Optimization of the chromium (Cr+6) reduction from waterways using chemically and bacterially treated agro-waste.

Heavy metals, a major source of pollution in the environment, pose a substantial threat due to their non-biodegradability and ability to accumulate in living organisms, causing health problems. Recently, researchers have been searching for cost-effective and safe ways to remove heavy metals from polluted waterways using agricultural waste substitutes. The present study focused on the low-cost treatments for the reduction of chromium Cr+6 metal from the effluent, wherein it has been found that chemically and bacterially treated agro-waste had increased heavy metal ion adsorption capabilities. A sequential optimization of the process parameters was attempted using Plackett-Burman design (PBD) and central composite design of response surface methodology (CCD-RSM) for the maximum reduction of the chromium metal from the effluent. A total of eight parameters were screened out using a 12-run PBD experiment. Out of the eight parameters, time, HCl, NaOH, and bacterial treatments were found to be significantly affecting the maximum reduction of Cr+6 from the effluent. To investigate the interactions' effects of the chosen parameters, they were evaluated using CCD-RSM. Maximum 74% Cr+6 reduction was achieved under the optimum treatment to rice husk of HCl 4.52 N, NaOH 3.53 N, bacterial suspension 7.41%, and with an interaction time 14.32 min using 30 run CCD-RSM experiment. A scanning electron microscope was used to confirm the effects of selected variables on the agro-waste for the Cr+6 reductions, as well as a Fourier transform infrared spectrometer.

Synthesis of X@DRHC (X=Co, Ni, Mn) catalyst from comprehensive utilization of waste rice husk and spent lithium-ion batteries for efficient peroxymonosulfate (PMS) activation.

Highly efficient resource recycling and comprehensive utilization play a crucial role in achieving the goal of reducing resource wasting, environmental protection, and achieving goal of sustainable development. In this work, the two kinds waste resources of agricultural rice husk and metal ions (Co, Ni, and Mn) from spent lithium-ion batteries have been skillfully utilized to synthesize novel Fenton-like catalysts. Desiliconized rice husk carbon (DRHC) with rich pore structure and large specific surface area from rice husk has been prepared and used as scalable carrier, and dandelion-like nanoparticles cluster could be grown in situ on the surface of the carrier by using metal ions contained waste water. The designed catalysts (X@DRHC) as well as their preparation process were characterized in detail by SEM, TEM, BET, XRD and XPS, respectively. Meanwhile, their catalytic abilities were also studied by activating potassium peroxomonosulfate (PMS) to remove methylene blue (MB). The results indicate X@DRHC displays excellent degradation efficiency on MB with wide pH range and stable reusability, which is suitable for the degradation of various dyes. This work has realized the recycling and high-value utilization of waste resources from biomass and spent lithium-ion batteries, which not only creates an efficient way to dispose waste resources, but also shows high economic benefits in large-scale water treatment.

Kinetic and thermodynamic studies on the thermal inactivation of lipase immobilized on glutaraldehyde-activated rice husk silica.

The objective of this study was to obtain sufficient information on the thermal stabilization of a food-grade lipase from Thermomyces lanuginosus (TLL) using the immobilization technique. To do this, a new non-porous support was prepared via the sequential extraction of SiO2 from rice husks, followed by functionalization with (3-aminopropyl) triethoxysilane - 3-APTES (Amino-SiO2), and activation with glutaraldehyde - GA (GA-Amino-SiO2). We evaluated the influence of GA concentration, which varied from 0.25% v v-1 to 4% v v-1, on the immobilization parameters and enzyme thermal stabilization. The thermal inactivation parameters for both biocatalyst forms (soluble or immobilized TLL) were calculated by fitting a non-first-order enzyme inactivation kinetic model to the experimental data. According to the results, TLL was fully immobilized on the external support surface activated with different GA concentrations using an initial protein load of 5 mg g-1. A sharp decrease of hydrolytic activity was observed from 216.6 ± 12.4 U g-1 to 28.6 ± 0.9 U g-1 of after increasing the GA concentration from 0.25% v v-1 to 4.0% v v-1. The support that was prepared using a GA concentration at 0.5% v v-1 provided the highest stabilization of TLL - 31.6-times more stable than its soluble form at 60 °C. The estimations of the thermodynamic parameters, e.g., inactivation energy (Ed), enthalpy (ΔH#), entropy (ΔS#), and the Gibbs energy (ΔG#) values, confirmed the enzyme stabilization on the external support surface at temperatures ranging from 50 to 65 °C. These results show promising applications for this new heterogeneous biocatalyst in industrial processes given the high catalytic activity and thermal stability.

