Search Results (1,017)

This work focused on the effect of combustion on the yield, composition, and strength of food-grade bio- alkali from lignocellulosic agro-waste. Seven lignocellulosic types of agro-waste, including plantain stalk, plantain peel (green and ripe), empty palm bunch, palm fiber, coconut fiber, and cocoa pod were sun-dried and combusted using two methods: open-air combustion (OAC) and muffle furnace combustion (MFC). Ash and potash yield from the two methods of combustion were determined using simple proportion calculations. A two-stage hydrothermal extraction process was carried out on the ash using a deionized water ratio of 1:10 for food-grade bio-alkali, and the leachates were evaluated for pH, alkalinity, and metallic ion contents using standard analytical methods. The data obtained were statistically analyzed via a two-way ANOVA. The OAC samples had a higher ash content range (8.24–18.6%) compared to MFC samples (7.37–9.89%). Potash yield (%) is both biomass and combustion-method dependent, with MFC having a higher average yield (3.05%) than OAC (2.35%). The pH of the leachates for all samples ranged from 10.3 to 12.0. All the agro-waste exhibited a similar pattern in the order of magnitude of the metals of which they were composed (K > Mg > Ca > Zn > Na). For the minerals, PO4 was highest (193.1 g/L) in plantain stalk, and KOH and K₂CO₃ were least (10.0 g/L) in coconut fiber, while the highest alkalinity was obtained in ripe plantain peel (62.1 mg/L). The yield and quality of bio-alkali produced were influenced by the combustion method and source of biomass. The bio-alkali from the different biomass types tested can be used as sources of food-grade emulsifiers due to their high nature of alkalinity. This signifies zero waste and is also a boost to the circular economy. The average alkalinity studied under MFC was 33.6 mg/L and for OAC was 27.3 mg/L, suggesting that MFC is a more promising approach. Worthy of exploration is the significant high content (19.3 mg/L) of chlorine in plantain stalk. Full article

The Sn-W ore deposits in the Krupka surroundings are associated with greisens, which occur in the upper parts of Late Variscan granitoid intrusions. Fluid inclusions were studied in samples of quartz, cassiterite, apatite, fluorite, and topaz in greisenized granites, greisens, and hydrothermal veins with Sn-W mineralization. The greisenization process took place at temperatures 370–490 °C and pressures 155–371 bars, and associated fluids had predominantly low salinity and a low gas (CO₂, N₂ and CH₄) content. The post-greisenization stage was connected with the formation of (i) low-salinity (0–8 wt. % NaCl eq.) fluid inclusions with homogenization temperatures <120–295 °C and (ii) high-salinity (18 to >35 wt. % NaCl eq.) fluid inclusions with homogenization temperatures 140–370 °C, often containing trapped crystals of quartz, topaz, and sulfides, or daughter crystals of salts and carbonates, which were identified by microthermometric measurements, electron microprobe analysis, and Raman spectroscopy. Analyses of fluid inclusion leachates have shown that Na and Ca chlorides predominate in fluids. According to hydrogen stable isotopes, the source of greisenizing and post-greisenizing fluids was not only magmatogenic but also meteoric water or fluids derived from sedimentary rocks. Full article

Arbuscular mycorrhizal fungi, plant-growth-promoting bacteria (PGPB) and vermicompost constitute important environmental and economic resources for improving the production and quality of tomato fruits. The present research aims to determine the single and combined effect of Glomus fasciculatum (Gf) fungus, Azotobacter chroococcum (Azot), PGPB and vermicompost leachate (VL) organic fertilizer on the yield and quality of tomato fruit. Thus, an open-field experiment was established with seven treatments, a control and three replicates. Total soluble solids, vitamin C, acidity, fruit mass and fruit diameter were evaluated as fruit quality variables; the yield was recorded and estimated in tons per hectare⁻¹. The results showed that Gf, Azot and VL were effective in promoting tomato yield and fruit quality. As a trend, the triple combination (Gf + Azot + VL) evidently obtained the highest values of total soluble solids, vitamin C and fruit acidity. The range of improvement concerning the fruit size was 66.6% (single treatment) compared to 78.5% (triple combination). The maximum yield of 54.5 t/ha⁻¹ was recorded for the Gf + Azot + VL combination. Therefore, G. fasciculatum, A. chroococcum and VL are considered useful as organic alternatives for open-field tomato biofertilization programs in tropical countries. Full article

