Low-cost Treatment Method Research Articles

Construction of an in-situ Se-linked ZnSe/ZnO heterojunction for efficient photocatalytic U(VI) reduction

U(VI) in nuclear wastewater threatens human health and the environment due to its high toxicity and mobility. Photocatalysis is seen as a promising, simple, low-cost, and sustainable method for wastewater treatment, but existing photocatalysts face challenges like complex preparation and severe electron-hole recombination. In this work, ellipsoidal Se-linked ZnSe/ZnO was in situ constructed using a simple one-pot hydrothermal method, with non-metallic selenium serving as the carrier. In 30 minutes, the removal rate of U(VI) can reach 90.2 % in 100 mg/L U(VI) solution. The reaction kinetics of the optimal Se/ZnSe/ZnO ratio reached 0.14939 min−1, which is nearly 10 times that of pure ZnO. Photocatalytic analysis revealed that introducing Se as the medium for electron transport in the composite material can effectively reduce electron-hole recombination, thereby enhancing photocatalytic efficiency. The results of this study offer a simple and efficient new method for photocatalytic reduction of U(VI) and provide an effective strategy for establishing a conductive medium in the heterojunction using a one-pot hydrothermal method.

A new ceramic microfiltration membrane based on olive seeds: development and characterization

ABSTRACT The development of low-cost methods for wastewater treatment and the separation of oil-in-water emulsions is of considerable significance. Recently, natural material-based, inexpensive membranes have become a hot area of research. In this work, natural olive seeds were used to develop a novel ceramic membrane support. With the oil filtration process in place, the choice was reached to utilize the olive kernels’ beneficial qualities best. The process involved blending plastic paste with water and organic ingredients, followed by extruding the resulting paste into a porous tubular. After firing at 200 °C/2 h, the membrane's water permeability and porosity were 1,852 L/h m2 bar and 45%, respectively, and its average pore width varied from 2 to 15 μm. The efficiency of the microfiltration membrane in separating oil-in-water emulsions was assessed using two test solutions containing oil concentrations of 500 and 1,000 mg/L. Under a transmembrane pressure of 1 bar, the membrane exhibited exceptional permeate flux exceeding 200 L/m2 h, along with a high oil rejection rate of over 96% across all feed concentrations.

Low Cost Water Purification: Harnessing Adsorbents for Sustainable Treatment Solutions

Water is essential for life, yet millions lack access to clean drinking water. Low-cost treatment methods are crucial to ensure equitable access to safe water and prevent waterborne diseases in underserved communities. The study devised a 12-liter water filter utilizing pebbles, sand, and adsorbents biochar of Julifora, cashew nut shell and rice husk. Results demonstrated the filter's effectiveness in sustaining pH levels while reducing chloride, fluoride, hardness and alkalinity. Particularly noteworthy was the capacity of cashew nut biochar to efficiently adsorb chloride, fluoride, hardness and alkalinity as 27%, 37%, 38% and 43% respectively. This indicates its promising role as an adsorbent for water purification. The findings underscore the potential of the designed filter in improving drinking water quality by mitigating contaminants. Further refinement and optimization of the filter could enhance its efficacy in meeting stringent water quality standards, addressing the pressing need for accessible and safe drinking water globally.

Effect of sandblasting and acid surface pretreatment on the specific capacitance of CuO nanostructures grown by hot water treatment for supercapacitor electrode applications

Crystalline copper oxide (CuO) nanostructures with micro, nano, and micro-nano surface roughness were grown on Cu sheet substrates by a facile, scalable, low-cost, and low-temperature hot water treatment (HWT) method that simply involved immersing Cu sheet in DI water at 75 °C for 24 h without any chemical additives. Various morphological features and sizes of CuO nanostructures were tuned by using different surface pretreatment techniques including acid treatment, sandblasting, or a combination of those two. The surface morphology of the prepared samples was analyzed by scanning electron microscopy. The crystal structure of the CuO nanostructures was investigated by x-ray diffraction XRD and Raman spectroscopy. To study the pseudocapacitive behavior, their potential supercapacitor performance, and equivalent series resistance, electrochemical analysis was done by cyclic voltammetry and electrochemical impedance spectroscopy for all the CuO/Cu samples in 1 M of Na2SO4 electrolyte. Among all, the best supercapacitive performance was achieved for CuO/Cu samples pretreated with Sandblasting followed by Acid treatment resulting in a specific capacitance of about 104 F g−1. The electrode with the sandblasted + acid pretreated sample showed a maximum of ∼69% capacitive retention after 2000 consecutive cycles. Our results indicate that CuO nanostructures on Cu substrates prepared with different surface pretreatment conditions and grown by HWT can be promising electrodes for supercapacitor device applications.

