Orthogonal Central Composite Design Research Articles

Parameter Optimization of a Conveying and Separating Device Based on a Five-Stage Screw and Vibrating Screen for Tiger Nut Harvesters

To tackle problems such as the difficult separation from sand and the high power consumption of tiger nut harvesting in the sandy areas of Xinjiang, a conveying and separating device for tiger nut harvesters was designed. The axial and radial migrations of materials under screw action and the separation process of materials under vibratory action were analyzed dynamically. A simulation analysis was carried out on the conveying and separating process based on EDEM software. The migration trajectories of tiger nuts and sand particles were extracted, the displacement variations of sand particles on the X-axis, Y-axis, and Z-axis were analyzed in the action area of the screen-cleaning spike teeth and the screw action area, respectively, and the conveying and separation law of the tiger nut harvest mixture was clarified. With key parameters such as the screw velocity ratio, amplitude, vibration frequency, and machine operation velocity as test factors, and with the sand removal rate, crushing rate, and power consumption as test evaluation indicators, a four-factor, five-level orthogonal central composite test design was implemented. The test results were analyzed via the regression variance analysis method, and relation models between variable factors and evaluation indicators were constructed. The test results show that under the combined conditions of a screw velocity ratio of 0.88, an amplitude of 4.7 mm, a vibration frequency of 7.5 Hz, and a machine operation velocity of 0.92 km/h, the sand removal rate is 90.40%, the crushing rate is 1.66%, and the power consumption is 2.24 kW in theory. The optimized results were verified by tests. The sand removal rate was 88.92%, the crushing rate was 1.71%, the total power consumption was 2.29 kW, and the errors from the predicted values were 1.6%, 3.0%, and 2.2%, respectively, meeting the requirements for tiger nut harvesting conveyance and separation. This research can provide support for the development of technology and equipment for mechanized harvesting of tiger nuts in the sandy areas of Xinjiang.

Eggshell waste bioprocessing for sustainable acid phosphatase production and minimizing environmental hazards

BackgroundThe Environmental Protection Agency has listed eggshell waste as the 15th most significant food industry pollution hazard. Using eggshell waste as a renewable energy source has been a hot topic recently. Therefore, finding a sustainable solution for the recycling and valorization of eggshell waste by investigating its potential to produce acid phosphatase (ACP) and organic acids by the newly-discovered B. sonorensis was the target of the current investigation.ResultsDrawing on both molecular and morphological characterizations, the most potent ACP-producing B. sonorensis strain ACP2, was identified as a local bacterial strain obtained from the effluent of the paper and pulp industries. The use of consecutive statistical experimental approaches of Plackett–Burman Design (PBD) and Orthogonal Central Composite Design (OCCD), followed by pH-uncontrolled cultivation conditions in a 7 L bench-top bioreactor, revealed an innovative medium formulation that substantially improved ACP production, reaching 216 U L−1 with an ACP yield coefficient Yp/x of 18.2 and a specific growth rate (µ) of 0.1 h−1. The metals Ag+, Sn+, and Cr+ were the most efficiently released from eggshells during the solubilization process by B. sonorensis. The uncontrolled pH culture condition is the most suitable and favoured setting for improving ACP and organic acids production. Quantitative and qualitative analyses of the produced organic acids were carried out using liquid chromatography-tandem mass spectrometry (LC–MS/MS). Lactic acid, citric acid, and hydroxybenzoic acid isomer were the most common organic acids produced throughout the cultivation process. The findings of TGA, DSC, SEM, EDS, FTIR, and XRD analysis emphasize the significant influence of organic acids and ACP activity on the solubilization of eggshell particles.ConclusionsThis study emphasized robust microbial engineering approaches for the large-scale production of a newly discovered acid phosphatase, accompanied by organic acids production from B. sonorensis. The biovalorization of the eggshell waste and the production of cost-effective ACP and organic acids were integrated into the current study, and this was done through the implementation of a unique and innovative medium formulation design for eggshell waste management, as well as scaling up ACP production on a bench-top scale.

