Bioethanol Wastewater Research Articles

Azolla microphylla and Pseudomonas aeruginosa for bioremediation of bioethanol wastewater

Abstract. Annisa K, Sutarno, Santosa S. 2021. Azolla microphylla and Pseudomonas aeruginosa for bioremediation of bioethanol wastewater. Biodiversitas 22: 1799-1805. Bioremediation is the right choice in wastewater treatment since it requires has low cost but works optimally. Azolla microphylla and Pseudomonas aeruginosa are considered to have the ability to optimize waste degradation. The aim of this study was to determine the best treatment for reducing pollutants in bioethanol waste, namely by using A. microphylla and P. aeruginosa. The twelve treatments in this experimental research included variations in the A. microphylla biomass and variations of biomass combinations with the density of the P. aeruginosa. Research method used was completely randomized design with three replications, and all 36 samples were taken on the seventh day. Research data collected were the quality parameters of bioethanol wastewater before and after the treatment. The results showed that TSS, BOD, COD were decreased during seven days of treatment, whereas pH and H2S levels were increased. The combination of 0.2 kg A. microphylla and 1010 cfu/mL P. aeruginosa showed the best result in reducing pollutants. This study showed that A. microphylla and P. aeruginosa could be used to reduce pollutants in bioethanol wastewater. Results of the research are expected to become an alternative solution to the bioethanol wastewater problem.

Co-generation of liquid biofuels from lignocellulose by integrated biochemical and hydrothermal liquefaction process

Different thermal stability of three major components is a challenge to efficiently liquefy lignocellulosic biomass into bio-oil because the degradation products from holocellulose can react with lignin, resulting in repolymerization reactions. In this work, a biorefinery approach of co-generation of bioethanol and bio-oil from rice straw that integrated separate hydrolysis and fermentation (SHF) and hydrothermal liquefaction (HTL) processes was proposed. SHF of dilute sulfuric acid pretreated rice straw gave a bioethanol concentration of 8.3 g/L with approximately 68% of theoretical yield. The maximum bio-oil yield 31.36 wt% via HTL of solid fermentation residues using bioethanol wastewater as the solvent was obtained under optimum conditions. Mass balance showed that 9.7 wt% bioethanol and 15.0 wt% bio-oil were produced corresponding to 56% energy recovery. Separate conversion of cellulose and lignin could be one promising way to enhance the overall energy recovery from lignocellulose to liquid biofuels.

High strength bioethanol wastewater inoculated with single‐strain or binary consortium feeding air‐cathode microbial fuel cells

Bioethanol industries generate a large volume of high strength wastewater called vinasse. This study compares the performance of microbial fuel cells (MFCs), inoculated with a single‐strain or a binary consortium, to produce bioelectricity while simultaneously reducing the COD levels and removing the vinasse color. The MFCs achieved the power density of 124.0 ±0.2 mW/m2 when inoculated with a strain of Shewanella oneidensis (MFC/So) and 178.0 ±0.8 mW/m2 after inoculation with a strain of Clostridium butyricum (MFC/Cb). However, a better performance in power density was reached by the MFC inoculated with both cultures (MFC/So‐Cb), which produced 205.0 ±0.5 mW/m2. Additionally, the results showed a decrease in the initial COD (36,440 mg/L), as well as a decolorization. Thus, the MFC/So, MFC/Cb, and MFC/So‐Cb caused a reduction in COD by 41.8 ± 2.4%, 20.1 ± 4.4%, and 53.8 ± 5.9%, respectively, and in color by 62 ± 4%, 70 ± 4%, and 58 ± 5%, respectively. These findings demonstrate that high power density can be produced using raw vinasse as a substrate in air‐cathode MFCs. However, the coulombic efficiency was low indicating that the COD conversion into electricity must be improved.Novelty: This work combines fermentative and metal‐reducing bacteria, instead of mixed cultures with unknown microorganisms, to break down complex organics in the vinasse, simultaneously to electricity generation. No studies have been found concerning Shewanella oneidensis and Clostridium butyricum strains for harvesting bioelectricity from bioethanol wastewater. Second, different from early studies, this work uses the real high strength wastewater, without dilution or any pre‐treatment, before MFC process. Third, here we consider the total biomass at the end process to calculate the COD removal rate. Finally, we employed electronic load, never used previously, in MFC polarization measurements. © 2018 American Institute of Chemical Engineers Environ Prog, 38: 380–386, 2019

Characteristics of the products of hydrothermal liquefaction combined with cellulosic bio-ethanol process