Biomarker profiling to determine clinical impact of microRNAs in cognitive disorders

Alzheimer’s disease (AD) and post-stroke cognitive impairment (PSCI) are the leading causes of progressive dementia related to neurodegenerative and cerebrovascular injuries in elderly populations. Despite decades of research, patients with these conditions still lack minimally invasive, low-cost, and effective diagnostic and treatment methods. MicroRNAs (miRNAs) play a vital role in AD and PSCI pathology. As they are easily obtained from patients, miRNAs are promising candidates for the diagnosis and treatment of these two disorders. In this study, we performed complete sequencing analysis of miRNAs from 24 participants, split evenly into the PSCI, post-stroke non-cognitive impairment (PSNCI), AD, and normal control (NC) groups. To screen for differentially expressed miRNAs (DE-miRNAs) in patients, we predicted their target genes using bioinformatics analysis. Our analyses identified miRNAs that can distinguish between the investigated disorders; several of them were novel and never previously reported. Their target genes play key roles in multiple signaling pathways that have potential to be modified as a clinical treatment. In conclusion, our study demonstrates the potential of miRNAs and their key target genes in disease management. Further in-depth investigations with larger sample sizes will contribute to the development of precise treatments for AD and PSCI.

Anti-Leishmanial Effects of a Novel Biocompatible Non-Invasive Nanofibers Containing Royal Jelly and Propolis against Iranian Strain of Leishmania major (MRHO/IR/75/ER): an In-Vitro Study.

Current medications especially the pentavalent antimonial compounds have been used as the first line treatment of cutaneous leishmaniasis (CL), but they have limitations due to serious side effects such as drug resistance, cardio and nephrotoxicity, and high costs. Hence, the demand to find more usable drugs is evident. Synthesis and development of natural, effective, biocompatible, and harmless compounds against Leishmania major is the principal priority of this study. By electrospinning method, a new type of nanofiber were synthesized from royal jelly and propolis with different ratios. Nanofibers were characterized by Scanning Electron Microscope (SEM), Transmission Electron Microscopy (TEM), Thermogravimetric Analysis (TGA), Contact angle, and Fourier-transform infrared spectroscopy (FTIR). The Half-maximal inhibitory concentration (IC50), Half-maximal effective concentration (EC50) and the 50% cytotoxic concentration (CC50) for different concentrations of nanofibers were determined using quantitative calorimetric methods. Inductively coupled plasma-optical emission spectrometry (ICP-OES) and flow cytometry were performed as complementary tests. The results showed that the proposed formulas provide a new achievement that, despite the significant killing activity on L. major, has negligible cytotoxicity on the host cells. Royal jelly nanofibers have significantly shown the best 72 hours results (IC50= 35 μg/ml and EC50=16.4 μg/ml) and the least cytotoxicity. This study presents a great challenge to introduce a new low-cost treatment method for CL, accelerate wound healing, and reduce scarring with minimal side effects and biocompatible materials. Royal jelly and propolis nanofibers significantly inhibit the growth of L. major in-vitro.

Effect of salinity on biological nitrogen removal from wastewater and its mechanism.