Electrochemical advanced oxidation of 2,4-D herbicide and real pesticide wastewater with an integrated anodic oxidation/heterogeneous electro-Fenton process

Pesticide wastewater is accused of polluting receiving waters with toxic and non-biodegradable organic pollutants. The present study has developed an integrated electrochemical oxidation process based on PbO2 anodic oxidation and Fe/SBA-15 heterogeneous electro-Fenton (PbO2/EF-(Fe/SBA-15)) for synergistic treatment of pesticide wastewater. PbO2 electrocatalyst was prepared by anodic deposition method and Fe/SBA-15 catalyst was synthesized by incipient wetness impregnation method. To optimize and model the removal of 2,4-D, a quadratic mathematical model by orthogonal central composite design (CCD) was proposed and validated. In optimal conditions including solution pH = 5, H2O2 concentration = 2000 mg/L, applied current = 10 mA/cm2, Fe/SBA-15 dose = 1.25 g/L and 2,4-D concentration = 30 mg/L, the experimental removal efficiency of 2,4-D after 35 min of reaction in the PbO2/EF-(Fe/SBA-15) process was 99.85 %. Moreover, the kinetics of 2,4-D removal in the integrated PbO2/EF-(Fe/SBA-15) process was about 3.84 times faster than the separate PbO2 anodic oxidation, confirming a remarkable degradation synergy. The mineralization of 2,4-D was confirmed by LC-MS and TOC analyses, and considering the identified intermediates, the possible degradation pathways of 2,4-D to CO2 and H2O were suggested. Real pesticide wastewater treatment was studied under optimal conditions. COD removal efficiency in PbO2/EF-(Fe/SBA-15) process and PbO2 anodic oxidation was 71.2 % and 32.5 %, respectively. Also, the energy consumption (EC) of these two processes was 17 kWh/kg COD and 38 kWh/kg COD, respectively. The results of this study suggest the integrated PbO2/EF-(Fe/SBA-15) process is a practical and cost-effective process for non-biodegradable pesticide wastewater treatment.

Effect of extrusion processing parameters on structure, texture and dietary fibre composition of directly expanded wholegrain oat-based matrices

Oat flour mixed with 30 g/100 g rice flour was extruded with a twin-screw extruder using a central composite orthogonal design. Temperatures (120 °C,140 °C, 160 °C) and moisture (14.5 g/100 g, 17.7 g/100 g, 20.6 g/100 g) were adjusted during extrusion, while screw speed was kept constant (400 rpm). Extrudates were analysed for structure (expansion, density, microstructure), texture (hardness), β-glucan (molecular weight and extractability), as well as fibre content. Expansion varied between 250 and 329%, density between 165 and 457 kg/m3 and hardness between 27 and 64 N. The response surface model showed that more expanded, less dense and less hard extrudates were achieved at low moisture, while high temperature resulted in lower density and hardness. Significant differences in β-glucan extractability were observed depending on extrusion conditions, with values ranging between 0.64 and 1.31 g/100 g. β-glucan extractability correlated with positively with porosity, and negatively with moisture content during extrusion, cell wall thickness and density. The results indicate that conditions that produce a more porous, crispier structure, also increases β-glucan extractability.

On Evaluation of Three Basic Properties of Central Composite Design

This work aims at making a choice of selecting the best property of central composite design (CCD). The three basic properties of CCD are rotatable, orthogonal and slope-rotatable with four optimality criteria; D, E, A and T. A complete 23 factorial experiment with increase in center points and non-replication of axial point was used for the entire work. The software applications used to run the analysis are Minitab and Excel. Minitab was used to create CCD with the respective center points and axial distances to fit the quadratic response polynomial. Excel was used to evaluate all the optimality criteria with respect to the properties of CCD and the efficiency of these criteria. Response surface graph was plotted to interpret how good the design is with the factors interaction. The result shows that A – optimality criterion is the best optimality criterion with respect to rotatable central composite design (RCCD), orthogonal central composite design (OCCD) and slope – rotatable central composite design (SRCCD) because of the increase in efficiency as the center point increases. Rotatable central composite design (RCCD) is considered in this context as the best property of central composite design in response surface methodology by comparing the increase in efficiency of the four optimality criteria as the center point increases.

