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Hexavalent chromium is a toxic heavy metal getting discharged into the environment and water bodies through various industrial processes. Conventional analysis methods call for expensive equipment and complicated sample pretreatment that made unsuitable for onsite detection. Paper is used as an enzyme immobilization platform because of its property to wick the liquid by capillary action; lightweight, cheap and can be easily patterned or cut according to the requirements for developing biosensor. In this study, enzyme immobilization of glucose oxidase (GOx) on filter paper were examined using three polysaccharides such as chitosan, sodium alginate and dextran for entrapment efficiency, activity and stability of the immobilized enzyme. Among the three, chitosan proved efficient for enzyme entrapment with about 90% efficiency at 0.3% (w/v) chitosan. The stability was checked after 1 week at 4 °C and room temperature, where the chitosan entrapped enzyme retained nearly 97% stability at 4 °C. Enzyme inhibition study of GOx and Cr(VI) was carried out using chronoamperometry shown uncompetitive type of inhibition. A paper-based electrochemical biosensor strip was developed by immobilizing GOx enzyme on filter paper using chitosan as an entrapping agent and associating it with a screen-printed carbon electrode for amperometric measurements. The linear range of detection was obtained as 0.05–1 ppm with the limit of detection as 0.05 ppm for Cr(VI), which is the standard permissible limit in potable water. The relative standard deviation (5.6%) indicates good reproducibility of the fabricated biosensor.

The present study is aimed at analysing the feasibility of bioelectrochemical treatment of bagasse-based paper mill wastewater. Bioelectrochemical treatment was carried out in dual-chambered microbial fuel cell with plain graphite plates as electrodes. Wastewater from sugarcane bagasse storage and washing units of paper mill was used as anolyte. High power density and current density of 53 mW m(−2) and 173 mA m(−2) at 470 Ω, respectively, could be produced with wastewater treatment efficiency of 85% and coulumbic efficiency of 6%. Whereas, wastewater from pulping and bleaching units of bagasse-based paper mill was not suitable for bioelectrochemical treatment, yielding low power density and current density of 4 mW m(−2) and 16 mA m(−2) respectively at 10,000 Ω. Later, treating blended wastewater containing bagasse wash water and pulping wastewater in the ratio of 9:1 v/v generated higher power density and current density of 73 mW m(−2)/202 mA m(−2), respectively, at 470 Ω, with wastewater treatment efficiency and coulumbic efficiency of 82% and 18%, respectively. Lignin and its derivatives present in pulping wastewater mediated electron transfer leading to high power density. Further, compounds in pulping wastewater were also toxic to methanogens growth in anode chamber of MFC, resulting in improved coulumbic efficiency of the blended wastewater treatment.

This study is aimed at assessing the biobleaching activity of fungal xylanase on paper pulp isolated from Tirumala forest, Eastern Ghats of India. Of the 98 fungal isolates obtained after initial screening, eight isolates were selected and one potential strain was further cultivated under submerged fermentation for production of xylanase. The biobleaching efficiency on waste paper pulp and paper industry effluent was tested with crude enzyme. Xylanolytic activity by the chosen organism in submerged fermentation reached the maximum (981.1 U ml−1) on the 5th day of incubation. Molecular characterisation of the isolate led to its identification as Trichoderma asperellum which exhibited the production of enzyme even at alkaline pH of the culture medium. Xylanase pretreatment of paper pulp had shown reduction in the Kappa number by 4.2 points and increased brightness by 4.0 points. FTIR and SEM studies revealed loosening of pulp fibres after enzyme treatment. In conclusion, xylanase of Trichoderma asperellum was effective as a pulp biobleaching agent and the process is economical as well as eco-friendly.

Xylanases are hydrolytic enzymes which cleave the β-1, 4 backbone of the complex plant cell wall polysaccharide xylan. Xylan is the major hemicellulosic constituent found in soft and hard food. It is the next most abundant renewable polysaccharide after cellulose. Xylanases and associated debranching enzymes produced by a variety of microorganisms including bacteria, actinomycetes, yeast and fungi bring hydrolysis of hemicelluloses. Despite thorough knowledge of microbial xylanolytic systems, further studies are required to achieve a complete understanding of the mechanism of xylan degradation by xylanases produced by microorganisms and their promising use in pulp biobleaching. Cellulase-free xylanases are important in pulp biobleaching as alternatives to the use of toxic chlorinated compounds because of the environmental hazards and diseases caused by the release of the adsorbable organic halogens. In this review, we have focused on the studies of structural composition of xylan in plants, their classification, sources of xylanases, extremophilic xylanases, modes of fermentation for the production of xylanases, factors affecting xylanase production, statistical approaches such as Plackett Burman, Response Surface Methodology to enhance xylanase production, purification, characterization, molecular cloning and expression. Besides this, review has focused on the microbial enzyme complex involved in the complete breakdown of xylan and the studies on xylanase regulation and their potential industrial applications with special reference to pulp biobleaching, which is directly related to increasing pulp brightness and reduction in environmental pollution.

