Showing papers on "Sawdust published in 2023"

Hydrothermal Carbonization of Sewage Sludge with Sawdust and Corn Stalk: Optimization of Process Parameters and Characterization of Hydrochar

Abstract: Disposal of sewage sludge (SS) is one of the problems in treatment plants; however, SS has a high-water volume and lacks some compounds and can be mixed with other biomass. The present study analyzed co-hydrothermal carbonization of sewage sludge with sawdust and corn stalk. This research aimed to optimize the process parameters, the temperature in the range of 180–300 °C, the reaction time in the range of 30–60 min, and pH in the range of 5–9 on the mass yield, energy yield, and high heat value (HHV) to increase the quality of hydrochar, and to analyze the effect of hydrothermal carbonization (HTC) on the characteristics of raw materials and hydrochar. The response surface method and Benken’s box model were conducted using Design Expert 10 software. The optimal conditions for HHV, mass yield, and energy yield were 15.802 MJ/kg, 63.754%, and 67.415% respectively which occurred in the 205.358 °C, 30 min reaction time, and pH of 5. The temperature was the most influential parameter. The morphological, physicochemical, thermal, and crystalline properties of the hydrochar with the maximum HHV, mass yield and energy yield were evaluated as well. These results demonstrate that HTC is a suitable process to produce hydrochar, which can be used as a direct solid fuel. • Hydrothermal carbonization of sewage sludge with sawdust and cornstalk was investigated. • Response surface optimization hydrothermal carbonization process was studied. • The morphological, physicochemical, thermal, and crystalline properties of the hydrochar are reported. • The optimal HHV was 15.802 MJ/kg. • The process can produce hydrochar which can be used for direct combustion or activated carbon.

Effect of Turning Frequency on the Survival of Fecal Indicator Microorganisms during Aerobic Composting of Fecal Sludge with Sawdust

Abstract: The study investigated the effect of turning frequency on survival of fecal indicator pathogens (E. coli, Enterococcus spp., Salmonella spp. and helminth eggs) during fecal sludge (FS) co-composting with sawdust. Dewatered FS was mixed with sawdust and composted on a pilot scale using different turning frequencies—i.e., 3 days (3TF), 7 days (7TF), and 14 days (14TF). Composting piles were monitored weekly for survival of fecal indicator microorganisms and evolution of selected physical and chemical characteristics for 14 weeks. Our results show that turning frequency has a statistically significant (p < 0.05) effect on pathogen inactivation in FS compost. The 3TF piles exhibited shorter pathogen inactivation periods (8 weeks) than 7TF and 14TF piles (10 weeks). Temperature-time was found to be the major factor responsible for the survival of pathogens in FS composting piles, followed by indigenous microbial activities and toxic by-products (monitored as NH4+-N). Our study findings suggest that even at low composting temperatures, the high turning frequency can enhance pathogen inactivation. This is a significant finding for composting activities in some rural areas where suitable organic solid waste for co-composting with FS to attain the recommended high thermophilic conditions could be greatly lacking.

Powdered and beaded sawdust materials modified iron (III) oxide-hydroxide for adsorption of lead (II) ion and reactive blue 4 dye

Abstract: Abstract The problems of lead and reactive blue 4 (RB4) dye contamination in wastewater are concerns because of their toxicities to aquatic life and water quality, so lead and RB4 dye removals are recommended to remove from wastewater before discharging. Sawdust powder (SP), sawdust powder doped iron (III) oxide-hydroxide (SPF), sawdust beads (SPB), and sawdust powder doped iron (III) oxide-hydroxide beads (SPFB) were synthesized and characterized with various techniques, and their lead or RB4 dye removal efficiencies were investigated by batch experiments, adsorption isotherms, kinetics, and desorption experiments. SPFB demonstrated higher specific surface area (11.020 m 2 g −1 ) and smaller pore size (3.937 nm) than other materials. SP and SPF were irregular shapes with heterogeneous structures whereas SPB and SPFB had spherical shapes with coarse surfaces. Calcium (Ca) and oxygen (O) were found in all materials whereas iron (Fe) was only found in SPF and SPFB. O–H, C–H, C=C, and C–O were detected in all materials. Their lead removal efficiencies of all materials were higher than 82%, and RB4 dye removal efficiencies of SPB and SPFB were higher than 87%. Therefore, adding iron (III) oxide-hydroxide and changing material form helped to improve material efficiencies for lead or RB4 dye adsorption. SP and SPB corresponded to Langmuir model related to a physical adsorption process whereas SPF and SPFB corresponded to the Freundlich model correlated to a chemisorption process. All materials corresponded to a pseudo-second-order kinetic model relating to the chemical adsorption process. All materials could be reused more than 5 cycles with high lead removal of 63%, and SPB and SPFB also could be reused more than 5 cycles for high RB4 dye removal of 72%. Therefore, SPFB was a potential material to apply for lead or RB4 dye removal in industrial applications.

