Low Concentrations Of Heavy Metals Research Articles

Chemical Constituents, Proximate Composition, and Heavy Metals of the Oil Seed of <i>Guizotia scabra</i> Consumed in Plateau State-Nigeria

<i>Guizotia scabra</i> (L. F cass. composite) is an oil seed crop found wildly and in some areas cultivated at middle and higher geographical locations in Nigeria and other African countries. The objectives of this research were to among other things determine the physicochemical properties, proximate composition, and chemical constituents. Standard methods for physicochemical properties, proximate analysis and GC/MS was used to determine the chemical constituents. The physicochemical properties revealed acid value 0.455 mg/KOH/g. The percentage yield was 21.34%. The saponification value was 33.10 mg of KOH/kg. Peroxide value revealed 16.35 meq/KOH/kg. The iodine value was 66.83g/100g. The Specific gravity was 0.9246 and the viscosity was 25.3 mPa.s. A proximate composition 6.95% of moisture content, ash content was 3.05%, crude protein was 21.72%, crude fat was 24.4%, crude fibre was 29.5%, dry matter content was 93.50% and organic matter content was 96.95%. The chemical constituents revealed 9, 12-Octadecadienoic acid (31.80%) as the predominant unsaturated fatty acid in the seed oil while Dodecanoic acid (Lauric acid) (3.46%) is the predominant saturated fatty acid. The concentration of Zn in the samples was (1.146±0.00 µg/g), is higher than the other metals (Cu, Fe, Ni, and Pb), Ni and Pb were not detected in the sample. <i>Guizotia scabra</i> seed oil from Plateau state is therefore good for consumption due to it low acid value, good protein content, good amount of unsaturated fatty acid, low concentration of heavy metals and some phytochemicals.

Extraction of Humic Acids from Lignite and Its Use as a Biochar Activator.

Current research focuses on extracting humic acid (HA) compounds from low-rank coals to obtain high value-added products. In this study, HAs with high purity and low heavy metal content were obtained from lignite by combining acid pretreatment with hydrothermal treatment. Scanning electron microscopy, elemental analysis (EA), Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction, and inductively coupled plasma optical emission spectrometry (ICP-OES) were used to analyze raw lignite and HAs. The effects of acid and hydrothermal treatments on the inorganic elements, functional groups, and yield of HAs were examined. The results showed that acid treatment reduced the ash content of lignite from 20 to 9%, and hydrothermal treatment increased the yield of HAs from 36 to 68%. The chemical properties of HAs exhibited an increase in molecular weight and improved aromaticity after acid and hydrothermal treatments. The results of ICP-OES analysis suggested that the combined method of acid and hydrothermal treatments resulted in a significant reduction of heavy metal elements in HAs. FTIR analysis confirmed the results and demonstrated that the extracted HA from nitric acid pretreated and hydrothermal generation of lignite PHA was rich in carboxyl and phenolic functional groups. PHA was applied to biochar as an activator for the adsorption of heavy metal ions. The experimental results showed that PHA was successfully loaded onto biochar and introduced a large number of functional groups, and the adsorption capacity of the modified biochar for Pb2+ was effectively improved.

Distribution and Statistical Analysis of Chemical Elements in Soil from the Territory of the Republic of Kosovo

ABSTRACT This research presents the results on the spatial distribution and concentration of different chemical elements in the topsoil (0–5 cm) and the subsoil (20–30 cm), focusing on the identification of natural and anthropogenic sources of elements at 99 locations and 198 samples throughout the territory of the Republic of Kosovo. The samples were digested with acid mixture in Teflon vessels and the technique of inductively coupled plasma-atomic emission spectroscopy (ICP-AES) and mass spectrometry (ICP-MS) was applied for the analysis of 20 elements (Al, As, Ba, Ca, Cd, Co, Cr, Cu, Fe, K, Li, Mg, Mn, Na, Ni, P, Pb, Sr, V and Zn). The multivariate statistical method was employed for the statistical processing of the data using cluster and factor analysis. Four groups of elements were identified, three of which were with geogenic factors: (Co, Cr, Ni, Fe, Mg), (Ba, K, Na, V), (Al, Ca, Sr) and one with local enrichment tendencies (anthropogenic origin) (Pb, Zn). The data obtained show natural presence of the analyzed elements and low concentration of heavy metals in the entire territory of Kosovo, with the exception of some areas where higher levels of concentration are shown as a result of the influence of the anthropogenic factor.

