Contaminated Soil Samples Research Articles

The Study on the Properties and TCLP of GGBFS-Based Heavy-Metal-Contaminated Soil Geopolymer

The objective of this study is to use the geopolymer technique to solidify/stabilize heavy metal contaminated soil. There are over 739,700 square meters of heavy-metal-contaminated sites in Taiwan; most sites are soil farmlands. These heavy metal contaminants in soil can also infiltrate into groundwater and cause more serious pollution problems. This study explores the possibility of using the geopolymer technique to solidify heavy metal contaminated soil (CS), stabilize heavy metal, and produce good mechanical and physical properties. The ground granulated blast furnace slag (GGBFS) was activated by an alkali solution to form a geopolymer binder that can be used to solidify CS and stabilize the heavy metal. The effect of GGBFS and CS mixing ratio on the mechanical and physical properties and the TCLP test was investigated. The test results show that the compressive strength of specimens made with a 1.5 CS/GGBFS ratio can reach 46.61 MPa and 47.66 MPa after curing for 14 and 28 days, respectively. TCLP tests show only 2 ppm Cu was detected from a geopolymer-treated contaminated soil sample. The influence of alkali solution, such as the molarity of the NaOH, SiO2/Na2O, and SiO2/Al2O3 molar ratio, were also evaluated. The specimens prepared with 8 M NaOH, 0.96 SiO2/Na2O, and 1.28 SiO2/Al2O3 molar ratio alkali solution have a compressive strength of 51.74 MPa and 58.63 MPa after 14 and 28 days of curing. The TCLP tests show no heavy metal ions leached from the sample.

Bioleaching of Metals from Printed Circuit Boards

Electronic waste or E-waste refers to the discarded electrical or electronic devices which have neared their useful life. Because of the toxicity and carcinogenicity of some compounds, the proper management and safe disposal of these electronic wastes have become serious challenges in recent years. Printed Circuit Boards (PCBs) are found almost in every other electronics these days, hence the present study focuses on bioleaching of metals from Printed Circuit Boards (PCBs) using bacterial and yeast strains (Stenotrophomonas maltophilia, Bacillus sp. and Candida tropicalis) isolated from heavily contaminated soil samples. A two-step bioleaching procedure was followed for maximum mobilization of metals. The isolated strains were able to mobilize metals from PCBs with different efficiencies depending on their ability to utilize the E-waste a carbon source when cultivated in minimal media. Bioleaching potential of isolated microbes on eight heavy metals (Cu, Ni, Mn, Pb, Fe, Cr, Zn & Co) in the sample were studied using AAS and SEM analysis before and after the two-step bioleaching process and found to be efficient. The study concludes that isolated bacterial and fungal species from the study can be further standardized with regard to the growth parameters and used on large scale to carry out the efficient recovery of metals that can help in recycling E-waste in the digital world.

Spectral response feature bands extracted from near standard soil samples for estimating soil Pb in a mining area

Heavy metal contamination has been a critical environmental issue in mining areas, while accurate environmental remediation still faces a great challenge because of the complex feature of historical left-over soil pollution and its unclear spatial distribution patterns. Hyperspectral-based remote sensing techniques became a hot issue in interdisciplinary research on remote sensing and soil contamination, for it enables economical and efficient contamination detection. However, the unclear spectral response feature of soil heavy metal challenges the widespread of its application. In this study, near standard soil samples (NSS) were employed to extract spectral response feature bands of soil Pb. First, NSS was produced by artificially adding heavy metal ion solution in the background soil. Next, based on the proximal hyperspectral data of NSS, the spectral response feature bands were precisely identified by the Monte Carlo Uninformative Variables Elimination (MC-UVE) method as it achieved the highest predicting accuracy of the Partial Least Squares Regression (PLSR) model. Finally, to verify the reliability of the above extracted spectral response feature bands, 46 naturally contaminated soil samples (NCS) were collected synchronously with field and laboratory spectra in a mining area of Hengyang city, China. Enhanced by the corresponding feature bands of NSS, the NCS predicted models for soil Pb achieved the highest accuracy both for laboratory spectra ( and RPD were improved from 0.45 and 1.36 to 0.71 and 1.87, respectively) and Direct standardization (DS)-converted field spectra ( and RPD were improved from 0.38 and 1.28 to 0.62 and 1.64, respectively). In conclusion, NSS could provide an effective way to clarify the spectral response feature bands from hyperspectral data. And when combined with MC-UVE, it could serve as a promising approach to inverse the concentration of regional soil heavy metal Pb. HIGHLIGHTS Near standard soil samples were used to extract Pb spectral response feature band. Spectral response feature bands of NSS were effective for the modeling of NCS. Spectral response feature bands of soil Pb are 570-760nm, 1710-2100 nm et al. MC-UVE was a relatively optimal method to extract spectral response feature bands.