Investigation of selected independent variables on extrusion of rice semolina with and without propeller

The influence of screws with and without propeller, as well as the independent variables of material moisture content, working screw speed, feeding screw speed and die temperature on the changes of some physical and mechanical properties during singles-screw extrusion of rice semolina was studied. The response surface methodology was used with an orthogonal central composite design. Optimum modes of operation which lead to the maximization of the mass flow rate and the sectional expansion index and the minimization of the specific mechanical energy were established. The obtained results show that the use of a propeller in single-screw extrusion leads to an increase in extruder mass flow rate, a decrease in the specific mechanical energy and an increase in the sectional expansion index.

A simulation modeling approach used in the crude oil refining process

Mathematical and simulation modeling methods are applied when defining parameters of effective operation of oil fractionation. There is a review of software packages of process modeling used for refining ventures in the study. Multisphere model of oil fractionation with a low capacity applied is offered in the paper. The designed model allows taking into account constructive peculiarities of the equipment of small capacity units. The flow diagram of the model calculation algorithm with the additional evaluator of petroleum products quality indices is given by the authors. A design matrix for a three-factor experiment involving a multisphere model is obtained. An orthogonal central composite design has been applied to improve the accuracy of the model and to consider a non-linear parameter link. The MatLab software was chosen as an enabler. The criterion was the energy cost of separation. Factors affecting the criterion are flow rate of superheated water steam, reflux rate, potential light fractions in the crude/feed. The adequate obtained regression quadratic dependency towards the initial values by Fisher’s criterion has been assessed. The average relative error was 0.21 percent. The obtained statistical model can be applied for solving an optimization problem by the criterion of power consumption within a variable fractional composition of the raw material. Quality indices of oil products (gasoline fraction and diesel oil) serve as constraints. The offered statistical model applied at oil fractionation low-power facilities promotes the efficiency of plant operation improvement and the efficiency of obtaining information about the quality of oil products.

Microwave-Assisted Extraction of Polyphenols from Blackcurrant By-Products and Possible Uses of the Extracts in Active Packaging.

The design of experiment (DoE) approach was used to optimize the extraction of polyphenols from blackcurrant by-products with microwave-assisted extraction and deionized water as a green solvent. Three factors (microwave power, extraction time, and solvent/matrix ratio) were evauated, and a central composite orthogonal design (CCO) was applied in order to reduce experimental runs. Empirical models relating the response and process parameters were developed. The validity of the models was tested using an analysis of variance (ANOVA). The optimal extraction conditions were found using the highest value of microwave power (780–800 W) and the lowest extraction time (60 min) and solvent/matrix ratio (10 m/g). Compared with conventional solvent extraction, the polyphenol yield increased by 25% after applying the optimized MAE process. The obtained extract was used to realize a sustainable active maltodextrin (Glucidex 2) pad using an electrospinning technique. The antimicrobial and antioxidant activities of the pads were tested on the post-harvest storage of raspberries. Two set of experiments were carried out. The recorded results showed that the pad had antimicrobial activity on the tested fruit samples and implied the possibility of using it to extend the shelf-life of the fruits.