Effect of garden and park waste hydrochar and biochar in soil application: a comparative study

Thethermochemical treatments of biowaste yield alternative renewable carbon-rich materials, while achieving waste valorization. These technologies allow to reduce amount of biowaste and enhance its life span avoiding the landfill disposal. The agronomic application as a soil amendment strategy using fresh hydrochar (obtained via the hydrothermal treatment of garden and park waste (GPW) at 180 °C for 1 h), post-treated hydrochar (washed, aged, and thermally treated), and biochar (obtained via the pyrolysis of GPW at 900 °C for 90 min) has been studied and compared in order to stablish the best approach for its valorization. We evaluated the effects of mixing fresh hydrochar (1–5% on dry weight) with different peat-based growth substrates on the seed germination index as well as the fresh and dry weights of Arabidopsis thaliana, Chenopodium quinoa, and Solanum lycopersicum (tomato). We also performed a germination assay with marginal agricultural soil mixed with fresh and post-treated chars as well as biochar using the same doses. All carbonaceous materials complied with the European legal framework being categorized as a class A amendment and present a favorable chemical composition for their agronomic use, carbon sources with a low heavy-metal content, and a high mineral and organic matter content. Application of post-treated hydrochar to the agricultural marginal soil improved the germination index of tomato seeds (by 10–20%) at low dosages (< 3% on dry weight) when washed and thermally treated hydrochar was used. However, fresh hydrochar negatively affected seed germination and plant growth when applied to marginal soil and peat-based growth media, particularly sandy substrates. Washing improved the germination index (by approximately 18%), reduced 90% of the total volatile fatty acid content, and effectively removed furans, amines, amides, pyridines, pyrazines, benzoic compounds, and organic acids that can affect seed germination and plant growth. Because the use of hydrochar in soils for agricultural purposes requires post-treatment to alleviate germination and plant growth inhibition, washing is the most suitable option considering the energy and technological requirements.

Identification and Characterization of the Determinants of Copper Resistance in the Acidophilic Fungus Acidomyces richmondensis MEY-1 Using the CRISPR/Cas9 System.

Copper (Cu) homeostasis has not been well documented in filamentous fungi, especially extremophiles. One of the main obstacles impeding their characterization is the lack of a powerful genome-editing tool. In this study, we applied a CRISPR/Cas9 system for efficient targeted gene disruption in the acidophilic fungus Acidomyces richmondensis MEY-1, formerly known as Bispora sp. strain MEY-1. Using this system, we investigated the basis of Cu tolerance in strain MEY-1. This strain has extremely high Cu tolerance among filamentous fungi, and the transcription factor ArAceA (A. richmondensis AceA) has been shown to be involved in this process. The ArAceA deletion mutant (ΔArAceA) exhibits specific growth defects at Cu concentrations of ≥10 mM and is transcriptionally more sensitive to Cu than the wild-type strain. In addition, the putative metallothionein ArCrdA was involved in Cu tolerance only under high Cu concentrations. MEY-1 has no Aspergillus nidulans CrpA homologs, which are targets of AceA-like transcription factors and play a role in Cu tolerance. Instead, we identified the Cu-transporting P-type ATPase ArYgA, homologous to A. nidulans YgA, which was involved in pigmentation rather than Cu tolerance. When the ΔArYgA mutant was grown on medium supplemented with Cu ions, the black color was completely restored. The lack of CrpA homologs in A. richmondensis MEY-1 and its high tolerance to Cu suggest that a novel Cu detoxification mechanism differing from the AceA-CrpA axis exists. IMPORTANCE Filamentous fungi are widely distributed worldwide and play an important ecological role as decomposers. However, the mechanisms of their adaptability to various environments are not fully understood. Various extremely acidophilic filamentous fungi have been isolated from acidic mine drainage (AMD) with extremely low pH and high heavy metal and sulfate concentrations, including A. richmondensis. The lack of genetic engineering tools, particularly genome-editing tools, hinders the study of these acidophilic and heavy metal-resistant fungi at the molecular level. Here, we first applied a CRISPR/Cas9-mediated gene-editing system to A. richmondensis MEY-1. Using this system, we identified and characterized the determinants of Cu resistance in A. richmondensis MEY-1. The conserved roles of the Cu-binding transcription factor ArAceA in Cu tolerance and the Cu-transporting P-type ATPase ArYgA in the Cu-dependent production of pigment were confirmed. Our findings provide insights into the molecular basis of Cu tolerance in the acidophilic fungus A. richmondensis MEY-1. Furthermore, the CRISPR/Cas9 system used here would be a powerful tool for studies of the mechanisms of adaptability of acidophilic fungi to extreme environments.