Xylanase is a hemicellulase enzyme that catalyses the hydrolysis of xylan to xylose which is widely used in processing of feed, pulp and paper. It is produced by many microorganisms especially filamentous fungi like Trichoderma and Aspergillus. A potential xylanolytic fungal isolate Aspergillus niger was isolated from forest soils of Tirumala, AP, India, and its crude enzyme was checked for its potential in paper bleaching. Under submerged fermentation, production of xylanase, cellulase, biomass, total protein and sugar released were analysed after 7 days of incubation at room temperature. Maximum enzyme activity was recorded on the fifth day of incubation, biomass after the seventh day, total protein and sugar released on the sixth day of incubation. Enzyme pretreatment of paper reduced 3.5 points in kappa number, 3.1 points increase in brightness and removal of chromophores and hydrophobic compounds. The FTIR and SEM analysis of enzyme-treated sample had shown modification in surface morphology and functional groups. These results clearly demonstrated that the xylanase produced by A. niger was effective as a pulp biobleaching agent which can be used on an industrial scale.

Biosynthesis of silver nanoparticles (AgNPs) using nest extract of paper wasp (Polistes sp) was investigated in this work. The AgNPs were characterized by UV–Vis spectroscopy, Fourier transform infrared spectroscopy (FTIR), and transmission electron microscopy (TEM), and evaluated for antibacterial, antifungal, dye degradation, blood anticoagulation, and blood clot dissolution (thrombolytic) activities. The crystalline polydispersed AgNPs with size range of 12.5–95.55 nm absorbed maximally at 428 nm and showed anisotropic structures of sphere, triangle, hexagon, rod, and rhombus. The FTIR data showed prominent peaks at 3426 and 1641 cm−1, which indicate the involvement of phenolics compounds and proteins in the synthesis of AgNPs. The prominence of Ag in the EDX spectra showed that indeed, AgNPs were formed. The AgNPs showed potent antibacterial activities (12–35 mm) against three multi-drug strains of Pseudomonas aeruginosa and Klebsiella granulomatis. While the growth of Aspergillus flavus and Aspergillus niger was completely suppressed, the AgNPs produced growth inhibition of 75.61 % against Aspergillus fumigatus at 100 µg/ml. Furthermore, the AgNPs degraded malachite green to the tune of 93.1 %. The AgNPs also prevented coagulation of blood, while it completely dissolved preformed blood clots within 5 min showing the potent anticoagulation and thrombolytic activities. This study, which is the first of its kind to use nest extract of paper wasp for the synthesis of nanoparticles, has shown that the biosynthesized AgNPs could be deployed for biomedical and catalytic applications.

Bioleaching is one of the well-known methods of metal recovery with Environmental benefits. This process has been extensively used for combating improper waste management issues along with metal reclamation. The aim of this study is to bioleach spent petroleum refinery catalyst at variant pulp densities (PD) (5, 10 and 15%) using microorganisms in acidic pH (1.5–1.6) and mesophilic temperature (30–35 °C). The study includes leaching yields of metals like nickel, molybdenum, copper and aluminum. The three bioleaching experiments with different pulp densities yielded a maximum of more than 90% nickel, 73% copper, 87% molybdenum and 24% aluminum. The results are validated 5, 10, and 15% pulp density and the result is validated with pH, Redox potential, microbial population, sulphate concentration and ferrous iron, concentration. The time saving due to faster nickel dissolution using iron and sulphur oxidizing microorganisms would be economical for the bioleaching process.

