Recently, sequential crushing and compression pretreatment of water hyacinth has gained attention for its ability in removing recalcitrant lignocellulose components and extract easily from biodegradable water hyacinth juice, facilitating rapid anaerobic digestion (AD) systems. In this work, AD experiments were performed in lab-scale upflow anaerobic sludge blanket (UASB) reactors using water hyacinth juice as a substrate. To ensure the stability and enhance performance of AD, a batch experiment was performed to select the carbonization temperature and biochar size. The selected biochar was then added to the reactor and compared with the control reactor. The reactors were continuously operated for 65 days to evaluate the treatment efficiency under different hydraulic retention times (HRTs) (4, 2, and 1 days).
RESULTS
A carbonization temperature of 800 °C with a particle size of 1.58 mm was found to have a higher specific surface area of 519.538 m2 g−1 and a better pore size of 0.078 mL g−1. Biogas yields were similar between reactors with and without biochar: 208 ± 86, 370 ± 93, and 393 ± 73 mL g-VS−1 (with biochar) and 218 ± 88, 375 ± 107, and 400 ± 74 mL g-VS−1 (without biochar) at 4, 2, and 1-day HRTs, respectively. However, biochar addition improved methane quality, increasing methane content from 78.11% to 81.64% and reducing CO2 from 21.89% to 18.54%. Both systems achieved high soluble chemical oxygen demand (COD) removal at 1 day HRT: 87.1% with biochar and 85.9% without.
Tania P. Mendoza-Tinoco, María del Carmen Fajardo-Ortiz, Ulises Durán-Hinojosa, Víctor Sánchez-Vázquez, Ignacio González, Ricardo Beristain-Cardoso
BACKGROUND
Anaerobic digestion is a widely used and cost-effective technology for wastewater treatment and renewable energy recovery through biogas production. However, its efficiency significantly decreases under sub-mesophilic or room-temperature conditions due to the low metabolic activity. Recent approaches have explored electrical stimulation to enhance microbial performance. This study investigates the effect of electrical stimulation via current density (ESCD) on the performance of an upflow anaerobic sludge blanket (UASB) reactor operating at room temperature.
RESULTS
Two 2 L UASB reactors were operated at a 12 h hydraulic retention time using domestic wastewater (chemical oxygen demand: 2 ± 0.1 g L−1). The control reactor (RC) had no electrodes, whereas the experimental reactor (RE) was equipped with RuO₂/Ti mesh electrodes, to which a current density of 0.54 mA cm−2 was applied. RE showed an 86% increase in biogas production with 68% CH4, 21% CO2 and 11% H2, resembling Hythane. Methane generation shifted toward hydrogenotrophic pathways (65%) over acetoclastic (35%). Compared to the biogas produced by RC, that from RE had a 23% higher calorific value and nearly twice the methane yield. Sludge from RE exhibited a 17% lower sedimentation rate, 44% higher sludge volumetric index, and more compact granules enriched with filamentous microbes (confirmed via scanning electron microscopy). Content of extracellular polymeric substances increased by 52% and was particularly rich in proteins.
Tran Minh Khang, Tran Thi Bich Quyen, Luong Huynh Vu Thanh, Ngo Nguyen Tra My, Bui Le Anh Tuan, Duy Toan Pham, Nguyen Thi Kim Lien, Doan Van Hong Thien, Ngo Truong Ngoc Mai
BACKGROUND
The overuse of dyes is causing serious water pollution globally, becoming an urgent environmental problem. Consequently, studying dye wastewater treatment solutions has become a crucial research field. While durian husk biochar (BDH) is recognized for its excellent adsorption of organic molecules, studies on its combination with ZnO and TiO2 nanoparticles (NPs) and enhancement of methylene blue (MB) degradation remain limited.