Early immune response of neuronal cells (U87) to heavy metal Cd or Pb exposure.

Heavy metals such as lead (Pb) and cadmium (Cd) exist as particulate matter (PM) in the air and can cause biological damage to cells, animals, and humans. However, the mechanism underlying the toxic effects of heavy metals on nerve cells has not yet been completely identified. Glioma is the most common and fatal tumor in the central nervous system; the U87 human glioblastoma cell line is commonly used when researching brain cancer, including aggressive malignant gliomas. Therefore, in this study, cell viability, cytotoxicity, and interleukin-6 (IL-6) levels were analyzed to confirm the effect of Cd and Pb exposure on U87 cells. On confirming the absence of significant effects on cell viability at low concentrations of heavy metals, Cd and Pb exposure had no effect on lactic acid dehydrogenase (LDH) activity at the concentrations (1 μg/L, 30 μg/L, and 1 mg/L) used in this study, and there was a remarkable effect of Cd and Pb exposure on the inflammatory response of these cells. Our findings provide a basis for future research elucidating the effects of heavy metal exposure on cellular pathology. Systematic studies with higher heavy metal concentrations and precision are warranted to deepen our understanding of the relationship between heavy metal exposure and neuronal responses.

Assessment of the chemical and radiological safety of wild mushrooms and berries growing in the Arkhangelsk region

AIM: To analyze the levels of contamination with heavy metals and radionuclides of wild mushrooms and berries growing in the Arkhangelsk region.&#x0D; METHODS: Data on the content of heavy metals (cadmium, mercury, lead, arsenic) and radionuclides (cesium-137 and strontium-90) in berries and mushrooms were studied in accordance with the protocols of the Agrochemical Service Station Arkhangelskaya and the Center for Hygiene and Epidemiology in the Arkhangelsk Region and the Nenets Autonomous Okrug during the period of 20152021. Total 201 samples of mushrooms and 175 samples of berries were analyzed.&#x0D; RESULTS: The levels of heavy metals did not exceed the maximum permissible concentrations in 94% of the studied samples of mushrooms and 86% of the studied samples of berries. All samples of mushrooms and berries corresponded the hygienic standards for the content of radionuclides. The mean concentrations of mercury (0.013 mg/kg) and cadmium (0.040 mg/kg) in mushrooms were higher than the average concentrations of these metals in berries by 2.1 (p=0.002) and 1.8 times (p 0.001), respectively. At the level of median concentration and 90th percentile, the content of mercury in tubular mushrooms (0.036 and 0.047 mg/kg, respectively) was 3.2 times higher in comparison to plate mushrooms (p=0.003). The highest content of arsenic (0.067 and 0.24 mg/kg, respectively) and lead (0.088 and 0.15 mg/kg) were found in the berries of the large-sized shrubs at the level of average concentration and the 90th percentile compared to other shrub species, but the differences were not statistically significant.&#x0D; CONCLUSION: The comparative analysis concluded that although mushrooms and berries from the Arkhangelsk region contain low concentrations of heavy metals and radionuclides, mushrooms tend to accumulate higher concentration of heavy metals and radionuclides in comparison to berries.

