The present study explores the potential of MSW gasification for exergy analysis and has been recently given a premier attention in a region like Pakistan where the urbanization is rapidly growing and resources are few. The plant capacity was set at 50 MW based on reference data available and the total exergetic efficiency was recorded to be 31.5 MW. The largest irreversibility distribution appears in the gasifier followed by methanation unit and CO2 capture. The effect of process temperature, equivalence ratio and MSW moisture content was explored for inspecting the variations in syngas composition, lower heating value, carbon conversion efficiency and cold gas efficiency. Special attention of the paper is paid to the comparative assessment of MSW gasification products in four regions, namely Pakistan, USA, UAE and Thailand. This extended study gave an insight into the spectrum of socioeconomic conditions with varying MSW compositions in order to explain the effect of MSW composition variance on the gasification products.
In this study freely suspended and Ca-alginate immobilized C. vulgaris cells were used for the biosorption of Fe(II), Mn(II), and Zn(II) ions, from the aqueous solution. Experimental data showed that biosorption capacity of algal cells was strongly dependent on the operational condition such as pH, initial metal ions concentration, dosages, contact time and temperature. The maximum biosorption of Fe(II) 43.43, Mn(II) 40.98 and Zn(II) 37.43 mg/g was achieved with Ca-alginate immobilized algal cells at optimum pH of 6.0, algal cells dosage 0.6 g/L, and contact time of 450 min at room temperature. The biosorption efficiency of freely suspended and immobilized C. vulgaris cells for heavy metals removal from the industrial wastewater was validated. Modeling of biosorption kinetics showed good agreements with pseudo-second-order. Langmuir and D-R isotherm models exhibited the best fit of experimental data. The thermodynamic parameters (ΔG°, ΔH°, and ΔS°) revealed that the biosorption of considered metal ions was feasible, spontaneous and exothermic at 25-45°C. The SEM showed porous morphology which greatly helps in the biosorption of heavy metals. The Fourier transform infrared spectrophotometer (FTIR) and X-rays Photon Spectroscopy (XPS) data spectra indicated that the functional groups predominately involved in the biosorption were C-N, -OH, COO-, -CH, C=C, C=S and -C-. These results shows that immobilized algal cells in alginate beads could potentially enhance the biosorption of considered metal ions than freely suspended cells. Furthermore, the biosorbent has significantly removed heavy metals from industrial wastewater at the optimized condition.
The potential of selected materials in treating metal-rich acid mine drainage (AMD) has been investigated in a series of batch experiment. The efficiencies of both single and mixed substrates under two conditions i.e. low- and high-concentration solutions containing heavy metals were evaluated. Synthetic metal-containing AMD was used in the experiments treated using spent mushroom compost (SMC), ochre, steel slag (SS), and limestone. Different ratios of treatment materials were incorporated in the substrate mix and were tested in an anoxic condition. In the batch test, physicochemical parameters (pH, redox potential, total dissolved solids, conductivity, and Ca concentration) and heavy metals (Fe, Mn, Pb, Zn, and Al) were analysed. The mixed substrates have shown satisfactory performance in increasing pH with increasing Ca concentration and removing metals. It has been found that SS and ochre played an important role in the treatment of AMD. The results showed that the mixed substrates SM1 (i.e. 10% SMC mixed with 20% ochre, 30% steel slag, and 40% limestone) and SM2 (i.e. 20% SMC mixed with 30% ochre, 40% steel slag, and 10% limestone) were effective in increasing the pH from as low as 3.5-8.09, and removing heavy metals with more than 90% removal efficiencies.
A magnetic graphene oxide (MGO) was developed for the adsorption of As(III) from aqueous solution. The characteristics of MGO were investigated using Fourier-transform infrared (FTIR), X-ray diffraction and field emission scanning electron microscope-E/energy-dispersive X-ray analyses. Batch adsorption experiments were designed using central composite design, and the effects of adsorbent dosage, pH, contact time and concentration of As(III) were investigated. The MGO showed an excellent performance, removing up to 99.95% of As(III) under the following condition: initial As(III) concentration = 100 mg/L, pH = 7, adsorbent dosage = 0.3 g/L and contact time = 77 min. MGO dosage and initial pH were the most significant parameters influencing the process performance. FTIR analysis of the used adsorbent confirms the adsorption of As(III) through complexation between surface functional groups of the MGO and the oxyanions of As(III). The adsorbent maintained a significant level of performance even after four cycles of adsorption. Thus, the developed MGO has the potential to be used for the abatement of arsenic pollution.