The key sulfometuron-methyl degrading bacteria isolation based on soil bacterial phylogenetic molecular ecological networks and application for bioremediation of contaminated soil by immobilization

The analysis of soil bacterial community has guiding significance for fully utilization of soil microbial resources. The results of high-throughput sequencing (HTS) showed that the bacteria in the three sulfometuron-methyl contaminated soil samples were mainly composed of 677 genera, including Phenylobacterium, Bacillus, belonging to 28 phyla, including Proteobacteria, Firmicutes. The diversity and richness of bacterial community decreased with the increase in sulfometuron-methyl concentration. In addition, sulfometuron-methyl could also affect the soil bacterial function based on PICRUSt functional predictive analysis. Combined with the results of HTS and phylogenetic molecular ecological networks (pMENs), 12 genera, including Ralstonia (Pi=0.64), were identified as the key soil microflora (intra-module connectivity Zi ≥ 2.5 or inter-module connectivity Pi ≥ 0.62), and the abundance of Ralstonia significantly increased with the concentration of sulfometuron-methyl, indicating that the strains of this genus might be the potential degrading bacteria and could form a stable relationship with indigenous microorganisms. Among the isolated bacteria of genus Ralstonia, one strain, named Ralstonia sp. JM-1, was verified to possess higher sulfometuron-methyl degradation efficiency, which completely degraded 20 mg L−1 of sulfometuron-methyl within 96 h. Furthermore, the immobilized strains generated by the mixture of 2.0 g bamboo charcoal and 3.0 mL bacterial suspension for 24 h had the highest sulfometuron-methyl degradation rate than that under other conditions, and the dynamic process degrading 10–30 mg L−1 of sulfometuron-methyl conforms to the zero-order kinetic equation. The bioremediation of contaminated soil showed the immobilized strains could completely degrade sulfometuron-methyl (1.39 mg kg−1) in contaminated soil within 9 d, which is higher than that application of strains in the free state (74.8%). This study could provide ideas for the isolation of functional strains and a theoretical basis for the bioremediation of STM and other contaminated soils.

Environmental Impact of Abattoir Waste Discharge on the Quality of Water Body and Soil in Ado-Ekiti, Ekiti State

