High Concentrations Of Heavy Metals Research Articles

Development and optimization of a polysilicon-aluminum alkali mineral-enhanced biochar composite for effective heavy metal removal in acidic environments

While traditional biochar demonstrates promising performance in diverse settings, its efficacy may be constrained under specific conditions of high acidity and heavy metal concentrations. In this study, researchers developed a new polysilicon-aluminum alkali mineral-enhanced biochar composite material, GBMSs (green biochar-metakaolin-sodium silicate), by pyrolyzing fibers from dragon fruit peels and blending them with metakaolin and sodium silicate. Using a response surface methodology, this environmentally friendly composite material was optimized for removing copper and zinc contaminants across a range of initial pH levels from 2 to 6. Experimental findings indicated that the adsorption capacity of GBMSs for copper and zinc was significantly enhanced, ranging from 1.5 to 4 times greater compared to pure biochar or biochar mixed solely with a silicon-aluminum mineral. Various analytical techniques including scanning electron microscopy, X-ray diffraction (XRD), and Fourier transform infrared (FTIR) spectroscopy were utilized to examine the influence of poly-silica-aluminum alkali minerals (GBMSs) on biochar composites. The findings revealed an upsurge in surface binding locations and oxygen-related functional groups because of integrating GBMSs. This augmentation of electronegative features on the biochar surface was credited to the development of stabilizing silica-aluminum connections, ultimately boosting its adsorption effectiveness in acidic surroundings. By applying Langmuir and Freundlich models, it was deduced that the adsorption of GBMSs adheres to a multilayer uniform adsorption mechanism, with surface ion interchange and complexation restricting the adsorption capability. This research highlights the potential of clay mineral-altered biochar in efficiently dealing with intricate environmental contamination.

Artisanal and Small-Scale Gold Mining Impact on Soil and Agriculture: Evidence from Upper Denkyira East Municipality, Ghana

The gold mining industry in Ghana has made a substantial contribution to the country's economic growth by generating diverse employment opportunities, both directly and indirectly, in mining communities. This has the potential to mitigate poverty and improve the quality of life for individuals and households in rural areas, where climate change is having a disproportionate impact on small-scale farmers. Nevertheless, it is crucial to recognize that this sector has also resulted in detrimental environmental impacts. A total 150 key informants in Upper Denkyira East Municipality, comprising representatives from the Environmental Protection Agency, the Forestry Commission, the Mineral Commission, and other stakeholders, were interviewed using standardize questionnaire to ascertain the impact of mining on the soil, agriculture and the environment. The study also employed inductively coupled plasma to assess the concentration of heavy metals in soils at a small-scale mining site. The soil analyses indicated high concentrations of heavy metals, such as mercury, arsenic, nickel, zinc, and iron. The Weighted Average Index, which was used to assess the impact of mining, revealed that communities face challenges such as deforestation, low crop yields, water pollution, land tenure issues, and a high cost of living. The study's analyses of measures to address small scale mining challenges revealed that alternative livelihood, law enforcement, training and support, and access to mining concessions were perceived as suitable for addressing artisanal and small scale mining. The study concluded that stricter mining regulations, promoting sustainable mining practices, and providing comprehensive training to miners on environmental protection and land reclamation can help mitigate the negative impacts of artisanal and small-scale mining. Additionally, supporting alternative means of livelihood for mining communities, such as agriculture or eco-tourism, can reduce reliance on mining and promote sustainable development.

Heavy metals and potential health risk assessment of Lactuca sativa and Daucus carrota from soil treated with organic manures and chemical fertilizer

