Hydrodynamic cavitation-assisted acid pretreatment and fed-batch simultaneous saccharification and co-fermentation for ethanol production from sugarcane bagasse using immobilized cells of Scheffersomyces parashehatae.

A new alternative for hydrodynamic cavitation-assisted pretreatment of sugarcane bagasse was proposed, along with a simultaneous saccharification and co-fermentation (SSCF) process performed in interconnected columns. Influential variables in the pretreatment were evaluated using a statistical design, indicating that an ozone flow rate of 10 mg min-1 and a pH of 5.10 resulted in 86 % and 72 % glucan and xylan hydrolysis yields, respectively, in the subsequent enzymatic hydrolysis process. Under these optimized conditions, iron sulfate (15 mg L-1) was added to assess Fenton pretreatment, resulting in glucan and xylan hydrolysis yields of 92 % and 71 %, respectively, in a material pretreated for 10 min. In SSCF, ethanol volumetric productivities of 0.33 g L-1 h-1 and of 0.54 g L-1 h-1 were obtained in batch and fed-batch operation modes, achieving 26 g L-1 of ethanol in 48 h in the latter mode.

Simultaneous hydrodynamic cavitation and glow plasma discharge for the degradation of metronidazole in drinking water.

In this study, a novel hydrodynamic cavitation unit combined with a glow plasma discharge system (HC-GPD) was proposed for the degradation of pharmaceutical compounds in drinking water. Metronidazole (MNZ), a commonly used broad-spectrum antibiotic, was selected to demonstrate the potential of the proposed system. Cavitation bubbles generated by hydrodynamic cavitation (HC) can provide a pathway for charge conduction during glow plasma discharge (GPD). The synergistic effect between HC and GPD promotes the production of hydroxyl radicals, emission of UV light, and shock waves for MNZ degradation. Sonochemical dosimetry provided information on the enhanced formation of hydroxyl radicals during glow plasma discharge compared to hydrodynamic cavitation alone. Experimental results showed a MNZ degradation of 14% in 15 min for the HC alone (solution initially containing 300 × 10-6 mol L-1 MNZ). In experiments with the HC-GPD system, MNZ degradation of 90% in 15 min was detected. No significant differences were observed in MNZ degradation in acidic and alkaline solutions. MNZ degradation was also studied in the presence of inorganic anions. Experimental results showed that the system is suitable for the treatment of solutions with conductivity up to 1500 × 10-6 S cm-1. The results of sonochemical dosimetry showed the formation of oxidant species of 0.15 × 10-3 mol H2O2 L-1 in the HC system after 15 min. For the HC-GPD system, the concentration of oxidant species after 15 min reached 13 × 10-3 molH2O2L-1. Based on these results, the potential of combining HC and GPD systems for water treatment was demonstrated. The present work provided useful information on the synergistic effect between hydrodynamic cavitation and glow plasma discharge and their application for the degradation of antibiotics in drinking water.

Evaluation of a hydrodynamic cavitation-type bubble generator in a prototype bench-scale flotation unit for poultry processing wastewater treatment.

Dissolved Air Flotation (DAF) systems are designed to remove oil and grease (O&G) and total suspended solids (TSS) in wastewater treatment. These systems require saturation tanks, water pumps, and high-pressure compressors to control the pressure, hydraulic retention time, and airflow parameters. DAF process efficiency depends on complex operational controls associated with these components, and the most critical aspect of an effectively operating DAF unit is a generated bubble size. This work presents the design and operational test of a flotation unit prototype that replaces the saturation tank and high-pressure compressors present in DAF with the CARMIN microbubble injector, the evaluation of the proposed system's TSS and O&G removal efficiency was carried out considering different initial configurations of the injector to change the generated microbubble size, four synthetic wastewater solutions, and poly aluminum chloride as a flocculant to establish the potential of this system for the poultry processing wastewater treatment. Mean microbubble size results were obtained from 47.41 µm to 116.17 µm. The average removal efficiency of TSS exceeded 65% under a high concentration of suspended particles (1,560 mg/l) and 80% under a lower TSS concentration (795 mg/l). Meanwhile, 70% and 90% of O&G were removed from high (400 mg/l) and low (100 mg/l) initial O&G concentrations, respectively. These removal levels are similar to those reported in the literature for DAF for poultry processing wastewater, albeit with a simple configuration and better controllability and scalability.

Intensification of Red-G dye degradation used in the dyeing of alpaca wool by advanced oxidation processes assisted by hydrodynamic cavitation.