Investigating the effectiveness of rice husk-derived low-cost activated carbon in removing environmental pollutants: a study of its characterization.

The chemically activated biochar was produced through the pyrolysis of rice husk. Thermal gravimetric and elemental analysis were conducted to characterize the raw rice husk. The activated biochar product underwent evaluation through SEM, BET and, FT-IR analysis. This cost-effective activated carbon was utilized as an adsorbent for the elimination of environmental pollutants. At a temperature of 25 °C, the activated biochar product exhibited an impressive maximum CO2 adsorption capacity of 152 mg/g. This exceptional performance can be attributed to its notable surface area and porosity, measuring at 2,298 m2/g and 0.812 cm3/g, respectively. This product was also utilized to remove methyl red (MR) dye from an aqueous solution. The optimal parameters for the removal of MR were determined as follows: a pH of 6.0, a temperature of 25 °C, an initial MR concentration of 50 mg/L, and an adsorbent dosage of 0.4 g/L. At a duration of 140 min, the system attained its maximum equilibrium adsorption capacity, reaching a value of 62.06 mg/g. Furthermore, the calculated maximum MR removal efficiency stood at an impressive 99.31%. The thermodynamic studies demonstrated that the MR removal process was spontaneous, exothermic, and increased randomness. Kinetic studies suggested that the pseudo-second-order model can fit well.

Rice is the staple food for a significant portion of the world's population. Rice husk, which is released during the production and processing of rice, is one of the most important agricultural wastes worldwide. In this study, low cost activated carbon was produced by converting renewable resource such as rice husk biomass into a product with high added value. The resulting product, with its high surface area, can offer a more sustainable, cost-effective, and versatile alternative for a range of industrial, environmental, and medical applications.

Soil-mustard revitalization via rice husk ash, a promising soil amendment material for sustainable management of heavy metal contamination in tropical ecosystem.

Prolonged wastewater irrigation in agriculture has led to the accumulation of heavy metals in soil, endangering both the soil quality and food safety, thereby posing a potential threat to human health through the consumption of contaminated crops. The present study aimed to enhance the yield of mustard (Brassica juncea L. cv. Varuna and NRCHB 101) plants and stabilize heavy metals (Cd, Cr, Ni, Cu, and Zn) in wastewater-irrigated soil using rice husk ash (RHA), rice mill by-product, collected from Chandauli region of Eastern Uttar Pradesh, India. Results demonstrated significant improvements in growth, biomass, physiology, and yield of mustard plant with increasing RHA application in wastewater irrigated soil (p ≤ 0.05). Heavy metal accumulation in different parts of mustard plants decreased as RHA application rate increased. Applying RHA at 2% in soil proved to be most effective in reducing Cd, Cr, Ni, Cu, and Zn accumulation in seeds by 29%, 29.6%, 23.1%, 21.3% and 20.1%, respectively in Varuna and 30.1%, 21.4%, 11.1%, 12.1%, and 28.5%, respectively in NRCHB 101cultivars. The present findings showed that RHA amendment in wastewater irrigated soil had reduced bioaccumulation of Cd, Cr, Ni, Cu, and Zn and consequently their toxicity in cultivated mustard plants. A novel application of RHA is unveiled in this research, offering a promising solution to promote sustainable agriculture and to reduce heavy metal associated health risks within the soil-mustard system.