The large-scale production of food crops with heavy application of chemical fertilizers in the effort to meet the astronomical increase in food demands may be counterproductive to the goal of food security. This study investigated the effect of different soil treatments on the levels of heavy metals (Cr, Cu, Fe, Ni, Pb, and Zn) in two types of vegetables Lactuca sativa (lettuce) and Daucus carrota (carrot). The potential carcinogenic and non-carcinogenic health risks from their consumption were also evaluated. Planting experiment was set up in a randomized block design, with different soil treatments of soil + cow dung (CD), soil + sewage sludge (SS), soil + chemical fertilizer (nitrogen-phosphorus-potassium (NPK)), and untreated soil (UNTRD). The vegetables were harvested at maturity, washed with distilled water, and subjected to an acid digestion process before the levels of heavy metals were measured by inductively coupled plasma spectrometry (ICP-MS). The mean concentrations of the metals in the vegetables across all treatments were below the maximum permissible limits. The pattern of heavy metal accumulation by the vegetables suggested that the lettuce from SS treatment accumulated higher concentrations of heavy metals like Cr (0.20 mg/kg), Cu (3.91 mg/kg), Ni (0.33 mg/kg), and Zn (20.44 mg/kg) than carrot, with highest concentrations of Fe (90.89 mg/kg) and Pb (0.16 mg/kg) recorded in lettuce from NPK treatment. The bioaccumulation factor (BAF) showed that lettuce, a leafy vegetable, has bioaccumulated more heavy metals than carrot, a root vegetable. The BAF was generally below the threshold value of 1 in both vegetables, except in lettuce from NPK and CD treatments and carrot from NPK treatments, with BAF values of 1.6, 1.69, and 1.39, respectively. The cancer risk assessment factors were well below the unacceptable maximum range of 10−4 suggesting that consuming these vegetables might not expose an individual to potential risk of cancer development. The hazard quotient estimations were below the threshold values of 1 for all heavy metals; however, the hazard index (HI) values of 1.27 and 1.58 for lettuce from NPK and SS treatments indicate a potential non-carcinogenic health risk to consumers from intake of all the heavy metals.

Actinomycetes as a Possible Source of Bioremediation of Heavy Metal Cadmium from Contaminated Soil

Annually, a significant volume of chemicals, encompassing fertilizers and pesticides, is administered to agricultural soils. Using pesticides and fertilizers, agricultural practices contribute to heavy metal Cadmium (Cd), Copper (Cu), Lead (Pb) and Zinc (Zn) pollution. Heavy metals and pesticides are high at the peak of ecological contaminants, presence of this has introduced grave risks to the health of the population and agronomics. Among heavy metals, cadmium (Cd) is recognized for its high mobility in various environmental settings. Cd has a deleterious effect on plant phenotypic, cytotoxicity (e.g., lowering chlorophyll concentration and limiting photosynthetic effectiveness), and metabolic activities (e.g., chlorosis and necrosis). Microbial bioremediation by using microorganisms is one of the secure, pure, cost operative and eco-friendly technology for decontaminating polluting sites as compared to physical and chemical techniques. Among microbes, Actinobacteria hold a paramount position, serving as key players in numerous biological processes, utilize toxins as carbon source and turn into high concentrations of pesticides, chemical complexes and heavy metals into commercially viable antibiotics, enzymes, proteins, and plant growth promoting hormones. This study is an effort to explore the potent cadmium resistance actinomycetes to reduce cadmium levels to enhance degradation. For this purpose, 53 actinomycetes strains were tested for heavy metal resistance and tolerance to Cadmium against different concentrations. After secondary screening Four potent isolate have the potential to grow at 1000 mg/L concentration of Cadmium in the medium. When they are able to grow on heavy metal containing media it could be beneficial for reduction and elimination of toxic metals from contaminated environment. When it comes to achieving a suitable level of metal tolerance, this potent powerful actinomycetes strain Streptomyces pactum have been identified to be promising.

Geophysical and physicochemical assessment of groundwater and the implication on the public health in rural and semi-urban areas of Northern Nigeria