Introduction: Wastes generated from abattoirs are an increasing source of pollution of water bodies.
 Aims: This study emphasizes on identifying environmental impacts caused by the abattoir along Iworoko Road, Ilokun Ado-Ekiti facility on its receiving water body and its users.
 Methodology: Wastewater, stream water, and soil samples were collected twice from the abattoir over a two-month period (June and August). Heavy metals, physiochemical and microbial analyses were carried out on the samples.
 Results: The sample collected in June from the study area showed mean bacterial count which ranges from 8.0 – 55.0x103 cfu/ml, and sample obtained in August showed mean bacteria count and this indicated that wastewater sample has the highest bacteria count of 8.0 x 103 cfu/ml. The lowest bacterial count was found in the stream water sample with 1.7 x 103 cfu/ml. The mean bacterial count in the contaminated soil sample was 2.8 x 103 cfu/ml. The results also show the occurrence of potentially pathogenic organisms such as Escherichia coli and Staphylococcus aureus. The heavy metals and physiochemical properties of samples collected from the study area are as follows; Fe (3.806 and 2.812), Cu (1.070 and 0.95), Cd (0.001 and 0.001), Ni (0.0055 and 0.0025), Pb (0.13 and 0.107), Zn (0.37 and 0.406), pH (8.475 and 8.600), temperature (26.250 and 27.750 oC), total dissolved solid (267.05 and 212.8), dissolved oxygen (1.65 and 2.45) for waste water sample; Fe (0.402 and 0.519), Cu (0.277 and 0.3095), Cd (0.0 and 0.001), Ni (0.002 and 0.003), Pb (0.04 and 0.016), Zn (0.126 and 0.16), pH (6.82 and 7.235), temperature (26.600 and 27.700 oC), total dissolved solid (103.4 and 125.95), dissolved oxygen (4.85 and 5.00) for stream water sample; and Fe (122.85 and 98.500), Cu (0.694 and 0.4745), Cd (0.004 and 0.001), Ni (0.02 and 0.010), Pb (0.3675 and 0.2885), Zn (0.3255 and 0.525), pH (6.200 and 6.495), temperature (23.300 and 27.800 oC) for soil sample – each figure representing June and August respectively.
 Conclusion: The concentration of the heavy metals reported in this study indicates that there is significant difference in the concentration of the pollutants taken at different sample points.

Effect of Heavy Metal Pollution on Total Microbial Count and Seed Germination Ability of Soil

A wide application of heavy metals in different human processes leads to its accumulation in environment. Atmospheric deposition of metals into soil ecosystem is majorly affecting the microbial count of soil and seed germination as well. In present study, soil samples were collected from metal polluted sites and agricultural fields to determine of heavy metal (Zn, Cu, Mn and Fe) content and total heterotrophic count of different soil samples. The microbial count, seed germination percentage and heavy metal concentration in agricultural field samples were found to be in permissible limit, while increased metal concentrations and lower bacterial count were observed in metal contaminated soil samples. Increasing heavy metal concentration found to be drastically affecting on total heterotrophic count of agricultural field soil samples, while high metal concentration tolerating bacterial count was found in metal contaminated soil samples. The study suggested that metal processing industries should accept new practices to avoid such metal incorporation in natural environment to save soil microbial diversity.

Isolation and Optimization of Hydrocarbon – Degrading Bacteria

Aims: To isolate and characterize hydrocarbon – degraders in a contaminated soil sample
 Study Design: This experiment was carried out under aseptic conditions. The result was confirmed by visible spectrophotometer
 Place and Duration of Study: Department of Biological Sciences, Microbiology Programme, Clifford University, Ihie Campus, Owerrinta, Abia State, Nigeria, between May 2021 to July 2021
 Methodology: Soil sample contaminated with hydrocarbon used in this experiment was from an automobile mechanic workshop. A ten-fold serial dilution was made for each soil sample, after which 1 ml of 10-5 dilutions was plated out using pour plate method and incubated at 37 0C for 48 hrs. The isolates were then grown on different hydrocarbons (crude oil, fuel or spent engine oil) and the degradation efficiency was confirmed by visible spectrophotometer.
 Result: The isolation of hydrocarbon – degrading bacteria in topsoil and subsoil samples of a mechanic workshop located in Isiala Ngwa North Local Government Area Junction, Abia State was carried out. Four bacterial species were isolated from the soil sample collected, the isolates were subjected to hydrocarbon degradation/utilization test of different hydrocarbons (crude oil, fuel or spent engine oil) it was observed that two of the isolates identified as Bacillus and Staphylococcus sp were able to utilize hydrocarbons in the medium more efficiently than other isolates.
 Conclusion: Hydrocarbon – degrading bacteria were isolated from an auto – mechanic workshop in Isiala Ngwa North, Abia State. Two of the four strains (Bacillus sp and Staphylococcus sp), have the highest potential to use different hydrocarbons (fuel, crude oil and condemn oil) as the sole carbon source. These strains' hydrocarbon – degrading abilities suggest that they could be effective in bioremediation of hydrocarbon – polluted locations. This could be used to combat contamination caused by motor mechanics who carelessly dispose of old motor oil in the environment, as well as general hydrocarbon contamination.