The nitrogen discharge from saline wastewater will cause significant pollution to the environment. As a high-efficiency and low-cost treatment method, biological treatment has a promising application prospect in the removal of nitrogen from high-salt wastewater. However, the inhibitory effect of high salt on microorganisms increases the difficulty of its treatment. This review discusses the influence of salinity on the nitrogen removal process, considering both traditional and novel biological techniques. Common methods to enhance the effectiveness of biological nitrogen removal processes and their mechanisms of action in engineering practice and research, including sludge acclimation and inoculation of halophilic bacteria, are also introduced. An outlook on the future development of biological nitrogen removal processes for high-salt wastewater is provided to achieve environmentally friendly discharge of high-salt wastewater.

Fabrication and characterization of CuO–SiO2/PVA polymer nanocomposite for effective wastewater treatment and prospective biological applications

ABSTRACT The quality of water significantly affects the health and walefare of all orginisms, highlighting the importance to develop low-cost and efficient wastewater treatment methods. Herein, we report the fabrication, characterization, and utilization of a polymer-based ternary nanocomposite (CuO–SiO2/PVA) for the removal of Nile Blue (NB) and Methylene Blue (MB) contaminants from wastewater, along with exploring its potential biological activities. We have successfully employed the cost-effective sol–gel and in-situ polymerization approaches to fabricate the CuO–SiO2/PVA based ternary composite, utilizing Cu(NO3)2·3H2O:Glycerol:TEOS:PVA in a ratio of 8:2:3:4. The desired fabrication of nanocomposite was confirmed through UV-Visible spectroscopy, SEM (scanning electron microscope), TEM (transmission electron microscope), EDX (energy dispersive X-ray diffraction), FTIR (Fourier transform infrared), DSC (differential scanning calorimetry), and TGA (thermogravimetric analysis). In addition to its biological potentialthe performance of the nanocomposite in catalytic / photocatalytic removal of NB and MB dyes is investigated and compared. The higher photodegradation performance of the composite for NB (85%) dye than for MB (76%) dye indicates that variables such as chemical structure, charge, molecular mass, and pH sensitivity of the dyes can influence the catalyst's removal potential. This composite is considered to have a higher capability for removing pollutants and microorganisms from wastewater.

Using aged oil to produce drilling-fluid lubricants

Aged oil is a product of oil and gas treatment and contains components such as oil, water, mud, sand, polymers, and surfactants. Normally, aged oil is mixed back into a crude-oil dehydration and separation treatment system to extract crude oil or treated separately using methods such as electric field dehydration, centrifugal separation, thermochemical dehydration, or biological treatment, amongst others. These methods all require the removal of water, mud, sand, etc. from the aged oil, which can be difficult and costly to treat, making a low-cost treatment method highly desirable. In this study, a resource utilization and treatment method for aged oil was proposed wherein aged oil was used as the base oil to produce lubricants for drilling fluids. This method exploits the emulsifying stability of aged oil and avoids the difficulties of removing mud, sand, and water from it. Through experiments, the components and concentration of the lubricant were optimized, and its performance was evaluated. The emulsifier used for developing lubricants based on aged oil was alkylphenol polyoxyethylene ether (OP-4), the wetting agent was sodium dodecylbenzenesulfonate (ABS), and the stabilizer was sodium carboxymethyl cellulose (Na-CMC). The optimal formula was determined to be 100 mL drilling fluid, 3 mL aged oil, 1.5 g OP-4, 0.15 g of ABS, and 0.015 g Na-CMC. The density, apparent viscosity, and sticking coefficient of the system mud cake satisfied the requirements of enterprise standards after the lubricant was added to the bentonite-based slurry. Consequently, using aged oil as a base oil to develop lubricants for drilling fluids was shown to be a feasible resource-utilization scheme and a viable processing method for achieving value-added aged oil.