Currently, major focus in the biopolymer field is being drawn on the exploitation of plant-based resources grounded on holistic sustainability trends to produce novel, affordable, biocompatible and environmentally safe polyhydroxyalkanoate biopolymers. The global PHA market, estimated at USD 62 Million in 2020, is predicted to grow by 11.2 and 14.2% between 2020-2024 and 2020-2025 correspondingly based on market research reports. The market is primarily driven by the growing demand for PHA products by the food packaging, biomedical, pharmaceutical, biofuel and agricultural sectors. One of the key limitations in the growth of the PHA market is the significantly higher production costs associated with pure carbon raw materials as compared to traditional polymers. Nonetheless, considerations such as consumer awareness on the toxicity of petroleum-based plastics and strict government regulations towards the prohibition of the use and trade of synthetic plastics are expected to boost the market growth rate. This study throws light on the production of polyhydroxybutyrate from lignocellulosic biomass using environmentally benign techniques via enzyme and microbial activities to assess its feasibility as a green substitute to conventional plastics. The novelty of the present study is to highlight the recent advances, pretreatment techniques to reduce the recalcitrance of lignocellulosic biomass such as dilute and concentrated acidic pretreatment, alkaline pretreatment, steam explosion, ammonia fibre explosion (AFEX), ball milling, biological pretreatment as well as novel emerging pretreatment techniques notably, high-pressure homogenizer, electron beam, high hydrostatic pressure, co-solvent enhanced lignocellulosic fractionation (CELF) pulsed-electric field, low temperature steep delignification (LTSD), microwave and ultrasound technologies. Additionally, inhibitory compounds and detoxification routes, fermentation downstream processes, life cycle and environmental impacts of recovered natural biopolymers, review green procurement policies in various countries, PHA strategies in line with the United Nations Sustainable Development Goals (SDGs) along with the fate of the spent polyhydroxybutyrate are outlined.

Biodiesel is a renewable, sulfur-free, toxic-free, and low carbon fuel which possesses enhanced lubricity. Transesterification is the easiest method employed for the production of biodiesel, in which the oil is transformed into biodiesel. Biocatalyst-mediated transesterification is more advantageous than chemical process because of its non-toxic nature, the requirement of mild reaction conditions, absence of saponification, easy product recovery, and production of high-quality biodiesel. Lipases are found to be the primary enzymes in enzyme-mediated transesterification process. Currently, researchers are using lipases as biocatalyst for transesterification. Lipases are extracted from various sources such as plants, microbes, and animals. Biocatalyst-based biodiesel production is not yet commercialized due to high-cost of purified enzymes and higher reaction time for the production process. However, research works are growing in the area of various cost-effective techniques for immobilizing lipase to improve its reusability. And further reduction in the production cost of lipases can be achieved by genetic engineering techniques. The reduction in reaction time can be achieved through ultrasonic-assisted biocatalytic transesterification. Biodiesel production by enzymatic transesterification is affected by many factors. Various methods have been developed to control these factors and improve biodiesel production. This report summarizes the various sources of lipase, various production strategies for lipase and the lipase-mediated transesterification. It is fully focused on the lipase enzyme and its role in biodiesel production. It also covers the detailed explanation of various influencing factors, which affect the lipase-mediated transesterification along with the limitations and scope of lipase in biodiesel production.

The present study was aimed at producing enhanced and sustained bioelectricity from distillery wastewater in a double chamber microbial fuel cell (MFC) by changing inter-electrode distance, inoculum and reactor volume. Using double chamber MFC with 1 L working volume, when the distance between the electrodes was kept shorter (1 cm), it generated power density of 1.74 W/m(3), which was 42.5% higher than that of MFC with electrode spacing of 10 cm (1 W/m(3)). Using inoculum from different sources viz. garden soil (MFC-GS), wetland sediment (MFC-WS) and sludge from wastewater treatment plant (MFC-S), the highest open circuit voltage (OCV) of 0.84 V and power density of 2.74 W/m(3) were produced by MFC-WS, which also showed sustained electricity production (1.68 W/m(3)) from the wastewater during a 10-day experiment. Relatively lower power density was generated from MFC-S (1.42 W/m(3)), while that from MFC-GS was the lowest (0.94 W/m(3)). Bioelectricity generation and overall performance were then assessed using a smaller reactor size. Smaller working volume of MFC (250 ml) favoured greater production of power density (3.2 W/m(3)) than that with 1 L working volume (2.96 W/m(3)) with electrode distance of 1 cm. The present study was novel in selecting a suitable mixed-microbial inoculum out of the diverse sources screened and reducing resistance by sharply narrowing down inter-electrode distance and reactor volume, which led to significantly enhanced and sustained electricity generation from double chamber MFC.

