Sugarcane Vinasse Research Articles

Effects of Fertilisation Using Organic Waste Products with Mineral Complementation on Sugarcane Yields and Soil Properties in a 4 Year Field Experiment

Sugarcane cultivation is suitable for the exploitation of organic waste products. However, minimum complementary mineral input is necessary for optimal fertilisation. Control mineral fertilisation treatments with mulch (MCM) or without mulch (MC) were compared with two organic waste treatments, a pig slurry with mulch (PSM) and without mulch (PS), and a sugarcane vinasse with mulch (SVM) and without mulch (SV) on a Nitisol in French Reunion Island. The sugarcane yields obtained with the different treatments differed each year. However, no trend was observed and no significant and recurrent effect of the presence of mulch or of the different treatments was identified over the course of the 4 year experiment. Soil pHw and pH KCl measured in the different treatments increased from year 3 in with the treatments including organic waste products (PS, PSM, SV and SVM) but remained constant with the treatments including only mineral fertilisation (MC and MCM). With the exception of PS and PSM, which were significantly higher in year 4, soil organic carbon content was not modified by the treatments. Soil cation exchange capacity increased only slightly with the PS and PSM treatments from year 3 on. The differences in yields and soil properties can be explained by the nature of the organic waste products, the accumulation of nutrients after several applications, and the specific characteristics of the sugarcane crop. The improvement in soil properties from the third year on was not reflected in the yield of sugarcane because it was too weak, and the crop explores a much larger volume of soil.

Opportunities and challenges for bioenergy-livestock integrated systems in Brazil

Bioenergy is seen as a key option to meet future energy demands and mitigate climate impacts. However, large-scale deployment of bioenergy can cause an additional pressure over land resources and correspondent sustainability impacts. Enhanced land management practices are fundamental to intensify land-based outputs under different climate mitigation scenarios. Bioenergy-livestock integration (BLI) is a win-win strategy to climate mitigation while ensuring food and fibers demands from the society by using bioenergy by-products as animal feed to release land to additional industrial crops production. This study comparatively assesses BLI opportunities in Brazil to better understand the sustainability issues of the alternatives for integration of these value chains, highlighting the key techno-economic and environmental aspects. When compared to conventional systems, the BLI systems present positive techno-economic impacts and lower greenhouse gas emissions, reaching mitigations up to 32 % and 22 % for meat and ethanol production, respectively. The expansion of BLI systems in Brazil could meet projected biofuels future demands, using less than 20 % of the expected area for this expansion. Potential expansion areas are concentrated in Center-South region of Brazil. BLI systems can be further advanced by including other synergies, such as codigestion of sugarcane vinasse and cattle manure, integration of flex ethanol plants with biodiesel plants, maximization of biofuels by-products as animal feed, and inclusion of novel promising alternative industrial crops such as macauba, sweet sorghum, energy cane and short rotation eucalyptus coppice. However, we identify many potential barriers including the operational complexity, specific know-how, and necessity of economic incentives. This study may provide important insights for strategic and integrated polices for both agricultural and livestock sections as the proper sustainability assessment of an early stage of the deployment of enhanced BLI systems may help to meet global future demands of energy while also contributing to climate change targets.

Biogas production from sugarcane vinasse at mesophilic and thermophilic temperatures by static granular bed reactor (SGBR)

This study aimed to investigate the production of methane from sugarcane vinasse using static granular bed reactors (SGBR) at mesophilic (35 °C) and thermophilic (55 °C) temperatures at three hydraulic retention time (HRT) levels, i.e., 2, 3 and 4 d. The thermophilic system outperformed the mesophilic one. Also, the methane production for HRT of 4 d is higher than two other HRTs (2 and 3 d), so that it is obtained 435 LCH4.kgvs−1. Furthermore, the highest methane production is 2.76 m3CH4.kgCOD-1 in which obtains at the thermophilic temperature and HRT of 4 d. The highest COD reduction is about 39% that achieves at thermophilic temperature and HRT of 4 d. The results show that SGBR systems have potential to be used in vinasse processing, but further research efforts are still required to define suitable operating conditions.

Microbiota profile in mesophilic biodigestion of sugarcane vinasse in batch reactors.