Natural Rubber Composites Using Hydrothermally Carbonized Hardwood Waste Biomass as a Partial Reinforcing Filler- Part I: Structure, Morphology, and Rheological Effects during Vulcanization

Abstract: A new generation biomass-based filler for natural rubber, ‘hydrochar’ (HC), was obtained by hydrothermal carbonization of hardwood waste (sawdust). It was intended as a potential partial replacement for the traditional carbon black (CB) filler. The HC particles were found (TEM) to be much larger (and less regular) than CB: 0.5–3 µm vs. 30–60 nm, but the specific surface areas were relatively close to each other (HC: 21.4 m2/g vs. CB: 77.8 m2/g), indicating a considerable porosity of HC. The carbon content of HC was 71%, up from 46% in sawdust feed. FTIR and 13C-NMR analyses indicated that HC preserved its organic character, but it strongly differs from both lignin and cellulose. Experimental rubber nanocomposites were prepared, in which the content of the combined fillers was set at 50 phr (31 wt.%), while the HC/CB ratios were varied between 40/10 and 0/50. Morphology investigations proved a fairly even distribution of HC and CB, as well as the disappearance of bubbles after vulcanization. Vulcanization rheology tests demonstrated that the HC filler does not hinder the process, but it significantly influences vulcanization chemistry, canceling scorch time on one hand and slowing down the reaction on the other. Generally, the results suggest that rubber composites in which 10–20 phr of CB are replaced by HC might be promising materials. The use of HC in the rubber industry would represent a high-tonnage application for hardwood waste.

Utilization of Azadirachta indica Sawdust as a Potential Adsorbent for the Removal of Crystal Violet Dye

Abstract: The current study examines the feasibility of recycling artificially polluted wastewater that contains crystal violet (CV) organic dye by using Azadirachta indica sawdust (AISD) waste as a highly cost-effective adsorbent. Different analytical techniques, viz., SEM/EDX, TEM/SAED, BET, XRD, TGA-DTG, point of zero charge (pHpzc), and FTIR, were used to characterize the adsorbent. Studies of batch adsorption were performed with varying contact times, starting concentrations of CV, pH levels, doses and particle sizes of AISD, and temperatures. After assessing the results using the Langmuir, Freundlich, and Temkin isotherm models, it was observed that the Langmuir model best fits the data. Various models were employed to analyze the kinetic findings, and it was confirmed that the pseudo-second-order model appears to be the most accurate. The values of ΔH° (50.01 kJ mol−1), ΔG° (−10.254 to −5.043 kJ mol−1), and ΔS° (182.47 J K−1mol−1), obtained in a temperature range of 303–333 K, revealed that the process was spontaneous, endothermic, and accompanied by an increase in entropy. Based on experimental findings and their analyses, it was concluded that the adsorbent made from AISD is one of the most effective among those obtained from domestic, agricultural, and industrial wastes. Thus, the present adsorbent can be effectively exploited to make dye-contaminated water reusable.

Efficient removal of bisphenol A by a novel biochar-based Fe/C granule via persulfate activation: Performance, mechanism, and toxicity assessment

Abstract: Fe–C microelectrolysis is an efficient wastewater treatment technology for biorefractory pollutants. However, the poor stability and complicated separation mechanism of microelectrolytic materials hinder their application in advanced oxidation processes. Thus, herein, catalytic Fe–C microelectrolysis granules (FeBCGs) were prepared using Fe powder and sawdust and were used as persulfate (PS) activators for bisphenol A (BPA) removal. The effects of the calcination temperature, Fe/sawdust mass ratio, FeBCG concentration, PS concentration, initial pH, and initial BPA concentration were investigated. Under optimal conditions ([FeBCG]0 = 0.5 g/L, [PS]0 = 1 mM, without pH adjustment), the BPA removal efficiency reached 100% within 20 min. The FeBCGs presented numerous functional groups and a porous structure, which are beneficial for PS activation and BPA removal. The BPA degradation mechanism was elucidated via radical capture experiments, electron paramagnetic resonance spectroscopy, electrochemical analysis, density functional theory calculations, and high-performance liquid chromatography–mass spectrometry, which revealed that SO4•−, •OH, O2•−, 1O2, and electron transfer contributed to BPA removal. Additionally, the ecotoxicity of the intermediates was evaluated. The FeBCGs exhibited high stability and resistance to inorganic anions and natural organic matter. These findings may provide guidelines for the design and development of integrated microelectrolysis materials coupled with advanced oxidation processes for water treatment.

