Efficiency of physicochemical and biological treatments of vinasse and their influence on indigenous microbiota for disposal into the environment

Comparative study of depotash vinasse and molasses as binder and production performance in lactating Murrah buffaloes

Dairy sector has recently focused a lot of attention on the addition of agricultural by-products as functional feed additives as an environmentally friendly and sustainable technology. Depotash vinasse (DPV) serves as a cheap source of nutrients and a binder for animal feed in dairy sector. However, there is little information available on the usage of depotash vinasse on animals. Therefore, the aim of the present study was to assess the role of depotash vinasse as pellet binder on nutrient digestibility, blood parameters and milk production in early lactating Murrah buffaloes. Fifteen Murrah buffaloes (daily milk yield 8.5 to 9.0 kg/day) were randomly assigned to three groups, viz., control, group 1 (G1) and group 2 (G2) on the basis of milk yield and days in milk. The control group animals received a basal diet of concentrate mix, oat greens and wheat straw, G1 animals received molasses as a binder (8%), while G2 received DPV as binder (8%). Results revealed that there was no significant effect on nutrient digestibility. Blood parameters and hepatic enzymes were statistically similar (P > 0.05). Supplementation of depotash vinasse as binder had no effect on plasma minerals and was comparable to control group. There were no changes in milk production and 6% fat-corrected milk yield in treated groups as compared to control. It was concluded that depotash vinasse (8%) may be used for pellet production with no negative impact on milk yield and composition, nutrient digestibility and blood biochemical parameters in early lactating buffaloes.

Distinct gut bacterial composition in Anoplophora glabripennis reared on two host plants

Anoplophora glabripennis (Coleoptera: Cerambycidae: Lamiinae) is an invasive wood borer pest that has caused considerable damage to forests. Gut bacteria are of great importance in the biology and ecology of herbivores, especially in growth and adaptation; however, change in the gut bacterial community of this pest feeding on different hosts is largely unknown. In this study, we investigated the gut bacterial communities of A. glabripennis larvae fed on different preferred hosts, Salix matsudana and Ulmus pumila, using 16S rDNA high-throughput sequencing technology. A total of 15 phyla, 25 classes, 65 orders, 114 families, 188 genera, and 170 species were annotated in the gut of A. glabripennis larvae fed on S. matsudana or U. pumila using a 97% similarity cutoff level. The dominant phyla were Firmicutes and Proteobacteria and the core dominant genera were Enterococcus, Gibbsiella, Citrobacter, Enterobacter, and Klebsiella. There was significantly higher alpha diversity in the U. pumila group than in the S. matsudana group, and principal co-ordinate analysis showed significant differences in gut bacterial communities between the two groups. The genera with significant abundance differences between the two groups were Gibbsiella, Enterobacter, Leuconostoc, Rhodobacter, TM7a, norank, Rhodobacter, and Aurantisolimonas, indicating that the abundance of larval gut bacteria was affected by feeding on different hosts. Further network diagrams showed that the complexity of the network structure and the modularity were higher in the U. pumila group than in the S. matsudana group, suggesting more diverse gut bacteria in the U. pumila group. The dominant role of most gut microbiota was related to fermentation and chemoheterotrophy, and specific OTUs positively correlated with different functions were reported. Our study provides an essential resource for the gut bacteria functional study of A. glabripennis associated with host diet.

Biohydrogen Producing Facultative Anaerobic Bacteria from Different Anaerobic Sludge