Several tonnes of shellfish wastes are generated globally due to the mass consumption of shellfish meat from crustaceans like prawn, shrimp, lobster, crab, Antarctic krill, etc. These shellfish wastes are a reservoir of valuable by-products like chitin, protein, calcium carbonate, and pigments. In the present scenario, these wastes are treated chemically to recover chitin by the chitin and chitosan industries, using hazardous chemicals like HCl and NaOH. Although this process is efficient in removing proteins and minerals, the unscientific dumping of harmful effluents is hazardous to the ecosystem. Stringent environmental laws and regulations on waste disposal have encouraged researchers to look for alternate strategies to produce near-zero wastes on shellfish degradation. The role of enzymes in degrading shellfish wastes is advantageous yet has not been explored much, although it produces bioactive rich protein hydrolysates with good quality chitin. The main objective of the review is to discuss the potential of various enzymes involved in shellfish degradation and their opportunities and challenges over chemical processes in chitin recovery.

Liquid waste from biological stains is considered non-domestic wastewater difficult to treat, generating high environmental impact. Therefore, the objective of this work was to carry out secondary and tertiary treatment of these effluents at a pilot scale, using a fungal/bacterial consortium followed by Chorella sp., for 15 days. In addition, to obtain an adsorbent material for Malachite Green dye removal, sludge generated in the plant and pine bark co-pyrolysis was performed. For microalgae isolation and selection of the Chlorophyceae class, Chlorococcales order, and Chorella sp. genus Winogradsky columns were employed. After 15 days of pilot plant treatment, removal percentages of 91 ± 2%, 90 ± 4% and 17 ± 2% were obtained for Colour Units, Chemical Oxygen Demand and Nitrates, respectively. Two types of class II biochar (BC500 and BC700) and one of class III (BC300) were produced. The highest value for Fixed carbon (FC) was obtained at 300 °C (27.3 ± 3%), decreasing as the temperature increased by 25.9 ± 5% and 24.8 ± 2%, for BC500 and BC700, respectively. Biochar yield was 62.1 ± 3%, 46.3 ± 4% and 31.6 ± 3% for BC300, BC500 and BC700, respectively. Finally, BC500 and BC700 biochar efficiently adsorbed Malachite Green obtaining qe values of 0.290 ± 0.032, 0.281 ± 0.015, 0.186 ± 0.009 and 0.191 ± 0.012 mg g−1 at pH values of 4.0 and 8.0 ± 0.2, respectively. Pseudo-second order model demonstrated a chemical adsorption took place, which was influenced by pH.

Utilized and waste jasmine flower contains a high portion of organic carbohydrate and other organic acids, making it a suitable substrate for bioethanol production. This study was designed to estimate the prospective of waste jasmine flower biomass applied with chemical (alkaline) and thermal pretreatment applied on samples through bioethanol production efficiencies. Therefore, pretreatment and enzymatic hydrolysis are directed to disrupt the complex cell wall layer and improve the accessibility towards polysaccharide fraction. Also, applying response surface methodology tools during fermentative bioethanol production to study the interactive effects of different bioprocess variables for higher bioethanol yield in batch small and large scale model is discussed. The immobilized yeast between jasmine found that jasmine sugar utilization was 50%. The jasmine flower's ethanol production was 6.54 g/L and after distillation of jasmine was 31.40 g/L at pH 4.5. Results showed that this immobilized yeast method could be successfully used for bioethanol production from waste jasmine flower.

Industrial wastewater discharges pose an environmental risk. Here, the effectiveness of an up-flow vertical hybrid system, operating with synthetic and industrial wastewater was investigated, as a new approach to perform nitrification/denitrification and desulfurization within a single reactor. The hybrid reactor is divided in two reaction zones, the oxic and anoxic. The removal of chemical oxygen demand (COD), ammonium, and sulfide was investigated, highlighting changes in microbial diversity. The reactor was evaluated at hydraulic residence time (HRT) of 1.6 days, and its performance throughout 180 days is presented in four stages. In stages I–II, high COD and ammonium removal was obtained with synthetic wastewater. In stage-III, sulfide-rich synthetic wastewater did not alter the system, attaining COD, ammonium, and sulfide removal efficiencies of 81, 99.5, and 99.7%, respectively. In the last stage, a mixture of effluents was fed into the reactor at loading rates of 277 mg COD/L-d, 46.5 mg NH(4)(+)-N /L-d, and 15 mg HS(−)-S /L-d. Sulfide and ammonium removals were 100% and 99.9%, respectively. However, low COD removal was observed, being of 51%, and the system removed 97% in terms of BOD(5). The structure and microbial diversity also changed. Sulfide feeding, induced the proliferation of sulfur oxidizers like Thiomiscropira and Thiobacillus. Industrial wastewater enhanced the abundance of Pseudomonas (15.53%) and favored the proliferation of new bacteria of the genus Truepera (2.98%) and Alicyclipilus (7.56%). This is the first study reporting simultaneous nitrification/denitrification and desulfurization to remove ammonium, COD and sulfide from complex industrial wastewater using an up-flow vertical hybrid reactor.