Currently, an extractive green palm oil-based emulsion liquid membrane (ELM) has been used for simultaneous extraction and enrichment of Reactive Red 3BS from simulated synthetic dye wastewater. The ELM consists of two main phases, which are organic liquid membrane (LM) and stripping solution. During the extraction process, the ELM was dispersed into the simulated synthetic dye wastewater containing the Reactive Red 3BS complexes. The organic LM contains tridodecylamine (TDA), Sorbitan Monooleate (Span 80) and palm oil as a carrier, surfactant and diluent, respectively. The sodium bicarbonate (NaHCO3) was used as stripping solution for the enrichment process. Several important parameters that affected the simultaneous extraction and enrichment of Reactive Red 3BS, such as carrier and stripping agent concentrations, extraction time and treat ratio, were investigated. The results showed that almost 90% of Reactive Red 3BS ions were successfully extracted with 10 times enrichment in the stripping phase at the optimum conditions of 0.2 M TDA, 0.1 M NaHCO3, 5 min of extraction time and 1:5 of treat ratio. Hence, it can be concluded that palm oil possesses a high potential as green diluent in future technology, especially in ELM process for the removal and recovery of Reactive Red 3BS from synthetic dye wastewater.
Benzo[a]pyrene is a high-molecular-weight polycyclic aromatic hydrocarbon highly recalcitrant in nature and thus harms the ecosystem and/or human health. Therefore, its removal from the marine environment is crucial. This research focuses on benzo[a]pyrene degradation by using enriched bacterial isolates in consortium under saline conditions. Bacterial isolates capable of using benzo[a]pyrene as sole source of carbon and energy were isolated from enriched mangrove sediment. These isolates were identified as Ochrobactrum anthropi, Stenotrophomonas acidaminiphila, and Aeromonas salmonicida ss salmonicida. Isolated O. anthropi and S. acidaminiphila degraded 26% and 20%, respectively, of an initial benzo[a]pyrene concentration of 20 mg/L after 8 days of incubation in seawater (28 ppm of NaCl). Meanwhile, the bacterial consortium decomposed 41% of an initial 50 mg/L benzo[a]pyrene concentration after 8 days of incubation in seawater (28 ppm of NaCl). The degradation efficiency of benzo[a]pyrene increased to 54%, when phenanthrene was supplemented as a co-metabolic substrate. The order of biodegradation rate by temperature was 30°C > 25°C > 35°C. Our results suggest that co-metabolism by the consortium could be a promising biodegradation strategy for benzo[a]pyrene in seawater.
This study demonstrated the generation of clean water from seawater collected at the beach coast in Universiti Malaysia Sabah, Malaysia, with carbonized rice husk coated melamine sponge as solar absorber by a solar still. Melamine sponge was utilized as a seawater transportation medium since its porous structure is excellent in channelling the seawater. Whereas carbonized rice husk was used as the photothermal conversion material for its efficient heat absorption due to its black colour and porous structure. Implementing air gap between the seawater body and solar absorber, and restricted water pathway assisted in localizing heat on the top surface of the solar absorber. Clean water was generated under direct solar radiation during the day at an open space with average solar intensity around 1.1∼1.2 kW/m2 (slightly higher than 1 sun) for about 4 h. Efficiency of the solar absorber was calculated, while the quality of the generated clean water was observed in terms of salinity and pH value. Insulated solar still with carbon-coated sponge showed the highest efficiency at about 54.74%. Salinity of the collected clean water significantly reduced to consumable level which was approximately 55 ppm, and the pH value at about 6.73 where it was within the safe limit of the drinkable water pH.