An efficient eco-friendly adsorbent material based on waste copper slag-biomass ash geopolymer: dye sorption capacity and sustainable properties.

The primary intent of the research is to comprehensively assess the environmental benefits and cost dynamics associated with the adsorption process of CS-RHA (Copper Slag and Rice Husk Ash) to produce a novel geopolymer adsorbent material for application in wastewater treatment. The geopolymer forms a polyiron sialate network under alkali activation by dissolving fayalite, and aluminium silicate to ferro-ferri silicate hydrate gel. The mechanical strength, leaching characteristics, and microstructure of the geopolymer were determined using XRD and FTIR, and magnetic properties by VSM as well surface properties were derived from BET surface area and zeta potential. Recognizing the critical role of sodium iron silicate hydrate (NFS) in the sorption of methylene blue (MB) dyestuff, batch experiments were carried out using different adsorbents. The results indicated that the dye removal efficiency increased from 60% in control samples (FS) to 98% for the blend (FS1) under different pH values. The data was found to fit with the nonlinear form of Freundlich isotherm and follow pseudo-second-order kinetics. The active adsorption sites were deduced as -O-Fe-O-Si-O-Na and Si-OH groups. The addition of RHA increases the adsorption capacity of the geopolymer in a short time through chemical adsorption. The significant negative surface charge promotes MB adsorption via improved electrostatic attraction. The spent adsorbents were recovered through magnetic separation with a retrieval rate of 80-85% and active sites were rejuvenated by calcination. Consequently, waste copper slag emerges as a promising adsorbent with minimum potential ecological risk and high effective recycling capacity.

Constructing Biomass-Based Ultrahigh-Rate Performance SnOy @C/SiOx Anode for LIBs via Disproportionation Effect.

To break the stereotype that silica can only be reduced via a magnesiothermic and aluminothermic method at low-temperature condition, the novel strategy for converting silica to SiOx using disproportionation effect of SnO generated via low-temperature pyrolysis coreduction reaction between SnO2 and rice husk is proposed, without any raw materials waste and environmental hazards. After the low-temperature pyrolysis reaction, SnOy @C/SiOx composites with unique structure (Sn/SnO2 dispersed on the surface and within pores of biochar as well as SiOx residing in the interior) are obtained due to the exclusive biological properties of rice husk. Such unique structural features render SnOy @C/SiOx composites with an excellent talent for repairing the damaged structure and the highly electrochemical storage ability (530.8 mAh g-1 at 10 A g-1 after 7500 cycles). Furthermore, assembled LiFePO4 ||SnOy -50@C/SiOx full cell displays a high discharge capacity of 463.7 mAh g-1 after 100 cycles at 0.2 A g-1 . The Li+ transport mechanism is revealed by density functional theory calculations. This work provides references and ideas for green, efficient, and high-value to reduce SiO2 , especially in biomass, which also avoids the waste of raw materials in the production process, and becomes an essential step in sustainable development.

Spirosoma oryzicola sp. nov., isolated from dried rice husk.