Energy Saving in Electromechanical Grain Cleaning Systems

The article is concerned with energy conservation in the process of cleaning grain. The study aimed to find ways of reducing energy consumption when cleaning food grains by using energy-saving operating modes (ESOM) on the production lines of grain storage facilities. For this purpose, experimental tests were performed which involved studying the effects of physical and chemical properties of grain as well as the influence of various operating modes of the production lines on the specific energy consumption (SEC), which was found to be the most informative indicator for determining ESOM. The mathematical description of the target function was carried out by conducting a multifactorial experiment with the application of the orthogonal central composite design (OCCD) of the second order. Calculations produced a number of mathematical models describing the dependence of the response function on the input parameters. The proposed approach made it possible to obtain the minimum SEC for cleaning food grains and to develop practical recommendations for ways to reduce energy consumption, which resulted in the development of scientifically based SEC standards for a grain cleaning machine.

Experimental determination of field microrelief ridgenessness after secondary tillage with Stepnyak 7.4 cultivator

Four wheels are installed on the frame in the front part, the rear part of the frame is supported by two rows of rollers to ensure stable operation of the Stepnyak-7.4 cultivator in depth and maintain the required ridgeness of the soil field. The speed of movement of the unit, the depth and the running uniformity of working tools, and the traction resistance of the machine depend on the ridgeness and microrelief of the field. A priori ranking of factors of the cultivator’s operation revealed that the most significant factors in studying the ridgeness of the cultivated soil are the speed of movement of the unit Va, the diameter of the rolling basket drum Drb and the setting angle of the scraper γ. The variation levels of natural factors are established and values of coded values of factors are calculated. An orthogonal central composite design was used to design the experiments. Based on the results of experimental data processing, a mathematical model of field ridgeness variation after processing depending on the varied factors is obtained, and rational ranges of operational parameters are determined. The studies revealed that the minimum ridgeness of the field soil is achieved with a rolling basket diameter of 0.40-0.45 m and an inclination angle of the scraper bend of 75-80 degrees with a unit speed ranging from 2.8 to 3.2 m/s.

Sweet-and-sour sauce of assai and unconventional food plants with functional properties: An innovation in fruit sauces

The fruit sauces importance is increasing as a result of the impact of these ingredients that enhance the functional properties of foods. Thus, the study aimed to produce a sweet-and-sour sauce with assai and unconventional food plants (UFP), as a healthy alternative in promoting the consumption of fruits and vegetables. Thus, 14 sauce prototypes were produced. A first-order orthogonal central composite design was used, and for the data analysis, the response surface methodology and the ridge analysis were used. The physical, physical-chemical, microbiological and sensory analyzes were performed. The characteristics of identity and quality of selected prototypes M2 and M5, were respectively: 24 and 28 oBrix; 0.72 and 0.86 (%) titratable acidity; 33.11 and 32.34 of ratio; 3.97 and 3.91 of pH; 1.00 and 1.10 μM Trolox mL−1 of antioxidant activity; 141.0 and 158.16 mg GAE/100 g of phenolic compounds; 12.7 and 14.5 cm/30s of Bostwick consistency; 39.03 and 45.15 (%) of syneresis. There was no microbial growth. The sauces’ prototypes obtained good sensory acceptance and this was not influenced by the consumers' profile. Thus, ensuring the safety and quality of the sauces. Therefore, it was possible to obtain two prototypes for the sauce, with characteristics of identity and quality similar to those of ketchup and with functional potential.

Blackberry (Rubus glaucus Benth.) fertilized with nitrogen, phosphorus, potassium and calcium: Effect on anthracnose under controlled conditions

In order to seek management alternatives for anthracnose caused by the fungus Colletotrichum gloeosporioides in blackberry (Rubus glaucus Benth.), at the Tibaitatá Research Center of the Colombian Agricultural Research Corporation AGROSAVIA (formerly CORPOICA), an experiment was conducted to evaluate the effect of the application of the major elements nitrogen (N), phosphorus (P), potassium (K) and calcium (Ca) on infections of the fungus C. gloeosporioides strain-52. For this purpose, a randomized complete block design was used with an arrangement of treatments in an orthogonal central composite design. To evaluate the relationship of fertilization levels and disease severity, an artificial inoculation was made on thorny blackberry stems using 0.5 cm mycelial discs at a concentration of 9.53 × 104 conidia. Observations consisted of: disease severity (S), incubation period (IP) and rate of development (r). Data analysis was done by the cluster method on the severity variable, a Pearson correlation analysis between variables, as well as a regression to estimate the effect of nutrients applied on the severity of C. gloeosporioides strain-52. The treatments were concentrated in four groups with the ranges (in parentheses) S (15.9% and 91.8%), PI (9 and 15.3) and Tr (0.0254 and 0.0468). A positive and significant correlation was observed between S and r (P < 0.001) and a negative correlation between PI with S and r (P < 0.001). By means of regression analysis, a linear model was generated that showed a reduction in disease severity with increasing N dose and an increase with the levels of P and Ca applied.