In recent years, there has been an increasing interest in the remediation of contaminated environments, and a suitable solution is in situ bioremediation. To achieve this, large-scale bacterial biomass production should be sustainable, using economic culture media. The main aim of this study was to optimize the physicochemical conditions for the biomass production of an actinobacterium with well-known bioremediation ability using inexpensive substrates and to scale-up its production in a bioreactor. For this, the growth of four strains of actinobacteria were evaluated in minimal medium with glucose and glycerol as carbon and energy sources. In addition, l-asparagine and ammonium sulfate were assayed as alternative nitrogen sources. The strain Streptomyces sp. A5 showed the highest biomass production in shake-flasks culture using glycerol and ammonium sulfate as carbon and nitrogen sources, respectively. Factorial designs with five factors (glycerol concentration, inoculum size, pH, temperature, and agitation) were employed to optimize the biomass production of Streptomyces sp. A5. The maximum biomass production was obtained using 5 g L(−1) of glycerol, 0.25 µL of inoculum, pH 7, 30 °C and 200 rpm. Finally, the production was successfully scaled to a 2 L stirred tank bioreactor. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s13205-020-02588-5.

The bacterial cellulose production (BCP) process, using cellulose microfibrils (CM) of Acetobacter xylinum enmeshed on luffa sponge matrices (LSM) as LSM-CM starter, has been successfully developed where the LSM-CM production process can be recycled through consecutive cycles in limited dissolved oxygen (DO) under continuous aeration. In this study, incremental aeration rates impacted the consecutive cycles. Gluconic acid production, during the process, resulting in the reduction of BCP, was increasingly generated at high aeration from 0.28 to 0.34% at 3 L/min to 0.83–0.97% and 1.52–1.99% at 6 and 9 L/min after 7 d culture at 30 ± 2 °C. To compensate for the negative impact of aeration, 0.10 and 0.15% (w/v) carboxymethyl cellulose (CMC) was found to create a microenvironment for recycled LSM-CM at both high aeration (6 and 9 L/min, respectively). Under nine consecutive BCP cycles, acceptable BC yields (from 5.54 ± 0.5 to 5.89 ± 0.5 g/L) were associated with high biomass at 6 L/min aeration. These results confirm that LSM-CM, combined with CMC called as LSM-CM-CMC, created microenvironments low in DO under high aeration rates and that the recycled LSM-CM-CMC with aeration is an alternative, sustainable, economic process that could be applied for mass BCP.

This study suggests a mathematical description and the optimization of the pre-saccharification time during simultaneous saccharification and fermentation with delayed yeast inoculation (dSSF) to ensure the fastest and fullest possible conversion of a substrate into the target product—bioethanol. A pulp derived by alkaline delignification of oat hulls was used as a substrate. The pre-saccharification step of oat-hull pulp was performed at a solid loading of 60 g/L, at 46 ± 2 °C, using mixed enzymes CelloLux-A and BrewZyme BGX, the pre-saccharification time was 8, 15, 24, 39, 48 and 72 h. Afterwards, the reaction mixture was cooled to 28 °C, a 10% inoculum of Saccharomyces cerevisiae Y-1693 was seeded, and fermentation combined with saccharification. The optimum pre-saccharification time (inoculation time) under these conditions was found to be 24 h, thus providing the maximum hydrolysis of cellulose and hemicelluloses and the highest yield of bioethanol. The procedure suggested herein for determining the optimum pre-saccharification time can be used for other model substrates from lignocellulosic feedstocks.

The main focus of this research work was to carry out the fermentative production of EPS with mixed fruit waste as substrate. The medium formulation studied by sequential addition of medium components and replacement of sugar with mixed fruit waste. Amongst the six species of Bacillus studied, Bacillus species SRA4 produced EPS in range of 3.0–17.9 g/L, which was highest amongst all the species selected for the study. Thus for further optimization, the response surface methodology was used making use of Bacillus species SRA4. EPS production enhanced to 23.75 g/L. In 10 L shake flask and fermenter scale-up study was carried out. In the study, 10 L flask showed the highest EPS production of 17.95 g/L in 120 h, whereas in 10 L fermenter, it was as high as 25.1 g/L that too in 72 h only. The optimization study resulted in 1.76-fold increase in EPS production with nearly 48 h reduction in EPS production time as compared to initial production procedure. Replacement of sucrose with fruit waste extract made the process environmentally friendly; omission of l-cystine and use of 50% reduced amount of sodium acetate in the medium lowered the production cost of EPS. This method also solved the fruit waste disposal problem.