The treatment of stabilized leachates with high refractory organic matter content, which are over 10 years old, presents a challenge. This study explored the potential of electro-coagulation (EC) and electro-oxidation (EO) treatment systems to address this issue. The objective of this study was to investigate the phytotoxicity of the proposed treatment system on seed growth and examine possible relationships between phytotoxicity results and the characterization of leachates, effluents, soil, and radicles. Phytotoxicity tests were conducted on seeds of Lactuca sativa, Cucumis sativus, and Phaseolus vulgaris, using Inductively Coupled Plasma-Optical analysis. The evolution of organic matter was monitored by fractionating the chemical oxygen demand (COD) and humic substances. The biodegradability index increased from 0.094 in raw leachate to 0.26 and 0.48 with EC and EO, respectively. Removal rates of 82%, 86%, 99%, and 81% were achieved for COD, dissolved organic carbon, color, and ammoniacal nitrogen, respectively. The biodegradable COD increased from 26% in raw leachate to 39% in the EC process and 58% in the EO process effluent. The proposed treatment system successfully broke the aromatic structures of the humic substances present in the raw leachate, thereby increasing the content of biodegradable material. Phytotoxicity tests revealed that the proposed treatment system significantly reduced the phytotoxicity of the generated effluents. Full article

During adaptation to waters that are rich in xenobiotics, biological systems pass through multiple stages. The first one is related to the restructuring of communities, pronounced destruction of the structure, and multiplication of active biodegradants. The purpose of the present research was to describe the microbiome restructuring that occurs during the adaptation stage in landfill leachate treatment. In a model SBR (sequencing batch reactor), a 21-day purification process of landfill leachate was simulated. Wastewater was fed in increasing concentrations. When undiluted leachate entered, the activated sludge structure disintegrated (Sludge Volume Index—4.6 mL/g). The Chemical Oxygen Demand and ammonium nitrogen concentration remained at high values in the influent (2321.11 mgO₂/L and 573.20 mg/L, respectively). A significant amount of free-swimming cells was found, and the number of aerobic heterotrophs and bacteria of the genera Pseudomonas and Acinetobacter increased by up to 125 times. The Azoarcus-Thauera cluster (27%) and Pseudomonas spp. (16%) were registered as the main bacterial groups in the activated sludge. In the changed structure of the microbial community, Gammaproteobacteria, family Rhizobiaceae, class Saccharimonadia were predominantly represented. Among the suspended bacteria, Microbactericeae and Burkholderiaceae, which are known for their ability to degrade xenobiotics, were present in larger quantities. The enzymological analysis demonstrated that the ortho-pathway of cleavage of aromatic structures was active in the community. The described changes in the leachate-purifying microbial community appear to be destructive at the technological level. At the microbiological level, however, trends of initial adaptation were clearly outlined, which, if continued, could provide a highly efficient biodegradation community. Full article

Intensive poultry production may result in substantial emissions of pollutants into the environment, including pharmaceuticals and other chemicals used in poultry farming. The objective of this study was to verify the presence of ciprofloxacin, enrofloxacin, carbamazepine, metoclopramide, trimethoprim, diflufenican, flufenacet, and p,p′-DDE in soil and water in the immediate vicinity of a poultry manure heap. The influence of soil contaminants on the growth and selected physiological parameters of seed peas and common duckweed (as indicator plants) was tested. It has been proven that the cultivation of pea plants on soil coming from the close proximity of a heap of manure results in a deterioration of both morphological parameters (root length, shoot length) and physiological parameters (chlorophyll absorption, aminolevulinic acid dehydrogenase (ALAD) activity, aminolevulinic acid (ALA) content, lipid peroxidation, mitochondrial damage or production of HSP70 proteins). Similarly, water extracts from cultivated soils had a significant effect on duckweed, and it was found that contaminant leachates are indeed detectable in soil, groundwater, and deep water. Special attention should, therefore, be paid to the location, methods of storage, and use of poultry fertilizer. Full article