This study aims to isolate and characterize efficient biohydrogen generating facultative anaerobic bacteria from various samples, viz., biogas plant (BGP), municipal sewage (MS), and dairy industry treatment plant (DTP). The physicochemical properties of various untreated anaerobic sludge samples reflect the anoxic state and appropriateness of the substrate for separating biohydrogen generating bacteria. The biohydrogen producing bacterial strains were separated from methanogens using the heat-treatment method. The facultative anaerobic bacterial load of heat-treated test samples was determined viz., 27.2±0.57×106 (BGP), 21.8±0.43×106 (MS), and 18.6±0.92×106 (DTP) CFU mL-1 (Colony forming unit), which decreased from the total anaerobic bacterial load of untreated anaerobic sludge viz., 32.1±0.28×106 (BGP), 42.2±0.16×106 (MS), and 34.7±0.12×106 (DTP) CFU mL-1. The 28 predominant bacterial isolates strains were isolated from the heat-treated test samples. All 28 bacterial strains were identified using microscopic and biochemical techniques. Biohydrogen producing potential bacterial strains were screened using the Hungate technique with glucose as a carbon source. Among them, 12 strains were capable of producing biohydrogen, among these 5 strains being excellent biohydrogen producers. Based on the16s rRNA molecular sequencing, the 5 selected biohydrogen generating organisms were authenticated as viz., Salmonella bongori (MZ636759), Escherichia coli (MZ636716), Staphylococcus hominis (MZ636713), Yersinia enterocolitica (OM009292), and Shewanella oneidensis (MZ636800). The gas composition study by GC-TCD in a fermentative medium shows that Shewanella oneidensis (MZ636800) could produce the best biohydrogen (111.4±8.3 mLH2/L), followed by Salmonella bongori (MZ636759) with 98.1±2.9 mL H2/L and Escherichia coli (MZ636716) with 86.7±6.2 mLH2/L.

Sugarcane vinasse as organo-mineral fertilizers feedstock: Opportunities and environmental risks

Fertigation using sugarcane vinasse is expected in the sugar and alcohol industries; however, its indiscriminate practice can trigger soil salinization and contamination of water sources. This review article appraises the vinasse use as a precursor material in producing organo-mineral fertilizers. Vinasse use could be an alternative for the increased demand for organo-mineral fertilizers. In that case, the vinasse reuse would be maintained but through controlled practices and lower environmental impact. The state-of-art points to possible advantages associated with the vinasse conversion into organo-mineral fertilizers, such as ease of transport and handling, low variability in its composition, and lower risks of soil and water resources contamination. It has been summarized and critically discussed the past ten years (2011-2021, total number papers revised: 175) of research data about vinasse composition, along with the limitations to be overcome in the near future to enable the application of organo-mineral fertilizers. Possible nutrients supplementation beyond those already present in vinasse composition would depend on the crop requirement, and the impact on the soil biota and integrity should be better understood. The aspects discussed along the manuscript would be aligned with circular economy principles, converting a residue (vinasse) into a potential resource for agricultural activities, including sugar and alcohol industries. After all, although promising, obtaining organo-mineral fertilizers from vinasse must be empirically validated and its feasibility proven by comparative studies between fertigation and the use of organo-mineral fertilizers.

A bioreactor and nutrient balancing approach for the conversion of solid organic fertilizers to liquid nitrate-rich fertilizers: Mineralization and nitrification performance complemented with economic aspects

Due to the high water- and nutrient-use efficiency, hydroponic cultivation is increasingly vital in progressing to environment-friendly food production. To further alleviate the environmental impacts of synthetic fertilizer production, the use of recovered nutrients should be encouraged in horticulture and agriculture at large. Solid organic fertilizers can largely contribute to this, yet their physical and chemical nature impedes application in hydroponics. This study proposes a bioreactor for mineralization and nitrification followed by a supplementation step for limiting macronutrients to produce nitrate-based solutions from solid fertilizers, here based on a novel microbial fertilizer. Batch tests showed that aerobic conversions at 35 °C could realize a nitrate (NO₃^--N) production efficiency above 90% and a maximum rate of 59 mg N L^-1 d^-1. In the subsequent bioreactor test, nitrate production efficiencies were lower (44-51%), yet rates were higher (175-212 mg N L^-1 d^-1). Calcium and magnesium hydroxide were compared to control the bioreactor pH at 6.0 ± 0.2, while also providing macronutrients for plant production. A mass balance estimation to mimic the Hoagland nutrient solution showed that 92.7% of the NO₃^--N in the Ca(OH)₂ scenario could be organically sourced, while this was only 37.4% in the Mg(OH)₂ scenario. Besides, carbon dioxide (CO₂) generated in the bioreactor can be used for greenhouse carbon fertilization to save operational expenditure (OPEX). An estimation of the total OPEX showed that the production of a nutrient solution from solid organic fertilizers can be cost competitive compared to using commercially available liquid inorganic fertilizer solutions.