EXTRACTION AND CHARACTERIZATION OF α-CELLULOSE-RICH RESIDUE FROM MAIZE (ZEA MAYS L.) HUSK

Agricultural waste leads to a number of environmental issues, including pollution and environmental degradation. In Nigeria, Zea mays husk is one of the most prevalent agricultural wastes, and it can be turned into a valuable resource of quality cellulose. The goal of this study was to establish a low-cost and sustainable chemical treatment method for isolating cellulose from Z. mays husk feedstock. A series of alkaline delignification, digesting, and bleaching techniques were used to extract and purify cellulose. TAPPI T203 OS-74, TAPPI T222 OS-83 and TAPPI T222 OM-02 methods were used to determine the cellulose, hemicellulose and lignin contents, respectively. The samples were also characterised by scanning electron microscopy, X-ray diffraction, Fourier transform infrared spectroscopy (FTIR), and CHNS/O analyses. The resulting product was found to contain 97.95% α-cellulose, 0.19% β-cellulose, and 1.86% γ-cellulose. The presence of 40.95% carbon, 2.98% hydrogen, 0.72% nitrogen, 0.07% sulphur, and 55.28% oxygen was found by the CHNS/O analysis of cellulose. The untreated husk microscopy displayed an uneven, flake-like, and non-uniform surface, whereas the delignified husk, digested husk, and pure cellulose (ZMH-C) micrographs revealed, respectively, a smooth non-uniform surface, an irregular porous surface, and a smooth wool-like surface. The FTIR spectra of the treated samples demonstrated an increase in the intensity of the polar property of the OH group, as well as the elimination of the hemiacetal group and β-1,4-glycosidic linkages. The ZMH-C diffractogram verified the existence of characteristic 2θ peaks of cellulose at 220, 240, and 300, as well as a 4.7% crystallinity index. The comparatively low-temperature sequential alkaline delignification, digesting, and bleaching method adopted extracted low-lignin crystalline cellulose material from Z. mays husk. The flexibility, biodegradability, and availability of husk make it a viable source of high-quality cellulose with several possible applications. Z. mays cellulose has been thus demonstrated to be an appealing material for a wide variety of industries seeking environmentally acceptable and sustainable solutions.

Removal of major nutrients by sono-direct and sono-alternate current electrocoagulation process from domestic wastewater

Background: Electrocoagulation is becoming a promising eco-friendly wastewater treatment technique. It is a low-cost wastewater treatment method suitably applied for various wastewater effluent characteristics. Nevertheless, there are different kinds of electrocoagulation; comparison among them in terms of nutrient removal is investigated in the present research. This study analyzed nitrate (NO3 - ) and phosphate (PO4 3-) removal potential of the sono-alternative and direct-current electrocoagulation process. Methods: Batch reactor and sono-direct current (SDC)/sono-alternative current (SAC) electrocoagulation cell were employed to investigate NO3 - and PO4 3- removal efficiency from domestic effluents. The data gathered from laboratory experiments were analyzed using response surface methodology (RSM). ANOVA was used to examine the interaction effects of diverse parameters in terms of NO3 _ and PO4 3- removal from domestic wastewater effluents. Results: At extreme experimental conditions, the percentage of NO3 - and PO4 3- removal attained with sono-direct current electrocoagulation (SDCE) and sono-alternative current electrocoagulation (SACE) were 96.5%, 96.2% and 96.8%, 96.5, respectively. The SACE was more successful in eliminating NO3 - and PO4 3- than the SDCE process. The appearance of resistant oxide coating on the cathode and the appearance of corrosion on the anode due to oxidation processes in the case of SDCE were identified as principal factors highly affecting NO3 - and PO4 3- removal efficiency. Conclusion: With optimum process efficiency, experimental findings show that the SACE process is more capable of NO3 - and PO4 3- removal than the SDCE process.

Pretreatment of Landfill Leachate Using Hydrodynamic Cavitation at Basic pH Condition