Nutrient enhancement potentials of moringa (Moringa oleifera), neem (Azadirachta indica), and pawpaw (Carica papaya) fortified composts in contaminated soils.

This study assessed the nutrient enhancement potentials of moringa (Moringa oleifera), neem (Azadirachta indica), and pawpaw (Carica papaya) fortified composts in contaminated soils. The composts were formulated from poultry manure; leaves of moringa, neem, and pawpaw; and sawdust for a period of 8weeks. Contaminated soil samples were collected from a dumpsite in Abeokuta, Ogun State. The contaminated soils were treated with the stabilized composts for a period of 4weeks. Castor oil plants were introduced to assess the nutrient quality of the composts. Soil and compost parameters (pH, electrical conductivity (EC), organic carbon (OC), total nitrogen (TN), C/N ratio, P, K, Na, Mg, and Ca) were determined using the standard procedures. Data collected were evaluated for simple descriptive and inferential statistics. Results showed non-significance (p > 0.05) of C/N ratios that ranged between 12.75 ± 2.43 and 12.96 ± 1.49. The pH values of moringa- and neem-fortified composts were slightly acidic, while the pawpaw-formulated compost was slightly alkaline. The levels of TN and OC were three times higher in moringa- and pawpaw-fortified composts than in the neem compost. Introduction of the composts to the contaminated soils decreased the soil pH but increased the nutrient quality parameters such as TN (33-50%), OC (56-77%), P (7-20%), Na (89-91%), K (12-25%), and Mg (10-13%). The three compost types increased the physiological properties of the castor oil plants. The study indicated the promising potentials of the three composts for nutrient enhancement of soil.

Genotoxicity assessment of textile waste contaminated soil and characterization of textile dye degradation by a novel indigenous bacterium Ochrobactrum intermedium BS39

The harmful effects of textile wastewater irrigation practices on the crop productivity and soil nutrient levels are primarily related with the accumulation of recalcitrant azo dyes in the soil. Therefore, toxicity assessment of the textile waste contaminated soil along with the development of a powerful soil bioremediation strategy is a challenging task for the researchers. Present study aimed to evaluate potential toxicity of the textile wastewater irrigated soil collected from Panki industrial site 5, Kanpur, India employing Ames Salmonella/mammalian microsome test, Escherichia coli DNA repair defective mutation assay and Allium cepa chromosomal aberration assay. The results of the Ames test and DNA repair defective mutation test showed that all the organic extracts of the contaminated soil samples induced different degrees of DNA damage, indicating the existence of mutagenicity and genotoxicity. Additionally, in A. cepa root cells, the contaminated soil altered mitotic index and caused chromosomal abnormalities. Results of the study demonstrated potential health risks related with the irrigation of textile wastewater. Keeping in view of the above scenario, the study led to the isolation and characterization of a novel indigenous bacterium capable of tolerating very high concentration of reactive black 5 dye (500 μg-mL−1) and salt (20 gL-1) with concurrently high efficiency of the dye degradation i.e., 93% decolorization at temperature of 37 °C and in pH range of 5–9. Based on the 16S rRNA gene sequencing, the bacterium was identified as Ochrobactrum intermedium. Further, dye degradation products were identified as sodium-2-hydrosulfonylethyl sulphate and sodium-3-aminonaphthalene-2-sulfonate by Gas Chromatography-Mass spectrometry; and this isolate can be exploited for bioremediation of textile waste contaminated soils.