The present research work focuses on the characterization and leachability evaluation of electric arc furnace dust (EAFD) and its vitreous outgrowths produced during vitrification with soda lime recycled glass (SLRG). EAFD is a hazardous industrial waste generated in the collection of particulate material during the steelmaking process via an electric arc furnace. Glasses of various syntheses were obtained during EAFD vitrification with various amounts of silica scrap (50, 60 and 70 wt%). The characterization of the as-received dust was carried out by using granulometry analysis, chemical analysis, X-ray diffraction (XRD), and scanning electron microscopy (SEM), in conjunction with Energy Dispersive X-ray Spectroscopy (EDS). The produced glasses during vitrification were studied by means of chemical and mineralogical analysis, whereas their microstructure in polished sections was examined by SEM/EDS. Their behavior during leaching was determined by the EN 12457-2 compliance leaching test and according to the results, the trace elements detected in the leachates were well below the corresponding regulatory limits. Full article

Environmental pollution caused by increasing levels of heavy metals (HM) is a pressing problem throughout the world. Phytoremediation is considered a prospective remediation approach for HM-contaminated soil, but more research is required to enhance remediation efficiency. Biochar is a promising bio-residue material that can be used for the sustainable remediation of heavy metal-contaminated soil. In this study, a pot experiment was conducted to investigate the effects of biochar from different bio-substrates (digestate, waste of biodiesel production from rapeseed, corn stalk) on HM (Cr, Cd, Cu, Ni, Pb, and Zn) accumulation in buckwheat and white mustard cultivated in sewage sludge-contaminated soil. The total amount of HM in soil, plant above- and below-ground biomass, leachate, and bioconcentration and translocation factors were studied to explore the mechanism of how the different bio-substrates’ biochar affects HM accumulation in selected plants. It was observed that rapeseed biochar showed the greatest significant effect in reducing the HM content in soil, plant biomass, and lysimetric water. Meanwhile, the incorporation of digestate biochar significantly increased the HM content in all the soil-plant systems and affected the HM leaching from the soil. The concentration of HM in the leachate decreased from 2.5 to 10 times. It was determined that phytostabilization is the core process of HM accumulation in buckwheat, in contrast to mustard, where the mechanism is phytoextraction. This study confirmed that biochar addition enhances the phytoremediation efficiency in soil, which can potentially improve the development of ecofriendly in-situ bioremediation technology for HM-contaminated sites. Full article

The IC lead frame is an essential component in semiconductor packaging, primarily composed of a nickel (Ni)–copper (Cu) alloy in which Ni is electroplated onto a Cu substrate. In this study, synergistic solvent extraction using a binary extractant containing LIX984N and Cyanex302, followed by two-stage selective stripping using sulfuric acid (H₂SO₄) and nitric acid (HNO₃) as the stripping agent, was employed to separate and recover Cu and Ni from the leachate of an IC lead frame. The results indicated that under the optimal conditions of synergistic solvent extraction with an extraction pH value of 1, an extractant concentration of 0.015 M LIX984N + 0.0375 M Cyanex302, an extraction aqueous/organic (A/O) ratio of 1:1, and an extraction time of 5 min, the extraction efficiencies for Cu and Ni were 99.8% and 1.17%, respectively. The distribution ratios were D_Cu 999 and D_Ni 0.012, resulting in a separation factor of 83,250. In addition, the separation factor was much higher than that of using individual extractant of LIX984N (6208.3) or Cyanex302 (22,185.2). Subsequently, under optimal first-stage stripping conditions, using 0.05 M H₂SO₄ at a stripping organic/aqueous (O/A) ratio of 1:1, and with a stripping time of 3 min, a stripping efficiency of 99.9% for Ni was achieved. Next, under optimal second-stage stripping conditions, using 5 M HNO₃ at a stripping O/A ratio of 2:1, and with a striping time of 3 min, a stripping efficiency of 99.9% for Cu was achieved. Finally, sodium hydroxide (NaOH) was added to the respective stripping solutions to precipitate Ni and Cu ions, followed by calcination treatment for the precipitates to obtain NiO and CuO, respectively. The purity of the former was 99.74% and that of the latter was 99.82%. The results demonstrate that synergistic solvent extraction using a binary extractant containing LIX984N and Cyanex302 can almost entirely extract Cu in the leachate of an IC lead frame at a lower extraction pH and a lower extractant concentration, thus reducing the co-extraction of Ni. In addition, less co-extracted Ni in the organic phase can be selectively stripped using dilute H₂SO₄, thus reducing the co-stripping of Cu. Hence, the effective separation and recovery of Cu and Ni in IC lead frame leachate can be achieved, which contributes to improving the sustainability of natural resources. Full article