The leachate generated from a landfill can cause significant harm to the environment and human health, so it must be treated before being discharged. A biochemical method is effective to treat the landfill leachate, but it requires a physicochemical pretreatment to help reduce the organic load and improve the biodegradability of the landfill leachate. In this work, hydrodynamic cavitation was used to pretreat the landfill leachate due to it being cost-effective, without additional chemicals, and environmentally friendly. The pretreatment experiments were conducted under an inlet pressure of 0.4 MPa and a basic pH. The influence of operating parameters such as the orifice opening rate, the arrangement of orifices, and the reaction time on the chemical oxygen demand, ammonium nitrogen, and biochemical oxygen demand removal in landfill leachate was studied, and the energy efficiency was evaluated. The results showed that under the above conditions, the removal rate for the chemical oxygen demand of the orifice plate with an annular orifice arrangement was better than that of the orifice plate with a radiation orifice arrangement, and the orifice plate with an orifice opening rate of 0.0417 had the best effectiveness. The energy efficiency under these two optimization conditions was also the highest. When the optimal operation time was 60 min, the removal rate of the chemical oxygen demand was 22.63%. The biodegradability of the landfill leachate was significantly improved with BOD5/COD increasing by 57.27%. The study provides a theoretical basis and data support for the application of hydrodynamic cavitation as a low-cost and efficient treatment method in the pretreatment of landfill leachate.

A fungal-algal self-flocculation system and its application to treat filter sludge leachate in the sugar industry

The efficient and economical treatment of wastewater using microalgae has attracted much attention. However, harvesting microalgae cells from treated wastewater remains challenging. In the present study, a Chlorella vulgaris suspension containing filamentous fungi Aspergillus niger and Chaetomium gracile was successfully used to construct a self-flocculating system, with a microalgae flocculation efficiency of 99.6% achieved by gravity sedimentation within 4 h. The diameter of fungi played an important role in determining flocculation efficiency, and the optimal particle size was 10 mm. Scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR) results indicated that the sweeping action of fungal mycelia and the interaction between the functional groups of fungi and the C. vulgaris surface contributed to improve flocculation. Co-cultivation of C. vulgaris and fungi could effectively remove 83.53%, 94.45% and 76.88% of total phosphorus, total nitrogen and chemical oxygen demand, respectively, from the sludge leachate from a sugar mill. The fungal-algal biomass reached 5.75 g/L. Herein, the constructed self-flocculation system had coupled efficient flocculation of C. vulgaris with removal of pollutants from wastewater in a short period of time, and providing a green, pollution-free, low-cost method for simultaneous wastewater treatment and the production of high quality biomass.

A low-cost and sustainable solution for nitrate removal from secondary effluent: Macroporous ion exchange resin treatment

Macroporous ion exchange resin has excellent selectivity to nitrogen (N), phosphorus (P) and partially soluble refractory organic compounds contained in the secondary effluent of wastewater treatment plants (WWTP). In this study, macroporous ion exchange resins were chosen as an alternative to single biochemical nitrogen removal processes. Various conditions were examined to optimize adsorption performance, and the adsorption mechanism was explored through isotherm fitting, thermodynamic parameter calculation, and kinetic analysis. The experiment demonstrated that the resin exhibited strong selectivity for nitrate (NO3−) and achieved an equilibrium adsorption amount of 9.8924 mg/g and an equilibrium adsorption time of 60 min at 25 °C. The resin denitrification pilot plant demonstrated stable operation for two months and achieved COD<20 mg/L, TN < 1.5 mg/L, and NH4+-N<0.5 mg/L. The removal rates of COD, TP, NH4+-N, NO3−-N, and TN were 41.65%, 42.96%, 55.37%, 91.8%, and 90.81%, respectively. After the resin was regenerated, the removal rates of NO3−-N, TN and the regeneration recovery rate were above 90%. Through cost analysis, the treatment cost of the pilot plant is only 0.104 $/m3. This study presents a practical, low-cost, and efficient treatment method for the deep treatment of secondary effluent from WWTP in practical engineering, providing new ideas and theoretical guidance.

Fabrication of Bi/BiOCOOH/PVDF with improved photocatalytic activity for the degradation of ciprofloxacin