Red-G dye is one of the main dyes used in the textile industry to dye alpaca wool. Therefore, considering the large volume of processed wool in Perú, the development of efficient technologies for its removal is a present scientific issue. In this study, an integrated system based on hydrodynamic cavitation (HC) and photo-Fenton process was evaluated to remove the Red-G dye. Using a hybrid cavitation device (venturi + orifice plate), the effect of pH was evaluated, achieving 21 % of removal at pH 2 which was more than 80 % higher compared to pH 4 and 6. The effect of temperature was also evaluated in HC-system at pH 2, where percentage of dye degradation increased at lower temperatures (around 20 °C). Then, 50.7 % of dye was removed under optimized condition of HC-assisted Fenton process (FeSO4:H2O2 of 1:30), that value was improved strongly by UV-light incorporation in the HC-system, increasing to 99 % removal efficiency with respect to HC-assisted Fenton process and reducing the time to 15 min. Finally, the developed cavitation device in combination with photo-Fenton process removed efficiently the dye and thus could be considered an interesting option for application to real wastewater.

Landfill leachate treatment using hydrodynamic cavitation: exploratory evaluation.

Hydrodynamic cavitation is a new technology used for the treatment of wastewater. Landfill leachates contain a large variety of organic pollutants and inorganic matter, with recalcitrant and bio-refractory compounds. The present study was designed to evaluate the effect of hydrodynamic cavitation on landfill leachate quality indices. Three experimental designs were proposed. First, the influence of collection climate on leachate quality characteristics was analyzed. Second, the best cavitation time was chosen, which promoted the greatest reduction in the effluent pollutant load. Finally, the hydrogen peroxide (H2O2) concentration was evaluated as an adjuvant in the cavitation process. A model TEKMASH TEK-1SL equipment was used. This cavitation unit operated with a flow rate of 30 m3 h-1, a temperature of 75 °C, and an inlet pressure of 3 bar. The cavitation chamber was of the annular flow type. The statistical analyses were run through ANOVA and Tukey's test, with significance α = 0.05. The response variables for the factors were biochemical oxygen demand (BOD5), chemical oxygen demand (COD), total organic carbon (TOC) and total suspended solids (TSS). An influence of the climatic condition on the leachate quality parameters was found, and the difference was marked in COD. In all cases, both for the cavitation process and for the cavitation-oxidant scheme, there was a reduction of 23%-51% BOD5, 30%-53% COD, 12%-21% TOC and 100% removal in TSS. In a 30-minute treatment, the highest COD removal percentage was reached, corresponding to 53.20%. Furthermore, a 200 ppm concentration of hydrogen peroxide enhanced the reduction of BOD5 and COD with proportions of 51.55% and 38.21%, respectively. Hydrodynamic cavitation offers advantages in the treatment of wastewater and can be used as an independent technique or as a hybrid method.

A review on recent developments in hydrodynamic cavitation and advanced oxidative processes for pretreatment of lignocellulosic materials.

Environmental problems due to utilization of fossil-derived materials for energy and chemical generation has prompted the use of renewable alternative sources, such as lignocellulose biomass (LB). Indeed, the production of biomolecules and biofuels from LB is among the most important current research topics aiming to development a sustainable bioeconomy. Yet, the industrial use of LB is limited by the recalcitrance of biomass, which impairs the hydrolysis of the carbohydrate fractions. Hydrodynamic cavitation (HC) and Advanced Oxidative Processes (AOPs) has been proposed as innovative pretreatment strategies aiming to reduce process time and chemical inputs. Therefore, the underlying mechanisms, procedural strategies, influence on biomass structure, and research gaps were critically discussed in this review. The performed discussion can contribute to future developments, giving a wide overview of the main involved aspects.

Hydrodynamic cavitation for lignocellulosic biomass pretreatment: a review of recent developments and future perspectives.

The hydrodynamic cavitation comes out as a promising route to lignocellulosic biomass pretreatment releasing huge amounts of energy and inducing physical and chemical transformations, which favor lignin-carbohydrate matrix disruption. The hydrodynamic cavitation process combined with other pretreatment processes has shown an attractive alternative with high pretreatment efficiency, low energy consumption, and easy setup for large-scale applications compared to conventional pretreatment methods. This present review includes an overview of this promising technology and a detailed discussion on the process of parameters that affect the phenomena and future perspectives of development of this area.

Hydrodynamic cavitation as a strategy to enhance the efficiency of lignocellulosic biomass pretreatment.

Hydrodynamic cavitation (HC) is a process technology with potential for application in different areas including environmental, food processing, and biofuels production. Although HC is an undesirable phenomenon for hydraulic equipment, the net energy released during this process is enough to accelerate certain chemical reactions. The application of cavitation energy to enhance the efficiency of lignocellulosic biomass pretreatment is an interesting strategy proposed for integration in biorefineries for the production of bio-based products. Moreover, the use of an HC-assisted process was demonstrated as an attractive alternative when compared to other conventional pretreatment technologies. This is not only due to high pretreatment efficiency resulting in high enzymatic digestibility of carbohydrate fraction, but also, by its high energy efficiency, simple configuration, and construction of systems, besides the possibility of using on the large scale. This paper gives an overview regarding HC technology and its potential for application on the pretreatment of lignocellulosic biomass. The parameters affecting this process and the perspectives for future developments in this area are also presented and discussed.