The vinasse is a residue of ethanol production with the potential for methane production, requiring an allochthonous inoculum. Several microorganisms act in the different phases of anaerobic digestion, and the identification of these microbial communities is essential to optimize the process. The characterization of the microbiota involved in the biodigestion of vinasse was observed in the initial stage (IS), at the peak of methane production (MS) and the end of the process (FS) of the best performance assay by high-throughput sequencing. The highest methane production was 0.78 mmolCH4.gVS.h-1 at 243.7 h in the substrate/inoculum ratio of 1.7, with consumption partial of acetic, propionic and isobutyric acids and an 82% reduction of chemical oxygen demand. High microbial diversity was found. The genera Clostridium, Acinetobacter, Candidatus Cloacamonas, Bacteroides, Syntrophomonas, Kosmotoga, the family Porphyromonadaceae and the class Bacteroidia were the most abundant in the maximum methane production. Methane production was driven by Methanobacterium and Methanosaeta, suggesting the metabolic pathways used were hydrogenotrophic and acetoclastic.

Enhanced Biogas Production from Sugarcane Vinasse using Electro-Fenton as Pre-treatment Method

High concentration of organic matter in the sugarcane vinasse is potential as a biogas feedstock, but its a very high organic matter (expressed by chemical oxygen demand (COD), >100,000 mg/L) disturbs the biological activity during anaerobic digestion (AD). The maximum COD concentration in vinasse that is recommended as an initial condition of biogas feedstock is ±75,000 mg/L. Furthermore, complex characteristics of vinasse make it necessary to be pre-treated before it is converted to biogas. Therefore, an advanced oxidation process (AOP) such as electro-Fenton (EF) is applied as a pre-treatment method in the AD of vinasse. The goal of this study was to investigate the effect of pre-treatment of vinasse using the EF method on biogas production. The process of EF was conducted with a variation of voltage (4, 6, 8 V) under the batch system and constant operating conditions such as treatment time, initial pH, the ratio of [H2O2] to [COD], and distance between electrodes. Moreover, the process of AD was run using anaerobic digesters having a volume of 2 L under the batch system at room temperature. The AD was conducted for 40 days. The results showed that the best EF could decrease the COD as much as 81.14% at 4 V with constant operation conditions (treatment time of 60 min, initial pH of 4.34, a ratio of [H2O2] to [COD] of 0.6 and distance electrodes of 3 cm). Furthermore, the pre-treatment of EF increased biogas volume successfully (6.02 L). The applicability of the first-order, second-order, and Behnajady-Modirshahla-Ghanbery (BMG) was investigated to evaluate the removal of the COD value. This primary concern is that the electro-Fenton treatment is favorable to decrease the organic matter of sugarcane vinasse.

Pros and cons of fertirrigation with in natura sugarcane vinasse: Do improvements in soil fertility offset environmental and bioenergy losses?

Managing vinasse in sugarcane biorefineries currently raises a direct debate between traditional industrialists of the sucro-energy sector and researchers. While the first group identifies fertirrigation (land disposal of in natura vinasse) as a well-consolidated approach, the latter understands vinasse as a potential substrate for numerous (bio)technological applications, in addition to associating environmental issues with fertirrigation. This study offers an unbiased assessment of fertirrigation using in natura vinasse by quantifying and qualifying its pros and cons. A comparative analysis using anaerobic digestion (AD) as an alternative management approach was carried out, presenting aspects of organic matter-derived pollution and bioenergy recovery from biogas. Field data obtained in five sugarcane cultivation areas subjected to fertirrigation within the period 2012–2016 revealed the adequate buildup of macronutrients (K+, Ca2+ and Mg2+) associated with high base (51.97–81.38%) and low aluminum (0.22–2.26%) saturation levels without evidences of overfertilization and sodification. However, the inputs of biodegradable organic matter along with nutrients trigger important environmental drawbacks, with emphasis on uncontrolled methane emissions (up to 732.10 kg–CO2–eq ha−1) and polluting potential levels equivalent to that of population densities as high as 293 inhab ha−1. Energy losses in all cultivation areas assessed could provide electricity to process at least 80% of the daily milling capacity of the reference biorefinery. Hence, gains in soil fertility do not offset the losses in environmental quality when land disposing in natura vinasse, and AD seems to be the primary approach to mitigate polluting issues and enhance resource recovery in sugarcane biorefineries.