Competitive adsorption of heavy metals between Ca–P and Mg–P products from wastewater during struvite crystallization

Wastewater usually contains high concentration of calcium (Ca), posing a competitive reaction with magnesium (Mg) on phosphorus (P) recovery during the struvite crystallization. The differences in the adsorption of heavy metals by Ca–P and Mg–P (struvite) generated are still unclear. Herein, we analyzed the residues of four kinds of common heavy metals (Cu, Zn, Cd, Pb) in Ca–P and Mg–P (struvite) under varying conditions (solution pH, N/P ratio, Mg/Ca ratio) in the swine wastewater and explored their possible competitive adsorption mechanisms. The experiments using synthetic wastewater and real wastewater have similar experimental patterns. However, under the same conditions, the metal (Pb) content of struvite recovered from the synthetic wastewater (16.58 mg/g) was higher than that of the real wastewater (11.02 mg/g), as predicted by the Box-Behnken Design of Response Surface Methodology (BBD-RSM). The results demonstrated that Cu was the least abundant in the precipitates compared to Zn, Cd, and Pb of almost all experimental groups with an N/P ratio greater than or equal to 10. The fact might be mainly attributed to the its stronger binding capacity of Cu ion with NH3 and other ligands. Compared with struvite, the Ca–P product had a higher adsorption capacity for heavy metals and a lower P recovery rate. In addition, the higher solution pH and N/P ratio were favorable to obtain qualified struvite with lower heavy metal content. It can be applied to reduce the incorporation of heavy metals by modulating pH and N/P ratio through RSM, which is suitable for different Mg/Ca ratios. It is anticipated that the results obtained would offer support for the safe utility of struvite from wastewater containing Ca and heavy metals.

Study of the hydraulic correlation in the removal of pollutants from synthetic wastewater by means of a filter with Musa Paradisiaca

Background: The objective of this work was to decontaminate synthetic sewage from fouracid blue (BRL) dye, with characteristics similar to those of the textile industry, to determine the correlation between flow rate, permeability and removal of hexavalent chromium (Cr+ 6), Cupper (Cu), chemical oxygen demand COD and color using Paradise Muse filter bed. Methods: three concentrations of BRL synthetic wastewater were prepared, determining the initial concentrations of Color, pH, COD, Cr +6 and Cu. In addition, the hydraulic characteristics of the fiber were determined in four types of fiber cut. The synthetic wastewater was filtered in a filtration cell with the three fiber cuts, using three speeds, the time used for these tests was 180 minutes. Water samples were collected every 5 minutes and then analyzed in the laboratory. Simple exponential smoothing was performed on the data obtained, and the statistical analysis of variance ANOVA of 2 factors. Results: The results show that flow velocity and permeability are correlated with color removal, COD and Cr+ 6, determining that the best treatment was to use 1 cm fiber and high flow velocity in which 77.92% and 70.01% for color and COD respectively. In contrast, for Cr+ 6 the best treatment was fiber at 1 cm and low flow velocity removing up to 80% of the concentration of this contaminant and for Cu the best treatment was fiber at 3 cm and low flow velocity removing up to 88.69%. Conclusions: It was determined that the Musa Pardisiaca fiber is capable of absorbing contaminants, but the effectiveness of the treatment depends on the initial conditions of the synthetic water, the cut of the fiber and the velocity. In addition, it is important to mention that, in order to lower heavy metal concentrations, low flow rates should be used.

