Sugarcane Vinasse Research Articles

Thermophilic anaerobic digestion of raw sugarcane vinasse

The application of thermophilic anaerobic digestion is a logical choice for the treatment of sugarcane vinasse (industrial wastewater from ethanol production) because this process enables the recovery of energy as hydrogen and methane without requiring energy for heat or interfering in its quality as a bio-fertilizer. Thus, this study evaluated the performance of thermophilic methanogenic up-flow sludge blanket reactors (UASB) operating continuously in single-stage (UASB I) and two-stage (UASB II) systems vinasse during the sugarcane harvesting season (180 days). The maximum methane yields were 250.9 NmL-CH4.g−1CODremoved and 316.0 NmL-CH4.g−1CODremoved for UASB I and II, respectively, corresponding to 71.7% and 90.3% of the maximum theoretical methane yield (350 NmL-CH4.g−1CODremoved). Furthermore, the energy production from the two-stage system was 25.7% higher than the single-stage system, indicating the need for an acidogenic phase to improve both the removal of organic matter and energy extraction from sugarcane vinasse.

Long-term effect of acid and heat pretreatment of sludge from a sugarcane vinasse treatment plant on the microbial community and on thermophilic biohydrogen production

This work investigated how heat and acid pretreatment affected thermophilic biohydrogen production by a mixed culture present in the sludge of a sugarcane vinasse treatment plant. Heat- (80 °C for 15 min) or acid- (pH 3 for 24 h) treated sludge samples were employed to seed batch bioreactors along 36 days. The heat- and acid-treated sludge samples afforded H2 production rates (HPRs) of 8.4 and 9.5 mmol/L.d, respectively. The lactic acid concentration increased in the bioreactor seeded with heat-treated sludge, whilst the lactic acid concentration diminished in the bioreactor inoculated with the acid-treated sludge. Identification of the microbial community revealed that Clostridiaceae predominated in all the sludge samples. The most abundant Clostridiaceae in the heat- and acid-treated sludge samples were Clostridium and Thermoanaerobacterium, respectively. Acid pretreatment modified the microbial community and enhanced consumption of lactic acid, a metabolite that is normally associated with decreased H2 production.

Sulfidogenesis interference on methane production from carbohydrate-rich wastewater.

Two anaerobic fixed-structured bed reactors were fed with synthetic wastewater simulating the soluble fraction of sugarcane vinasse to evaluate the interference of sulfidogenesis on methanogenesis. The reactors running in parallel were subjected to the same operating conditions. The influent organic matter concentration (in term of chemical oxygen demand (COD)) remained close to 4,000 mgCOD L(-1) and the hydraulic retention time was 24 hours. One reactor, the methanogenic (control reactor), received sulfate only to provide the sulfur required as a nutrient to the methanogenic biomass. The other one, the sulfidogenic/methanogenic reactor (SMR), received sulfate concentration corresponding to COD/sulfate ratios of 4, 5 and 3. In the last phase, the COD removal efficiencies were higher than 96% in both reactors and the SMR achieved 97% of sulfate removal efficiency (COD/sulfate ratio of 3 and influent sulfate concentration close to 1,300 mgSO4(2-) L(-1)). Both reactors also had similar methane yields in this phase, close to 350 mLCH4 gCODremoved(-1) at standard temperature and pressure. These results indicated no significant inhibition of methanogenic activity under the sulfidogenic conditions assessed.