Effect of reinforced recycled sawdust-fibers additive on the performance of ecological compressed earth bricks

Abstract: This study assesses the potential of waste wood sawdust, as a construction material additive, on the mechanical, thermal and physicochemical properties of compressed earth bricks. Following X-Ray Diffraction and Fluorescence analysis, the used raw clay material, retrieved from Ifrane, Morocco, was found to be of type Illite, with a prominent SiO2 content, 59.60%, making it a suitable construction material. Multiple waste additive proportions were analyzed (0%, 1%, 3%, 7%, 15% and 20%), by weight, at different sizes: small size: (δ ≤ 0.5 mm), medium size: (0.5 mm < δ ≤ 1 mm), and large size: (1 mm < δ ≤ 3 mm). The incorporation of higher recycled sawdust waste additive content at larger sizes produced bricks with higher porosity levels. This resulted in manufacturing lightweight brick structures, below the 1.70 g/cm3 permissible limit, with higher water absorption rates. Improvements in compressive strength in prepared samples were observed with the incorporation of smaller additive sizes. In fact, 3% additive specimens recorded a 6.05 MPa at larger sizes, compared to 7.69 MPa with smaller additive sizes, reflecting a 22% mechanical compressive strength gain. Produced samples manifested enhanced thermal performances with the use of the sawdust waste additive in the 60% and 36% range for thermal conductivity and specific heat capacity, respectively; in addition to recording prominent energy savings in terms of thermal heating and cooling loads, with energy gains in the 50% interval. Theoretical models were developed to test the accuracy of the experimental findings. An obtained good correlation coefficient, very close to 1, corroborated the accuracy of the collected findings.

Scheffe’s Simplex Optimization of Flexural Strength of Quarry Dust and Sawdust Ash Pervious Concrete for Sustainable Pavement Construction

Abstract: Pervious concrete provides a tailored surface course with high permeability properties which permit the easy flow of water through a larger interconnected porous structure to prevent flooding hazards. This paper reports the modeling of the flexural properties of quarry dust (QD) and sawdust ash (SDA) blended green pervious concrete for sustainable road pavement construction using Scheffe’s (5,2) optimization approach. The simplex mixture design method was adapted to formulate the mixture proportion to eliminate the set-backs encountered in empirical or trials and the error design approach, which consume more time and resources to design with experimental runs required to evaluate the response function. For the laboratory evaluation exercise, a maximum flexural strength of 3.703 N/mm2 was obtained with a mix proportion of 0.435:0.95:0.1:1.55:0.05 for water, cement, QD, coarse aggregate and SDA, respectively. Moreover, the minimal flexural strength response of 2.504 N/mm2 was obtained with a mix ratio of 0.6:0.75:0.3:4.1:0.25 for water, cement, QD, coarse aggregate and SDA, respectively. The test of the appropriateness of the developed model was statistically verified using the Student’ t-test and an analysis of variance (ANOVA), and was confirmed to be acceptable based on computational outcomes at the 95% confidence interval. Furthermore, the scanning electron microscopy (SEM) and energy dispersive X-ray (EDX) were used to evaluate the morphological and mineralogical behavior of green prior concrete samples with various additive mixture compositions. The addition of QD and SDA, on the other hand, aided the creation of porous microstructures in the concrete matrix due to fabric changes in the concrete mixture, potentially aided by the formation of cementitious compounds such as calcium aluminate hydrate and calcium silicate hydrate.

Effect of Acid Pretreatment on the Primary Products of Biomass Fast Pyrolysis

Abstract: A high load of inorganics in raw lignocellulosic biomass is known to inhibit the yield of bio-oil and alter the chemical reactions during fast pyrolysis of biomass. In this study, palm kernel shell (PKS), an agricultural residue from palm oil production, and two other woody biomass samples (mahogany (MAH) sawdust and iroko (IRO) sawdust) were pretreated with distilled water or an acidic solution (either acetic, formic, hydrochloric (HCl) or sulfuric acid (H2SO4)) before fast pyrolysis in order to investigate its effect on the primary products and pyrolysis reaction pathways. The raw and pretreated PKS, MAH and IRO were pyrolysed at 600 °C and 5 s with a micro-pyrolyser connected to a gas chromatograph–mass spectrometer/flame ionisation detector (GC-MS/FID). Of the leaching solutions, HCl was the most effective in removing inorganics from the biomass and enhancing the primary pyrolysis product formed compared to the organic acids (acetic and formic acid). The production of levoglucosan was greatly improved for all pretreated biomasses when compared to the original biomass but especially after HCl pretreatment. Additionally, the relative content of the saccharides was maximised after pretreatment with H2SO4, which was due to the increased production of levoglucosenone. The relative content of the saccharides increased by over 70%. This increase may have occurred due to a possible reaction catalysed by the remaining acid in the biomass. The production of furans, especially furfural, was increased for all pretreatments but most noticeable when H2SO4 was used. However, the relative content of acids and ketones was generally reduced for PKS, MAH and IRO across all leaching solutions. The relative content of the phenol-type compound decreased to a large extent during pyrolysis after acid pretreatment, which may be attributed to dehydration and demethoxylation reactions. This study shows that the production of valuable chemicals could be promoted by pretreatment with different acid solutions.