Groundwater resource plays a central role in every sector of life globally. Unfortunately, the roles of groundwater are often unappreciated in many parts of the world, especially in developing nations. The paper applied a combined geo-electrical method and hydrochemical analysis alongside physical surveys to investigate aquifer promising zones, the quality and the source of water supply in the selected regions. The geo-electric resistivity data were used to select the most aquifer-promising zone for groundwater development with a key interest in groundwater potential and aquifer overburden protective capacity overlying the water-bearing unit. Seventeen (17) vertical electrical sounding (VES) acquired in four regions reveals that the regional weathered/fractured unit which constitutes the aquifer unity extends from 13.4 m to 41.3 m in depth with the subsurface resistivity value varying between 53 Ωm–1013 Ωm in terms of resistivity values. The overburdened thickness (protective soil layers) stretches from 2.5 m to 13 m with a resistive layer of resistivity values ranging from 111 Ωm to 2877 Ωm, which could provide high aquifer protective cover for the regional groundwater systems. The computed aquifer transmissivity and hydraulic conductivity range from 0.54 m2/h\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${m}^{2}/h$$\\end{document}–15.85 m2/h\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${m}^{2}/h$$\\end{document}, and 0.95 m/day–9.19 m/day, respectively. The estimated average longitudinal conductance (0.2 moh) reveals that the regional groundwater systems are moderately protective against surface contaminants. In addition, the physicochemical water analysis was examined, which exposes the level of heavy metals (HMs) compositions in the regional groundwater systems and the possible public health risks compared to WHO permissible drinking water limits. The sample water from the Rivers had the highest concentration of HMs (0.089 mg/I–2.012 mg/l), followed by the hand-dug wells (HWDs) (0.033 mg/l–1.555 mg/l) and the lowest in the borehole (0.011 mg/l–0.511 mg/l). In contrast, the borehole water sample shows a moderation where the HMs presence falls within the WHO standard for drinking water. The outcomes of the study show that 63% of the investigated region consumed water with a high concentration of HMs above the WHO permissible standard allowance for drinking water, while only 37% took water that falls within the WHO permissible standard. In conclusion, the study showed significant impacts of anthropogenic activities on the regional water quality, which provides vital information about the regional groundwater systems and the quality of water supply for adequate groundwater development and sustainability.

Influencing Factors, Risk Assessment, and Source Identification of Heavy Metals in Purple Soil in the Eastern Region of Guang’an City, Sichuan Province, China

Soil heavy metal contamination poses a significant threat to both environmental health and ecological safety. To investigate the influencing factors, ecological hazards, and sources analysis of heavy metals in purple soil, 27 sets of soil samples were collected from varying genetic horizons within Guang’an City, and the contents of As, Cd, Cu, Cr, Hg, Ni, Pb, and Zn were analyzed. The results indicated higher concentrations of heavy metals in soil A horizon, compared to that of C horizon. The relevance analysis indicated that the soil’s heavy metals were strongly correlated with the soil’s physicochemical properties. The enrichment factor, pollution load index, and potential risk index highlighted slightly to severely polluted levels of soil Cd and Hg, which significantly contribute to the ecological hazards posed by soil heavy metals. The potential source of heavy metals analyzed using the APCS-MLR model identified both anthropogenic inputs and natural sources as primary contributors to heavy metal presence in soils. The Cu, Cr, Ni, Pb, and Zn contents in the samples from different genetic horizons were chiefly influenced by natural sources, such as soil matrix erosion and weathering, while the concentrations of Cd and Hg were largely affected by anthropogenic activities, specifically coal combustion and agriculture. Conversely, the As content was found to be influenced by a combination of both factors. Anthropogenic activities greatly impacted soil heavy metals at various depths within the study area, thereby underscoring the importance of monitoring these heavy metals. The findings gained from this research can give a scientific basis for the potential utilization of purple soil.

Implications of Heavy Metal Accumulation in Fish Feed, Water, Sediment, and Different Fish Species in a Polyculture System.