Sequential fermentative and phototrophic system for hydrogen production: An approach for Brazilian alcohol distillery wastewater

This study evaluated the possibility of using sugarcane vinasse for biological hydrogen production under non-sterile conditions via sequential two-stage fermentative and phototrophic processes, which simultaneously allows bioenergy production and chemical oxygen demand (COD) removal. The fermentative process was performed in an anaerobic fluidized bed reactor (AFBR) fed with a mixture of sucrose and sugarcane vinasse (5:10 g COD L−1). The phototrophic process was performed using a microbial consortium (Rhodopseudomonas related microorganisms) as inoculum and batch reactors fed with different concentrations of the AFBR effluent (10, 20, 40, 70 and 80%, v/v). The hydrogen yield (HY) (0.34 mol H2 g−1 CODinfluent) observed in the fermentative step was justified by the establishment of microbial community composed predominantly by Lactobacillus related microorganisms. The highest HY observed in the phototrophic stage (5.5 mmol H2 g−1 CODremoved) was observed for the lowest AFBR concentration. Increasing the AFBR effluent concentration as the substrate for the phototrophic reactors had a negative impact on cell growth, hydrogen production and COD removal mostly due to the occurrence of sulfate reduction. Hydrogen production was not observed in batch reactors fed with 70 and 80% of AFBR effluent; however, under those conditions, the sulfate removal rate was 86.5 and 86.9%, respectively.

Evaluation of hydrogen and methane production from sugarcane vinasse in an anaerobic fluidized bed reactor

This study evaluated the hydrogen and methane production from sugarcane vinasse in an anaerobic fluidized bed reactor. Two reactors were operated with two different substrate concentrations: R5 (5 g COD L−1) and R10 (10 g COD L−1). During the first stage, glucose was used as the primary carbon source; vinasse was then added from 0% to 100% of the organic source in hydraulic retention time (HRT) of 6 h. Later, HRT was changed to 4, 2 and 1 h.The best hydrogen production rate was 0.57 L h−1 L−1 (R5, HRT = 1 h, 100% vinasse). The best hydrogen yield was 3.07 mmol H2 g−1 CODadded (R5, HRT = 6 h, vinasse:glucose = 1:3). Main metabolites were ethanol, butyric acid, propionic acid and methanol. Denaturing gradient gel electrophoresis analysis identified Prevotella sp. and Megasphaera sp. belonging to the Bacteria domain and Methanobacterium sp. and Methanosphaera sp. belonging to the Archaea domain.

Comparison of Aerobic and Anaerobic Biodegradation of Sugarcane Vinasse

Vinasse is the main liquid waste from ethanol production, and it has a considerable pollution potential. Biological treatment is a promising alternative to reduce its organic load. The aim of this study was to analyze the biodegradation of sugarcane juice vinasse in aerobic and anaerobic conditions. The content of carbohydrates, proteins and volatile fatty acids was evaluated. Vinasse samples showed a high biodegradability (>96.5 %) and low percentage of inert chemical oxygen demand (COD) (<3.2 %) in both aerobic and anaerobic conditions. The rates of substrate utilization were slightly higher in aerobic reactors, but COD stabilization occurred simultaneously in the anaerobic reactors, confirming its suitability for anaerobic digestion. Inert COD in anaerobic conditions was lower than in aerobic conditions. On the other hand, COD from metabolic products in the anaerobic reactors was higher than in the aerobic ones, indicating an increased release of soluble microbial products (SMPs) by anaerobic microorganisms. The results indicated that carbohydrates were satisfactorily degraded and protein-like substances were the major components remaining after biological degradation of vinasse.

Ecotoxicological characterization of sugarcane vinasses when applied to tropical soils

The impact of sugarcane vinasse on soil invertebrates was assessed through ecotoxicological assays. Increasing concentrations of two vinasses from different distillery plants (VA and VB), and a vinasse from a laboratory production (VC), were amended on two natural tropical Oxisols (LV and LVA) and a tropical artificial soil (TAS) to characterize the effects of the vinasses on earthworms (Eisenia andrei), enchytraeids (Enchytraeus crypticus), mites (Hypoaspis aculeifer) and collembolans (Folsomia candida). The highest concentrations of VA and VB were avoided by earthworms in all soils and by collembolans especially in the natural soils. The presence of VC in all of the tested soils did not cause avoidance behavior in these species. The reproduction of earthworms, enchytraeids and collembolans was decreased in the highest concentrations of VA and VB in the natural soils. In TAS, VB reduced the reproduction of all test species, whereas VA was toxic exclusively to E. andrei and E. crypticus. The vinasse VC only reduced the number of earthworms in TAS and enchytraeids in LVA. The reproduction of mites was reduced by VB in TAS. Vinasses from distillery plants were more toxic than the vinasse produced in laboratory. The vinasse toxicities were influenced by soil type, although this result was most likely because of the way the organisms are exposed to the contaminants in the soils. Toxicity was attributed to the vinasses' high salt content and especially the high potassium concentrations. Data obtained in this study highlights the potential risk of vinasse disposal on tropical soils to soil biota. The toxic values estimated are even more relevant when considering the usual continuous use of vinasses in crop productions.

