Treatment Of Sugarcane Vinasse Research Articles

Harnessing the Energy Potential and Value-Added Products from the Treatment of Sugarcane Vinasse: Maximizing Methane Production Through Co-Digestion with Sugarcane Molasses and Enhanced Organic Loading.

This study assessed the impact of organic loading rate (OLR) on methane (CH4) production in the anaerobic co-digestion (AcoD) of sugarcane vinasse and molasses (SVM) (1:1 ratio) within a thermophilic fluidized bed reactor (AFBR). The OLR ranged from 5 to 27.5kg COD.m-3.d-1, with a fixed hydraulic retention time (HRT) of 24h. Organic matter removal varied from 56 to 84%, peaking at an OLR of 5kg COD.m-3.d-1. Maximum CH4 yield (MY) (272.6 mL CH4.g-1CODrem) occurred at an OLR of 7.5kg COD.m-3.d-1, while the highest CH4 production rate (MPR) (4.0L CH4.L-1.d-1) and energy potential (E.P.) (250.5 kJ.d-1) were observed at an OLR of 20kg COD.m-3.d-1. The AFBR exhibited stability across all OLR. At 22.5kg COD.m-3.d-1, a decrease in MY indicated methanogenesis imbalance and inhibitory organic compound accumulation. OLR influenced microbial populations, with Firmicutes and Thermotogota constituting 43.9% at 7.5kg COD.m-3.d-1, and Firmicutes dominating (52.7%) at 27.5kg COD.m-3.d-1. Methanosarcina (38.9%) and hydrogenotrophic Methanothermobacter (37.6%) were the prevalent archaea at 7.5kg COD.m-3.d-1 and 27.5kg COD.m-3.d-1, respectively. Therefore, this study demonstrates that the organic loading rate significantly influences the efficiency of methane production and the stability of microbial communities during the anaerobic co-digestion of sugarcane vinasse and molasses, indicating that optimized conditions can maximize energy yield and maintain methanogenic balance.

Electrocoagulation treatment of sugarcane vinasse: Operating parameters and cost analysis by response surface methodology

The production of ethanol biofuel using sugarcane as substrate generates vinasse as the main wastewater from the fermentation–distillation process. The Brazilian legislation allows the use of vinasse for fertigation in limited volumes, and the remaining effluent must be treated prior to its reuse or discharge into the environment. The study aimed to evaluate the electrocoagulation (EC) technique as an alternative treatment process for raw sugarcane vinasse. The effects of the electrode gap (1–3 cm), applied electric charge (0–39000 C/L), current density (2.2–20 mA/cm2), and stirrer speed (0–680 rpm) were evaluated in a batch electrolytic reactor with aluminum electrodes. The evaluation results revealed that dissolved solids were removed and the pH increased during electrolysis in all experimental conditions, which suggested that EC was suitable for the pH neutralization of vinasse without the requirement of salt addition. An electrode gap of 1 cm and a current density of 2.2 mA/cm2 resulted in the lowest electric energy consumption (11.0 kW h/m3) and the lowest increment in the electrolyte temperature (9.5 °C). High vinasse clarification was achieved under the optimal operating conditions of 1 cm electrode gap, 31,000 C/L applied electric charge, 6.1 mA/cm2 current density, and 430 rpm stirrer speed, with 13.5 kW h/m3 and 2.88 kg Al/m3 of consumption. The treatment cost was calculated to be 6.95 US$/m3, from which the electrode dissolution was determined to be 75%. The sludge settling velocity was 0.14 cm/min, which suggested poor sedimentability, possibly due to bubble gas adsorption on the surface of the formed flocs. Results of the proposed operational parameters indicate that EC can be used as a pre-treatment of vinasse, adapting the main sugarcane processing wastewater biotechnological use.