Regulation of Hydrogen Peroxide Dosage in a Heterogeneous Photo-Fenton Process

In this work, a classical linear control approach for the peroxide (H2O2) dosage in a photo-Fenton process is presented as a suitable solution for improving the efficiency in the treatment of recalcitrant organic compounds that cannot be degraded by classical wastewater treatment processes like anaerobic digestion. Experiments were carried out to degrade Lignin, Melanoidin, and Gallic acid, which are typical recalcitrant organic compounds present in some kinds of effluents such as vinasses from the Tequila and Cachaça industries. Experiments were carried in Open-Loop mode for obtaining the degradation model for the three compounds in the form of a Transfer Function, and in Closed-Loop mode for controlling the concentration of each compound. First-order Transfer Functions were obtained using the reaction curve method, and then, based on these models, the parameters of Proportional Integral controllers were calculated using the direct synthesis method. In the Closed-Loop experiments, the Total Organic Carbon removal was 39% for lignin, 7% for melanoidin, and 29% for Gallic acid, which were greater than those obtained in the Open-Loop experiments.

Efficacy of polyextremophilic Aeribacillus pallidus on bioprocessing of beet vinasse derived from ethanol industries

This work aimed to evaluate the applicability of Aeribacillus pallidus for the aerobic treatment of the concentrated beet vinasse with high chemical oxygen demand (COD 685 g.L^-1) that is defined as an environmental pollutant. This bacterium is a polyextremophilic strain and grow aerobically up to 7.5% vinasse at high temperature (50 °C). In the bioreactor and under controlled conditions, A. pallidus reduced the soluble COD content of 5% vinasse up to 27% during 48 h and utilized glucose and glycerol, completely. Furthermore, a reduction of manganese, copper, aluminum, and nickel concentrations was observed in the treated vinasse with A. pallidus. The obtained results make this strain as an appropriate alternative to be used for the aerobic bioprocessing of the vinasse.

Sequential degradation of raw vinasse by a laccase enzyme producing fungus Pleurotus sajor-caju and its ATPS purification

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Vinasse degradation and laccase production by Pleurotus sajor-caju were performed;

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Laccase activity induction by copper sulfate and ethanol in raw vinasse as substrate was confirmed;

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Fermentation time to maximum laccase activity was reduced to just 3 days when cooper sulfate was used as inducer;

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The use of laccase inducers does not interfere with decolorization and turbidity removal;

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Aqueous two-phase systems reached 2.88-fold in laccase purification, with recovery of ∼ 99.9% to upper phase (PEG-rich phase).

This study evaluated simultaneously the raw vinasse degradation, an effluent from the sugar-alcohol industry, the laccase production by Pleurotus sajor-caju and its purification using aqueous two-phase systems (ATPS). To improve laccase production, different concentrations of inducers (ethanol and CuSO₄) were added. The higher laccase production promoted an increase of 4-fold using 0.4 mM of CuSO₄ as inducer, with maximum enzymatic activity of 539.3 U/L on the 3^rd day of fermentation. The final treated vinasse had a decolorization of 92% and turbidity removal of 99% using CuSO₄. Moreover, the produced laccase was then purified by ATPS in a single purification step, reaching 2.9-fold and recovered ≈ 99,9 %, in the top phase (PEG-rich phase) using 12 wt% of PEG 1500 + 20 wt% of citrate buffer + enzyme broth + water, at 25 °C. Thus, an integrated process of vinasse degradation, laccase production and purification with potential industrial application was proposed.

Effect of pH and temperature on vinasse decolorization by lactic acid bacteria in batch processes

The waste-free policy is part of the process of sugar production from beets in which the resulting molasses are used for ethanol production. However, during this process another byproduct, namely vinasse, is created. Therefore, there is a problem with the utilization of wastewater, which cannot be disposed to the environment without being treated. Melanoidins, caramels, and hexoses alkaline degradation products contained in the vinasse give it a dark brown color. The aim of the study was to investigate the effect of the pH and the temperature on the decolorization of vinasse by lactic acid bacteria (Lactobacillus plantarum, L. casei, and Pediococcus parvulus). Experiments were performed in batch mode in a BioStatB bioreactor for 72 hrs. The medium consisted of 25% v/v sugar beet molasses vinasse, 77.34 gdm^-3 of glucose, and 2.24 gdm^-3 of yeast extract. The maximum decolorization was 25.14% and was achieved at noncontrolled pH 6.5 and at 30°C. PRACTITIONER POINTS: Lactobacillus plantarum, L. casei and Pediococcus parvulus showed potential for decolorization of sugar beet molasses vinasse. Controlled pH has a negative effect on sugar beet molasses vinasse decolorization. Toxic substances, i.e. acrylamide, 4-methylimidazole , 5-hydroxymethylfurfural and furfural after decolorization was not detected. Bacteria showed high degradation potential of 2-acetyl-4-(1,2,3,4)-tetrahydroxy-butylimidazole.