Mesophilic hydrogen production in acidogenic packed-bed reactors (APBR) using raw sugarcane vinasse as substrate: Influence of support materials

Bio-hydrogen production from sugarcane vinasse in anaerobic up-flow packed-bed reactors (APBR) was evaluated. Four types of support materials, expanded clay (EC), charcoal (Ch), porous ceramic (PC), and low-density polyethylene (LDP) were tested as support for biomass attachment. APBR (working volume – 2.3 L) were operated in parallel at a hydraulic retention time of 24 h, an organic loading rate of 36.2 kg-COD m−3 d−1, at 25 °C. Maximum volumetric hydrogen production values of 509.5, 404, 81.4 and 10.3 mL-H2 d−1 L−1reactor and maximum yields of 3.2, 2.6, 0.4 and 0.05 mol-H2 mol−1 carbohydrates total, were observed during the monitoring of the reactors filled with LDP, EC, Ch and PC, respectively. Thus, indicating the strong influence of the support material on H2 production. LDP was the most appropriate material for hydrogen production among the materials evaluated. 16S rRNA gene by Terminal Restriction Fragment Length Polymorphism (T-RFLP) analysis and scanning electron microscopy confirmed the selection of different microbial populations. 454-pyrosequencing performed on samples from APBR filled with LDP revealed the presence of hydrogen-producing organisms (Clostridium and Pectinatus), lactic acid bacteria and non-fermentative organisms.

COD and nitrogen removal from sugarcane vinasse by heterotrophic green algae Desmodesmus sp.

Vinasse is the main wastewater from the ethanol fermentation–distillation process, generated in large volumes during industrial sugarcane processing. Desmodesmus is a green algae genus with recognized ability to treat wastewater containing organic matter and to consume nutrients under heterotrophic growth conditions. Thus, the aim of this research was to evaluate Desmodesmus sp. growth in sugarcane vinasse. Results indicated slight elevation of pH, low oxygen, and low carbon dioxide consumption. Nitrogen and chemical oxygen demand (COD) removal were 52.1 and 36.2%, respectively. Specific growth rate of 0.15 h−1 and high yield of COD to biomass at first hour (0.5 mg mg−1) suggest the feasibility of biomass production of this green algae in sugarcane vinasse.

Greenhouse gas emissions from sugarcane vinasse transportation by open channel: a case study in Brazil

Sugarcane ethanol has been proposed to be one of the best options to substitute fossil fuels. However, despite its benefits, ethanol production generates large amounts of residues, especially vinasse, a liquid residue that may result in environmental problems, such as greenhouse gas emissions (GHG). The aim of this study was to quantify the CH4 and N2O emissions during vinasse transportation by open channel in a sugarcane Mill in Brazil. Additionally, we estimated the contribution of vinasse emission to total sugarcane ethanol emissions. We set up six points to collect gas samples and quantify the emissions of CH4 and N2O along the main vinasse transportation channel. The emissions of CH4 accounted for over 98% of the total emissions, while the N2O fluxes represented, on average, less than 2%. We estimated an emission factor of 1.43 kg CO2 eq m−3 of transported vinasse. Improvements in vinasse storage and transportation methods, either by coating the open channels or by use of coated tanks and pipes should significantly reduce GHG emissions. The reduction of GHG emissions in ethanol production can make a significant contribution toward a cleaner production of biofuels.