Chemical and biological combined treatment for sugarcane vinasse: selection of parameters and performance studies

Sugarcane vinasse has been reported as a high strength industrial wastewater that could cause severe environmental pollution due to its complex and bio-refractory compounds. Thus, the combined coagulation and sequencing batch biofilm reactor (SBBR) system was employed for the sugarcane vinasse treatment. This study aims to determine the recommended conditions of various parameters under coagulation and SBBR and investigate the effectiveness of combined processes. First, the approach of the coagulation process could achieve the maximum COD reduction and decolorization efficiencies of 79.0 ± 3.4% and 94.1 ± 1.9%, respectively, under the recommended conditions. Next, SBBR as an integrated biofilm reactor showed excellent synergistic biodegradability, removing 86.6 ± 4.3% COD concentration and 94.6 ± 3.8% color concentration at 3.0g·COD/L of substrate loading concentration. The kinetic studies of SBBR revealed that the first-order kinetic model was the best fit for COD reduction efficiency. In contrast, the second-order kinetic model was the best fit for decolorization efficiency. The SBBR reaction was further investigated by ultraviolet-visible spectrophotometry (UV-Vis). In the combined processes, SBBR followed by the coagulation process (SBBR-CP) showed greater COD reduction and decolorization efficiencies (97.5 ± 0.3 and 99.4 ± 0.1%) when compared to the coagulation process followed by SBBR (CP-SBBR). This study demonstrated the removal performance and potential application of the combined sequential process to produce effluent that can be reused for bioethanol production and fertigation. This finding provides additional insight for developing effective vinasse treatment using combined chemical and biological processes.

Efficiency of nutrients recovery from sugarcane vinasse treatment by different electrodialysis configurations and in sequential-batch operation

Electrodialysis (ED) is reported as a promising technique for vinasse desalination and nutrients recovery for mineral (K-struvite) and organomineral fertilizers production. The use of ultrafiltered vinasse as an electrolyte solution, as well as fouling layer formation on membrane surface, were evaluated by operating the ED for a longer operation time. After 40 h of test time, it was observed that the ED performance was stable, with high efficiencies of removal (>77 %) and recovery (>70 %) of potassium. Ultrafiltered vinasse did not affect the efficiencies of nutrient removal and recovery, and provides as benefits a reduction in the costs of water and chemical demand, and the production of organo-mineral fertilizer. Membrane fouling was considerably reduced after the cleaning procedure. Also, ED operation was evaluated in three configurations, namely A, B, and C, with 5, 3, and 2 compartments, respectively. The lower number of compartments did not affect the ED performance, with similar performance as that observed for the Configuration A. Removal and recovery efficiencies for potassium, calcium and magnesium were similar in all experiments, being 80 and 72 %, 57 % and 49 %, 46 % and 8 %, respectively. For the specific energy consumption per mole of K+ (E/K+), no significant differences were found between the three configurations for both electrolyte solutions, being around 0.3049 ± 0.012 KWh/Kg K+. Of the configurations evaluated, Configuration C demonstrated to be a viable alternative for implementation in a biorefinery for sugarcane vinasse treatment. Besides the high performance presented, this configuration has advantages such as: reduction in energy use, membrane area, area required for system installation, water and chemical demand, and the potential recovery of gaseous chlorine, which can be used as a decolorizing agent.

Treatment of Sugarcane Vinasse Using Heterogeneous Photocatalysis with Zinc Oxide Nanoparticles

Vinasse is the main by-product of the ethanol industry; for each liter of ethanol, 13 to 18 L of vinasse is generated. Vinasse is composed of 93% water and 7% organic and inorganic solids and has an acidic pH and a high concentration of macro- and micronutrients used by plants, which is the reason for its widespread application in soil fertigation. However, over time, excessive direct discharge of vinasse into the soil causes damage, such as salinization and groundwater contamination. In this study, we used heterogeneous photocatalysis with zinc oxide nanoparticles (ZnO-NPs) to reduce chemical oxygen demand (COD) and biochemical oxygen demand (BOD) and as an antimicrobial treatment. ZnO-NPs were synthesized by the precipitation of zinc sulfate heptahydrate and sodium hydroxide, resulting in nanoparticles with a size of 21.6 ± 0.3 nm and an energy bandgap of 2.6 eV. Microscopic examinations revealed that Saccharomyces cerevisiae microorganisms are present in vinasse and that the minimum inhibitory concentration for the ZnO-NPs is 1.56 g/L. Photocatalysis with 40 mg/L of ZnO-NPs for 4 h of exposure to sunlight resulted in COD and BOD reduction efficacies of 17.1% and 71.7%, respectively. This study demonstrates the viability of using ZnO-NPs in vinasse treatment, contributing to sustainable applications and reducing the environmental impacts of fertigation.