Bioconversion of sugarcane vinasse into fungal biomass protein and its potential use in fish farming

The intensification of pisciculture operation requires the provision of an adequate supply of good quality fish feed. Many commercial feeds consist in fishmeal or soybean meal-based formulations, but they constitute costly protein sources. Hence, dietary transition from conventional fish ingredients towards fungi protein sources produced from vinasse could address concern about both fish feed cost and the detrimental environmental effects of distillery waste disposal. This work investigated the nutritional and toxicological aspects of Aspergillus sp. V2 grown on vinasse to be used as a possible fish feed. Proximate analysis of biomass obtained from 50% (v/v) residue supplemented with 2.0 g/L (NH4)2H2PO4 revealed a total proteins content (34.0%), fat (4.7%), ash (15.8%), crude fiber (4.0%), moisture (0.3%) and carbohydrate (45.2%) within acceptable levels for commercial fish diets. The biomass protein composition was similar to soybean meal, containing all the essential amino acids (EAAs) for fish feeding. Finally, total aflatoxins level was 6.8 ± 0.2 µg per kg of dry weight, which does not exceed the permissible levels established for feedstuffs. These findings provide evidence that biomass of Aspergillus sp. V2 produced from vinasse could meet the nutritional requirements for use in fish diet, reducing economic pressures for the pisciculture and distilleries.

Counting Enchytraeus crypticusJuveniles in Chronic Exposures: An Alternative Method for Ecotoxicity Studies Using Tropical Artificial Soil.

Soil toxicity tests are commonly applied using Enchytraeus crypticus to analyze reproductive outputs. However, the traditional method for counting potworms takes a long time due to the significant number of offspring. This paper compares the conventional total counting of E. crypticus juveniles (M1) and an alternative methodology (M2). The proposed methodology (M2) uses a simple random counting method (1/4) for the partial counting of juveniles and total estimation. Chronic bioassays (21 days of exposure) were performed in tropical artificial soil (TAS) using sugarcane vinasse as a hazardous substance. Comparing the final density of juveniles recorded in M1 and M2, no statistical differences were pointed out in either one. Applying analyses based on effective concentration (EC10 and EC50), no statistical differences were identified there either. The t-test showed that there was no statistical difference between the counting methods (M1 and M2) in each treatment (control and dilutions). Moreover, we ran the Tukey test for M1 and M2 methods separately and observed that 100 % of the vinasse showed a statistical difference compared to the control treatment in both (p ≤ 0.05), affirming that independent of the counting method, the ecotoxicological outputs were similar. Therefore, the proposed alternative is a suitable method for bioassay using. E. crypticus in tropical artificial soil, decreasing to 1/4 the total time required for counting.

ACHIEVING SUSTAINABLE RICE PRODUCTION WITH THE APPLICATION OF SUGARCANE INDUSTRIAL BY-PRODUCTS

Sugarcane industries generate a variety of by-products, which create disposal and environmental problems. The aim of current study was to find out the ways for utilization of these by-products in rice production. To elucidate this, a field trial was conducted at the research area (30.2°E; 71.5N°) of Bahauddin Zakariya University Multan, Pakistan. The calcareous soil with high pH (8.6) and low organic matter (0.5%) was used with following treatments: no input control (CK), only chemical fertilizer, nitrogen, phosphorus and potassium (NPK; CF), NPK+ Sugarcane Bagasse (SB), NPK+ Press Mud (PM), NPK+ Sugarcane Vinasse (SV), NPK+SB+PM (SB+PM), NPK+SB+SV (SB+SV), NPK+PM+SV (PM+SV), NPK+SB+PM+SV (SB+PM+SV). The results showed that SB significantly increased the plant height (16.3%), panicle length (9.3%), paddy yield (213.1%), and straw yield (189. 9%). Nutrient uptake was also improved, SB enhanced TN (324.6%), while the SB+PM increased the total phosphorus (318.2%), and total potassium (163.7%) contents in grains. Likewise, agronomic nutrient use efficiency was enhanced in SB treatment for N (274.2%), P (81.4%), and K (378.5%). Maximum net profit and benefit-cost ratio was observed in SB (93925 rupees; 0.54), followed by PM (91150; 0.53), SB+PM (85338; 0.51), and minimum was in control (12400; 0.22), respectively. The study concludes, application of organic by-products (SB+PM) can increase rice productivity and farm income with environmental safety.