Vertical Distribution and Pollution Assessment of Heavy Metals in Sugarcane Soils by Using Sugarcane Vinasse

This paper studied the vertical distribution of heavy metals in sugarcane soils by using sugarcane vinasse. The results showed that the sugarcane vinasse not only reduced the pH value of the sugarcane fields, but also increased the concentration of organic matter. The Cu content decreased with soil depth, and six sampling points appeared peaks in the range of 30~40cm.There was not obvious change of Cd content in soil depth of 0~60cm. And the content of Zn and Pb showed different changes with different sampling points. The study also showed that the mobility of four heavy metals followed the order Cu&gt; Zn&gt; Pb&gt; Cd. Besides, the content of Cu and Cd in some layers were exceeded soil background value of Guangxi. The geo-accumulation index indicated that the 36 samples collected from different layers were not contaminated by Cu, Zn, Pb and Cd, and the sugarcane soils were in clean state.

Atributos químicos, estoque de carbono orgânico total e das frações humificadas da matéria orgânica do solo em diferentes sistemas de manejo de cana-de-açúcar

Mechanized harvesting maintenance of trash from cane sugar and soil application of waste as vinasse and filter cake can improve the system of crop yield. Thus, this study aimed to evaluate the changes in the chemical, the stock of total organic carbon and humified organic matter fractions in an Oxisol cultivated with cane sugar with the following management systems: with sugarcane vinasse application (CCV), without application of burnt cane waste (CQS), with burnt cane vinasse application (CQV), with application of burnt cane filter cake (CQTF) and burnt cane with joint application of vinasse and filter cake (CQVTF). For reference we used an area of natural vegetation (NV), Cerrado sensu stricto . Treatment CQVTF showed improvement in soil chemical properties, increased inventory levels of total organic carbon – TOC (values ranging from 21.28 to 40.02 Mg ha-1) and humified fractions of soil organic matter in relation to other treatments. The CQS area at a depth of 0-0.05 m, showed the greatest losses of soil TOC stocks (56.3%) compared to NV. The adoption of management presented CCV and chemical attributes of the soil TOC stocks equivalent to those observed in areas with CQV CQTF and despite the short period of adoption (3 years). The TOC correlated with the sum of bases (r = 0.76 **), cation exchange capacity (r = 0.59 **) and base saturation (r = 0.63 **), while the humic acids (r = 0.40 **) fulvic acids (r = 0.49 **) and humin (r = 0.59 **) correlated with the cation exchange capacity of the soil. These results indicate that the preservation of trash in the management of cane sugar added to the application of vinasse and filter cake increases the TOC stocks promoting improvement in soil chemical properties.

Sugar cane vinasse in water bodies: Impact assessed by liver histopathology in tilapia

Aquatic ecosystems are the main receptors of toxic substances from human activities. With the increase in sugar cane production, vinasse – the main residue of ethanol production – is a potential contaminant of water resources, due to its high organic matter content. This study was aimed at evaluating the toxicity of vinasse by examining the liver of the fish Oreochromis niloticus exposed to different dilutions of sugar cane vinasse (1%, 2%, 5%, 5% and 10%) in laboratory bioassays. Portions of liver were collected and fixed for histological and histochemical techniques to detect total proteins, polysaccharides and lipids. In the histological analysis, the groups treated with vinasse exhibited significant alterations, such as loss of cytoplasmic integrity, loss of cell limit and tissue disorganization. Protein and lipid profiles were not altered. Higher accumulation of polysaccharides was detected in fish exposed to lower concentrations of vinasse, with a gradual decrease in animals treated with vinasse in higher concentrations. We concluded that vinasse has a dose-dependent toxic and cytotoxic potential in water bodies and that the liver is strongly affected when acutely exposed to this contaminant.