Evaluating granulometry and metal content in sludge from UASB reactors treating sugarcane vinasse

Few studies have been carried out on sludge blankets in treatment systems. However, the sludge blanket in a UASB system is the area where microorganisms responsible for converting organic matter into biogas are concentrated. Considering its importance, the present research aimed to study the sludge blanket of three UASB reactors used in the treatment of sugarcane vinasse (pilot scale). The main difference between them was the applied effluent recirculation rate (100 %, 200 %, and 400 %). The research objective was to analyze the sludge blanket of these reactors: to determine the granulometry; the concentration of zinc, lead, cadmium, nickel, iron, manganese, copper, total chromium, calcium, magnesium, sodium, and potassium; and the organic and inorganic contents, aiming to identify the physical-chemical alterations in the sludge caused during the operational period. A reduction in the granular diameter was observed in all systems up to the range between 0.4 and 1 mm, provided by the increase in the hydraulic load, the organic loading rate and biogas production, and the increase in the mineral fraction in the sludge blanket, associated with the metal contribution of vinasse to the sludge blanket. Metal accumulation such as magnesium, sodium, calcium, and potassium was not detrimental to the methanogenic process due to the strategy of adapting biomass to vinasse, by gradually increasing the vinasse load, and the effects of antagonisms between magnesium and sodium and between potassium and sodium, which reduced its toxic effects.

Microbial dynamics and methanogenic potential of co-digestion of sugarcane vinasse and dairy secondary effluent in an upflow anaerobic sludge blanket reactor

Co-digestion is a strategy that may prevent microbial inhibition during the anaerobic treatment of sugarcane vinasse, a substrate with highly biodegradable organic load, acidity, and toxic compound levels (e.g., sulfates, phenols). In this context, this study evaluated the microbial dynamics and methanogenic potential throughout the co-digestion of sugarcane vinasse and secondary effluent from the dairy industry in a mesophilic lab-scale upflow anaerobic sludge blanket (UASB) reactor. Periodic next-generation sequencing (NGS) analyses revealed an increase in the relative abundance of the phylum Euryarchaeota (+8.6 % after inoculation), predominating hydrogenotrophic methanogens (Methanobacterium and Methanobrevibacter) at the end of the operation. Moreover, the average methane yield was 221 mLCH4 gCODrem-1, with 69 % of organic matter removal. These results evidenced a progressive acclimation of the anaerobic microbial community to the substrate and a stable operation. Therefore, the proposed experiment demonstrates energy advantages for the agro-industrial sector by implementing a similar but full-scale treatment plant.

Effect of electrolyte solution recycling on the potassium recovery from vinasse by integrated electrodialysis and K-struvite precipitation processes

Brazil is the largest importer of potassium-based fertilizers, with Russia and Belarus accounting for 44% of these imports. However, recent events elevated the risk of disruptions in the global fertilizer trade. Thus, the nutrients recovery from potassium-rich industrial wastewater, such as sugarcane vinasse, can contribute to the conservation of natural resources and a guaranteed supply of the product. In this work, the integration of electrodialysis and chemical precipitation processes was evaluated for sugarcane vinasse treatment, aiming at potassium recovery and electrolyte solution recycling. The electrodialysis cathode concentrate was submitted to chemical precipitation to form K-struvite, while the supernatant from this step was recirculated to the cathode concentrate compartment for the next electrodialysis batch, for a total of 3 sequential electrodialysis-chemical precipitation batches. The electrolyte solution recycling implies a reduction in water consumption in the electrodialysis process. Also, through conducting sequential batches, it is possible to evaluate the number of consecutive times that the supernatant can be reused, maximizing the reduction in water consumption for the recovery of the maximum amount of nutrients, however without harming the electrodialysis performance. The electrodialysis presented stable performance throughout the three batches performed, with potassium removal efficiencies around 76% and recovery around 68%. As for the chemical precipitation step, the removal efficiencies of potassium, phosphorus, and magnesium were 69%, 92%, and 88%, respectively, with no significant differences from the Kruskal-Wallis test between the three batches. From the SEM/EDS and X-ray diffraction analyses, the formation of the K-struvite fertilizer in the precipitates was confirmed, leading to the production of 3.2 kg K-struvite/m3 of treated vinasse. The proposed system was suitable for water saving in the electrodialysis stage, recovery of K-struvite fertilizer, and increase in the vinasse application rate to the soil (equivalent to an increase of 330% in the maximum vinasse application rate), while reducing the costs with wastewater transportation for soil irrigation. Thus, this process integration could help a possible fertilizer supply shortage, reduce environmental impacts and reduce costs regarding the electrodialysis concentrate treatment.