A novel approach to sorbent-based remediation of soil impacted by organic micropollutants and heavy metals using granular biochar amendment and magnetic separation

Soil remediation by sorbent amendment is a popular method to immobilize contaminants but it is limited by the fact that the sorbent cannot be retrieved from the soil, posing as a threat to its quality, due to the gradual leaching of the sorbed contaminants. To address this challenge, this work proposes the use of granular-sized, magnetically retrievable sorbents for soil remediation. Specifically, granular biochar, that offers favorable sorption sites for both organic and inorganic contaminants, was used to treat contaminated soil samples. It is demonstrated that sorbent size plays a crucial role in its separation from the soil matrix by magnetic field. Granular magnetic biochar (gMBC) of 1–2 mm was found to be the most suitable sorbent size because it does not assimilate into the soil matrix and can be quantitatively retrieved both from wet and dry soil by means of magnetism, yielding a sorbent-free matrix. In this manner, the soil is relieved from both the hazardous contaminants and the contaminant-laden sorbent. Using gMBC, the remediation of contaminated soil from both organic micropollutants and heavy metals was optimized accomplishing remediation efficiencies from 40% to 90% for organic compounds and 30–65% for heavy metals through sorption and chemical transformation of the contaminants. The results of the study show that granular magnetic sorbents can be an effective and practical solution to the remediation of soils by facilitating their retrieval directly from the solid matrix which is not possible with micro/nanoparticle sorbents.

The Effect of Kerosene Pollution on the Cellulolytic Activity of Albic Retisols and Arenosols (Aridic): A Laboratory Experiment.

The results of a laboratory experiment modeling the effect of kerosene contamination on the cellulolytic activity of microbiocenosis of the Albic Retisol (Kaluga oblast, Russia) and Arenosol (Kyzylorda oblast, Republic of Kazakhstan) humus horizons are described. Cellulolytic activity is assessed according to the rate of weight loss in linen cloth fragments during the incubation for 0–3, 3–7, and 7–13 months. The intensity of cellulolytic activity in the unpolluted Albic Retisol is higher as compared with the Arenosol, which is determined by low acidity and an elevated content of organic matter and nutrients. The soil pollution with kerosene to 10 g/kg causes a reversible change in cellulolytic activity of both Albic Retisol and Arenosol (Aridic). A high load of kerosene (≥25 g/kg) inhibits cellulolytic activity in both soils over 13 months of observation.Supplementary InformationThe online version contains supplementary material available at 10.1134/S1064229322020119.Fig. S1. Cellulolytic activity of soils in a laboratory experiment: (a) initial state of linen tissue (test object) and (b) linen tissue after three months of incubation. Table S1. Properties of soil humus horizons.Table S2. Initial water content in the studied soil samples with due account for the added kerosene.Table S3. Cellulolytic activity in soils grouped according to kerosene load (rate of mass loss, mg/g soil per day.Table S4. Significance of differences between cellulolytic activities of contaminated soil samples relative control samples according to the Mann–Whitney U-test. Table S5. Kerosene content in the studied soil samples at the end of the experiment, % of the initial content.

Ecotoxicity and bioremediation potential assessment of soil from oil refinery station area