Restoration of open-pit mines may utilize waste rock for landscape reconstruction, which can include the construction of backfill aquifers. Weathering and contaminant transport may be different in backfill aquifers compared to the surrounding aquifer because of newly available mineral surfaces and transportable nano- to micro-scale particles generated during mining. Waste rock from the Cordero Rojo open-pit coal mine in the Powder River Basin was exposed to benchtop leachate experiments for 20 weeks at temperatures of 5 °C and 20 °C. Collected leachate was analyzed for Eh, pH, specific conductance, alkalinity, and cation and anion concentrations as unfiltered and 0.45-μm and 0.2-μm filtered concentrations. During the experiment, leachate Eh and pH substantially varied during the first 55 days, which corresponds to a period of high specific conductance (>1000 µS/cm) and alkalinity (>200 mg/L). Correspondingly, anion and cation concentrations were the largest during this early weathering stage, and the filter fractions indicated multiple forms of transported elements. After this early weathering stage, column leachate evolved towards a weathering equilibrium of neutral, oxidizing, and low solute conditions indicated by positive Eh values, pH near 7, and specific conductance <500 μS/cm. This evolution was reflected in the decline and stabilization or non-detection of metal(loid) concentrations reflective of a shift to primarily bulk aluminosilicate weathering when coal- and salt-associated elements, such as arsenic, cadmium, and selenium, were not detected or at minimal concentrations. Over the course of the experiment, the solute trend of certain elements indicated particular weathering processes—cadmium and nanoparticle transport, selenium and salt dissolution, and arsenic and pyrite oxidation. The mining of overburden formations and use of the waste rock for backfill aquifers as part of landscape reconstruction will create newly available mineral surfaces and nanoparticles that will weather to produce solute concentrations not typically found in groundwater associated with the original overburden. Full article

The current high-salinity wastewater treatment technology is complex, costly, and carries the risk of secondary contamination. As a traditional desalination technology, the combined method using frozen technology has broad development prospects in wastewater treatment. This study investigates the desalination effects of waste leachate using three different methods: the frozen–gravity method (FGM), frozen–centrifugal method (FCM), and frozen–blowing methods (FBMs), under various experimental conditions. The results showed that the salt rejection of all three methods could reach more than 75% under the conditions of a freezing time of 12 h, freezing temperature of −15 °C, and ice production rate of 40%; the salt rejection of FGM increased at higher ambient temperatures, but it was not conducive to the removal of organic pollutants; the salt rejection of FCM was sensitive to the centrifugal time and centrifugal speed, with a significant correlation (p < 0.05), the increase in centrifugal time and centrifugal speed can help to improve the salt rejection, and the increase in centrifugal speed in the range of 1000–2000 rpm can accelerate the discharge of concentrated brine more effectively; the frozen–crushed–blowing method (FCBM) in FBM has a salt rejection as high as 93.86% at an ice production rate of 25.80%, which reduces the salinity of the effluent from 4.07% to 0.25%, speeds up the desalination process, and improves the salt rejection compared to the other methods. This study provides a new perspective and reference for the treatment of high-saline wastewater. Full article

The aim of this study was to support the use of waste materials formed from a mixture of technogenic soils for growing plants through adding vermicompost leachates. The effect on the growth of underground and above-ground biomass was evaluated on plants of the bush variety of tomato (Solanum lycopersicum). Three different types of biodegradable waste (apple pomace, matolin, and horse manure) were used in the experiments, from which individual vermicomposts were subsequently produced. The effect of the addition of vermicompost leachates to the soil was manifested in all the statistically evaluated parameters of the bush tomato plants. It was found that the highest values were achieved for the root weight (+2.91 g; p < 0.01) and for the stem (+1.92 g, p < 0.01). The lowest values were observed in the control plants without application of the vermicompost leachates. Full article

