the depleting natural resources. The lixiviant pool of bioleaching was chosen for the study for the extraction of metal. Copper has been chosen among all metals because of its increased usage and high content of about 30% on the PCB. Adsorption is used as a key tool in the extraction process. An attempt has been made to minimise waste and convert them into activated carbon. The activated carbon synthesised with banana peel (BAC) could replace commercial-activated carbon (CAC) which could reduce the depletion of natural resources. The copper adsorption capacity for BAC was more than 80%. The results of atomic absorption spectroscopy (AAS) indicated that banana peel is an effective adsorbent of copper from electronic waste leachate which results in waste minimisation.

Lipases occupy a prominent place amongst biocatalysts as they can hydrolyse fats into fatty acids and glycerol at the water-lipid interface. Lipase production is a prime area of interest for microbiologists, process engineers and biochemists. Recent advances in green energy have led to renewed interest in the ability of microbial lipases to catalyse transesterification reaction for biodiesel production. Research carried out in this field has revealed that microbes, especially fungi and bacteria, are the tools of choices for commercial production.

The primary objective of the study was to isolate lipase-producing microbes from the waste product of oil industries and to assess their ability to grow in different oil medium. Samples (oil cakes) were collected from a mustard oil factory in Barrackpore, Kolkata. Lipid-degrading microbes were trapped in specialized medium containing various types of oils. All isolated strains were morphologically, physiologically and biochemically characterized. Strain L_J was found to be the most efficient strain as it showed highest lipase activity (25 μmoles/ml/min) after 24 h of incubation at 37 °C amongst the strains.

Though the lipase activity obtained was lower compared to reported fungal lipases, the study is significant because of its exploratory nature and has the potential of identifying new organisms having lipolytic capability.

The producer gas and biogas are biomass-based renewable energy sources drawing increased attention worldwide. Substantial quantities of by-products are also generated during the production of these fuels from biomass. While primary emphasis is on main energy form, management and utilization of by-products are also of concern, both from economic and environmental points of view, as these are the inevitable commodities. There have been some reports on utilization of these by-products, mostly traditionally, to supplement soil nutrients. However, lack of proper management could lead to their nonoptimal use through loss of nutrients. The present investigation considers the by-products of two bioenergy systems, viz. digested slurry from anaerobic digestion unit and tar from bio-gasification unit, available in food industry through case studies to understand the rate of by-product generation, characterization and prospective utilization. From the total slurry generated using cow dung as feedstock, an estimated amount of 3.68 kg of dry mass (solid digestate) and 36.28 l of liquid (liquid digestate) per cubic metre of biogas were obtained. While analysing the digested slurry in terms of thermal and nutritional characteristics, it is known that recovery of second-stage thermal energy without losing essential nutrients could be possible if appropriate management strategy is taken. It has been estimated that 54.56 MJ energy could be made available per cubic metre of biogas, considering second-stage energy recovery route through briquetting technology using solid fraction of digestate. While estimating gasification tar, for generating 1 m³ of producer gas using bamboo, an average of 0.041 g tar could be obtained. The prospects of utilization of gasification tar could be possible from the presence of a number of useful chemicals as indicated by characterization study.

Today, a huge volume of jet fuel is consumed through air transportation. Petroleum-based jet fuels, including Jet A-1, produce considerable amount of particulate and gaseous pollutions which affect the world climate change. To overcome these pollutions, portion of jet fuel should be replaced by jet biofuels. This can be achieved by blending Jet A with efficient energy source with lowest emission such as biofuels from vegetable oils. Biodiesel from palm, Jatropha curcas, and waste cooking oils show promising potential in producing aviation biofuels when blending with Jet A. Various volumetric ratios of biodiesel (5–25%) were blended with high-grade kerosene. The binary blends of jet biofuels were characterized and compared with Jet A fuels. The comparison indicated that biofuels with 5% ester content have almost similar characteristics with Jet A aviation. The physicochemical properties of 5% binary blends of palm, Jatropha curcas, and waste cooking oils were kinematic viscosity (at −20 °C) of 8.6, 5.1, and 5.1; high heating value (HHV) around 43 Mj/kg and freezing point of −14.5, −15.5, and −25.5 °C for binary blends of the biodiesel from the three types of oils with Jet A, respectively. Additives may be added to binary blends to reach exact Jet A physicochemical characteristics. The yield %│C8–C15 were determined for the 5% ester content for each binary blends using GC-mass spectrometry.

Banana (Musa sp.) which is a popular fruit consumed worldwide has a yearly production of over 145 million tons approximately. The peel is generally discarded after consumption of the fruit, which eventually leads to the generation of a significant amount of organic waste causing environmental pollution. Meaningful utilization of this nutrient-rich waste has not drawn much attention. The peel can be biotechnologically converted to value-added products which can reduce environmental pollution to a great extent. Cellulases represent a major group of the industrially important enzyme. Its production has been studied widely by the technique of solid-state fermentation (SSF). The present study deals with the cost-effective biosynthesis of endoglucanase (CMCase) utilizing solid waste, banana peel. Optimization of nutritional parameters was done by the conventional one variable at a time (OVAT) method followed by chemical characterization of banana peel by energy-dispersive X-ray spectroscopy (EDX). By applying OVAT methodology for optimization of nutritional parameters for cellulase production, the specific activity of endoglucanase (CMCase) was found to be 54 U/mg. EDX analysis showed that, as the solid waste was found to be rich in carbon source, no additional carbon supplement was essential for the growth of cellulase-producing microorganism used for the production of secondary metabolite by SSF.

The tannery industry waste was used in this study as a low-cost biosorbent. The presence of large number of functional groups in the tannery waste resulting from both live and dead microbial fractions positively favours for higher and faster sequestration rate of metal ions. The batch mode of biosorption process were performed with dried activated tannery sludge for removal of Ni(II), Co(II), Zn(II) and Cd(II) ions in multi-metal system. Zn(II) and Cd(II) ions showed 99% removal efficiency within 10 min of contact time, while Ni(II) and Co(II) attained 98% removal at 20–24 h. The influence of various experimental variables like pH, contact time, biosorbent dosage and initial metal concentrations was studied. The biosorbent was characterized using FESEM-EDX and XPS analysis.

One of the major challenges in the field of biosorption is the management of the hazardous spent biosorbent even after metal recovery and effectively reuse over several cycles. The conventional ways of the disposal of such materials involve storage, landfill disposal or incineration which in turn again pollutes the environment. Landfill disposal are not suitable due to groundwater contamination prospects by leaching of metal ions. Again, the biomass burning processes create air pollution, generate hazardous volatiles and produce ash having high concentration of the desired metal. To solve this issue, the present investigation was designed for vitrification of toxic metals waste in a glass matrix.

Safe management of spent biosorbent has been developed as inertization in phosphate glass formulation. Control and multi-metal-loaded biosorbent up to 25% were successfully incorporated into phosphate glass matrix for safe disposal to the environment. Amorphous nature of good glass preparation was confirmed by XRD analysis. Results of dissolution test on the prepared phosphate glass showed no leaching of hazardous heavy metal ions up to 1 month of incubation under DI water with thermal cycle at 75 °C for 8 h/day.