PurposeThe aim of the present study was to evaluate the toxicity and biodegradation potential of oil hydrocarbons contaminated soil samples obtained from different depths at an oil refinery station area. An approach involving chemical, microbiological, respirometry and ecotoxicity assessment of soil polluted by oil hydrocarbons was adopted, in order to determine the biodegradability of pollutants and ecotoxicological effects of natural attenuation strategy.MethodsThe ecotoxicity of soil samples was evaluated using an ostracod test kit and a seed germination test. The results of the phytotoxicity assay were expressed as a percentage of seedling emergence and as the relative yield of fresh and dry biomass compared to control plants. The intrinsic biodegradation potential of the contaminated soil was examined using a Micro-Oxymax respirometer. Intrinsic biodegradation rates were estimated from the slopes of linear regressions curves plotted for cumulative O2 uptake. The obtained values were then entered in the mass balance equation for the stoichiometric reaction of hydrocarbon decomposition and converted per kg of soil per day.ResultsAlthough the tested contaminants were biodegradable in the respirometric assay, they were slightly to moderately toxic to plants and extremely toxic to ostracods. The noxious effects raised with the increased concentration of contaminants. The monocotyledonous oat was more tolerant to higher concentrations of oil hydrocarbons than the other test plants, indicating its greater suitability for soil reclamation purposes.ConclusionBy assessing phytotoxicity and effect on ostracod mortality and progress of soil self-decontamination process, proper approach of reclamation of demoted area can be provided.

Isolation of functional bacterial strains from chromium-contaminated site and bioremediation potentials

In this study, two Cr(VI)-reducing functional bacterial strains (TJ-1 and TJ-5) were successfully isolated and screened from the chromium-contaminated soil from a real site. The 16S rRNA gene sequences were analysed, which showed high similarity (>99%) with Stenotrophomonas maltophilia (TJ-1) and Brucella intermedius (TJ-5) species. The optimum growth for the two bacteria to reduce Cr(VI) were achieved at pH 7.0 and initial inoculation amount of 5%. The two strains were applied to real contaminated soil samples and showed better Cr removal when external carbon sources were added. Using sawdust as a solid-phase carbon source supplement, both TJ-1 and TJ-5 showed higher remediation efficiency (99.77% and 93.86%) than using glucose as the carbon source (68.56% and 70.87%). Results of the stability of soil Cr(VI) bioremediation revealed that the water-soluble Cr(VI) content of bioremediated sample remained unchanged, indicating that Cr(VI) is not easily released after death of the strains. Solid-phase carbon source supplements may help the cells to attach and grow into biofilms, creating a better growth condition which improved the remediation efficiency. Column experiments showed that the total remediation efficiencies by the two strains were 34.23% and 20.63%, respectively, within a short time period (76 h). Therefore, the two strains showed great bioremediation potentials for chromium-contaminated sites and can be used in future application of in-situ bioremediation.

Hazardous effects of road-side soils on the redox and cholinesterasic homeostasis of mound-building termite (Cornitermes cumulans)

For our knowledge, the roadside soils end up being the deposit of various residues discarded by drivers or passengers, plus, that coming from the runoff of rainwater. Basically, we do not know the impacts that this pollution causes on animals which inhabit these environments. Thus, in this study, our objective was to evaluate how the presence of plastic microfibers (MPFs), organic compounds and heavy metals affect the redox and cholinesterase homeostasis of mound-building termite [Cornitermes cumulans (workers) adults]. As a result, we noticed that MPFs were present in all sampled areas, being higher in road area (RA). Regardless of the presence of these pollutants, animals sampled in the RA were those in which we observed greater production of reactive oxygen species (ROS), hydrogen peroxide (H2O2) and nitric oxide (NO) (via nitrite), whose higher activities of antioxidant enzymes, superoxide dismutase (SOD) and catalase (CAT), was not able to counterbalance the oxidative stress suggested by the evaluated biomarkers. Moreover, we observed increase in acetylcholinesterase (AChE) activity in these same animals, which suggests a cholinesterasic effect. Such alterations were positively correlated with the contamination of soil samples by Cd, Pb, Zn, Fe and Cu, as well as with the presence of the 11,10-guaiane-type sesquiterpenoid compound, identified only in the RA. Thus, our unique study reveals that the contamination of roadside soils constitutes an additional environmental stressor to populations of C. cumulans, which reinforces the need for greater attention and further investigation to be given to the pollution of these environments.