Strain RHs26T is an aerobic, Gram-stain-negative, non-flagellated and rod- or filamentous-shaped (1.0-1.1×2.3-50 µm) bacterium that was isolated from dried rice husk. It was positive for oxidase and catalase, hydrolysed starch and Tween 80, and weakly hydrolysed CM-cellulose. The strain grew at temperatures between 10 and 37 °C (optimum, 28 °C), in 0-1 % NaCl (optimum, 0 %) and at pH 6.0-9.0 (optimum, pH 7.0-8.0). The predominant membrane fatty acids were summed feature 3 (C16 : 1 ω7c and/or C16 : 1 ω6c), C16 : 1 ω5c, iso-C15 : 0 and iso-C17 : 0 3-OH. The major polar lipids were phosphatidylethanolamine, an unidentified aminolipid, two unidentified aminophospholipids and two unidentified lipids. The predominant quinone was menaquinone MK-7. Phylogenetic analysis based on 16S rRNA gene sequences indicated that strain RHs26T belongs to the genus Spirosoma, presenting the highest sequence similarity to Spirosoma agri S7-3-3T (95.8 %). The genomic DNA G+C content of strain RHs26T was 49.5 %. Strain RHs26T showed the highest orthologous average nucleotide identity (OrthoANI) and digital DNA-DNA hybridization (dDDH) values of 76.4 % and 20.0 % with S. agri KCTC 52727T while sharing OrthoANI and dDDH values of 74.6 % and 19.2 % with Spirosoma terrae KCTC 52035T, the closest relative in the phylogenomic tree. Based on the results of a polyphasic taxonomic study, strain RHs26T represents a novel species in the genus Spirosoma, for which the name Spirosoma oryzicola sp. nov. is proposed. The type strain is RHs26T (=JCM 35224T=KACC 17318T).

Using a promising biomass-based biochar in photocatalytic degradation: highly impressive performance of RHB/SnO2/Fe3O4 for elimination of AO7.

The release of industrial dyes into the environment has recently increased, resulting in harmful effects on people and ecosystems. In recent years, the use of adsorbents in photocatalytic nanocomposites has attracted significant interest due to their low cost, efficiency, and eco-friendly physical and chemical characteristics. Herein, Acid Orange 7 (AO7) removal was investigated by photocatalytic degradation using Rice Rusk Biochar (RHB), Tin (IV) Oxide (SnO2), and Iron Oxide (Fe3O4) as heterogeneous nanocomposite. After the preparation of RHB, the nanocomposite was synthesized and characterized using Field Emission Scanning Electron Microscope (FESEM), X-ray Powder Diffraction (XRD), Brunauer-Emmett-Teller (BET), and Fourier-Transform Infrared Spectroscopy (FT-IR). To optimize the elimination of AO7 by the One-Factor-At-a-Time (OFAT) method, effective parameters including mixing ratio (RHB:SnO2:Fe3O4), dye concentration, solution pH, and nanocomposite dose were studied. The results showed that the removal efficiency of AO7 after 120 min under the optimal mixing ratio of 1:1.5:0.6, dye concentration of 75 mg/l, solution pH of 4, and nanocomposite dose of 0.7 g/l was 92.37%. Moreover, Chemical Oxygen Demand (COD) and Total Organic Carbon (TOC) removal rates were obtained at 82.22 and 72.22%, respectively. The Average Oxidation State (AOS) and Carbon Oxidation State (COS) of the AO7 solution were increased after the process, indicating biodegradability improvement. Various scavenger effects were studied under optimal conditions, and the results revealed that O2- and H+ reactive species play a crucial role in the photocatalytic degradation of AO7. The reusability and stability of nanocomposite were tested in several consecutive experiments, and the degradation efficiency was reduced from 92 to 79% after five consecutive cycles. It is expected that this research contributes significantly to the utilization of agricultural waste in photocatalytic nanocomposites for the degradation of environmental pollutants.

Synthesis and characterization of nanobiochar from rice husk biochar for the removal of safranin and malachite green from water.