Dynamics of sulfate reduction in the thermophilic dark fermentation of sugarcane vinasse: A biohydrogen-independent approach targeting enhanced bioenergy production

Dark fermentation (DF) systems usually exploit bioH2 production aiming to improve the energetic potential (EP) of anaerobic digestion (AD) schemes. In the case of sulfate-rich substrates, the versatility of fermentative consortia may favor the establishment of sulfidogenic conditions, minimizing/eliminating the competition between sulfate-reducing bacteria (SRB) and methanogens in the sequential stage and providing sulfide-free biogas. This study details the establishment of sulfidogenesis on the thermophilic DF of sugarcane vinasse in a continuous polyurethane-filled fixed-film reactor, also estimating the EP for vinasses according to different AD-related approaches. High sodium levels naturally stimulated SRB by maintaining high pH values (> 6.0), whilst NaHCO3 dosing was required when natural buffering conditions were not maintained. High acetate (~ 3 g-COD L−1) and COD/sulfate ratio (> 25.0) levels indicated a high-quality substrate for further methanogenesis. High butyrate concentrations (~11 g-COD L−1) coupled to caproate detection indicated the occurrence of chain elongation processes, leading to low bioH2 production levels (<400 NmL-H2 L−1 d−1). However, estimates indicated 12.2%- and 51.7%-increases in the methane-based EP (MJ m−3) of sulfate-free fermented vinasse (216.72) relative to sulfate-rich fermented (193.10) and fresh (142.88) vinasses. Hence, the ultimate approach for maximizing bioenergy production from sugarcane vinasse is detailed in this study.

Haldane-Andrews substrate inhibition kinetics for pilot scale thermophilic anaerobic degradation of sugarcane vinasse

A pilot scale anaerobic degradation of sugarcane vinasse was carried out at various hydraulic retention time (HRT) in the Anaerobic Suspended Growth Closed Bioreactor (ASGCB) under thermophilic temperature. The performance and kinetics were evaluated through the Haldane-Andrews model to investigate the substrate inhibition potential of sugarcane vinasse. All parameters show great performance between HRT 35 and 25 days: chemical oxygen demand (COD) reduction efficiency (81.6 to 86.8%), volatile fatty acids (VFA) reduction efficiency (92.4 to 98.5%), maximum methane yield (70%) and maximum biogas production (19.35 L/day). Furthermore, steady state values from various HRT were obtained in the kinetic evaluation for: rXmax (1.20 /day), Ks (19.95 gCOD/L), Ki (7.00 gCOD/L) and YCH4 (0.33 LCH4/gCOD reduction). This study shows that anaerobic degradation of sugarcane vinasse through ASGCB could perform well at high HRT and provides a low degree of substrate inhibition as compared to existing studies from literature.

Variation of the Prokaryotic and Eukaryotic Communities After Distinct Methods of Thermal Pretreatment of the Inoculum in Hydrogen-Production Reactors from Sugarcane Vinasse.

The aim of this study is to evaluate the effect of different thermal pretreatments of the inoculum on the diversity of the microbial community producing hydrogen from sugarcane vinasse. High-throughput sequencing of the 16S and 18S rRNA genes was performed. The reactor samples were also selected for the isolation of strict anaerobes. Decreased microbial diversity was observed with increasing pretreatment temperatures, with Firmicutes predominating: 90% to 97%. The highest abundance of Staphylococcus (7.9%) was found in pretreatment at 120 °C / 20 min at pH 6. The fungal analysis revealed a high prevalence of Candida (47%), Agaricomycetes, Pezizomycotina and Aspergillus in assays with higher H2 production (90° C / 10 min at pH 6). Three species of Clostridium were isolated: C. bifermentans, C. saccharoperbutylacetonicum and C. saccharobutylicum. The isolates were tested separately and in co-cultures for the production of hydrogen. Hydrogen-producing capacity by co-culture of Clostridium species was increased by 18%. Knowing microorganisms and understanding the interaction between eukaryotes and prokaryotes is essential to obtain strategies for biotransformation of vinasse for the production of bioenergy.