Effects on geotechnical properties of soil by leachate in landfill vicinity: Cauvery River, Pallipalayam, India

Mostly soil components are polluted due to the accumulation of untreated effluents from different synthetic industries such as paper manufacturing, dyeing, spinning, and paint manufacturing, by adding external chemical components which infects the soil properties. Consequently, an appropriate treating system for polluted soil in vicinity of industrial zone is necessary to reduce the risks in construction activities. The soil characterization such as geotechnical properties, pH and metal concentrations are affected due to direct discharge of effluent on ground surface and the performance in strength parameters of soil properties are degrading from higher medium to poor medium. By improving the effluent discharging systems in industrial areas, soil properties can reduce the risk for construction purpose. For assessing geotechnical properties, three soil samples were collected from industrial zone and analyzed for physicochemical parameters along with a virgin sample. Additionally, construction demolition waste materials were added as stabilizer with contaminated soil samples. The assessment was carried out at different proportions of construction demolition waste for improving the soil performance. The evaluated results based on the different ratio of 5%, 10% and 15% construction demolition waste confirms significant increases strength properties in soil characterization.

Removal of Cd, Cu, Ni, and Pb from Nanoscale Zero-Valent Iron Amended Soil Using 0.1 M Acetic Acid Solution

Abstract The purpose of the study was to evaluate the possibility of removing heavy metal cations from single-metal spiked soil samples, which were pretreated with nanoscale zero-valent iron (nZVI) particles. Sandy soil was artificially contaminated with copper (Cu), cadmium (Cd), nickel (Ni), and lead (Pb). Contaminated soil samples were amended with different doses of nZVI (0.35, 0.70 and 1.05 %). A sequential extraction method was used to determine the fractionation of heavy metal cations in the control and nZVI amended soil samples. A solution of 0.1 M acetic acid (pH 3.0) was used to investigate the removal of heavy metals from control and nZVI-amended soil samples. The results showed that nZVI reduced the amount of metals in the exchangeable form and increased the proportion of these metals associated with amorphous iron (Fe) oxides. The results also showed that the removal efficiencies of heavy metals increased with increasing nZVI dose, that is, from 46.9 %, 5.77 %, 33.5 %, and 2.70 % to 55.9 %, 12.3 %, 46.2 %, and 3.79 % for Cd, Cu, Ni, and Pb, respectively. The study indicated that the application of nZVI in soil could be beneficial for subsequent removal of heavy metals from soil using 0.1 M acetic acid solution.

Removal of copper, lead and zinc from artificially contaminated soil samples using EDTA, rhamnolipids, and soapnut in batch experiments.

Removal of copper, lead and zinc from artificially contaminated soil samples using EDTA, rhamnolipids, and soapnut in batch experiments.

SORPTION OF OIL BY MECHANOCHEMICALY ACTIVATED SHUNGITE

In the paper the sorption capacity of shungite rocks of the Koksu field (Kazakhstan) in relation to the oil from the Karazhanbas and Tengiz fields (Kazakhstan) were studied. Oil spills occurring during production, gathering, transportation, storage and refining, and repair work on wells are an urgent environmental problem. There are effective methods of soil purification, including particular interests addressed to sorption process. The aim of this research is to study oil sorption by shungite rocks of the Koksu deposit after mechanochemical activation. The mechanochemical activation of shungite rock samples was carried out in a planetary ball mill at different speeds of rotation and ratios of ball mass to the sample. The developed sorbents based on shungite rocks of the Koksu deposit were tested for cleaning samples of oil-contaminated soils and their sorption capacities under dynamic and static conditions were determined. For the sorption of oil, the sorbent based on shungite of shale grade (TS) after mechanochemical activation is recommended, which sorption capacity under dynamic conditions is 2.57-2.85 g/g. Sorption of oil from 10 % of oil contaminated soil samples with the sorbents based on shungite after mechanochemical activation showed sorption capacity of 0.44-0.45 g/g in 60 days under static conditions. The practical significance of the research lies in the prospects of using shungite rocks to clean up oil spills.