Alkali Modification: An Approach to Improve Surface Properties of Biochar From Easily Available Feedstocks

Biochar is a stable carbon-rich material whose potentials can be greatly enhanced by modification with simple treatments. Easily available two different biochars such as rice stubble biochar (RSB) and saw dust biochar (SDB) were slowly pyrolyzed (450±50°C) and modified with KOH as RSB-M and SDB-M respectively. Represented biochars were analyzed to know their physicochemical characteristics and nutrient contents. Results revealed that nutrient contents such as total N, P and S of RSB and SDB were found maximum whereas RSB-M and SDB-M showed the lowest nutrient contents. All the biochars possessed pH value higher than 7. In case of organic C, the values of RSB-M (19.97%) and SDBM (17.83%) were the highest and RSB (17.32%) and SDB (14.80%) were the lowest. All the biochars showed very low concentration of heavy metals (such as Cr, Cd, Pb and Ni). Water holding capacity, average particle size and surface area were higher in the RSB-M and SDB-M compared to unmodified RSB and SDB. These findings showed that alkali-modified biochars had better surface properties than unmodified biochars. Dhaka Univ. J. Biol. Sci. 31(2): 213-223, 2022 (July)

Evaluation of sludge quality in Indian sewage treatment plants to develop quality control indices.

Dewatered sludges from twenty-two sewage treatment facilities were characterized to develop the quality control indices in India. This study used fertilizer index (FI) and clean index (CI) as a tool for categorizing sludge utilization into different classes (A, B, C and limited use classes LU-1, LU-2, LU-3) by their fertilizing potential, toxicity level, pathogen presence, and vector attraction reduction criteria. The findings revealed that total P (as P2O5), total N, and K (as K2O) in the sludge samples ranged from 0.9 to 5.7%, 1.2 to 3.8%, and 0.1 to 1.5%, respectively. Moreover, all sludges belong to Class C and lower category due to the presence of toxic metals and pathogens. The helminth eggs were found in the range of 25-1450 Numbers/4gTS in sludge samples. The highest number of helminth eggs of 1450/4g of TS was found in the fecal sludge. The specific oxygen uptake rate (SOUR) values in the sludge samples varied from 0.3 to 4.9, with a median value of 1.3 and an RSD of 86% is way too high. It indicates that the sludge samples need further treatment to be less attractive as a food source for vectors and rodents. However, sludge samples have fertilizing potential and FI values ranges from 4.1 to 4.9, and CI value ranges from 2.5 to 5.0. It indicates that compost is best in quality and has high-fertilizer potential and low heavy-metal content, which is suitable for high-value crops such as organic farming. Further sludge treatment using typical composting, aerobic or anaerobic digestion, and solar or thermal drying could bring the sludges into the Class A and B categories.

Synergistic effect of biochar amendment in milk processing industry sludge and cattle dung during the vermiremediation

The effective and sustainable management of fast growing and large quantities of industrial waste is a serious issue. The purpose of the present study was to assess the synergistic effect of biochar (BC) amended in milk processing industry sludge (MS) mixed with cattle dung (CD) in different ratios through vermiremediation. The MS25 and MS25BC10 (25:75 + 10 % BC) showed the least mortality and greatest earthworm growth and development. The final product from all feed mixtures recorded a decrease in pH, total organic carbon and C/N ratio. Other parameters viz., electrical conductivity, total available phosphorus, total Kjeldahl nitrogen, total sodium, total potassium and ash content was observed to be increased after vermicomposting. Significantly lower heavy metal content was found in all biochar amended feed mixtures than in mixtures without biochar. The germination index of Trigonella foenum-graecum showed a value ranging from 89.14 to 131.46 % for mixtures without BC and 115.18–153.47 % for biochar amended mixtures.