In this paper, the feasibility of multi-walled carbon nanotube (MWCNT)-modified clay as a landfill liner material is investigated. Experiments were conducted on the modified clay with 0.5%, 1%, and 2% MWCNTs. The effects of the MWCNTs on the compaction characteristics, permeability coefficient, stress–strain curve, peak deviation stress, shear strength parameters (internal friction angle and cohesion), microstructures, and adsorption performance of the clay were analyzed. The results showed that the optimum moisture content (OMC) increased from 16.15% to 18.89%, and the maximum dry density (MDD) decreased from 1.79 g/cm³ to 1.72 g/cm³ with the increase in MWCNTs. The permeability coefficients firstly fell and then gradually rose as the MWCNTs increased; the minimum permeability coefficient was 8.62 × 10⁻⁹ cm/s. The MWCNTs can also effectively increase the peak deviation stress of the clay, and at the maximum level, the peak deviation stress was increased by 286%. SEM images were processed using the Pore and Crack Analysis System (PCAS), and the results showed that the appropriate amount of MWCNTs could fill the pores and strengthen the clay structure. The effect of the MWCNT-modified clay on the adsorption performance of common heavy metal ions Cd²⁺, Mn²⁺ and Cu²⁺ in landfill leachate was analyzed by batch adsorption tests. The maximum adsorption capacities (Q_max) of Cu²⁺, Cd²⁺ and Mn²⁺ in the 2% MWCNT-modified clay were, respectively, 41.67 mg/g, 18.69 mg/g, and 4.97 mg/g. Compared with the clay samples without MWCNTs, the adsorption properties of Cu²⁺, Cd²⁺, and Mn²⁺ were increased by 228%, 124%, and 202%, respectively. Overall, the results suggest that MWCNT-modified clays have the potential to be suitable barrier materials for the construction of landfills. Full article

The management of the increasing volume of municipal solid waste is an essential activity for the health of the environment and of the population. The organic matter of waste deposited in landfills is subject to aerobic decomposition processes, bacterial aerobic decomposition, and chemical reactions that release large amounts of heat, biogas, and leachates at high temperatures. The control of these by-products enables their recovery, utilization, and treatment for energy use, avoiding emissions to the environment. UAVs with low-cost thermal sensors are a tool that enables the representation of temperature distributions for the thermal control of landfills. This study focuses on the development of a methodology for the generation of 3D thermal models through the projection of TIR image information onto a 3D model generated from RGB images and the identification of thermal anomalies by means of photointerpretation and GIS analysis. The novel methodological approach was implemented at the Meruelo landfill for validation. At the facility, a 4D model (X,Y,Z-temperature) and a 13.8 cm/px GSD thermal orthoimage were generated with a thermal accuracy of 1.63 °C, which enabled the identification of at least five areas of high temperatures associated with possible biogas emissions, decomposing organic matter, or underground fires, which were verified by on-site measurements and photointerpretation of the RGB model, in order to take and assess specific corrective measures. Full article

Measuring the physical and chemical parameters of substrates in the cells of nursery containers during production is difficult. Monitoring these parameters, however, is required for optimizing the use of substrates and their components in nursery production, specifically important in the progressive reduction in the use of peat. A new solution—leachate tables—for those studies is presented. The leachate tables enable the collection of liquid samples draining from individual cells in nursery containers during long-term irrigation and fertilization. During our 2-month-long experiment, changes in the physical and chemical parameters of the substrate were analyzed, as well as the process of accumulation of elements fed to the substrate via fertilizer and irrigation water. It was found that, due to the different cell volumes, filling the containers with the substrate under the same parameters of vibration and initial moisture resulted in different fractions of the substrate ending up inside the cells. In the smaller cells, the larger diameter fraction was dominant, and in the larger cells, the smaller fraction was dominant. This may have influenced the differences in air and water capacity of the substrate in cells of different volumes and confirmed the need for the selection of individual vibration parameters for the containers. In addition, over time, the granulometric composition of the substrate in the containers changed. Along with the systematic administration of elements via fertilization from the sprinkler ramp, their leachate content increased as a result of increased leaching from the substrate. With time, the physical parameters of the substrate in the cells stabilized, which may have affected the accumulation and leaching of elements during irrigation and fertilization. Full article