RESULTS
In this study, BDH/ZnO/TiO2 NPs were synthesized via a hydrothermal method using ethanol and ammonia as solvents. BHD was produced through pyrolysis under oxygen-limited conditions and activated with H3PO4 to enhance its physicochemical properties. The resulting TiO2 (anatase phase, 20–35 nm) and ZnO (wurtzite structure, 100–240 nm) were well dispersed on the porous biochar matrix, which exhibited increased porosity (14.761–34.143 Å) and surface area approximately 5.5 times higher than raw biochar. The photocatalytic and adsorption performance of the materials were evaluated under UV irradiation (365 nm, 100 min) using 10 ppm MB. The removal efficiency of BDH achieved 75.77%, significantly outperforming pure TiO2 (58.52%) and ZnO (40.38%). The novel BDH/ZnO/TiO2 nanocomposite exhibited superior capabilities, achieving 98.57% removal and maintaining over 95% efficiency after three regeneration cycles. The adsorption of MB by BDH/ZnO/TiO2 best fits the Freundlich isotherm model, showing a maximum adsorption capacity of 52.21 mg g−1.
Nurul Nabila Huda Baharudin, Nor Hasmaliana Abdul Manas, Rohaida Che Man, Rosli Md Illias, Siti Kholijah Abdul Mudalip, Siti Zubaidah Sulaiman
BACKGROUND
The efficiency of recombinant enzyme secretion into the medium is essential for simplifying purification and increasing yield. However, Escherichia coli, a commonly used expression host, faces challenges such as cell lysis and plasmid instability during enzyme secretion. Cell immobilization is proposed to address this problem. This study aimed to investigate the performance of immobilized recombinant E. coli focusing on β-cyclodextrin glucanotransferase (β-CGTase) secretion, cell lysis and plasmid stability in a membrane bioreactor. The study compared two immobilization configurations, IC-9 (9 hollow-fiber membranes) and IC-19 (19 hollow-fiber membranes), as well as a shake flask system.
RESULTS
IC-9 exhibited superior performance, achieving 1.5-fold higher β-CGTase activity than IC-19. Additionally, IC-9 showed 87% lower cell lysis and 12% higher plasmid stability compared to IC-19, indicating improved process reliability. The immobilized cells in the membrane bioreactor exhibited 2.5-fold higher β-CGTase secretion, 75% lower cell lysis and 29% higher plasmid stability compared to the shake flask system. Moreover, β-CGTase secretion by immobilized cells was twice as high as that of free cells and remained stable over seven cycles, achieving a cumulative β-CGTase activity of 1120.21 U mL−1. Kinetic analysis showed that immobilized cells exhibited a lower maximum specific growth rate (0.012 h−1) compared to free cells (0.149 h−1), but significantly higher β-CGTase secretion, with an α (growth-associated production coefficient) of 1.317 U mg−1 mL−1 compared to 0.004 U mg−1 mL−1 for free cells.
Monoethanolamine-based deep eutectic solvent (MEADES) at different molar ratios (1:2, 1:3, 1:4, 1:5, 1:6, and 1:7) was prepared and used for the isolation of cardanol from cashew nutshell liquid (CNSL).
RESULTS
In this work, the density of MEADES at different molar ratios (1:2, 1:3, 1:4, 1:5, 1:6, and 1:7), isobutyl methyl ketone (IBMK), ethyl acetate (EtAc), acetone, hexane, methanol, ethanol, and butanol was measured at different temperatures (293.15–343.15 K). Subsequently, the density of the binary mixture of IBMK with EtAc over the whole composition range was measured at different temperatures (293.15–343.15 K). Further, the pH of all the prepared MEADES was determined and functional group analysis was carried out using Fourier transform infrared (FTIR) spectroscopy. Finally, the experimental isolation of cardanol was conducted with feed:ternary mixtures at different solvent ratios (50:150, 50:125, 5:100, and 50:75 mL) and characterized using FTIR spectroscopy and gas chromatography–mass spectrometry.
The conversion of organic matter in sulfate-rich wastewater to methane presents a significant challenge due to the competition between methanogenesis and sulfidogenesis. In this study, we investigated the potential of Earleaf acacia-based biochar (EA-biochar) to enhance methane production and alleviate sulfide toxicity in skim latex wastewater (SLW). The role of biochar as an extra carbon source was minimized by washing it three times before use. Anaerobic digestion of SLW was investigated under both batch and fed-batch operational modes.