Heavy metals, rare earth elements and isotopic fingerprint of Venetian Protected Designation of Origin sparkling wines

PurposeWorld imports of Italian sparkling wines fell by 9% in value and 5% in quantities. In view of this, the quality characterisation of these products is desirable to increase their market value and restore their global visibility.Design/methodology/approachFor this purpose, in this paper, heavy metals (Cd, Co, Cr, Cu, Fe, Ga, Hf, Hg, Mn, Mo, Nb, Ni, Pb, Re, Sb, Sn, Ta, Th, Tl, U, W, V, Zn, Zr), rare Earth elements (REEs) (Ce, Dy, Er, Eu, Gd, Ho, La, Lu, Nd, Pr, Sm, Tb, Tm, Yb) and isotopes ratio (208Pb/206Pb, 207Pb/206Pb, 206Pb/204Pb, 208Pb/207Pb, 87Sr/86Sr) were analysed in Italian sparkling wines with Protected Designation of Origin (PDO) certification by High Resolution Inductively Coupled Plasma Mass Spectrometry (HR-ICP-MS) and MultiCollector Inductively Coupled Plasma Mass Spectrometer (MC-ICP-MS). The samples were produced in the Veneto region, and they were compared to white and red wines from the same area.FindingsSparkling wines present a characteristic elemental pattern compared to white and red ones, with lower content of heavy metals and higher content in REEs. The ratio 87Sr/86Sr resulted in a powerful micro-scale geographical origins marker while Pb ratios as winemaking process one, both useful to prevent possible frauds. Multivariate data analyses, such as PCA and PLS-DA, were used to develop a model of recognition of Venetian sparkling wines.Originality/valueThe good classification of sparkling wines was achieved (95%), proving the suitable use of these analytes as markers for recognising sparkling wines and their geographical origin verification. To the best of the authors’ knowledge, this is the first study investigating heavy metals, REEs and isotopes in Venetian sparkling wine for their recognition.

ASSESSMENT OF HEAVY METALS IN SABARMATI RIVER: A CASE STUDY BEFORE AND DURING THE LOCKDOWN

Sabarmati is one of the largest rivers in Gujarat and passes through cities like Gandhinagar and Ahmedabad. The municipal pollutants in the river comprise untreated domestic and sewage wastes. In contrast, industrial pollutants constitute the discharge of heavy metals into the river, responsible for increasing metal load in the water. Increasing heavy metal concentration in the water can cause severe problems. In this work, Cu, Mn, Fe, Cr, Zn, Pb, and Cd heavy metals were analyzed from the five selected sites for two years, 2020 and 2021, in Two seasons pre and post-monsoon. In 2020, there was a lockdown situation because of Covid-19, so all industrial the activities were shut down. Therefore pollution levels were decreased, and the environment was clean. Our study indicates that in the pre-monsoon season in 2020, Iron metal was highest, and in post-monsoon, Chromium was the highest. In the Post-monsoon season 2020, Iron metal was the highest, and Lead was the highest in the post-monsoon season. Because of the covid-19 lockdown, the result of post-monsoon 2020 shows the low concentration of heavy metals.

Heavy metal removal from produced water by chemical-mechanical treatment

This paper proves the presentation features of chemical and mechanical aimed at action of heavy metal in produced water (PW). The Electro-catalytic (EC) is one of chemical- mechanical remained made and reflects the extent of its custom in purifying this wastewater. Throughout EC behavior, numerous operating limits were inspected, for instance titanium dioxide, rpm electrolysis time, and copper metal in produced water. The belongings of the working variables including the rpm (100-300), TiO2 concentration (10-30 mg/L), and the electrolysis time (5-15 min) by using Response surface methodology (RSM) and Minitab 17. The current and pH of the solution had remained occupied by way of 1 Amps, 3 respectively. Underneath the finest standards of the employed variables more than 98% removal of copper was found. The elective catalytic method is appropriate aimed at water contaminated by heavy metal, especially aimed at low concentrations of heavy metal in produced water.