Xenobiotic pollution in environment is a potential risk to marine life, and human health. Nanobiotechnology is an advanced and emerging solution for the removal of environmental pollutants. Adsorption-based technologies are being used to alleviate the global prevalence of xenobiotics like dyes, due to their high efficacy and cost effectiveness. Current study explored the potential of nanobiochar syntehsized via ultrasonication and centrifugation from rice husk for dye removal from water. It involves the synthesis of nanobiochar from rice husk biochar for removal of Safranin, Malachite green, and a mixture of both from aqueous water. Biochar was synthesized through pyrolysis at 600 °C for 2 h. To convert it into nanobiochar, sonication and centrifugation techniques were applied. The yield obtained was 27.5% for biochar and 0.9% for nanobiochar. Nanobiochar analysis through Fourier-Transform Spectrometer (FTIR), X-ray Power Diffraction (XRD) and scanning electron microscopy (SEM) suggested its crystalline nature having minerals rich in silicon, with a cracked and disintegrated carbon structure due to high temperature and processing treatments. Removal of dyes by nanobiochar was evaluated by changing different physical parameters i.e., nanobiochar dose, pH, and temperature. Pseudo-first order model and pseudo-second order model were applied to studying the adsorption kinetics mechanism. Kinetics for adsorption of dyes followed the pseudo-second order model suggesting the removal of dyes by process of chemical sorption. High adsorption was found at a higher concentration of nanobiochar, high temperature, and neutral pH. Maximum elimination percentages of safranin, malachite green, and a mixture of dyes were obtained as 91.7%, 87.5%, and 85% respectively. We conclude that nanobiochar could be a solution for dye removal from aqueous media.

Adsorption and photodegradation of micropollutant in wastewater by photocatalyst TiO2/rice husk biochar.

With the acceleration of global industrialization, organic pollutants have become a threat to ecological safety and human health. This work prepared TiO2/rice husk biochar (TiO2/BC) for removal of bisphenol A (BA) micropollutant in wastewater. Experiment results revealed a low BA removal efficiency by TiO2/BC was observed at 34.5% under the dark environment. However, the removal rate of BA by UV light-assisted TiO2/BC significantly increased to 97.6% in 1 h. The results also demonstrated that the removal performance of BA using TiO2/BC was 2.1times higher than that of commercial TiO2 (46.4%). Besides, the removal efficiency of BA by reused TiO2/BC after eight cycles slightly decreased by 12.8%, demonstrating the excellent properties of the prepared composite. TiO2/BC also exhibited high removal efficiency of BA (over 89%) from the synthetic wastewater sample, indicating the potential utilization of composite for removing BA in wastewater. This work provides a new way to turn biomass waste into useful material and effective method to remove micropollutant BA.

Dilute acid pretreatment for enhancing the enzymatic saccharification of agroresidues using a Botrytis ricini endoglucanase.

The enormous amount of agroindustrial residues generated in Brazil can be used as biomass to produce fermentable sugars. This study compared the pretreatments with different proportions of dilute acid. The method involved pretreatment with 0.5%, 1%, and 1.5% (v/v) sulfuric acid, followed by hydrolysis using the halotolerant and thermostable endoglucanase from Botrytis ricini URM 5627. The physicochemical characterization of plant biomass was performed using XRD, FTIR, and SEM. The pretreatment significantly increased the production of fermentable sugars following enzymatic saccharification from wheat bran, sugarcane bagasse, and rice husk: 153.67%, 91.98%, and 253.21% increment in sugar production; 36.39 mg⋅g-1 ± 1.23, 39.55 mg⋅g-1 ± 1.70, and 42.53 mg⋅g-1 ± 7.61 mg⋅L-1 of glucose; and 3.26 ± 0.35 mg⋅g-1 , 3.61mg⋅g-1 ± 0.74 and 3.59 mg⋅g-1 ± 0.80 of fructose were produced, respectively. In conclusion, biomass should preferably be pretreated before the enzymatic saccharification using B. ricini URM 5627 endoglucanase.

Development of Bacteria biofertilizers using locally isolated rhizosphere populations and agricultural refuse and their impacts on growth of local test crops.