The integration utilization of fermentation residues from cellulosic bio-ethanol has attracted a great deal of attention to balance the total cost of bio-ethanol production while simultaneously dealing with bio-ethanol wastewater. A process of hydrothermal liquefaction (HTL) of intact materials from cellulosic bio-ethanol in a batch reactor was proposed. The effects of the reaction temperature and time on the liquefaction characteristics were examined. The optimum condition for liquefaction fermentation residues was 370 °C (21.25 MPa) and 30 min with a bio-oil yield of 40.79 wt%. GC-MS results indicated that the major chemical species in the bio-oil were phenols, ketones, long-chain hydrocarbons and fatty acids. Supercritical conditions (375 °C, 23.50 MPa) was favored for the low-molecular-weight species formation compared to subcritical conditions (370 °C, 21.25 MPa), as some long-chain species decreased. This work thus can provide a novel idea for bio-oil production from HTL of cellulosic bio-ethanol fermentation residues.

Intensified green production of astaxanthin from Haematococcus pluvialis

The objectives of this study were to evaluate bioethanol wastewater streams (thin stillage, process condensate and scrubber/dryer samples) as potential ‘green’ media to culture microalgae Haematococcus pluvialis, and to assess the effectiveness of ultrasound in microalgal cell disruption and astaxanthin extraction. H. pluvialis was cultured in wastewater dilutions (20–80 times) and formulations. Astaxanthin was extracted using ultrasound with cell-disrupting chemicals (acetic acid, citric acid, hydrogen peroxide and sodium hydroxide) and astaxanthin extracting solvents (acetone, ethanol and methanol) at different extraction durations (5–35min). The results demonstrated that 60 times as the optimum dilution factor of thin stillage for microalgal growth, and a formulation known as GroAst media (60% of 60 times diluted thin stillage, and 40% of process condensate) was proposed as the best media for astaxanthin production: 0.634±0.009mg/ml cyst density, a 10.5% improvement over standard media. Astaxanthin extraction using ultrasound intensified the process in terms of short extraction time (25min), less chemical consumption (2M NaOH), usage of GRAS solvent (methanol), high efficiency in cell disruption, high extraction yield (80.6±0.9%), and suitability to extract thermolabile astaxanthin.

Optimization and kinetics of treating cassava bioethanol wastewater with low-grade pyrolusite in sulfuric acid solution

Cassava bioethanol wastewater treatment using low-grade pyrolusite as oxidant in sulfuric acid solution was investigated. In order to obtain the optimal level and optimal combination of factors for high COD (chemical oxygen demand) removal rate of cassava bioethanol wastewater, orthogonal experiment was employed. The results indicated that the COD removal rate which depended more on the H2SO4 concentration, could reach 94.56% under the conditions of H2SO4 concentration of 2.5 mol/L, temperature of 90°C, reaction time of 90 min, and liquid-to-solid ratio of 2 mL/g. A shrinking core model was applied to describe the treating process, and the results revealed that the leaching rate increased with the increase in temperature, concentration of cassava bioethanol wastewater and sulfuric acid. Apparent activation energy for this model was calculated to be 33.05 kJ/mol, the reaction order of H2SO4 concentration was 1.12 and cassava bioethanol wastewater concentration was 0.73. And the kinetics analysis showed that the reaction was controlled by the diffusion through the product layer composed of the associated minerals.

Sugarcane molasses-based bio-ethanol wastewater treatment by two-phase multi-staged up-flow anaerobic sludge blanket (UASB) combination with up-flow UASB and down-flow hanging sponge

This study was designed to evaluate a treatment system for high strength wastewater (vinasse) from a sugarcane molasses-based bio-ethanol plant in Thailand. A laboratory-scale two-phase treatment system composed of a sulfate reducing (SR) tank and multi-staged up-flow anaerobic sludge blanket (MS-UASB) reactor was used as the pre-treatment unit. Conventional UASB and down-flow hanging sponge (DHS) reactors were used as the post-treatment unit. The treatment system was operated for 300 days under ambient temperature conditions (24.6-29.6 °C). The hydraulic retention time (HRT) in each unit was kept at 25 h for the two-phase system and 23 h for the UASB&DHS. The influent concentration was allowed to reach up to 15,000 mg chemical oxygen demand (COD)/L. COD removal efficiency (based on influent COD) of the two-phase MS-UASB and the UASB&DHS was 54.9 and 18.7%, respectively. Due to the effective removal of sulfide in the SR tank, the MS-UASB achieved a high methane conversion ratio of up to 97%. In DHS, nitrification occurred at the outside portion of the sponge media while denitrification occurred at the inside. Consequently, 27% of the total nitrogen (TN) was removed. An amount of 32% of residual nitrogen (28 mgN/L) was in the form of nitrate, a better nitrogen state for fertilizer.