Enhancing secondary metabolite production by Chlorella sorokiniana using an alternative medium with vinasse

Microalgae production is expensive and requires high volumes of water and energy. The use of sugar cane vinasse as an alternative medium, has gained attention for microalgae cultivation. In this study, we compared the biomass yield and secondary metabolite production by Chlorella sorokiniana grown in a commercial medium (Sueoka) and versus those grown in a medium prepared with cane vinasse (0.1%) supplemented with N:P:K (20-5-20 g.L-1). Microalgae reached the maximum growth point 14 days faster in the alternative medium. Increased average phenolic compound levels and flavonoid content were found in the vinasse medium (15.28 ± 0.32 mg GAE.g-1 and 72.30 ± 5.28 mg QE. g-1, respectively) compared to that of the commercial medium (6.02 ± 0.13 mg GAE .g-1 and 13.12 ± 1.33 mg QE g-1, respectively). The maximum antioxidant activity (AOA) of C. sorokiniana grown in vinasse medium was 88.05% with an extract concentration of 1500 µg.mL-1, and an IC50 of 357.7 ± 27.35 µg.mL-1. Different factors, such as stress due to chemical oxygen demand (COD), and vinasse-added ions, may have induced variances in secondary metabolite synthesis. Further investigations are needed to explore natural and low cost alternatives to increasing flavonoid yield for the bioprospection of microalgae.

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.

Underivatized amino acids detection by anion-exchange chromatography coupled to a nanostructured detector

This work reports the development of a fast and reliable amperometric sensor for the detection of amino acids. The detector was constructed using copper nanoparticles (CuNPs) supported on reduced graphene oxide (RGO) modified glassy carbon electrode (CuNPs-RGO/GCE) and based on the application of high performance anion-exchange chromatography with pulsed amperometric detection (HPAEC-PAD). Under optimized isocratic HPAEC-PAD conditions (using 40 mmol L−1 NaOH as mobile phase, flow rate of 0.30 mL min−1 and detection potential of 0.45 V vs. Pd/PdO), the linear dynamic ranges of the concentration of amino acids obtained were 0.50–50 µmol L−1 for lysine, 1.0–100 µmol L−1 for alanine, glycine and serine, and 5.0–100 µmol L−1 for leucine. The limits of detection (S/N = 3) obtained ranged from 0.10 (for lysine and leucine) to 0.50 µmol L−1 (for alanine, glycine and serine) and sensitivity varied from 6.1 (for leucine) to 21.5 nA µmol−1 L (for serine). The average recovery percentages ranged from 97% (for glycine) to 102% (for leucine and serine). The results obtained showed that the CuNPs-RGO/GCE has good long-term stability, repeatability and reproducibility; this makes the device suitable for application as an electrochemical detector. The successful application of the proposed method for the analysis of sugarcane vinasse demonstrates its suitability for separation and determination of amino acids in complex matrices.

Validation by Molecular Dynamics of the Major Components of Sugarcane Vinasse, On a Surface of Calcium Carbonate (Calcite).

There is ongoing interest in the alcohol industry to significantly reduce and/or add value to the liquid residue, vinasse, produced after the distillation and rectification of ethanol from sugar cane. Vinasse contains potassium, glycerol, and a protein component that can cause environmental issues if improperly disposed of. Currently, some industries have optimized their processes to reduce waste, and a significant proportion of vinasse is being considered for use as an additive in other industrial processes. In the manufacture of cement and asphalt, vinasse has been used in the mixtures at low concentrations, albeit with some physical and mechanical problems. This work is the first molecular approximation of the components of the sugar cane vinasse in an industrial context, and it provides atomic details of complex molecular events. In the current study, the major components of sugar cane vinasse, alone or complexed on the surface of calcium carbonate, were modeled and simulated using molecular dynamics. The results showed that the protein component, represented by the mannoprotein Mp1p, has a high affinity for forming hydrogen bonds with potassium and glycerol in the vinasse. Additionally, it provides atomic stability to the calcium carbonate surface, preserving the calcite crystalline structure in the same way potassium ions interact with the carbonate group through ion–dipole interactions to improve the cohesion of the modeled surface. On the contrary, when the glycerol molecule interacts with calcium carbonate using more than two hydrogen bonds, it triggers the breakdown of the crystalline structure of calcite expanding the ionic pair.

Biochemical and phylogenetic characterization of the wastewater tolerant Chlamydomonas biconvexa Embrapa|LBA40 strain cultivated in palm oil mill effluent.