Effect of organic loading rate on hydrogen production from sugarcane vinasse in thermophilic acidogenic packed bed reactors

This study evaluated the effect of organic loading rate (OLR) on hydrogen production in up-flow anaerobic packed bed reactors (APBR) continuously fed with sugarcane vinasse. Four thermophilic up-flow APBR were operated in parallel at different ORL. Continuous hydrogen production was detected. The optimum OLR of 84.2 kg-COD m−3 d−1 was assessed by polynomial adjustment, which predicted a maximum Volumetric Hydrogen Production (VHP) and hydrogen yield (YH2) of 1117.2 mL-H2 d−1 L−1reactor and 2.4 mol-H2 mol−1total carbohydrates, respectively. The microbial composition was monitored using 16S rRNA gene by Terminal Restriction Fragment Length Polymorphism (T-RFLP) analysis and quantification of Fe-hydrogenase gene by real-time PCR which was affected by the OLR. The number of the Fe-hydrogenase genes was proportional to the monitored hydrogen production and yield. Hydrogen-producing strains were isolated, and the 16S rRNA gene sequences were highly homologous to those of Thermoanaerobacterium thermosaccarolyticum. The ability of vinasse as substrate for hydrogen production was confirmed for both strains.

Nitrogen Mineralization from Sugarcane Vinasse

Vinasse is a liquid residue applied as a fertilizer in sugarcane crops. However, in areas far away from sugarcane mills the cost of the distribution can be very high due, the large volume of water. So, one solution is to concentrate the vinasse by the evaporation process to reduce transport costs. Considering that the nitrogen mineralization kinetics is not known in concentrated vinasse, the objective of this study was to evaluate the net and potential nitrogen mineralization in soil that received vinasse concentrated and not concentrated. The treatments with concentrated vinasse provided the highest values of net mineralization and total nitrogen, which presented significant correlation each other, the same way as the potential mineralization values had a positive correlation with the doses and the amounts of total nitrogen. The total nitrogen values can be used as an index of nitrogen availability in soils that received concentrated vinasse.

Hydrogen production from diluted and raw sugarcane vinasse under thermophilic anaerobic conditions

Two continuous anaerobic fluidized bed reactors (AFBRs) were operated under thermophilic (55 °C) temperature for 150 days to investigate the effect of dark H2 fermentation of diluted and raw sugarcane vinasse on H2 production using mixed seed sludge. Although effective H2 production (52.8% of H2; 0.80 L H2 h−1 L−1; 0.79 mmol gCODadded−1) was observed using an elevated substrate concentration (30,000 mg COD L−1), the optimal operational conditions were found for the AFBR1 (10,000 mg COD L−1) fed with diluted sugarcane vinasse (HRT 6 h; OLR 40 kg COD m−3 d−1), achieving a H2 yield of 2.86 mmol H2 g CODadded−1. H2 production was inhibited by elevated volatile fatty acid (VFA) concentrations (butyric and acetic acids = 3.7 and 3.0 g L−1, respectively) in the raw feedstock. Denaturing gradient gel electrophoresis (DGGE) analyses revealed changes in the bacterial population of the expanded clay biofilm as a function of the substrate concentration.

Sugarcane vinasse as substrate for fermentative hydrogen production: The effects of temperature and substrate concentration

The present study aimed to evaluate the hydrogen production of a microbial consortium using different concentrations of sugarcane vinasse (2–12 g COD L−1) at 37 °C and 55 °C. In mesophilic tests, the increase in vinasse concentration did not significantly impact the hydrogen yield (HY) (from 1.72 to 2.23 mmol H2 g−1 CODinfluent) but had a positive effect on the hydrogen production potential (P) and hydrogen production rate (Rm). On the other hand, the increase in the substrate concentration caused a drop in HY from 2.31 to 0.44 mmol H2 g−1 CODinfluent in the tests performed at 55 °C with vinasse concentrations from 2 to 12 g COD L−1. The mesophilic community was composed of different species within the Clostridium genus, and the thermophilic community was dominated by organisms affiliated with the Thermoanaerobacter genus. Not all isolates affiliated with the Clostridium genus contributed to a high HY, as the homoacetogenic pathway can occur.