Application of a fluidized three-dimensional electrochemical reactor with Ti/SnO2–Sb/β-PbO2 anode and granular activated carbon particles for degradation and mineralization of 2,4-dichlorophenol: Process optimization and degradation pathway

A three-dimensional electrochemical reactor with Ti/SnO2–Sb/β-PbO2 anode and granular activated carbon (3DER-GAC) particle electrodes were used for degradation of 2,4-dichlorophenol (2,4-DCP). Process modeling and optimization were performed using an orthogonal central composite design (OCCD) and genetic algorithm (GA), respectively. Ti/SnO2–Sb/β-PbO2 anode was prepared by electrochemical deposition method and then its properties were studied by FESEM, EDX, XRD, Linear sweep voltammetry and accelerated lifetime test techniques. The results showed that lead oxide was precipitated as highly compact pyramidal clusters in the form of β-PbO2 on the electrode surface. In addition, the prepared anode had high stability (170 h) and oxygen evolution potential (2.32 V). A robust quadratic model (p-value < 0.0001 and R2 > 0.99) was developed to predict the 2,4-DCP removal efficiency in the 3DER-GAC system. Under optimal conditions (pH = 4.98, Na2SO4 concentration = 0.07 M, current density = 35 mA cm−2, GAC amount = 25 g and reaction time = 50 min), the removal efficiency of 2,4-DCP in the 3DER-GAC system and the separate electrochemical degradation process (without GAC particle electrode) were 99.8 and 71%, respectively. At a reaction time of 80 min, the TOC removal efficiencies in the 3DER-GAC and the separate electrochemical degradation system were 100 and 57.5%, respectively. Accordingly, the energy consumed in these two systems was calculated to be 0.81 and 1.57 kWh g−1 TOC, respectively. Based on the results of LC-MS analysis, possible degradation pathways of 2,4-DCP were proposed. Trimerization and ring opening reactions were the two dominant mechanisms in 2,4-DCP degradation.

Complying with the Guideline for Quality and Equivalence for Topical Semisolid Products: The Case of Clotrimazole Cream.

Semisolids constitute a significant proportion of topical pharmaceutical dosage forms available on the market, with creams being considered profitable systems for releasing active substances into the skin. This work aimed at the development of a generic Clotrimazole topical cream, based on the assumptions that assist the development of such formulations. First, the critical parameters to obtain a final formulation as similar as possible to the reference product were defined. Then, the percentages of cetyl palmitate and octyldodecanol were identified as critical variables and chosen for optimization in further studies. A “quality by design” approach was then used to identify the effect of process variability on the structural and functional similarity (Q3) of the generic product qualitatively (Q1) and quantitatively (Q2). A two-factor central composite orthogonal design was applied and eleven different formulations were developed and subjected to physicochemical characterization and product performance studies. The results were used to estimate the influence of the two variables in the variation of the responses, and to determine the optimum point of the tested factors, using a design space approach. Finally, an optimized formulation was obtained and analysed in parallel with the reference. The obtained results agreed with the prediction of the chemometric analysis, validating the reliability of the developed multivariate models. The in vitro release and permeation results were similar for the reference and the generic formulations, supporting the importance of interplaying microstructure properties with product performance and stability. Lastly, based on quality targets and response constraints, optimal working conditions were successfully achieved.