Heavy metal bioaccumulation in organisms is primarily a result of dietary uptake. The current study examines the concentrations of heavy metals (Pb, Cd, Cr, and Cu) in fish feed, water, sediment, and three fish species (Catla catla, Labeo rohita, and Cyprinus carpio) from different feeding zones in a polyculture pond system. Furthermore, associated human health risks were also evaluated. The fish samples (n = 25 for each species) were collected from 10 different fish ponds in the Kohat district, Pakistan. Heavy metals were determined using an atomic absorption spectrometer. Results revealed higher concentrations of heavy metals in sediment, followed by water. However, the concentration of heavy metals in fish feed was lower than the standard limits. In the case of fish, the bottom feeder (C. carpio) notably exhibited higher (P < 0.05) levels of heavy metals than the column feeder (L. rohita) and surface feeder (C. catla) fish. Moreover, in the liver of all fish species, the bioaccumulation of heavy metals was higher, followed by the gills. Principal component analysis (PCA) demonstrated a strong correlation of heavy metals in C. carpio gills, flesh, feed, and pond water, while the heavy metals in the liver correlated with the detected metals in sediment. The human health risk analysis shows that bottom feeder fish had higher estimated daily intake (EDI), target hazard quotient (THQ), and hazard index (HI) values (> 1). Consequently, the exposed population may experience adverse health effects. The findings of this study suggest that the bottom feeder (C. carpio) bioaccumulates a higher concentration of heavy metals than column (L. rohita) and surface feeder (C. catla) in the polyculture system.

Co-hydrothermal carbonization as a potential method of utilising digested sludge and screenings from wastewater treatment plants towards energy application

Anaerobic digestion is one of the most recommended methods for utilising sewage sludge produced by wastewater treatment plants. However, the increasing amount of micropollutants in digested sludge can significantly limit its future utilisation. Recent studies suggests that the hydrothermal carbonization process can be used as a complementary method for sludge management, due to the improved quality of solid products - hydrochar. Moreover, this allows for the possibility of reusing liquid by-products in the anaerobic digestion process for biogas production. However, hydrochar generated from hydrothermal carbonization has a higher concentration of heavy metals and low energy value, which limits its use in agriculture and energy sectors. This study highlights a partial resolution to this problem, by mixing digested sludge with screenings in the co-hydrothermal carbonization process. The findings of this study show improvements in the properties of hydrochar including total solids measured according to ISO, inorganic fractions determined by inductively coupled plasma optical emission spectrometry and higher calorific values measured by the calorimetric bomb. Biomethane potential tests were conducted on liquid by-products. The results showed an average increase in biomethane potential from liquids obtained from co-hydrothermal carbonization compared to liquids from hydrothermal carbonization of digested sludge without screenings in series 1, 2 and 3 - up to 60 %, 40 % and 26 % for three different sludges with initial total solids content of 2.6 %, 12.5 % and 21.5 % w/w.

Assessment of water quality using entropy-weighted quality index, statistical methods and electrical resistivity tomography, Moti village, northern Pakistan

In this study, twenty-two water samples were collected from boreholes (BH), and streams to evaluate drinking water quality, its distribution, identification of contamination sources and apportionment for Moti village, northern Pakistan. An atomic absorption spectrophotometer (AAS) is utilized to determine the level of heavy metals in water such as arsenic (As), zinc (Zn), lead (Pb), copper (Cu), cadmium (Cd), manganese (Mn), and ferrous (Fe). Groundwater chemistry and its quantitative driving factors were further explored using multivariate statistical methods, Principal Component Analysis (PCA) and Positive Matrix Factorization (PMF) models. Finally, a total of eight electrical resistivity tomographs (ERTs) were acquired across i) the highly contaminated streams; ii) the villages far away from contaminated streams; and iii) across the freshwater stream. In the Moti village, the mean levels (mg/l) of heavy metals in water samples were 7.2465 (As), 0.4971 (Zn), 0.5056 (Pb), 0.0422 (Cu), 0.0279 (Cd), 0.1579 (Mn), and 0.9253 (Fe) that exceeded the permissible limit for drinking water (such as 0.010 for As and Pb, 3.0 for Zn, 0.003 for Cd and 0.3 for Fe) established by the World Health Organization (WHO, 2018). The average entropy weighted water quality index (EWQI) of 200, heavy metal pollution index (HPI) of 175, heavy metal evaluation index (HEI) of 1.6 values reveal inferior water quality in the study area. Human health risk assessment, consisting of hazard quotient (HQ) and hazard index (HI), exceeded the risk threshold (>1),indicating prevention of groundwater usage. Results obtained from the PCA and PMF models indicated anthropogenic sources (i.e. industrial and solid waste) responsible for the high concentration of heavy metals in the surface and groundwater. The ERTs imaged the subsurface down to about 40 m depths and show the least resistivity values (<11 Ωm) for subsurface layers that are highly contaminated. However, the ERTs revealed relatively high resistivity values for subsurface layers containing fresh or less contaminated water. Filtering and continuous monitoring of the quality of drinking water in the village are highly recommended.