Performance and Microbial Community Analysis of a full-scale Hybrid Anaerobic–Aerobic Membrane System for Treating Molasses-Based Bioethanol Wastewater

We evaluated the efficacy of a full-scale combined biophysicochemical system for treatingmolasses-based bioethanol wastewater in terms of organic substances, nutrient, and dark brown color removal. The main organic removal unit, i.e., the upflow anaerobic sludge blanket (UASB) reactor, achieved 80.7% removal and 4.3 Nm3 methane production per cubic meter of wastewater with a hydraulic retention time of 16.7 h. Downflow hanging sponge (DHS) reactors were important in reducing the biochemical oxygen demand (BOD), and the lowest possible organic waste intake prevented excessive biomass formation. The BOD removal efficiency was 71.2–97.9%. The denitrification upflow anaerobic fixed bed (UFB) reactor achieved 99.2% total nitrogen removal. Post-physicochemical membrane treatment reduced the total phosphate, color, and remaining organic matter by 90.4%, 99.1%, and 99.8%, respectively. We analyzed the microbial diversity of the sludge from the UASB reactors. Methanosaeta was the dominant archaeal genus in the system, followed by Methanolinea, Methanomicrospillum, Caldiserica, Bacteroidetes, and Deltaproteobacteria.

Enhanced Biofuel Production from High-Concentration Bioethanol Wastewater by a Newly Isolated Heterotrophic Microalga, Chlorella vulgaris LAM-Q

Microalgal biofuel production from wastewater has economic and environmental advantages. This article investigates the lipid production from high chemical oxygen demand (COD) bioethanol wastewater without dilution or additional nutrients, using a newly isolated heterotrophic microalga, Chlorella vulgaris LAM-Q. To enhance lipid accumulation, the combined effects of important operational parameters were studied via response surface methodology. The optimal conditions were found to be temperature of 22.8℃, initial pH of 6.7, and inoculum density of 1.2 × 10(8) cells/ml. Under these conditions, the lipid productivity reached 195.96 mg/l/d, which was markedly higher than previously reported values in similar systems. According to the fatty acid composition, the obtained lipids were suitable feedstock for biodiesel production. Meanwhile, 61.40% of COD, 51.24% of total nitrogen, and 58.76% of total phosphorus were removed from the bioethanol wastewater during microalgal growth. In addition, 19.17% of the energy contained in the wastewater was transferred to the microalgal biomass in the fermentation process. These findings suggest that C. vulgaris LAMQ can efficiently produce lipids from high-concentration bioethanol wastewater, and simultaneously performs wastewater treatment.

Lipid production by Rhodosporidium toruloides Y2 in bioethanol wastewater and evaluation of biomass energetic yield

The oleaginous yeast Rhodosporidium toruloides Y2 was employed to remove waste nutrients from bioethanol wastewater while simultaneously producing biomass enriched in microbial lipids. Under optimal conditions, the COD degradation ratio, biomass and lipid content reached 72.3%, 3.8g/l and 34.9%, respectively. For accelerating biomass and lipid accumulation, different feeding strategies of substrate were conducted. The biomass and lipid production increased by 39.5% and 53.8%, respectively, when glucose at 1.2g/(ld) was added during the last three days of the cultivation. An equation was established to estimate biomass energetic yield. Under optimal conditions, the biomass energetic yield was 50.9% and an increase of 26.0% was obtained by feeding glucose at 1.2g/(ld) during the last three days. The fatty acid composition of the lipids was similar to that from plant oils and other microbial lipids, and could thus be used as raw material for feed additives and biodiesel production.

Performance and Spatial Succession of a Full-Scale Anaerobic Plant Treating High-Concentration Cassava Bioethanol Wastewater

A novel two-phase anaerobic treatment technology was developed to treat high-concentration organic cassava bioethanol wastewater. The start-up process and contribution of organics (COD, total nitrogen, and NH4 +-N) removal in spatial succession of the whole process and spatial microbial diversity changing when sampling were analyzed. The results of the start-up phase showed that the organic loading rate could reach up to 10 kg COD/m(3)d, with the COD removal rate remaining over 90% after 25 days. The sample results indicated that the contribution of COD removal in the pre-anaerobic and anaerobic phases was 40% and 60%, respectively, with the highest efficiency of 98.5%; TN and NH4 +-N had decreased to 0.05 g/l and 0.90 g/l, respectively, and the mineralization rate of total nitrogen was 94.8%, 76.56% of which was attributed to the anaerobic part. The microbial diversity changed remarkably among different sample points depending on the physiological characteristics of identified strains. Moraxellaceae, Planococcaceae, and Prevotellaceae were dominant in the pre-anaerobic phase and Bacteroidetes, Campylobacterales, Acinetobacter, Lactobacillus, Clostridium, and Bacillus for the anaerobic phase. Methanosarcinaceae and Methanosaeta were the two main phylotypes in the anaerobic reactor.