Anaerobic treatment of sugarcane vinasse pretreated with a calcium-based biopolymer

This study investigated the influence of a previous sugarcane vinasse coagulation, by using a calcium-based biopolymer, on anaerobic treatment in a lab-scale reactor. Two anaerobic reactors (R1 and R2) were operated for 155 days. R1 was fed only with raw sugarcane vinasse and R2 was fed with pretreated effluent. The operation was divided into three stages: E1 (inoculation and adaptation); E2; and E3. The major difference between E2 and E3 was the fact that R2 failed at the end of E2. Thus, R2 was recovered by applying a low organic loading rate (OLR) of raw vinasse for 29 days. In E2 and E3, for both reactors, pH, alkalinity, COD (influent and effluent samples), and methane production were monitored. During E1, an OLR of 2.0 kgCOD. m-3.d-1 1 was applied, and R1 and R2 sludges showed good adaptation to the wastewater in this condition. Then, the OLR was progressively increased to 7.0 kgCOD.m-3.d-1 in both systems. The average COD removal efficiencies were 82.9 ± 4.4% and 72.2 ± 18.1% for R1 and R2, respectively. R2, operated with pretreated vinasse, showed a decrease in the COD removal and methane production, which could be caused by the biopolymer presence. The average COD removal efficiencies in E3 were 77.5 ± 9.4% and 79.2 ± 9.7% for R1 and R2, respectively. After 155 days of operation, a decrease in the COD removal and methane production was identified again in R2, indicating a new failure. The quality of sludge granules from the inoculum and also from the granules developed at the end of R1 and R2 operation was analyzed by scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS). These analyses indicated a rise in the rugosity of R1 and R2 granules, possibly due to the deposition of sedimentable compounds present in both raw and pretreated vinasse. The EDS analyses indicated a high presence of calcium in R2 granules, indicating that this compound acted in the reduction of mass transfer between organic load from vinasse and the granules’ microbiota.

Microbial and functional characterization of granulated sludge from full-scale UASB thermophilic reactor applied to sugarcane vinasse treatment

ABSTRACT Considering the scarcity of data in the literature regarding phylogenetic and metabolic composition of different inocula, especially those from thermophilic conditions, this research aimed at characterizing the microbial community and preferable metabolic pathways of an UASB reactor sludge applied to the thermophilic treatment (55°C) of sugarcane vinasse, by means of shotgun metagenomics. After its metabolic potential was depicted, it was possible to observe several genes encoding enzymes that are of great importance to anaerobic digestion processes with different wastes as substrate, especially regarding the biodegradation of carbohydrates and ligninolytic compounds, glycerolypids, volatile fatty acids and alcohols metabolism and biogas (H2 and CH4) production. The genera identified in higher relative abundances for Bacteria domain were Sulfirimonas (37.52 ± 1.8%), possibly related to the sludge endogenic activity due to its strong relation with a peptidoglycan lyase enzymes family, followed by Fluviicola (5.01 ± 1.0%), Defluviitoga (4.36 ± 0.2%), Coprothermobacter (4.32 ± 0.5%), Fervidobacterium (2.93 ± 0.3%), Marinospirillum (2.75 ± 0.2%), Pseudomonas (2.14 ± 0.2%) and Flavobacterium (1.78 ± 0.1%), mostly related with carbohydrates fermentations and/or H2 production. For Archaea domain, Methanosarcina (0.61 ± 0.1%), Methanothermobacter (0.38 ± 0.0%), Methanoculleus (0.30 ± 0.1%), Thermococcus (0.03 ± 0.0%), Methanolobus (0.02 ± 1.8%), Methanobacterium (0.013 ± 0.0%), Aciduliprofundum and Pyrococcus (0.01 ± 0.0%) were the most dominant ones, being Methanosarcina the most related with methanogenesis. It was concluded that the robust inoculum description performed in this study may subside future biotechnological researches by using similar inocula (UASB sludges), focusing on the obtainment of value-added by-products by means of anaerobic digestion, such as volatile fatty acids, alcohols and biogas (H2 and CH4), by using several types of waste as substrate.