Mechanisms of Toxicity of Heavy Metals and the Microbial Strategies for their Mitigation: A Review

Heavy metals toxicity is a major concern worldwide, especially in areas where untreated industrial effluents are released in the environment. Most important heavy metals in this context are arsenic, cadmium, chromium, copper, cobalt, lead, mercury, nickel, selenium and zinc. Some of these are also essential trace elements and play crucial roles in different biological processes. Exposure to high concentration of heavy metals is hazardous for life and can lead to various medical conditions including different types of cancers. The remediation strategies to treat these contaminants involve physical, chemical as well as biological techniques, the latter of which is considered most environment friendly and inexpensive. Bioremediation is the process of removal and detoxification of toxic pollutants using microorganisms. Many microorganisms have evolved different strategies to resist and detoxify such heavy metals. This may include excluding the metals out of the cell, binding of the metals to metal binding proteins to sequester it, conversion of metals into less or non-toxic form by enzymes and alternation of cell components to reduce metal sensitivity. Different genes and proteins are involved in these processes which can be explored for biotechnological interventions and practical applications of bioremediation. This review article discusses the mechanisms of heavy metals’ toxicity, different remediation technologies available, and the various strategies that microorganisms employ to detoxify them.

The effect of heavy metals (Cd, Cu, and Pb) on plant growth parameters and the phytoremediation capacity of corn

Heavy metal contamination is currently a major global environmental issue. Heavy metals contaminate the soils where crops and vegetables grow. Maize (Zea mays L.) is widely employed for phytoremediation because of its high biomass output and metal accumulation capacity. Depending on the plant and soil properties, some metals can be dangerous in high amounts. During our in vitro experiment, different levels of Cd, Cu, and Pb were introduced to a growth medium to allow maize plants to develop under diverse conditions. The study examined numerous growth features under certain metal stress conditions, including seed germination, plant height, biomass, and chlorophyll content, as well as the toxicity symptoms and mechanisms of the most common heavy metals. The study revealed that, while the maize plant is a good heavy metal accumulator, high heavy metal concentrations had a negative impact on several growth indicators: at 250 ppm, Cd inhibited captive seed germination by 50% and wild seed germination by 42.9%; Pb suppressed captive seed germination by 57% and wild seed germination by 42.9%; and Cu inhibited germination in both seed types by 40%. Similarly, plant height decreased in the following order: Pb (36.2%), Cd (24.8%), and Cu (9.7%) for the captive seed plant, and Pb (46.7%), Cd (28%), and Cu (13%) for the wild seed plant. Keywords: MAIZE, STRESS, TOXICITY, HEAVY METAL, POLLUTION, PHYTOREMEDIATION, BIOACCUMULATION

APPLICATION OF BIOREMEDIATION IN MITIGATION OF HEAVY METAL STRESS ON PLANTS

Heavy metals are toxic metals which are persistent in nature due to their nondegradable nature.Due to increase in industrialization and urbanization heavy metals are being added to theenvironment and consequently causing heavy metal pollution of water and soil. These heavy metals cause significant stress on crop plants and effect various parameters such as growth and yield. Manymethods like physical, chemical and biological methods are available to degrade these heavymetals. Recently, bioremediation is being widely used because of its cost-effective andenvironment friendly approach. Bioremediation is a biological process which makes use ofmicroorganisms to remove hazardous substances or environmental pollutants from air, water,soil, industrial effluents etc. Bacteria and fungi are mostly employed for bioremediation.These organisms are genetically engineered for effective use in bioremediation. This not onlydiscussed about the importance of bacteria for bioremediation of heavy metals but alsodiscussed about the challenges and limitations of bacteria for bioremediation. In this chapter, a variety of mechanisms responsible for adaptation of microorganisms to high heavy metal concentrations, e.g. metal sorption, uptake and accumulation, extracellular precipitation and enzymatic oxidation or reduction, will be reported. Moreover, molecular mechanisms responsible for their metal tolerance will be described.