The aim of the present study is to investigate the potential of magnetic field application as an alternative approach for controlling sludge bulking due to long sludge retention time (SRT) while enhancing nitrification efficiency upon the occurrence. Two sequencing batch reactors, reactor A (SBR(A), magnetic field intensity 88.0 mT) and reactor B (SBR(B), control) were operated under long SRT to induce the growth of filamentous microorganisms. The effect of magnetic field on nitrification, viz. ammonia–nitrogen (NH(4)–N) and nitrite removal, as well as biomass properties were studied under the sludge bulking condition. Results indicated that nitrification efficiency of SBR(A) was consistently higher with 90% NH(4)–N removal and 74–81% nitrite removal, which could be credited to the enhanced biomass properties of activated sludge due to the induced magnetic field. Metabolism activity and biodegradability of aerobic bacteria were also enhanced through the application of magnetic field, even under long SRT condition. This was evidenced by the average oxygen uptake rate (OUR) in SBR(A) that was higher with 11.7 ± 1.2 mg/L·h compared to SBR(B) with 9.5 ± 0.4 mg/L·h. Occurrence of filamentous sludge bulking was likewise minimized.

Industrial development has increased wastewater (WW) volume; generating contamination and disturbing ecosystems, because of breeching disposal parameters. In this work, Coloured Laboratory Wastewater (CLWW), (1500.00 colour units, CU) was separately submitted to two secondary treatments. For the first one CLWW was treated for three cycles C1, C2 and C3 with P. pastoris X33/pGAPZαA-LaccPost-Stop producing rPOXA 1B laccase, immobilized in calcium alginate beads. For the second-one, rPOXA 1B enzyme concentrate was used (three processes: P1, P2, and P3). Both treatments were carried out in a 15 L reactor with 10 L effective work volume (EWV) with 72 h hydraulic retention time. C1, C2, and C3 effluents were flocculated and filtered through quartzite sand, while P1, P2, and P3 effluents were only filtered through quartzite sand. The mixture of secondary effluents was submitted to a tertiary treatment with Chlorella sp. For C1, C2, C3, P1, P2, and P3, CU removal was of 99.16, 99.58, 99.53, 96.72, 97.05 and 96.47%, respectively. Discharge parameters, total organic carbon (TOC), inorganic carbon (IC), chemical oxygen demand (COD) and biological oxygen demand (BOD5) decreased, although they reached different final values. After the tertiary treatment (144 h) effluent discharge parameters were reduced to 34 ± 4 CU, TOC to 6.6 ± 0.9 mg L−1 and COD to 155 ± 4 mg L−1. It was demonstrated that secondary treatments (immobilized recombined cells or recombinant enzyme concentrate) combined with Chlorella sp., (tertiary treatment) attained a considerable removal of discharge parameters, demonstrating a promissory alternative for CLWW sequential treatment.

In the present work, bioethanol was produced by sugar fermentation obtained from water hyacinth using a novelty hybrid method composed of steam explosion and enzymatic hydrolysis, using hydrolytic enzymes produced by solid-state fermentation and water hyacinth as substrate. The highest activity, 42 U for xylanase and 2 U for cellulase per gram of dry matter, respectively, was obtained. Steam explosion pretreatment was performed at 190 ℃ for 1, 5, and 10 min, using water hyacinth sampled from the Maria Lizamba Lagoon, the Arroyo Hondo and the Amapa River. The highest amounts of reducing sugars of water hyacinth were obtained form the samples from the lagoon (5.4 g/50 g of dry matter) after 10 min of treatment. Steamed biomass was hydrolysed using the enzymes obtained by solid-state fermentation, obtained reducing sugars (maximum 15.5 g/L); the efficiency of enzymatic hydrolysis was 0.51 g of reducing sugars per gram of water hyacinth. Finally, reducing sugars were fermented using Saccharomyces cerevisiae for conversion to ethanol, with the highest ethanol concentration (7.13 g/L) and an ethanol yield of 0.23 g/g of dry matter.