Application of microbial fuel cell technology for vinasse treatment and bioelectricity generation

OBJECTIVE

Our study evaluated the performance of different two-chambered microbial fuel cell (MFC) prototypes, operated with variable distance between electrodes and Nafion membrane and specific inoculum concentration, applied for vinasse treatment.

RESULTS

The performance of the developed MFC resulted in a maximum current density of 1200 mA m^-2 and power density of 800 mW m^-2 in a period of 61 days. MFC performed a chemical oxygen demand removal at a rate ranging from 51 to 60%.

CONCLUSIONS

Taking our preliminary results into consideration, we concluded that the MFC technology presents itself as highly promising for the treatment of vinasse.

Investigating the efficiency of co-composting and vermicomposting of vinasse with the mixture of cow manure wastes, bagasse, and natural zeolite

Fermentation of ethanol as a product of sugarcane agro-industry causes the discharge of large amounts of a liquid waste called vinasse into the environment. In this study, co-composting followed by vermicomposting process of the mixtures of vinasse, cow manure, and chopped bagasse was performed for 60days using earthworms of Eisenia fetida species. The results showed that the trend of changes in C/N was decreasing. The pH of the final fertilizer was in alkaline range (8.1-8.4). The total potassium decreased during the process, ranging from 0.062 to 0.15%, while the total phosphorus increased and its values ranged from 0.06 to 0.10%. The germination index (GI) for all samples was 100%, while the cellular respiration maturity index was<2mg C-CO₂g^-1 organic carbon day^-1, confirming a very stable compost. The results of this study indicate that the compost obtained from the co-composting-vermicomposting process could be used as a sound soil amendment.

Comet assay and micronucleus tests on Oreochromis niloticus (Perciforme: Cichlidae) exposed to raw sugarcane vinasse and to phisicochemical treated vinasse by pH adjustment with lime (CaO)

In Brazil vinasse, a main sugarcane distillery residue, stands out because every liter of alcohol generates 10-15 L of vinasse as waste. An alternative for the disposal of this waste is the fertirrigation of the sugarcane culture itself. However, the high amount released can saturate the soil and through leaching/percolation contaminate water resources. The aim of this study is verifying the toxic potential of vinasse in tilapias and effectiveness of the physicalchemical treatment of this waste with pH adjustment with lime (CaO). The comet assay and the micronucleus test were applied on animals exposed to dilutions of raw vinasse and vinasse adjusted to neutral pH. Bioassays with raw vinasse dilutions indicated a toxic and genotoxic potential; fish exposed to the highest concentration died less than 48 h after the exposure; the incidence of micronucleus was significantly higher when compared to negative control for all dilutions. For the comet assay, the scores of damage were statistically higher for all dilutions, with the exception of the 1% dillution. However, in the bioassay with the chemically treated vinasse (neutral pH), most fish in the 10% dilution survived and there was no significant difference when compared to the control. Damage scores in the comet assay were similar to the results of the untreated vinasse. The chemical treatment of vinasse with lime to neutralize the pH proved to be an effective alternative for the toxicity reduction of this residue, since it reduced the mortality of fish at higher concentrations and the incidence of damage to DNA.

Mixed yeasts inocula for simultaneous production of SCP and treatment of vinasse to reduce soil and fresh water pollution

This study evaluated the use of vinasse as a substrate for microbial biomass production and its disposal impact on the environment. After grown in vinasse, the microbial biomass (SCP) of two Saccharomyces cerevisiae strains, CCMA 0137 and CCMA 0188, showed high levels of essential amino acids (3.78%), varying levels of chemical elements, and low nucleic acid content (2.38%), i. e, good characteristics to food supplemements. Following biological treatment, spent vinasse biochemical oxygen demand (BOD) and chemical oxygen demand (COD) decreased to 51.56 and 29.29%, respectively. Cultivation with S. cerevisiae significantly reduced short term phytotoxicity and toxicity on soil microbiota of spent vinasse.