Insights into modified sequencing batch reactor for the treatment of sugarcane vinasse: role of recirculation process

Insights into modified sequencing batch reactor for the treatment of sugarcane vinasse: role of recirculation process

Metataxonomic characterization of bacterial and archaeal community involved in hydrogen and methane production from citrus peel waste (Citrus sinensis L. Osbeck) in batch reactors

In order to obtain enhanced value-added products, Citrus Peel Waste (CPW) was used as a lignocellulosic substrate for H2 and Volatile Fatty Acids (VFA) production (Stage I), combined with the CH4 production using these metabolites as substrate (Stage II). Stage I used 15 gCPW.L−1, 2.25 gTVS.L−1 of autochthonous inoculum, 3 gTVS.L−1 of allochthonous inoculum (UASB sludge applied to sugarcane vinasse treatment) in batch reactors operated with 40% of headspace, at 30 °C and under static conditions and pH adjusted to 8.5. These conditions allowed obtaining 13.29 mmolH2. L−1 and 1340 mg L−1 of acetic acid in Stage I. Using 125 mL of the acidified effluent (filtered liquid fraction), in Stage I, as substrate in 250 Duhran flasks, with pH adjusted to 7.0, 3 gTVS.L−1 of the same allochthonous inoculum and Zinder medium, 50.2 mmolCH4. L−1 was obtained in Stage II. The metataxonomic and metabolic potential were inferred by means of high throughput amplicon sequencing of the 16S rRNA gene on the Illumina HiSeq platform. It can be stated that the cellulolytic enzymes producers Escherichia and Clostridium were the main bacteria genera involved in CPW fermentation in Stage I, while Methanoplasma and Methanosarcina were the main archaea genera involved in CH4 production in Stage II. Besides that, it was possible to infer that Acetyl-CoA synthetase was the enzyme inferred in higher proportions in Stage II, probably due to the predominance of acetoclastic methanogenesis at this stage.

Temporal analysis of the microbiota involved in the anaerobic degradation of sugarcane vinasse in a full-scale methanogenic UASB reactor

The treatment of sugarcane vinasse is still a challenge to develop a sustainable bioethanol production. Anaerobic digestion (AD) is the most promising treatment of vinasse since energy in the form of biogas can be recovered. The aim of this work was to understand the dynamics of the microbial community in a 100-m3 upflow anaerobic sludge blanket (UASB) methanogenic reactor at start-up and during two periods of bioethanol production. An inter-harvest period in which the reactor was not fed was also studied. Metabarcoding analysis of the V4 region of the 16S rRNA gene showed that Firmicutes, Synergistetes, Chloroflexi, and Proteobacteria were the dominant phyla. Firmicutes was abundant, suggesting that this group plays a specific role in the treatment of vinasse. The inoculum adaptation to vinasse was correlated with the microbiota diversity and dynamics. The microbiota diversity was higher during the first harvest and reflected the initial microbial composition. During the second harvest, the increasing organic loading rate (OLR) and the adaptation to the new effluent selected a less diverse community which produced the biogas in the reactor. The qPCR of the mcrA gene and methanogenic activity tests showed that the abundance of methanogens increased over time and remained stable even after the stop period. This work shows the plasticity of the microbial community, which adapted its structure to the changes in the feed and persisted during starvation periods in the reactor. A time-series of microbiological information is necessary to a comprehensive understanding of full-scale reactor maintenance.

Treatment of sugarcane vinasse using an autochthonous fungus from the northwest of Argentina and its potential application in fertigation practices

Vinasse, the most important liquid residue of the bioethanol production, is often used in fertigation programs. However, this practice may have negative effects on crops if applied without a prior conditioning treatment. In the present study, the efficiency of a fungus-based process as a method for vinasse treatment was evaluated. Phytotoxicity of the residue, before and after biological treatment, was tested on two plant species used for human consumption (Triticum aestivum L. and Raphanus sativus) in order to evaluate the application of vinasse in fertigation. The fungus, identified as Aspergillus sp. V2, showed high tolerance to vinasse, resulting in an optimal growth even when is cultivated on the undiluted residue. Biologically treated vinasse with a cycle of re-inoculation of spores resulted in a COD removal of 52%, whereas pH was increased from 4.4 to 6.1 at the end of treatment. Toxicity studies demonstrated a substantial improvement in the growth parameters (vigor index and fresh weight) of plant species exposed to treated vinasse compared to those exposed to raw residue. These results show that Aspergillus sp. V2 is useful for the recovery of an actual wastewater like sugarcane vinasse, enhancing its fertilizing properties.