The increasing demand for water, food and energy poses challenges for the world´s sustainability. Tropical palm oil is currently the major source of vegetable oil worldwide with a production that exceeds 55 million tons per year, while generating over 200 million tons of palm oil mill effluent (POME). It could potentially be used as a substrate for production of microalgal biomass though. In this study, the microalgal strain Chlamydomonas biconvexa Embrapa|LBA40, originally isolated from a sugarcane vinasse stabilization pond, was selected among 17 strains tested for growth in POME retrieved from anaerobic ponds of a palm oil industrial plant located within the Amazon rainforest region. During cultivation in POME, C. biconvexa Embrapa|LBA40 biomass productivity reached 190.60 mgDW • L-1 • d-1 using 15L airlift flat plate photobioreactors. Carbohydrates comprised the major fraction of algal biomass (31.96%), while the lipidic fraction reached up to 11.3% of dry mass. Reductions of 99% in ammonium and nitrite, as well as 98% reduction in phosphate present in POME were detected after 5 days of algal cultivation. This suggests that the aerobic pond stage, usually used in palm oil industrial plants to reduce POME inorganic load, could be substituted by high rate photobioreactors, significantly reducing the time and area requirements for wastewater treatment. In addition, the complete mitochondrial genome of C. biconvexa Embrapa|LBA40 strain was sequenced, revealing a compact mitogenome, with 15.98 kb in size, a total of 14 genes, of which 9 are protein coding genes. Phylogenetic analysis confirmed the strain taxonomic status within the Chlamydomonas genus, opening up opportunities for future genetic modification and molecular breeding programs in these species.

Effect of sugar industrial wastes on sweet potato (Ipomoea batatas L.) yield and roots quality

Two field experiments were conducted at a private farm in Malawi city, El-Minya, Egypt during two successive seasons of 2018 and 2019 respectively, to study the effect of organic, inorganic and its combination fertilizers on sweet potato yield and quality in a sandy clay loam soil, Treatments were (T1) 100% of inorganic fertilizer (NPK at mineral form), (T2) 100% organic fertilizer (sugarcane bagasse ash plus sugarcane vinasse), (T3) 75% organic fertilizer + 25% inorganic, (T4) 50% organic fertilizer + 50% inorganic, (T5) 25% organic fertilizer + 75% inorganic. A random complete block design (RCBD) with three replications was used. The data showed a high response to the full dose of organic fertilization treatments (5 ton /feddan of sugarcane bagasse ash plus 80 L /feddan of sugarcane vinasse (feddan = 4200 m² = 0.420 hectares = 1.037 acres)) at all vegetative growth and tuberous roots yield and quality. Meanwhile, the lowest values of sweet potato characters were obtained with full dose of inorganic fertilizers (NPK).

Full-Scale Application of Up-flow High Rate Anaerobic Reactor with Substrate Modification and Effluent Recirculation for Sugarcane Vinasse Degradation and Biogas Generation

Full-Scale Application of Up-flow High Rate Anaerobic Reactor with Substrate Modification and Effluent Recirculation for Sugarcane Vinasse Degradation and Biogas Generation

Sugarcane vinasse extreme thermophilic digestion: a glimpse on biogas free management.

The high temperature in which sugarcane vinasse (SV) is generated (~ 90°C) and the positive effect of higher temperatures in biochemical reactions have motivated the evaluation of SV anaerobic digestion (AD) under extreme temperature conditions. Two-stage (acidogenic/methanogenic) and single-stage (methanogenic) AD of SV were evaluated under 70°C in structured-bed reactors. The extreme temperature was beneficial to the acidogenic step of the two-stage AD process. The methane production, however, was hindered at 70°C. The VMP of the single and two-stage reactors accounted, respectively, for only 13% and 7% of the production rate reported in sugarcane vinasse AD at 55°C. At 70°C, the main genera responsible for methane production was Methanothermobacter and the acetoclastic methanogenesis did not occur, resulting in acetic acid build up (15,800mgL-1). These results brought a new perspective for sugarcane vinasse management, with acetic acid production alternatively to methanization. In this perspective, two-stage process would be composed of acidogenic and acetogenic reactors, and beyond acetate, hydrogen and other soluble compounds could be recovered in a complete biorefinery process.