Assessment of water quality and heavy metal contamination in ballast water: Implications for marine ecosystems and human health

The global menace of non-compliance with ballast water management poses a pressing environmental threat, as it facilitates the transfer of harmful organisms and sediment contaminants. This study investigates the environmental impact of ballast water discharged by ships, focusing on water quality and heavy metal concentrations. The release of ballast water, often containing elevated levels of heavy metals like mercury, lead, and cadmium, poses a significant threat to marine ecosystems. The research, involving water sample collection from ten different vessels across various countries, assesses physicochemical parameters and heavy metal concentrations. Results indicate variations in temperature, turbidity, conductivity, dissolved oxygen, and pH levels among samples. Turbidity values surpassing WHO limits suggest potential anthropogenic pollution. The study identifies significant differences in pH values, potentially influencing microbial populations. Total dissolved solids and total suspended solids values vary, affecting the distribution of potential pathogens. The results reveal varying total concentrations of heavy metals (mg/L) in the following decreasing order: SA&gt;SE&gt;SF&gt;SB&gt;SC&gt;SD&gt;SH&gt;SI&gt;SG&gt;SJ(6.07 &gt;4.95 &gt; 2.07 &gt; 1.59&gt;0.24&gt;1.22&gt;0.09&gt;0.04&gt;0.03&gt;0.01). The highest concentration of heavy metals is recorded for iron (SA= 5.78), zinc (mg/L) (SB = 1.36, SE = 1.30, and SF = 1.35) and lead (Pb) (SE = 2.39). The elevated iron levels in vessels from SA are potentially linked to corrosion processes. Cadmium, lead, and nickel were not detected, except for lead in the sample from SE. Copper concentrations were aligned with EU standards in the vessels. Proper ballast water management is vital for monitoring water qualities, preventing environmental spread of heavy metals, ensuring marine ecosystem health, and developing compliance strategies for ships docking in ports. Highlights Global shipping causes heavy metal pollution, affecting human and ecosystem health Physicochemical parameters variations suggest potential pollution and microbial impact Mercury, lead, and cadmium in ballast water (BW) pose threats to marine ecosystems Increased iron levels could be associated with corrosion processes Effective BW management is crucial for environmental conservation

Valorization of biomass bottom ash in alkali-activated GGBFS-fly ash: Impact of biomass bottom ash characteristic, silicate modulus and aluminum-anodizing waste

Growing production of green energy from biomass has led to a surge in biomass bottom ash (BBA) generation, often relegated to landfills due to high leachable heavy metal content. This study proposed solidifying BBA in alkali-activated granulated ground blast furnace slag (GGBFS) and class F fly ash (CFA) blended binders. Investigations into the influence of BBA content, fineness, silicate modulus of activators, and aluminum-anodizing waste (AAW) on solidification performance were conducted, focusing on reaction mechanisms, phase assemblages, mechanical properties and leaching behavior. Results indicate relatively low reactivity of BBA and high leachable chloride (Cl-), sulphate (SO42-), chromium (Cr), molybdenum (Mo), lead (Pb) and zinc (Zn) contents from BBA. Increased BBA substitution leads to strength deterioration, while ground biomass bottom ash (GBBA) improves the mechanical performance slightly. This improvement is attributed to the increased reactive aluminosilicate content and an enhanced packing system resulting from finer particles. However, GBBA induces an increased heavy metals leaching. Higher silicate modulus activators enhance mechanical properties and reduce the leaching of Mo and Cl-, while lower silicate modulus activator accelerates the reaction process, promoting the formation of hydrotalcite-like phases and reducing the leaching of Cr and SO42-. Incorporating 0.5 wt% aluminum-anodizing waste improves immobilization efficiency of toxic ions, but further increases in dosage lead to higher leaching due to weakened mechanical performance. Overall, hybrid binders with 10 wt% G/BBA exhibit desirable mechanical properties, along with sufficient immobilization of leachable heavy metals, enabling their use as potential construction materials.