Combination of Persulfate /Peroxymonosulfate Activated By Ion (II) with Hydrogen Peroxide for Mineralization and Valorization of Vinasse

Recently, there is an increasing demand for water due to rapid industrialization and a growing human population. There is a too shortage of available water sources; thus, one option for increasing existing resources is the treatment and reuse of wastewaters. Vinasse poses a long-term risk to public health because of its toxic nature and a huge amount. This study investigates a new prospect of a combination of persulfate (PS)/ peroxymonosulfate (PMS) (activated by Ion (II)) and hydrogen peroxide (H2O2) for reducing total organic carbon (TOC) from vinasse and reuse of treated vinasse as well. Behaviors of PS/Fe(II)/ H2O2 and PMS/ Fe(II)/ H2O2 on total organic carbon (TOC) removal are explored by evaluating various effects, including H2O2 dosage, Fe (II) dosage, pH and reaction time. Hydrogen peroxide was used as an oxidation agent to improve the degradation of the organic matter of vinasse. The addition of H2O2 to PS/ Fe (II) or PMS/ Fe (II) generates highly oxidizing radicals, which enhanced, significantly, the removal of TOC. Both of PS/ Fe (II)/ H2O2 and PMS/ Fe (II)/ H2O2 systems favored neutral pH in removing the organic matter, and they were very active in the first 5 minutes. At the optimum conditions, about 86 % and 83% of TOC removal were achieved by PS/ Fe (II)/ H2O2 and PMS/ Fe (II)/ H2O2, respectively. Therefore, a combination of PS/PMS activated by Fe (II) with H2O2 can be considered as a capable technique for sugarcane vinasse treatment and allowing to reuse the effluents in many applications.

Start-Up Strategy and Process Performance of Semi-Continuous Anaerobic Digestion of Raw Sugarcane Vinasse

The sugarcane distillery waste water is generated throughout the sugarcane molasses fermentation and distillation. In Reunion Island, a part of the vinasse production is treated by methanisation process. However, the remaining part is diluted then discharged into the sea. The aim of this work is to study the anaerobic treatment of sugar cane vinasse, with energy recovery. Nonetheless, vinasse pollutant load is difficult to treat. Regarding the experimentations, the biochemical potential (BMP) test is used for the determination of the methanogen potential. The BMP is then modelled with the modified Gompertz and the first order kinetic models. Furthermore, a laboratory study is carried out for studying the methane production of vinasse in semi-industrial scale over a period of 130 days. The start-up strategy of the 16 L pilot is proposed, in particular the gradual increase of organic load. The physico-chemical analysis of the medium is needed to prevent and explain the failure of the process. Indeed, the biogas production and physico-chemical measurements during the digestion are presented and discussed. The maximum methane yield of the BMP is 185 $${\text{NL}}_{{{\text{CH}}_{4} }} \,{\text{kg}}_{{{\text{COD}}}}^{ - 1} ,$$ obtained with I/S ratio in terms of volatile solids of 0.7. The outcomes showed that the first-order kinetic and modified Gompertz models fit well with the BMP test curves. Concerning the pilot, the start-up period lasted 45 days the maximum specific production was 151.00 $${\text{NL}}_{{{\text{CH}}_{4} }} \,{\text{kg}}_{{{\text{COD}}}}^{ - 1}$$ (232.31 $${\text{NL}}_{{{\text{biogas}}}} \,{\text{kg}}_{{{\text{COD}}}}^{ - 1}$$ ). In further studies, different mixing strategies will be studied.