A Study on Isolation and Identification of Exopolysaccharide (EPS) producing Bacteria from Soil

Abstract: Polysaccharides are important potent molecules with their structural and compositional complexity which led to wide range of applications in various industries. The exopolysaccharides of microbial origin are released in response to extreme environmental conditions for the purpose of survival. The present study focuses on the isolation of exopolysaccharide producing bacteria from the soil sample and oil contaminated soil sample. Screening for the EPS production by the isolates is determined by the dry weight determination of precipitates of EPS and quantitative estimation of glucose content of EPS by PhenolSulphuric acid method. In the present study, out of 5 bacterial isolates isolated on screening, Lactobacillus sps and Pseudomonas sps. isolates produced the precipitates of EPS whose dry weight was determined to be 0.09g and 0.17g respectively. Further, glucose concentration of EPS was quantitatively determined. The glucose content of Lactobacillus sps. isolate was 0.1125mg/ml and Pseudomonas sps. isolate is 0.2875mg/ml. The EPS producing isolates were further grown in the presence of carbon sources like Glucose, Lactose, Maltose and Sucrose to determine the best utilizable carbon for their growth. The most utilizable carbon source for maximum growth of EPS producing isolates was determined to be sucrose with 2% concentration. All the 5 bacterial isolates were screened for their ability of antibiotic resistance. The EPS producing isolates, Lactobacillus sps, Pseudomonas sps were found to be resistant towards all the antimicrobial agents owing to the presence of EPS protective layer around their cell wall than non-EPS producing isolates. Keywords: Exopolysaccharide, Screening, Carbon sources, Antibiotic resistance.

Microbial studies of biosurfactant producing bacteria from crude oil contaminated soil

Soils contaminated with crude oil collected from three sites in Delta State were analyzed using serial dilution and pour plate methods. The physicochemical characteristics of the soil were determined using standard methods. The mean heterotrophic bacteria count and the mean hydrocarbon utilizing bacteria count were also determined. Blood haemolysis, foaming activity, oil spreading techniques and emulsification assay was used to screen the microorganisms for biosurfactant production. The biosurfactant producing bacteria were selected and their effect on metal removal and growth kinetics was also determined. The pH of the contaminated soil samples ranged 4.82 to 5.62. The mineral elements such as potassium (k+) and sodium (Na+) ranged from 0.20 to 0.80 Meq/100g and 0.07 to 0.81 Meq/100g respectively. The heavy metal content such as zinc (Zn2+) and lead (Pb2+) ranged from 10.13 to 19.24 mg/kg and 19.24 to 49.63 mg/kg respectively. Organic carbon and THC ranged from 5.44 to 6.87 % and 2720.00 to 3110.00 mg/kg respectively. The mean heterotrophic bacteria and hydrocarbon utilizing bacteria ranges from 1.4 ± 0.4 x 106 to 1.6 ± 0.7 x 106 and 1.0 ± 0.2 x 106 to 1.2 ± 0.4 × 106 respectively in the soil samples. Bacteria isolated and identified from the three sites include Corynebacterium spp., Bacillus subtilis., Pseudomonas aeruginosa, Micrococcus varians, Streptococcus spp., Klebsiella spp. and Enterobacter spp. with Bacillus subtilis and Pseudomonas aeruginosa having the highest prevalence and among these isolates only Corynebacterium spp., Bacillus subtilis., Pseudomonas aeruginosa and Micrococcus varians showed positive result for the production of biosurfactant. Bacillus subtilis had the highest metal removal capacity of 29.44% of 100 ppm of lead. Corynebacterium spp. and Bacillus subtilis had an optimum growth at pH 8 and 7 respectively while Pseudomonas aeruginosa and Micrococcus varians has an optimum growth at pH.