Biochar is a high-carbon-content organic compound that has potential applications in the field of energy storage and conversion. It can be produced from a variety of biomass feedstocks such as plant-based, animal-based, and municipal waste at different pyrolysis conditions. However, it is difficult to produce biochar on a large scale if the relationship between the type of biomass, operating conditions, and biochar properties is not understood well. Hence, the use of machine learning-based data analysis is necessary to find the relationship between biochar production parameters and feedstock properties with biochar energy properties. In this work, a rough set-based machine learning (RSML) approach has been applied to generate decision rules and classify biochar properties. The conditional attributes were biomass properties (volatile matter, fixed carbon, ash content, carbon, hydrogen, nitrogen, and oxygen) and pyrolysis conditions (operating temperature, heating rate residence time), while the decision attributes considered were yield, carbon content, and higher heating values. The rules generated were tested against a set of validation data and evaluated for their scientific coherency. Based on the decision rules generated, biomass with ash content of 11-14 wt%, volatile matter of 60-62 wt% and carbon content of 42-45.3 wt% can generate biochar with promising yield, carbon content and higher heating value via a pyrolysis process at an operating temperature of 425°C-475°C. This work provided the optimal biomass feedstock properties and pyrolysis conditions for biochar production with high mass and energy yield.
Membrane fouling during the filtration process is a perennial issue and could lead to reduced separation efficiency. In this work, poly(citric acid)-grafted graphene oxide (PGO) was incorporated into a matrix of single-layer hollow fibre (SLHF) and dual-layer hollow fibrr (DLHF) membranes, respectively, aiming to improve membrane antifouling properties during water treatment. Different loadings of PGO ranging from 0 to 1 wt% were first introduced into the SLHF to identify the best PGO loading for the DLHF preparation with its outer layer modified by nanomaterials. The findings showed that at the optimized PGO loading of 0.7 wt%, the resultant SLHF membrane could achieve higher water permeability and bovine serum albumin rejection compared to the neat SLHF membrane. This is due to the improved surface hydrophilicity and increased structural porosity upon incorporation of optimized PGO loading. When 0.7 wt% PGO was introduced only to the outer layer of DLHF, the cross-sectional matrix of the membrane was altered, forming microvoids and spongy-like structures (more porous). Nevertheless, the BSA rejection of the membrane was improved to 97.7% owing to an inner selectivity layer produced from a different dope solution (without the PGO). The DLHF membrane also demonstrated significantly higher antifouling properties than the neat SLHF membrane. Its flux recovery rate is 85%, i.e. 37% better than that of a neat membrane. By incorporating hydrophilic PGO into the membrane, the interaction of the hydrophobic foulants with the membrane surface is greatly reduced.
Using natural deep eutectic solvents (NADESs) as a green reagent is a step toward producing environmentally friendly and sustainable technology. This study screened three natural DESs developed using quaternary ammonium salt and organic acid to analyse their capability to extract nickel ions from contaminated mangrove soil, which are ChCl: Acetic Acid (ChCl-AceA), ChCl: Levulinic Acid (ChCl-LevA), and ChCl: Ethylene Glycol(ChCl-Eg) at molar ratio 1:2. The impact of various operating parameters such as washing agent concentration, pH solution, and contact time on the NADES performance in the dissolution of Ni ions batch experiments were performed. The optimal soil washing conditions for metal removal were 30% and 15% concentration, a 1:5 soil-liquid ratio, and pH 2 of ChCl-LevA and ChCl-AceA, respectively. A single removal washing may remove 70.8% and 70.0% Ni ions from the contaminated soil. The dissolution kinetic of Ni ions extraction onto NADES was explained using the linear kinetic pseudo and intraparticle mass transfer diffusion models. The kinetic validation demonstrates a good fit between the experimental and pseudo-second-order Lagergren data. The model's maximum Ni dissolution capacity, Qe are 51.56 mg g-1 and 52.00 mg g-1 of ChCl-LevA and ChCl-AceA, respectively. The synthesised natural-based DES has the potential to be a cost-effective, efficient, green alternative extractant to conventional solvent extraction of heavy metals.