Enhanced degradation of furfural by heat-activated persulfate/nZVI-rGO oxidation system: Degradation pathway and improving the biodegradability of oil refinery wastewater

Oil refinery wastewater is characterized by high values of temperature and furfural concentration. Furfural is a toxic and non-biodegradable substance in aqueous media that its absorption through the skin causes acute neurological and pulmonary effects. In this study, a heat-activated persulfate (HAP) system in combination with reduced graphene oxide-supported nano zero-valent iron catalyst (nZVI-rGO) was developed for oil refinery wastewater treatment. Five operational parameters regarding furfural removal were statistically modeled by an orthogonal central composite design (OCCD) and then optimized by genetic algorithm (GA) technique. The main characteristics of the nZVI-rGO as well as its reusability were investigated by field emission scanning electron microscopy (FESEM), energy-dispersive X-ray spectroscopy mapping (EDX-mapping), X-ray diffraction analysis (XRD) and vibrating sample magnetometer (VSM) analysis. The optimum values for the solution temperature, nZVI-rGO dosage, persulfate (PS) concentration, solution pH and reaction time were predicted to be 70 °C, 1.25 g L−1, 4.28 mmol L−1, 5.46 and 50 min, respectively. Under the optimized conditions, the experimental furfural removal efficiency in HAP/nZVI-rGO and HAP oxidation systems were obtained to be 97.80 and 68.20 %, respectively. Sulfate radical (SO4•-) has greater participation in furfural mineralization than hydroxyl radical (HO•). The major intermediates resulting from the furfural mineralization were short-chain acids including acetic acid and formic acid. Regardless, almost complete furfural mineralization was achieved after 100 min of the oxidation reaction. The optimized HAP/nZVI-rGO process was able to significantly improve the biodegradability of wastewater by more than 2 times.

Influence of discharge energy on the properties steel alloy after EDM

In this comprehensive study, the influence of discharge energy of the EDM process was correlates with the formation of heat-affected zone (HAZ) depth in 40CrNi steel alloy. The change in micro-hardness distribution of the treated surface measured cross-sectionally from the machined surface and represented the extent of HAZ. The orthogonal central composite design methodology was used to conduct the experiment. An empirical model has presented the relationship between the EDM discharge energy and the depth of the heat-affected zone. It was found that the change in the surface layer after EDM reduces the fatigue life of samples up to 30% as compared to the sample prepared by the conventional turning process.

DEVELOPING A NEW ESTERIFICATION METHOD FOR THE DETERMINATION OF FATTY ACID COMPOSITIONS OF MARINE OIL SUPPLEMENTS BY GAS CHROMATOGRAPHY WITH ORTHOGONAL CENTRAL COMPOSITE DESIGN AND RESPONSE SURFACE METHODOLOGY

In this study, an efficient, applicable, and special esterification method for the quantification of fatty acid compositions of MOs has been created with chemometric techniques. The esterification variables which are the temperature of esterification (A), the time of esterification (B), and the amount of hexane (C), were optimized by using the orthogonal central composite design (OCCD). The relationships of the variables with each other and with the response value (R) are interpreted with response surface methodology (RSM). The optimal conditions were as follows: the temperature of esterification, 60°C; the time of esterification, 40 min; and the amount of hexane, 4.3 mL. Even MOs that are difficult to esterify can be easily esterified and the fatty acid compositions of all MOs, especially important fatty acids such as eicosapentaenoic acid (20:5) and docosahexaenoic acid (22:6), have been successfully analyzed by gas chromatography with the new method developed.