Use of the nematode Caenorhabditis elegans in toxicity tests in water samples from the Calera river, Ecuador

The province of El Oro is the most important gold mining area in Ecuador, but the activity has caused damage to the ecosystem and human health, due to the dumping of extraction waste loaded with heavy metals into the Calera River, which is a tributary with the Yellow River of the Puyango river. This work presents the results of the evaluation of the toxicity of the water and sediments of the Calera River using the nematode Caenorhabditis elegans as a bioindicator for environmental monitoring. The quantification of heavy metals by atomic absorption spectroscopy in samples collected along the Calera River, both in water and in sediments, revealed that the concentration in water was below the permissible limits established by the Ecuadorian Environmental Standard, while in the sediment sample, the concentration values of heavy metals considerably exceeded the permissible limits, particularly Arsenic and Cadmium, which were the ones detected with the highest concentrations. In the bioassays with C. elegans subjected to different concentrations and exposure times of 12, 18, 24 and 36 hours, no mortality rate was detected in the water samples analyzed, which is attributed to the low concentration of heavy metals. The exposure of the nematodes to the sediment extracts, induced mortality in all the samples, mainly in those coming from the sector in which the rock material processing plants are located.

Influence of Technical Parameters of the Pyrolysis Process on the Surface Area, Porosity, and Hydrophobicity of Biochar from Sunflower Husk Pellet

Biochar is a product that has been of interest to many researchers in recent years. The use and positive effect of biochar depend on its properties, which in turn result primarily from the type of substrate used for production and the technical parameters of the pyrolysis process used. From the point of view of sustainable development, agricultural raw materials, such as sunflower husks, are good materials for biochar synthesis. The research aimed to determine the effect of changing the technical parameters of the pyrolysis process (i.e., temperature, heating rate, and residence time) on the properties of biochar obtained from sunflower husk pellets. The pellets were heated to 480 °C, 530 °C, and 580 °C. The applied heating rate for 480 °C was 4.00 and 7.38 °C·min−1, for 530 °C it was 4.42 and 8.15 °C·min−1 and for 580 °C it was 4.83 and 8.92 °C·min−1. Determining these properties is important due to the use of biochar, e.g., in the processes of sorption of pollutants from the water and soil environment. The technical parameters of the pyrolysis process used allowed us to obtain hydrophilic materials with porosity in the range of 10.11% to 15.43% and a specific surface area of 0.93 m2·g−1 to 2.91 m2·g−1. The hydrophilic nature of biochar makes it possible to use them in the processes of removing inorganic pollutants and polar organic pollutants. The presence of macropores in biochar may contribute to the improvement of water management in the soil and affect the assimilation of microelements by plants. The low content of heavy metals in biochar does not pose a threat to the environment.

Heavy metals removal using natural zeolite adsorption from Tigris river water at Samarra city (Iraq)

Purpose. The current study was conducted to evaluate the heavy metals adsorption and sorption rate when removing them from water and processing it in the Tigris River in Samarra city, Salah El-deen, Iraq in 20212022 and evaluate the efficiency of zeolite for removing heavy metals, as well as to determine the high and low adsorption percentage from all heavy metals found in the river. Methodology. The study included the analysis and measurement of physical and chemical properties with low-cost natural processing with no side effects to reduce the heavy metal in the Tigris River. Finding. The results of the present study showed that the conductivity and turbidity of water decreased from 1596 to 727 c/cm, from 343 to 22 naphthalene unit (NTU), respectively, and turbidity decreased from 633 to 491 ml/L. The concentrations of biological dissolved oxygen, total suspended solid, and total dissolved solid increased, while those of preprocessing nitrates (12.2mg/l) differed significantly from the results of post processing (52 mg/l). Repetitive measurements showed good results for heavy metals such as Cr3+, Cd2+, Cu2+, Pb2+, Zn2+, Ni2+ and Co2+ with 16.3, 23.1, 6.3, 14.4, 8.1, 12.5 and 17.4 mg/l, respectively; the adsorption percentage was 81.6, 81.5, 86.7, 87.3, 76.4, 89.5 and 79.7%, respectively. Originality. The work showed the efficient processing of sewage water when treated with zeolite rocks powder being low cost and easy to use to adsorb heavy metals from water. Practical value. Zeolite as a powder ground in different sizes could be used as a layer in the filter that purifies the water to become a drinking water with low heavy metal concentrations as well as with some other factors.