The development of a low-cost and recyclable method for wastewater treatment has been a major challenge. Polyvinylidene fluoride (PVDF) membranes have received considerable attention owing to their excellent mechanical strength, unique antioxidant properties, and low cost. In this study, Bi/BiOCOOH/PVDF composite membrane materials were prepared using a simple two-step solvent thermal method and phase conversion method. The results showed that under the synergistic action of adsorption and photocatalysis, the photocatalytic degradation efficiency of Bi/BiOCOOH composite material and Bi/BiOCOOH/PVDF composite membrane material for ciprofloxacin (CIP) was much higher than that of BiOCOOH. The introduction of PVDF acted as a carrier, improved the adsorption of the catalytic material to CIP, and facilitated the effective collision of the photocatalytic active site and CIP. The experimental results and theoretical calculations confirmed that the combination of Bi and BiOCOOH effectively improved the light absorption capacity and photocatalytic performance. The reproducibility test revealed that the small amount of new composite catalyst for Bi/BiOCOOH/PVDF as a carrier was lost and that the Bi/BiOCOOH/PVDF catalyst still had high catalytic activity. In addition, the influence of water matrix factors, such as pH and anion, on the photocatalytic degradation experiment was investigated, which would provide some reference for the actual wastewater treatment of the composite catalyst. This study demonstrates a photocatalytic activation mechanism between metals and semiconductors and provides some basis for constructing catalysts for the synergistic and effective treatment of water pollution through a combined adsorption and photocatalysis process.

Green functionalization for chelating ligand-like and π-conjugated active sites on carbon nanotubes and its use for vanadium redox flow batteries

An imide bond-based functional group is proposed for the catalyst's active site in vanadium redox flow batteries (VRFBs). Based on the functional group's inherent property produced by the optimized process, the catalytic activity toward vanadium ion redox reaction (VIRR) on both sides was increased sixfold without adversely affecting VIRR reversibility in comparison to the raw material, carboxylic acid-functionalized carbon nanotubes. These advantages were attributed to the imide bond-based functional groups acting as a chelating ligand to form strong interactions with vanadium redox couples while also inducing facile electron transfer by the π-conjugated bonds, resulting in increased catalytic activity and reversibility. Moreover, the treatment used an eco-friendly process comprising low-cost precursors (citric acid and urea) and mild conditions (80 °C, 2 h), thereby improving the commercial availability of VRFBs. In VRFB driving tests, the fabricated electrode outperformed the electrode with a polymer-like structure in terms of catalytic activity and long-term stability due to leaching of the active sites from the latter. Overall, the proposed catalyst could be a practical option for enhancing VRFB performance based on a low-cost and eco-friendly treatment method.

A review of color and COD removal from textile effluent by coagulation and advanced oxidation processes

The textile sector has a long history, and it makes significant contributions to the national economy. Disposing of colored wastewater poses serious environmental risks. Over the past few decades, the elimination of color from textile industries has proven to be quite challenging because it contains a high percentage of organic and inorganic ingredients, which makes it difficult to handle. The textile industry poses a severe environmental hazard due to its heavy use of water. Therefore, wastewater treatment is an environmental challenge. Several wastewater treatment processes are available. However, Research is still ongoing to find low-cost and high-efficiency treatment methods. Keeping in mind the permissible limitations of the wastewater systems, treatment techniques for water consumption are studied again. Recently, coagulation, flocculation, and advanced oxidation processes (AOPs) have been studied for water treatment in textile factories around the globe. There are several treatment options for the waters where AOPs were used for only tissue pretreatment or in combination with biological, physical, and chemical treatments. The objective of this research is to investigate the main variables influencing process effectiveness, namely COD, color BOD, pH, and temperature. According to research, the combination of treatment technologies helps improve water quality and create an environmentally friendly climate, regardless of the physical and chemical characteristics of the effluent.

Low-cost treatment method for organic matter and nutrients in landfill leachate.

In this study, the ability of low-cost composite adsorbents to treat organic compounds in terms of chemical oxygen demand (COD), total nitrogen (TN), and total phosphorus (TP) was investigated. The composite adsorbents were composed of washed sea sand (WSS), dewatered alum sludge (DAS), zero-valent iron (ZVI), and granular activated carbon (GAC). The removal efficiency of COD in landfill leachate by a composite adsorbent (composed of WSS (40%), DAS (40%), ZVI (10%), and GAC (10%) in weight) was 79.93 ± 1.95%. The corresponding adsorption capacity was 8.5 mg/g. During batch sorption experiments, the maximum COD removal efficiencies given by DAS, WSS, ZVI, and GAC were 16, 51.3, 42, and 100.0%, respectively. The maximum removal efficiencies of the above composite adsorbent for TN and TP were 84.9 and 97.4%, respectively, and the adsorption capacities were 1.85 and 0.55 mg/g, respectively. The Elovich isotherm model gave the best fit for COD, TN, and TP adsorption. This composite adsorbent can treat more than one contaminant simultaneously. The application of DAS and ZVI to make an efficient adsorbent for wastewater treatment would be a good re-use application for them, which would otherwise be landfilled directly after their generation.