Organophosphates (OPs) and synthetic pyrethroids (SPs) are the most popular broad spectrum pesticides, used in agriculture as they have a strong pesticidal activity while also being biodegradable in the environment. The present study aimed to demonstrate the effects of these pesticides on the Acetylcholinesterase (AChE) activity in brain, gills and body muscles of Oreochromis niloticus - an important enzyme for the assessment and biomonitoring pollution caused by neurotoxins in the environment. The fish were exposed for 24 and 48 h to the LC0 concentrations of the malathion (1.425 mg/L), the chlorpyrifos (0.125 mg/L) and the λ-cyhalothrin (0.0039 mg/L), respectively. The activity of the AChE was significantly increased (p
ABSTRACTThis research examines the trends in environmental footprints through energy innovations, digital trade, economic freedom, and environmental regulation from the context of G7 economies. Quarterly observations from 1998-2020 have been utilized for the advanced-panel model entitled Method of Moments Quantile Regression (MMQR). The initial findings confirm slope heterogeneity, interdependence between the cross-sectional units, stationarity properties, and panel cointegration. The results through FM-OLS, D-OLS, and FE-OLS justify that energy innovations, digital trade, and environmental regulations control ecological damages. In contrast, economic freedom and growth are causing more damage to nature, like ecological footprints (EFP). Similarly, the results through MMQR confirm that the impact of energy innovations, digital trade, and environmental regulations is accepted as a panacea to control environmental degradation in G7. However, the magnitude of the coefficient varies across different quantiles. More specifically, the findings show that the impact of energy innovations is highly significant at 0.50th quantile. In contrast, through digital trade, the impact on EFP is only significant under medium and higher order quantiles (i.e. 0.50th, 0.75th-1.0th). Contrarily, economic freedom is causing more EFP across all the quantiles, where the findings are highly significant at 0.75th quantile. Besides, a few other policy implications are also discussed.
AbstractIn this paper, the adsorption of the chlorinated organic compound, 2,4-dichlorophenol, using activated carbon (AC), bagasse fly ash (BFA) and rice husk fly ash (RHFA) in a packed bed column was simulated using Aspen Adsorption software. The purpose of this study was to demonstrate the effectiveness of simulation software for identifying alternative low-cost adsorbents and optimising the adsorption process. The effect of process parameters such as initial concentration, bed height and inlet feed flow rate were evaluated using breakthrough curves. It was shown that the longest breakthrough times were at a higher bed height of 3 m and lower flow rate of 2 m3/hr and concentration had no effect on breakthrough time. After optimisation using response surface methodology, the AC, BFA and RHFA had a breakthrough time of 534 s, 426 s and 209 s, respectively. This shows the potential of BFA as a potential alternative for AC for the adsorption of 2,4-dichlorophenol and shows RHFA to be a relatively poor adsorbent in comparison. The economic evaluation illustrates that the overall cost of wastewater treatment with BFA and RHFA is lower than AC. The cost for the BFA and RHFA adsorbents is only a handling charge, but the cost for using AC adsorbent is £10,603/year. Therefore, the company can produce 17,520 m3/year of fresh water from the adsorbent and save £87,600/year. Therefore, it was concluded that BFA had a slightly weaker adsorption efficiency than AC but was more cost effective, allowing it to be more affordable and increasing its availability.
In the present investigation, a total of 108 combinations of ionic liquids (ILs) were screened using the conductor-like screening model for real solvents (COSMO-RS) with the aid of six cations and eighteen anions for the extraction of succinic acid (SA) from aqueous streams through dispersive liquid-liquid microextraction (DLLME). Using the screened ILs, an ionic liquid-based DLLME (IL-DLLME) was developed to extract SA and the role of different reaction parameters in the effectiveness of IL-DLLME approach was investigated. COSMO-RS results suggested that, quaternary ammonium and choline cations form effective IL combinations with [OH¯], [F¯], and [SO42¯] anions due to hydrogen bonding. In view of these results, one of the screened ILs, tetramethylammonium hydroxide [TMAm][OH] was chosen as the extractant in IL-DLLME process and acetonitrile was adopted as the dispersive solvent. The highest SA removal efficiency of 97.8% was achieved using 25 μL of IL [TMAm][OH] as a carrier and 500 μL of acetonitrile as dispersive solvent. The highest amount of SA was extracted with a stir time of 20 min at 300 rpm, followed by centrifugation for 5 min at 4500 rpm. Overall, the findings showed that IL-DLLME is efficient in extracting succinic acid from aqueous environments while adhering to the first-order kinetics.