New Proposal for Sugarcane Vinasse Treatment by Hydrothermal Carbonization: An Evaluation of Solid and Liquid Products

Vinasse is a residue of ethanol production from sugarcane. In view of the problems associated with its disposal, this study aimed to propose a treatment for vinasse by hydrothermal carbonization. The influence of temperature (100 to 200 oC), acidity (1.7 to 8.3%) and reaction time (12 to 48 h) on the hydrothermal treatment was evaluated, as well the characteristics of the solid (hydrochar) and liquid (process water) products. For the solid product, two hydrothermal carbonization conditions stood out as leading to higher carbonization and yields. These conditions were 200 oC, 8.3% acidity and times of 12 and 48 h. For the process water, the carbonization reaction at 200 oC, 8.3% acidity and 48 h produced the highest discoloration and 77% reduction of total organic carbon. Thus, hydrothermal carbonization proved to be an efficient method to treat vinasse, and the hydrochar presents potential for use as fertilizers / soil conditioners, and also the process water after pre-treatment.

Evaluation of the effect of different treatment methods on sugarcane vinasse remediation

Sugarcane vinasse is a by-product obtained during ethanol production in sugar-ethanol plants. For each 1 L of ethanol produced approximately 11 L of vinasse are generated. As this residue is obtained in high amounts, it is used as fertilizer in sugarcane crops. However, despite being rich in nutrients, sugarcane vinasse is approximately one hundred times more polluting than domestic sewage, making it an environmental problem. Thus, the aim of the present study was to propose a treatment sequence for sugarcane vinasse and evaluate the possibility of energetic use of the generated sludge in the coagulation/flocculation stage. pH, conductivity, turbidity and decreases in UV/Vis absorption spectra were determined for each treatment step. In addition, the upper calorific value of the generated sludge was also determined, while ash (adsorption treatment) and catalyst (heterogeneous photocatalysis) characterizations were also carried out. At the end of the treatment, initial vinasse turbidity was reduced by 100% and pH and conductivity values were stabilized. The sludge presented a higher calorific value of approximately 3,000 kcal kg−1 and the ash and catalyst displayed favorable characteristics to be applied to the sugarcane vinasse treatment stages.

Treatment of sugarcane vinasse from cachaça production for the obtainment of Candida utilis CCT 3469 biomass

Ethanol and “Cachaça” production processes generate considerable amounts of residues known as vinasse. The indiscriminate disposal of this waste represents a potential risk to both surface water and groundwater, soil, animals, and ultimately the entire environment. This work describes an alternative to reduce the environmental impact through cachaça vinasse management practices by using it as a culture medium for the growth of Candida utilis CCT 3469 to produce biomass, replacing the conventional production from cane molasses. For that both, the raw and vacuum evaporated, vinasses from cachaça were treated by using different pH adjustments and activated charcoal adsorption (2.5%). The vinasses treated at pH 6.0 were selected to produce Candida utilis CCT 3469 biomass (2.25 g L−1). In this case, higher values of volumetric biomass productivity (0.08 gL−1 h−1) and biomass yield (0.13 gg−1) were obtained, as also for the higher specific rates for glucose consumption (1.354 gglucose gcell−1 h−1), fructose consumption (0.811 gfructose gcell−1 h−1) and biomass (0.616 h−1). The ratio values for BOD/COD (0.02) characterized the vinasse as an effluent of difficult degradation and biological treatability. Probably this fact favored the obtainment of yeast biomass in the treated vinasse at the lowest concentration factor.

Genome sequence of the H2-producing Clostridium beijerinckii strain Br21 isolated from a sugarcane vinasse treatment plant.

We report on the nearly complete genome sequence of Clostridium beijerinckii strain Br21, formerly isolated from a sugarcarne vinasse wastewater treatment plant. The resulting genome is ca. 5.9 Mbp in length and resembles the size of previously published C. beijerinckii genomes. We annotated the genome sequence and predicted a total of 5323 genes. Strain Br21 has a genetic toolkit that allows it to exploit diverse sugars that are often found after lignocellulosic biomass pretreatment to yield products of commercial interest. Besides the whole set of genes encoding for enzymes underlying hydrogen production, the genome of the new strain includes genes that enable carbon sources conversion into butanol, ethanol, acetic acid, butyric acid, and the chemical block 1,3-propanediol, which is used to obtain polymers. Moreover, the genome of strain Br21 has a higher number of ORFs with predicted beta-glucosidase activity as compared to other C. beijerinckii strains described in the KEGG database. These characteristics make C. beijerinckii strain Br21 a remarkable candidate for direct use in biotechnological processes and attest that it is a potential biocatalyst supplier.