Optimization of Biodegradation of Long Chain n-Alkanes by Rhodococcus sp. Moj-3449 Using Response Surface Methodology

Oil spills and subsequent pollution of marine ecosystems are associated with oil exploitation. The ultimate fate of unrecoverable portion of spilled oil is biodegradation by microorganisms. Rhodococcus sp. Moj-3449 has proven ability of growth on aliphatic hydrocarbons. In this study Response Surface Methodology was employed to optimize the biodegradability of Moj-3449 by changing salinity, pH, temperature and n-C16 concentration. The duplicate experiments conducted were based on a 5-levels rotatable and orthogonal central composite design (CCD) done in 2 separate blocks. The effect of each factor and their interactions on the biodegradation of n-C16 revealed that the optimal conditions for the biodegradation are 0 % salinity at pH= 6.97, T=28°C and 52.98 % wt/V n-C16 concentration. Under these conditions, the maximum biodegraded amount was predicted at 45.52 % wt/V out of 52.98 % wt/V. The experimentally obtained biodegradation amount at the optimum condition was 44.27 ±0.07 % wt/V. The ability of the strain to effectively break down long-chain n-alkanes at concentration up to 55 % wt/V shows at that this strain is an outstanding candidate for industrial bioremediation of crude oil spills in marine environment.

Modeling and optimization of multi-hole rotary electrical discharge drilling of die steel

This research proposed a mathematical model focused on the artificial neural network (ANN) and the response surface methodology for gas-assisted electrical discharge drilling (GAEDD) of die-steel. The GAEDD was performed with multi-hole rotary electrode in this work. Orthogonal central composite rotable design (CCRD) method employed for conduction of experiments. An overall of thirty two experiments were executed at five levels. In this exploration, pulse duration, discharge current, duty cycle, tool rotation, and discharge gas pressure has been selected as input parameters, while the material removal rate (MRR) and the surface roughness (SR) were selected as process output. Analysis of variance was implemented to instigate and to know the competency of the established models of MRR and SR. The fit outline supports that the statistical model is proper and the lack of fit is irrelevant. Mean square error and root mean square error obtained through response surface methodology was utilized for the modeling and anticipating potential of models developed through artificial neural network (ANN). The exploratory and forecast estimates of MRR and SR of the GAEDD, acquired by RSM and ANN were observed to be as per one another. In addition, the ANN technique has shown that, when contrasted with the RSM, the response is even more appropriate. A genetic algorithm has been used to extract optimum parameters by optimizing the GAEDD process to maximize MRR and minimize SR. The optimal value of MRR and SR obtained through genetic algorithm was found to be 22.34 mg/min. and the SR at 3.80 µm respectively.

Valorization of Industrial Vegetable Waste Using Dilute HCl Pretreatment

A solid vegetable waste stream was subjected to dilute acid (HCl) pretreatment with the goal of converting the waste into a form that is amenable to biochemical processes which could include microbial lipids, biohydrogen, and volatile organic acids production. Specifically, this study was conducted to identify the most suitable pretreatment condition that maximizes the yield or concentration of sugars while minimizing the production of compounds which are inhibitory to microbes (i.e., furfural, hydroxymethylfurfural, and organic acids). Temperatures from 50–150 °C and HCl loading from 0–7 wt % were studied to using an orthogonal central composite response surface design with eight center points. The effects of the variables under study on the resulting concentrations of sugars, organic acids, and furans were determined using the quadratic response surface model. Results indicated that the biomass used in this study contains about 5.7 wt % cellulose and 83.8 wt % hemicellulose/pectin. Within the experimental design, the most suitable pretreatment condition was identified to be at 50 °C and 3.5 wt % HCl. A kinetic study at this condition indicated process completion at 30 mins. that produced a hydrolyzate that contains 31.30 ± 0.44 g/L sugars and 7.40 ± 0.62 g/L organic acids. At this condition, a yield of ~0.47 g sugar/g of dry solid vegetable waste was obtained. The absence of furans suggests the suitability of the resulting hydrolyzate as feedstock for biochemical processes. The results suggested that the sugar concentration of the pretreated biomass is highly affected by the presence of other compounds such as amines, amino acids, and proteins. The effect however, is minimal at low levels of HCl where the highest total sugar production was observed.