Aggregate breakdown and dispersion of soil samples amended with sugarcane vinasse

Soil aggregation is a very complex issue related to important soil attributes and processes. The aggregate breakdown and dispersion of soil samples amended with sugarcane vinasse were evaluated using ultrasonic energy. Vinasse is an important byproduct of sugarcane industries, intensively applied to soils in Brazil as liquid fertilizer. Samples of two Oxisols and one Ultisol were used in this study. The physical and chemical characterization of soils was performed, and the 1 to 2 mm size aggregates (200 g) were packed in PVC columns (6.0 cm high and 4.0 cm internal diameter) and incubated with sugarcane vinasse under lab conditions for 1, 30 and 60 days. After incubation, aggregates were submitted to levels of ultrasonic energy, and the particle size distribution (53 to 2,000 µm, 2 to 53 µm, and < 2 µm fractions) was quantified. Mathematical equations were used to relate the mass of aggregates in each of these fractions to the applied ultrasonic energy, and parameters related to aggregate stability were then obtained. Soils showed an aggregate-hierarchy resulting in a stepwise breakdown under ultrasonic agitation. Considering this soil-aggregation hierarchy, vinasse contributed even in a short time to the bonding between and within 2 to 53 µm aggregates, mainly in the Oxisols. This may be related to organic compounds present in the vinasse, cementing soil particles. Potassium enrichment of soil samples did not contribute to soil dispersion.

Influence of organic loading rate on the anaerobic treatment of sugarcane vinasse and biogás production in fluidized bed reactor

This study evaluated an anaerobic fluidized bed reactor (AFBR) that contained polystyrene particles as a support material for the treatment of vinasse that resulted from the alcoholic fermentation of sugarcane molasses. The AFBR was inoculated with sludge from an upflow anaerobic sludge blanket reactor that treated poultry slaughterhouse wastewater. The AFBR was operated with a hydraulic retention time of 24 h at a temperature of 30°C with influent vinasse concentrations that ranged from 2273 to 20,073 mg COD L−1. The reactor was subjected to increased organic loading rates (OLR) that ranged from 3.33 to 26.19 kg COD m−3 d−1, with COD removal efficiencies that ranged from 51% to 70% and maximum removal at an OLR of 13.93 ± 2.18 kg COD m−3 d−1. The maximum biogas productivity was 5.37 m3 CH4 m−3 d−1 for an OLR of 25.32 kg COD m−3 d−1 (average removal of 51%).,

Sugarcane vinasse: Environmental implications of its use

The inadequate and indiscriminate disposal of sugarcane vinasse in soils and water bodies has received much attention since decades ago, due to environmental problems associated to this practice. Vinasse is the final by-product of the biomass distillation, mainly for the production of ethanol, from sugar crops (beet and sugarcane), starch crops (corn, wheat, rice, and cassava), or cellulosic material (harvesting crop residues, sugarcane bagasse, and wood). Because of the large quantities of vinasse produced, alternative treatments and uses have been developed, such as recycling of vinasse in fermentation, fertirrigation, concentration by evaporation, and yeast and energy production. This review was aimed at examining the available data on the subject as a contribution to update the information on sugarcane vinasse, from its characteristics and chemical composition to alternatives uses in Brazil: fertirrigation, concentration by evaporation, energy production; the effects on soil physical, chemical and biological properties; its influence on seed germination, its use as biostimulant and environmental contaminant. The low pH, electric conductivity, and chemical elements present in sugarcane vinasse may cause changes in the chemical and physical–chemical properties of soils, rivers, and lakes with frequent discharges over a long period of time, and also have adverse effects on agricultural soils and biota in general. Thus, new studies and green methods need to be developed aiming at sugarcane vinasse recycling and disposal.