Biofertilizers are the preparations of live microorganisms added to the root, seed or soil to promote plant growth. In this study, Plant Growth Promoting Bacteria able to solubilize insoluble phosphate (P) and potassium (K) forms were isolated, characterized and identified. Two isolates that demonstrated excellent solubilization of potassium or phosphate from abundant and bio-available waste biomass (rice husk and cattle bone) were used to produce biofertilizers by solid-state fermentation. The biofertilizers were applied to grow three food security crops, Zea mays, Solanum lycopersicum, and Arachis hypogea, in a screenhouse, and monitored for growth impacts. Treatments A, B, and A + B biofertilizers caused a significant (p < 0.05) increase in plant dry weights. The highest microbial colonization was obtained from treatment A + B (for S. lycopersicum) with a microbial count (log 2.89 (108) cfu/g), whereas treatment with B (for A. hypogea) had the least microbial count (log 2.73 (108) cfu/g). Maximum values of experimental parameters: shoot height, leaf number, plant dry weight and leaf width were obtained with the combined application of both biofertilizers. P and K solubilizing PGPB have shown potential for use as biofertilizers in growing these key crops under the soil conditions and in the environment studied.

This work demonstrates a first, sensitive and reliable method for low-cost, sustainable, eco-friendly production and utilization of biofertilizers for improved growth of major tropical food security crops using native bacterial strains in a defined tropical agronomic environment. Its novelty is the choice of Bacillus cereus and Pseudomonas aeruginosa singly and in combination (synergy/additive) as biofertilizers for growing tropical test crops. It also demonstrated the use of a novel and cheap delivery method/carrier that ensured the establishment and persistence of PGPB in the rhizosphere. Native B. cereus and P. aeruginosa were able to solubilize and make available to plants phosphate and potassium, thereby improving soil quality and plant growth while the process achieved the reuse of waste biomass.

Cadmium removal from aqueous solution by blended bamboo sawdust/rice-husk biochar; optimization of influencing parameters.

This study attempted to investigate the adsorptive potential of blended bamboo (Oxytenanthera abyssinica) sawdust/rice husk (BSD/RH) at a ratio of 1:1 carbonized at 400 °C for the sorption of cadmium ions from synthetic solutions in batch mode. The Box-Behnken Design in response surface methodology (RSM) was used to achieve the best removal efficiency and adsorption capacity of the biochar. With a p-value of 0.0001, the initial Cd2+ concentration and adsorbent dose were discovered to be the most significant parameters controlling the adsorption capacity and removal efficiency of Cd2+ from the solution. At a pH of 8.95, ionic strength of 0.020 mol/L KNO3, a contact time of 15 min, an initial concentration of 200 mg/L, and an adsorbent dose of 0.5 g, the optimum Cd2+ removal and adsorption capacity of 99.97% and 358.65 mg/g, respectively, were obtained. The optimized conditions were later used to determine the removal efficiency and adsorption capacity of pristine biochars of rice husk and bamboo sawdust, which were found to be 79.8% and 83.7%, respectively. This finding indicates the potential for using biosorbent derived from blended feedstock materials to remove heavy metals such as cadmium.

Many studies investigated the pollutant removal potential of agricultural wastes as single feedstock adsorbent materials. The novel aspect of this study is that it examines their potentials on Cd²⁺ removal by combining two feedstocks (bamboo saw dust and rice husk) while optimizing the common influencing factors. Furthermore, a comparative analytical study was carried out between the blended feedstock biochar and their respective pristine ones. According to the findings, using blended biochar instead of pristine biochar results in a significant increase in Cd removal efficiency.

Efficacy of rice husk and halophilic bacterial biofilms in the treatment of saline water.

Water salinity causes less production of agricultural productivity, low economic returns, soil destructions, less sustainability, and reduction in the germination rate. The current study was aimed to understand the combined potential of halophilic bacteria and rice husk in treating water salinity. In total, 10 halophilic bacterial isolates were isolated from Khewra Mines, Pakistan. Bacterial isolates were characterized by biochemical tests. 16S rRNA gene sequencing identified the isolate SO 1 as Bacillus safensis (accession number ON203008) being the promising halophilic bacteria tolerating upto 3 M NaCl concentration. Next, rice husk was used as carbon source for bacterial biofilm formation, growth and propagation. For saline water treatment, the experimental setting comprising glass wool, rice husk and artificial sea water (3 M) was set. B. safensis biofilm was developed in test samples to desaline the saline water containing 3 M NaCl concentration. Following NaCl decline, flame photometric analysis was used to check the desalination extent of treated saline water. Results showed decreased sodium level in sea water in the presence of rice husk and glass wool. The eluted water used for the germination of Zea mays seeds showed improved growth performance. Also, decreased photosynthetic pigments (chlorophyll "a" = 18.99, and chlorophyll "b" = 10.65), sugar contents (0.7593), and increased carotenoid (1526.91), protein contents (0.4521) were noted compared to control. This eco-friendly approach for bioremediation of salt-affected soils to optimize crop yields under stress through halophilic bacteria and rice husk may overcome the problem of the reduced yield of cash crops/agriculture and water shortage by salinity.