RESULTS
The methane yield of the batch with EA-biochar addition was 252.85 ± 5.37 mL g−1 COD, significantly higher than that of the batch without EA-biochar (192.93 ± 5.52 mL g−1 COD). In addition, the methane production rate of the batch with EA-biochar was 25% higher than that of the batch without EA-biochar addition. The increased methane yield was correlated with lower levels of volatile fatty acids and total organic carbon in the media, highlighting the role of EA-biochar in mediating electron transfer for methanogenesis rather than providing additional carbon sources.
Arturo Pérez-Roman, Teresa Lopez-Arenas, Mauricio Sales-Cruz, José Rocha-Rios
BACKGROUND
In this work, a biorefinery process was designed and simulated in Aspen Plus® V.10 for production of biogas, bioethanol, and biofertilizer from the Organic Fraction of Municipal Solid Waste (OFMSW) generated in Mexico City (CDMX). The process consists of five stages: (i) anaerobic digestion, (ii) acid hydrolysis, (iii) simultaneous saccharification and co-fermentation, (iv) conventional distillation, and (v) dehydration by extractive distillation. Stirred tank and stoichiometric reactors were used for the anaerobic biodigester simulation, while stoichiometric reactors were employed for simulation of the acid hydrolysis, and simultaneous saccharification and co-fermentation.
RESULTS
The overall results of the simulated process show that it is possible to obtain 149.6 Tons of Biogas, 41.9 Tons of Biofertilizer and 19.7 Tons of Bioethanol from 1000 Tons of OFMSW processed daily, which is equivalent to a total yield of 0.21 Ton Bioproducts/Ton OFMSW or 0.947 Ton Bioproducts/Ton Volatile Solids contained in the OFMSW.
Water scarcity and increasingly stringent discharge regulations are driving the adoption of sustainable water management strategies, necessitating the reuse of industrial wastewater and the implementation of zero or near-zero liquid discharge systems. Reverse osmosis (RO) is an effective technology for recycling wastewater in the textile industry. The elevated resistivity and decreased biodegradability of contaminants in RO concentrates generate a novel wastewater stream.
Results
This study examines the reutilization of these wastewaters through Fenton and Fered-Fenton processes. The Box–Behnken design (BBD) was used to model process variables. The operational parameters for both processes were the H2O2/chemical oxygen demand (COD) ratio, Fe2+/H2O2 ratio, current density and reaction time. The evaluated system responses were COD, color index (CI) and ultraviolet absorbance at 254 nm (UV254) and 280 nm (UV280). The correlation coefficients (R2) for all created models approached 1, demonstrating the efficacy of the BBD method in modeling pollutant removal with the Fenton and Fered-Fenton processes. The Fenton process achieved removal efficiency of 73.5% for COD, 94.5% for CI, 84% for UV254 and 81% for UV280. The efficiencies obtained in the Fered-Fenton process were 87% for COD, 97.5% for CI, 94.5% for UV254 and 89% for UV280 under optimum conditions.
Bashir M Ghanim, Ronan Courtney, J Tony Pembroke, James J Leahy, Thomas F O'Dwyer, John G Murnane
BACKGROUND
Vanadium (V) is a critical raw material which is extensively used in metallurgical, aerospace and chemical industries. However, V-enriched wastewaters pose risks to human and environmental health due to their tendency to persist and bioaccumulate. Active V treatment processes generate significant quantities of byproducts with associated high operating costs and there is a need therefore to investigate novel passive technologies such as biosorption. This study investigates the capacity and reusability of KOH-modified seaweed biochar (BCKOH) to (re-)adsorb, desorb and recover V, and evaluates the influences of initial V concentration, contact time, solution temperature and pH.
RESULTS
The maximum uptake of 48.8 mg V g−1 BCKOH occurred within 75 min and followed an exothermic adsorption process best described by the Langmuir isotherm model. The magnitude of enthalpy change suggested a physisorption binding interaction with optimum uptake in the range pH 3.5–4.5. Introduction of a saline content (100–400 mg Na+ L−1) into the adsorption solution resulted in a modest reduction in the V adsorption level by BCKOH but further increases in saline concentration thereafter had only limited impact. Successive V(V) adsorption/desorption cycles indicated that V(V) binding to BCKOH displays effective reversibility with the adsorbent material demonstrating good regeneration characteristics.
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