Pilot scale intensification of rubber seed (Hevea brasiliensis) oil via chemical interesterification using hydrodynamic cavitation technology.

Chemical interesterification of rubber seed oil has been investigated for four different designed orifice devices in a pilot scale hydrodynamic cavitation (HC) system. Upstream pressure within 1-3.5bar induced cavities to intensify the process. An optimal orifice plate geometry was considered as plate with 1mm dia hole having 21 holes at 3bar inlet pressure. The optimisation results of interesterification were revealed by response surface methodology; methyl acetate to oil molar ratio of 14:1, catalyst amount of 0.75wt.% and reaction time of 20min at 50°C. HC is compared to mechanical stirring (MS) at optimised values. The reaction rate constant and the frequency factor of HC were 3.4-fold shorter and 3.2-fold higher than MS. The interesterified product was characterised by following EN 14214 and ASTM D 6751 international standards.

Hydrodynamic cavitation-assisted alkaline pretreatment as a new approach for sugarcane bagasse biorefineries.

Hydrodynamic cavitation (HC) was employed in order to improve the efficiency of alkaline pretreatment of sugarcane bagasse (SCB). Response surface methodology (RSM) was used to optimize pretreatment parameters: NaOH concentration (0.1-0.5M), solid/liquid ratio (S/L, 3-10%) and HC time (15-45min), in terms of glucan content, lignin removal and enzymatic digestibility. Under an optimal HC condition (0.48M of NaOH, 4.27% of S/L ratio and 44.48min), 52.1% of glucan content, 60.4% of lignin removal and 97.2% of enzymatic digestibility were achieved. Moreover, enzymatic hydrolysis of the pretreated SCB resulted in a yield 82% and 30% higher than the untreated and alkaline-treated controls, respectively. HC was found to be a potent and promising approach to pretreat lignocellulosic biomass.

Optimisation on pretreatment of rubber seed (Hevea brasiliensis) oil via esterification reaction in a hydrodynamic cavitation reactor.

Pretreatment of the high free fatty acid rubber seed oil (RSO) via esterification reaction has been investigated by using a pilot scale hydrodynamic cavitation (HC) reactor. Four newly designed orifice plate geometries are studied. Cavities are induced by assisted double diaphragm pump in the range of 1-3.5 bar inlet pressure. An optimised plate with 21 holes of 1mm diameter and inlet pressure of 3 bar resulted in RSO acid value reduction from 72.36 to 2.64 mg KOH/g within 30 min of reaction time. Reaction parameters have been optimised by using response surface methodology and found as methanol to oil ratio of 6:1, catalyst concentration of 8 wt%, reaction time of 30 min and reaction temperature of 55°C. The reaction time and esterified efficiency of HC was three fold shorter and four fold higher than mechanical stirring. This makes the HC process more environmental friendly.

O uso da cavitação hidrodinâmica aplicado ao tratamento de água / Use of the cavitation hydrodynamics applied to water treatment

A cavitação hidrodinâmica se apresenta como um processo oxidativo avançado (POA), permitindo integrar-se aos processos de tratamento de água para consumo humano. Esta pesquisa teve como objetivo investigar os efeitos de diferentes reatores de cavitação hidrodinâmica para tratar água contaminada com esgoto doméstico, avaliando a contaminação microbiológica e os parâmetros físico-químicos. Foram construídos três modelos de reatores com diferentes rotores (R1, R2 e R3). Os resultados obtidos nos reatores R1, R2 e R3 mostraram redução nas concentrações dos parâmetros químicos em todas as amostras, particularmente nitritos, nitratos, bicarbonatos e dureza total, ao passo que a contaminação microbiológica teve inativação completa dos microrganismos estudados (coliformes totais e Escherichia coli).

The hydrodynamic cavitation is presented as an advanced oxidation process (AOP), allowing to integrate the processes of water treatment for human consumption. This research aimed to investigate the effects of different hydrodynamic cavitation reactors for treating water contaminated with sewage, evaluating the microbiological contamination and physicochemical parameters. Three models were constructed with different rotors reactors (R1, R2 and R3). The results obtained in the reactors R1, R2 and R3 have shown a reduction in the concentrations of chemical parameters in all samples, particularly nitrites, nitrates, bicarbonates, and total hardness, while the microbiological contamination was completely inactivation (total coliforms and Escherichia coli).