Experimental investigation on composites incorporating rice husk nanoparticles for environmental noise management.

Environmental noise characteristics are determined by factors besides its source. One such factor is reverberation time, which in city canyons tends to be high due to the reflective characteristics of materials commonly used in building facades. Incorporating sound absorbing materials into building facades can help improve urban environments. This research evaluates different facade materials (concrete mix, mortar mix, vinyl spackling, and epoxy resin) incorporated with rice husk nanoparticles (NPs). Rice husk, in addition to presenting good properties for acoustic absorption, is one of the main agricultural wastes worldwide. Additionally, the characteristic of rice husk nanoparticles is correlated with milling time (longer grinding times enhance production of rice husk NPs). Sound absorption coefficients levels increase for compounds with a greater amount of rice husk NPs.

Biochar improves compost humification, maturity and mitigates nitrogen loss during the vermicomposting of cattle manure-maize straw.

Maintaining humidification and inhibiting nitrogen losses during vermicomposting process have emerged to be key factors for high-quality productions. Previous data have showed outstanding functions of biochar addition in improving vermicomposting quality. In this study, the influence of bamboo biochar (BB) and rice husk biochar (RHB) addition on compost maturity, humification and nitrogen loss was evaluated in the vermicomposting of cattle manure and maize straw. Results revealed that BB or RHB amendment improved organic matter decomposition, enhanced humification and maturity of compost, particularly in the 10% BB treatment, which exerted the highest humic acids content and GI value. Furthermore, BB or RHB addition significantly reduced nitrogen losses, in which the volatilization of NH3 and N2O were reduced by 24.93%-66.23% and 14.91%-55.12%. The fewest nitrogen loss was detected in the treatment of 10% BB. Biochar inhibited nirK, nirS but promoted AOB-amoA, nosZ expression; fewer N2O producing bacteria (Pseudomonas, Devosia, Luteimonas genus) were observed in the biochar treatment, and thereby decreased the N2O emission. Therefore, 10% BB addition for co-vermicomposting cattle manure and maize straw is an efficient way to increase humification, maturity, and reduce nitrogen loss, and future applications following this strategy is believed to generate better productions.

Rice husk biochar - A novel engineered bio-based material for transforming groundwater-mediated fluoride cycling in natural environments.