Acid–Base Pretreatment and Enzymatic Hydrolysis of Palm Oil Mill Effluent in a Single Reactor System for Production of Fermentable Sugars

Palm oil mill effluent (POME) is one of the main agro-industrial wastewaters in Malaysia. Highly polluting POME is a serious threat to the environment. In recent years, the methods used to treat POME are inefficient and complex in terms of cost or environmental preservation. The main object of this research is to propose a single reactor system (SRS) obtained from POME wastewater discharge as a promising low-cost treatment and high-energy method for harvesting the fermentable sugar by applying acid–base–enzyme pretreatment and hydrolysis of POME by locally produced cellulase enzymes to enhance biofuel production. Several experiments were conducted to produce fermentable sugars through the statistical methods, including the characterization of POME, acid-base pretreatment, and enzymatic hydrolysis process for reducing sugar production. The one-factor-at-a-time (OFAT) results showed that the highest reducing sugar yield, 23.5 mg/mL of POME, was achieved by enzymatic hydrolysis in an SRS without having a separation and purification. Based on OFAT performance, optimization of two factors such as substrate concentration (total suspended solids, TSS %w/v) and enzyme loading (μmol/min) was carried out by applying face-centered central composite design (FCCCD) under the response surface methodology (RSM) to develop a second-order regression model. The optimum reducing sugar production was 26.6 mg/mL (53.14%) with the conditions of 5% w/v, TSS, and 80 μmol/min/mL of the enzyme dose. In addition, the results of this research can be further considered in biofuel production using other wastewaters to enhance biofuel production as well as wastewater treating functions and minimize the negative environmental impacts.

Effect of Flame Treatment on Bonding Performance of GF/EP Pultrusion Sheets Used for VARI Process

This paper presents an easy and low-cost flame treatment method to improve the bonding performance of GF/EP (Glass Fiber-Reinforced Epoxy) pultrusion plates, which are using widely for large size wind blades. In order to explore the effect of flame treatment on the bonding performance of the precast GF/EP pultruded sheet vs. the infusion plate, the GF/EP pultruded sheets were treated with different flame treatment cycles and were embedded in the fiber fabrics during the vacuum-assisted resin infusion process (VARI). The bonding shear strengths were measured by tensile shear tests. It is found that after 1, 3, 5, and 7 flame treatments, the tensile shear strength between the GF/EP pultrusion plate and infusion plate increased by 8.0%, 13.3%, 22.44%, and -2.1%, respectively. This indicates that the maximum tensile shear strength can be obtained after five times of flame treatment. In addition, DCB and ENF tests were also adopted to characterize the fracture toughness of the bonding interface with the optimal flame treatment. It is found that the optimal treatment gives increments of 21.84% and 78.36% for G I C and G II C, respectively. Finally, the surficial topography of the flame-treated GF/EP pultruded sheets were characterized by optical microscopy, SEM, contact angle test, FTIR, and XPS. The results show that flame treatment plays an impact on the interfacial performance through the combination of physical meshing locking and chemical bonding mechanism. Proper flame treatment would remove the weak boundary layer and mold release agent on the surface of the GF/EP pultruded sheet, etch the bonding surface and improve the oxygen-containing polar groups, such as C-O and O-C=O, to improve the surface roughness and surface tension coefficient of pultruded sheet to enhance the bonding performance. Excessive flame treatment destroys the integrity of epoxy matrix on bonding surface which results into the exposure of the glass fiber, and the carbonization of release agent and resin on the surface loosen the surficial structure, which reduces the bonding properties.