Risk assessment of Artemia egg shell-Mg-P composites as a slow-release phosphorus fertilizer during its formation and application in typical heavy metals contaminated environment

Artemia egg shell loaded with nano-magnesium (shell-Mg) can be used to recover phosphorus from wastewater. The exhausted Artemia egg shell-Mg (denoted as shell-Mg-P) can be used as a slow-release fertilizer for phosphorus reuse. However, due to the coexistence of heavy metal ions in the environment, the application of slow-release fertilizer for phosphorus removal and reuse may have potential risks. In this paper, the potential risks of Pb2+, Cd2+, Zn2+ and Cu2+ in phosphorus wastewater and soil were studied from the formation and application process of shell-Mg-P. The result showed that shell-Mg adsorbed Pb2+, Cd2+, Zn2+ and Cu2+ in phosphate wastewater during the formation of shell-Mg-P and became shell-Mg-P-metal hybrid biomaterial. Although the experiment proved that the existence of heavy metal ions did not affect the phosphorus slow-release behavior of slow-release fertilizer, but the heavy metal ions in the shell-Mg-P-metal were also slow released. The pot experiment results confirmed that the slow-release phosphorus fertilizers (shell-Mg-P and shell-Mg-P-metal) in the soil polluted in low concentration of heavy metals can reduce the amount of heavy metals in whole wheat seedlings and promote wheat seedling growth. However, the application of slow-release fertilizers increased the translocation efficiency (TFR to SL) of metal from root (R) to aboveground part (stem and leaves, SL), promoted the transportation of heavy metals from roots to the stems and leaves, and increased the safety risk of the wheat seedling edible. Therefore, besides the positive role of slow-release fertilizers in retaining heavy metals and reducing the amount of heavy metals in whole seedlings, the risk that it may aggravate the translocation of heavy metals to stems and leaves should be paid more attention, so as to ensure the safe and reliable application of slow-release fertilizers.

Microbial phosphorus removal and recovery by struvite biomineralisation in comparison to chemical struvite precipitation in municipal wastewater

Microbial biomineralisation is attracting significant interest as an innovative process to recover nutrients from wastes. Nevertheless, little is understood about the requirements to form struvite using biological pathways in wastewater and how does this compare with conventional chemical processes. To address this gap, Halobacterium salinarum, Bacillus pumilus, Brevibacterium antiquum, Myxococcus xanthus and Idiomarina loihiensis were grown in wastewater to explore the relationships between cell growth, nutrients levels and properties of the recovered precipitates. The microorganisms were capable of removing ortho-phosphate (PO4-P) from municipal wastewater at concentrations ranging from 5.4 to 62.4 mg PO4-P/L. Visible crystals of biological struvite (bio-struvite) (identified by morphology XRD and elemental analysis), were observed at PO4-P ≥ 19.7 mg/L, compared to chemical struvite precipitation at 62.4 mg/L PO4-P (with pH adjustment). The initial nutrient concentrations presented a strong positive correlation with bio-struvite production yields and crystal size distribution. B. antiquum distinguished itself by relatively stable PO4-P removal (68–97%) independent of the initial nutrient concentration, with effluents containing as low as 1 mg PO4-P/L. The recovered bio-struvite presented high purity with low heavy metal contents, meeting regulations for inorganic fertiliser. The microbial processes for phosphorus (P) recovery as bio-struvite presented several key advantages: bio-struvite crystals were released to the wastewater and recoverable by filtration at PO4-P ≥ 19.7 mg/L, no need to adjust pH, bio-struvite crystals had purity equivalent to 11.8–12.3% P and low heavy metal content, which was similar or better than that of chemical struvite (12.6% P). This study validates bio-struvite’s relevance for low nutrient concentrations.