Biochar, a promising carbon-rich and carbon-negative material, can control water pollution, harness the synergy of sustainable development goals, and achieve circular economy. This study examined the performance feasibility of treating fluoride-contaminated surface and groundwater using raw and modified biochar synthesized from agricultural waste rice husk as problem-fixing renewable carbon-neutral material. Physicochemical characterizations of raw/modified biochars were investigated using FESEM-EDAX, FTIR, XRD, BET, CHSN, VSM, pHpzc, Zeta potential, and particle size analysis were analyzed to identify the surface morphology, functional groups, structural, and electrokinetic behavior. In fluoride (F-) cycling, performance feasibility was tested at various governing factors, contact time (0-120 min), initial F- levels (10-50 mg L-1), biochar dose (0.1-0.5 g L-1), pH (2-9), salt strengths (0-50 mM), temperatures (301-328 K), and various co-occurring ions. Results revealed that activated magnetic biochar (AMB) possessed higher adsorption capacity than raw biochar (RB) and activated biochar (AB) at pH 7. The results indicated that maximum F- removal (98.13%) was achieved using AMB at pH 7 for 10 mg L-1. Electrostatic attraction, ion exchange, pore fillings, and surface complexation govern F- removal mechanisms. Pseudo-second-order and Freundlich were the best fit kinetic and isotherm for F- sorption, respectively. Increased biochar dose drives an increase in active sites due to F- level gradient and mass transfer between biochar-fluoride interactions, which reported maximum mass transfer for AMB than RB and AB. Fluoride adsorption using AMB could be described through chemisorption processes at room temperature (301 K), though endothermic sorption follows the physisorption process. Fluoride removal efficiency reduced, from 67.70% to 53.23%, with increased salt concentrations from 0 to 50 mM NaCl solutions, respectively, due to increased hydrodynamic diameter. Biochar was used to treat natural fluoride-contaminated surface and groundwater in real-world problem-solving measures, showed removal efficiency of 91.20% and 95.61%, respectively, for 10 mg L-1 F- contamination, and has been performed multiple times after systematic adsorption-desorption experiments. Lastly, techno-economic analysis was analyzed for biochar synthesis and F- treatment performance costs. Overall, our results revealed worth output and concluded with recommendations for future research on F- adsorption using biochar.

Effect of passively aerated biological pretreatment on different biomasses with diverse lignocellulosic fiber profiles.

Passively aerated biological pretreatment was applied to four different lignocellulosic biomasses with varying fiber content profiles: sugar beet pulp (SBP), brewery bagasse (BB), rice husk (RH), and orange peel (OP). In order to analyze the organic matter solubilization yield at 24 and 48 h, different percentages of activated sewage sludge (2.5-10%) were utilized as inoculum. The OP achieved the best organic matter solubilization yield in terms of soluble chemical oxygen demand (sCOD) and dissolved organic carbon (DOC) at 2.5% inoculation and 24 h: 58.6% and 20%, respectively, since some total reducing sugars (TRS) consumption was identified after 24 h. On the contrary, the worst organic matter solubilization yield was obtained with RH, the substrate with the highest lignin content among the tested, with percentages of 3.6% and 0.7% in terms of sCOD and DOC respectively. In fact, it could be considered that this pretreatment was not successful with RH. The optimum inoculation proportion was 7.5% (v/v) except for the OP (2.5% (v/v)). Finally, due to the counterproductive organic matter consumption at longer pretreatment durations, the optimal time for BB, SBP, and OP was 24 h.

Appraisal of agroforestry biomass wastes for hydrogen production by an integrated process of fast pyrolysis and in line steam reforming.

The pyrolysis and in line steam reforming of different types of representative agroforestry biomass wastes (pine wood, citrus wastes and rice husk) was performed in a two-reactor system made up of a conical spouted bed and a fluidized bed. The pyrolysis step was carried out at 500 °C, and the steam reforming at 600 °C with a space time of 20 gcatalyst min gvolatiles-1 and a steam/biomass ratio (S/B) of 4. A study was conducted on the effect that the pyrolysis volatiles composition obtained with several biomasses has on the reforming conversion, product yields and H2 production. The different composition of the pyrolysis volatiles obtained with the three biomasses studied led to differences in the initial activity and, especially, in the catalyst deactivation rate. Initial conversions higher than 99% were obtained in all cases and the H2 production obtained varied in the 6.7-11.2 wt% range, depending on the feedstock used. The stability of the catalysts decreased depending on the feedstock as follows: pine wood â‰« citrus waste > rice husk. A detailed assessment of the mechanisms of catalyst deactivation revealed that coke deposition is the main cause of catalyst decay in all the runs. However, the volatile composition derived from the pyrolysis of citrus waste and rice husk involved the formation of an encapsulating coke, which severely blocked the catalyst pores, leading to catalyst deactivation during the first minutes of reaction.