In vitro and in vivo screening of bacterial species from contaminated soil for heavy metal biotransformation activity

Heavy metals (HMs) are widely used in various industries. High concentrations of HMs can be severely toxic to plants, animals and humans. Microorganism-based bioremediation has shown significant potential in degrading and detoxifying specific HM contaminants. In this study, we cultivated a range of bacterial strains in liquid and solid nutrient medium containing different concentrations of different HMs to select and analyze bacteria capable of transforming HMs. The bacterial strains most resistant to selected HMs and exhibiting the ability to remove HMs from contaminated soils were identified. Then, the bacterial species capable of utilizing HMs in soil model experiments were selected, and their ability to transform HMs was evaluated. This study has also generated preliminary findings on the use of plants for further removal of HMs from soil after microbial bioremediation. Alcaligenes faecalis, Delftia tsuruhatensis and Stenotrophomonas sp. were selected for their ability to grow in and utilize HM ions at the maximum permissible concentration (MPC) and two times the MPC. Lysinibacillus fusiformis (local microflora) can be used as a universal biotransformation tool for many HM ions. Brevibacillus parabrevis has potential for the removal of lead ions, and Brevibacillus reuszeri and Bacillus safensis have potential for the removal of arsenic ions from the environment. The bacterial species have been selected for bioremediation to remove heavy metal ions from the environment.

Treatment of electroplating wastewater using electrocoagulation and integrated membrane.

Electroplating wastewater contains heavy metal ions and organic matter. These contaminants not only endanger the environment but also pose risks to human health. Despite the development of various treatment processes such as chemical precipitation MBR, electrocoagulation (EC) ceramic membrane (CM), coagulation ultrafiltration (UF) reverse osmosis (RO), and CM RO. These methods are only effective for low concentrations of heavy metals and struggle with high concentrations. To address the challenge of treating electroplating wastewater with high heavy metal content, this study focuses on the wastewater from Dongfang Aviation Machinery Processing Plant. It introduces an EC and integrated membrane (IM) treatment process for electroplating wastewater. The IM comprises microfiltration (MF) membrane, nanofiltration (NF) membrane, and RO membrane. Results indicated that under specific conditions, such as a pH of 8, current density of 5 A/dm2, electrode plate spacing of 2 cm, 35 min of electrolysis time, and influent pH of 10 for the IM, removal rates of Zn2+, Cu2+, Ni2+, and TCr in the wastewater exceeded 99%. The removal rates of chemical oxygen demand (COD), suspended solids (SS), total phosphorus (TP), total nitrogen (TN), and petroleum in wastewater exceed 97%. Following a continuous cleaning process, the membrane flux can consistently recover to over 94.3%.

Bioremoval and Resistance of Some Heavy Metals by Bacterial Isolates from the Sediments of the Diyala River

Background:Heavy metals are pollutants that do not decompose, but enter the food chain, and thus form toxic compounds that have a harmful effect on biological functions. There are an unlimited number of organisms in various environments, including bacteria, that are able to degrade and reduce the high levels of many pollutants, most of which have not been as important to researchers as they are interested in pathological microorganisms. Objective: This research sheds light on a number of bacterial isolates that were isolated and identified, one of which showed its high ability to grow in culture environments with high concentrations of heavy metals. Materials and Methods: Twelve sediment samples were collected from the Diyala River within the boundaries of the study area, which included four main sites. Fifteen bacterial isolates capable of resisting heavy metals were recognized at a concentration of (50 mg / L), and then five isolates were selected as the best isolates to grow and resistance of cobalt between (400-750 mg/L), chromium between (1600-2600 mg/L), nickel between (1200-1600 mg/L) and lead between (1200 - 2200 mg/liter). One of these isolates, (iso 4) showed a high ability to remove heavy metals (chromium, cobalt, nickel, and lead) after the test, with concentrations of (25, 50, and 100 mg/L), and the removal rate for 5 days of chromium was (36, 55, 68, 73 and 77%) respectively, and the removal rate of cobalt was (22, 34, 44, 54 and 59%) and the removal rate of nickel was (23, 40, 56, 68 and 80%) and the removal rate for lead is (58, 68, 74, 80 and 86%). The same isolate also showed high efficiency in removing lead due to the ability to resist high concentrations with a 100% percentage of lead removal at a concentration of 25 mg/L from the first day until the fifth day. The biochemical diagnosis of the selected bacterial isolates was adopted and the diagnosis was made using the VITEK-2 system for isolate No. 4, as the results showed that it belongs to the genus Klebsiella pneumonia. Conclusions: These environmental isolates can be applied in many bioremediations techniques to remove many toxic compounds cheaply and safely.