The scarcity of energy and water resources is a major challenge for humanity in the twenty-first century. Engineered osmosis (EO) technologies are extensively researched as a means of producing sustainable water and energy. This study focuses on the modification of substrate properties of thin film nanocomposite (TFN) membrane using aluminium oxide (Al2O3) nanoparticles and further evaluates the performance of resultant membranes for EO process. Different Al2O3 loading ranging from zero to 0.10 wt% was incorporated into the substrate and the results showed that the hydrophilicity of substrate was increased with contact angle reduced from 74.81° to 66.17° upon the Al2O3 incorporation. Furthermore, the addition of Al2O3 resulted in the formation of larger porous structure on the bottom part of substrate which reduced water transport resistance. Using the substrate modified by 0.02 wt% Al2O3, we could produce the TFN membrane that exhibited the highest water permeability (1.32 L/m2.h.bar, DI water as a feed solution at 15 bar), decent salt rejection (96.89%), low structural parameter (532.44 μm) and relatively good pressure withstandability (>25 bar).
This study's main goal is to evaluate how the research will look at the impact of geothermal energy production on the quality of the subterranean in the 27 European nations from 1990 to 2021. A considerable decline in the subterranean water supply can occur in EU14 emerging nations employing geothermal energy growth compared to EU13 emerging economies, according to research that uses the autoregressive distributed lag (ARDL). Fossil fuel use, population growth, and economic expansion are some factors that have a more detrimental effect on the subterranean water supply in EU14 emerging economies than in EU13 emerging nations. In contrast, the study's findings indicate that EU13 emerging nations may be better able to enhance their underground water supply than EU14 emerging economies because of more effective institutional qualities. The findings so indicate that increasing the amount of geothermal energy generation among the 27 European Union countries can accelerate subsurface water degradation at a high capacity and help achieve unionism's 2030 energy-related goals. When this is achieved, climate change will be put to check, as pollution of the environment. All calculations projected were seen to be of a good level of validity, and this is ascertained through three estimators considered in this study.
Polyaniline composites consisting of carboxymethyl cellulose (CMC) have enhanced adsorption properties, but recent studies indicate that the oxidised species - dialdehyde carboxymethyl cellulose (DCMC) - outperforms CMC-based composites. However, these studies fail to study the effect of DCMC's aldehyde content and compare the composites with CMC-based composites; numerous experiments required to investigate each adsorbent for each factor limit such studies. We explored a way to study whether villi-structured polyaniline (VSPANI), its CMC composite (CMC/PANI), and its DCMC composites with 35% (DCMC(A)/PANI) and 77% (DCMC(B)/PANI) aldehyde content would be great adsorbents for removing bisphenol-A (BPA). We first customised a D-optimal screening design to alleviate the pitfalls of definitive screening design (DSD), hence estimating all the main effects: initial concentration, pH, flow rate, adsorbent amount, sample volume and type of adsorbent. We excluded CMC/PANI and DCMC(A)/PANI composites, both with low adsorption capacities of 56.57 and 57.27 mg/g from further investigation. The DSD followed to estimate all second-order effects through which we projected a response surface method (RSM) to optimise and model the active factors. Increasing the aldehyde content on the composites favoured adsorption, but there lacked evidence to suggest VSPANI and DCMC(B)/PANI differed significantly in performance. The models were numerically and graphically proven adequate, explaining 80% and 99% of the variation when predicting removal efficiency and adsorption capacity. VSPANI showed potential as an adsorbent for BPA removal with 85% removal efficiency and 129 mg/g adsorption capacity. This comprehensive approach, combining both designs, allows for sustainable investigation of multiple adsorbents and factors, minimising experimental waste.