Heavy metals in soil, finger millet and weeds due to nutrient management practices under a 43-year-old long term fertilizer experiment

Chemical fertilizers contain traces of heavy metals and long-term use of fertilizers in agriculture could lead to the accumulation of heavy metals in the soil. Specific amounts of fertilizers and manure have been consistently applied for the past 43 years. Soil and plant samples were collected and quantified for heavy metals. The results revealed that the application of FYM and inorganic fertilizers led to a higher concentration of heavy metals in surface soil and decreased with soil depth. The application of 100% RDF resulted in higher concentrations of metals in samples of finger millet and all the heavy metals were below toxic limits. The PLI of heavy metals was found to have a value &lt;10, indicating that soils are less polluted. Cd and Pb had BCF values of &lt;1 for grain and straw, which indicates a lower concentration of metals in soil than those taken up by plants, while &gt;1 for As and Cr indicates a higher uptake in grain and straw than in soil.

Bioconcentration of Heavy Metals in Milkfish Reared in Stick-Net Pens System: Implications for Open Water Environmental Contamination and Food Safety

The coast of Tanjung Mas, Semarang City, is an industrial area used by the community to cultivate milkfish using stick-net pens. Furthermore, heavy metal contamination such as Cr, Cd, Cu, and Pb potentially disrupts milkfish meat's growth, quality, and safety. This study aims to determine heavy metals concentration in the waters and milkfish meat in stick-net pens cultivation in Tanjung Mas, Semarang City. The study was conducted using exploration, with five observation sites representing household waste disposal flow, industrial discharge, open sea, and intermediate areas. The observation sites were selected based on the milkfish cultivation activity. The sample and data, including water, milkfish, and environmental factors (temperature, pH, salinity, water current, and dissolved oxygen), were collected three times every two weeks. The heavy metals were detected using Atomic Absorption Spectrometry (AAS). The highest heavy metal concentration is Cr, which ranges from 1.70 ± 0.32 ppm to 2.36 ± 0.63 ppm in milkfish and 2.77 ± 0.65 ppm to 3.05 ± 0.58 ppm in the environment. The heavy metals contamination in Semarang City’s water areas is still relatively low and has no impact on milkfish growth. Industrial waste, mainly heavy metals, potentially threatens the stick-net pens cultivation model developed by the community in Semarang City. This study can be used as an input for mitigation and adaptive action in anticipating future environmental changes and maintaining their business sustainability.

Association of Acidotolerant Cyanobacteria to Microbial Mats below pH 1 in Acidic Mineral Precipitates in Río Tinto River in Spain.

This report describes acidic microbial mats containing cyanobacteria that are strongly associated to precipitated minerals in the source area of Río Tinto. Río Tinto (Huelva, Southwestern Spain) is an extreme acidic environment where iron and sulfur cycles play a fundamental role in sustaining the extremely low pH and the high concentration of heavy metals, while maintaining a high level of microbial diversity. These multi-layered mineral deposits are stable all year round and are characterized by a succession of thick greenish-blue and brownish layers mainly composed of natrojarosite. The temperature and absorbance above and below the mineral precipitates were followed and stable conditions were detected inside the mineral precipitates. Different methodologies, scanning and transmission electron microscopy, immunological detection, fluorescence in situ hybridization, and metagenomic analysis were used to describe the biodiversity existing in these microbial mats, demonstrating, for the first time, the existence of acid-tolerant cyanobacteria in a hyperacidic environment of below pH 1. Up to 0.46% of the classified sequences belong to cyanobacterial microorganisms, and 1.47% of the aligned DNA reads belong to the Cyanobacteria clade.