Overgrowth of microalgae will result in harmful algae blooms that can affect the aquatic ecosystem and human health. Therefore, the quantitation of chlorophyll pigments can be used as an indicator of algae bloom. However, it is difficult to monitor the geographical and temporal distribution of chlorophyll in the aquatic environment. Accordingly, an innovative and inexpensive method based on the red-green-blue (RGB) image analysis was utilized in this study to estimate the microalgae chlorophyll content. The digital images were acquired using a smartphone camera. The colour index was then evaluated using software and associated with chlorophyll concentration significantly. A regression model, using RGB colour components as independent variables to estimate chlorophyll concentration, was developed and validated. The Green in the RGB index was the most promising way to estimate chlorophyll concentration in microalgae. The result showed that acetone was the best extractant solvent with a high R-squared value among the four extractant solvents. Next, the isolation of useful biomolecules, such as proteins, fatty acids, polysaccharides and antioxidants from the microalgae, has been recognized as an alternative to regulating algae bloom. Microalgae are shown to produce bioactive compounds with a variety of biological activities that can be applied in various industries. This study evaluates the biochemical composition of mixed microalgae species, Desmodesmus sp. and Scenedesmus sp. using the liquid triphasic partitioning (TPP) system. The findings from analytical assays revealed that the biomass consisted of varied concentrations of carbohydrates, protein, and lipids. Phenolic compounds and antioxidant activity were at 60.22 mg/L and 90.69%, respectively.
ABSTRACTThe current work focused on the intermediate pyrolysis of Bambara Groundnut Shells (BGS-G1), Sweet Sorghum Stalk (SSS), and Shea Nutshells (SNS). These feedstocks are readily available as wastes or by-products from industrial and agricultural activities. The thermo-gravimetric analysis of the biomass samples exhibited decomposition and devolatilization potentials in the temperature range of 110-650°C. The kinetic modelling resulted in the activation energy of BGS G1 being the lowest as 20.43 kJ/mol and SNS as the highest 24.89 kJ/mol among the three biomass samples. Intermediate pyrolysis was conducted in a vertical tube reactor at a temperature of 600°C, with nitrogen flow at 10 ml/min and heating rate ≥ 33.0℃/min. The yield of pyrolysis bio-oil was 38.0 ± 6.4, 44.2 ± 6, and 39.7 ± 5.2 wt.% for BGS-G1, SSS, and SNS, respectively. The HHV of bio-oil varied as 23.7 ± 1.8, 23.8 ± 1.8, to 26.5 ± 2.0 MJ/kg for BGS-G1 SSS and SNS respectively. The biochar recorded the lowest HHV for BGS-G1 as 18.8 ± 1.2 MJ/kg and the highest for SNS as 26.4 ± 1.8 MJ/kg. The FTIR of bio-oil revealed significant functional groups, and GC-MS (Gas Chromatography and Mass Spectrometry) analysis categorized the compounds in bio-oils as ketones, furans, phenolics, acids, phenols and benzene derivatives. The physicochemical analysis of the feedstocks and the products (bio-oil and biochar) showed their potential for bioenergy and biochemical (green chemicals) production.
Oil palm fibre is a type of solid waste generated from palm oil processing plant. At present, there is no proper utilization of this abundant waste. Ammoniacal nitrogen (NH3-N) has received a lot of attention as a water pollutant due to its toxicity, which has an impact on both the environment and human health. In aquaculture wastewater (AQW), NH3-N is present in low concentrations (<10 ppm), and removing low concentrations of NH3-N is tedious. Thus, this study focuses on the potential of oil palm fibre biochar (OPFB) for sustainable low concentration NH3-N recovery from AQW and the recovered spent adsorbent to be used as a bio-fertilizer. The Physico-chemical properties of OPFB show a positive correlation with NH3-N recovery. A significant reduction of value-added metals in OPFB has confirmed the recovery of NH3-N through the ion exchange process. The adsorption isotherms and kinetics of NH3-N recovery had good correlation coefficients under the Freundlich and pseudo-second-order kinetic model confirming a multilayer heterogeneous and chemical adsorption respectively. Thermodynamic parameters indicated that the recovery process via adsorption was exothermic and had a Physio-chemical mechanism. At optimum conditions, OPFB could recover up to 66% of NH3-N actual AQW. The properties of spent OPFB showed potential reutilization as a soil amendment agent or biofertilizer which could be easily degraded.