Issues about application of bioremediation for cleaning up of contaminated sites

The heterogenity of biological, chemical and physical properties of microbial environments has presented many problems to understand the microbe-insecticide interactions. In fact, many studies have examined such interactions only under laboratory conditions and thus the scientific literature on this subject is dominated by in vitro studies with pure and mixed cultures of microorganisms (Ware and Roan 1970; Cox 1972; Tu and Miles 1976; Wainright 1978; Lal and Saxena 1980, 1982; Lal 1982; Lal and Dhanaraj 1984). Such studies have considerable scientific value but there has been an unfortunate and undesirable tendency to assume that they also reflect the interaction of insecticides with microorganisms in natural environments.

Enhanced mineralization of oxalate by highly active and Stable Ce(III)-Doped g-C3N4 catalyzed ozonation

Introduction This study investigated the detection and mineralization of organic pollutants in the Mesopotamian marshes. Methods Over the course of seven days of treatment, a batch bioreactor system and natural microbial communities from marsh sediments were able to break down contaminants in a remarkable way. Results Water samples collected from five distinct marsh locations revealed significant contamination, with the Central marshes showing the highest pollutant concentrations (aliphatic hydrocarbons, 100 μg/L; phenols, 40 μg/L; aromatic hydrocarbons, 5000 μg/L; and pesticides, 120 μg/L). Notable findings included the near-complete elimination of aliphatic hydrocarbons (85%-99% reduction) across all sites, as well as substantial decreases in aromatic hydrocarbons (79%-92%). Phylogenetic analysis revealed that previously unidentified bacterial species labeled as FF-A5 and FF-A6 were the dominant bacterial species in the batch reactor. These bacterial species have most likely been native bacteria with an exceptional capacity for breaking down pollution. Discussion The results suggested the possibility of using native microbial community bioremediation methods to effectively restore marsh ecosystems and lower organic pollution in these important wetlands in a sustained manner. Conclusion Customized treatments guided by the synergistic interactions among the several bacterial species revealed in this work could help to improve pollution degradation and ecological restoration of the Mesopotamian wetlands.

Non-thermal plasma-induced photocatalytic degradation of 4-chlorophenol in water

There are two regulations for mine reclamation success in the forestry area in Indonesia, namely Minister of Forestry Regulation No. P.60/Menhut-II/2009 and Minister of Energy and Mineral Resources Decree No. 1827.K/30/MEM/2018. Both regulations rule vegetation and soil success. This study aims to analyse criteria parameters from both regulations in the mine reclamation and compare them to the surrounding secondary natural forest (SNF). This study was conducted in 6 six types of mine reclamation stand structures: 1, 4, 6, 9, 11-year-old plantation and SNF using 1 hectare of the circular plot each (total 6 ha). Soil samples were collected from 40 cm depth to analyse physical, biological and chemical conditions. Mine reclamation areas had almost similar physical, biological and chemical soil conditions with SNF. Nevertheless, due to the potential acid-forming (PAF) material from overburden, the 1-year-old plantation had pH = 3.23-3.27. The highest diversity index and the number of species and families in all reclamation areas were H’ = 1.82 (11-year-old); 14 species (9-year-old); and 11 families (9-year-old), comparing with SNF were H’ = 3.48; 67 species, and 31 families. Conversely, vegetation structure parameters in mine reclamation areas were higher than SNF (diameter at height breast (DBH; 1.3 m) = 28.42 cm; tree density = 469/ha; basal area = 35.04 m2/ha; and total height = 16.85 m). Compared to the SNF, vegetation structure and soil conditions are mostly possible for mine reclamation success. Still, species composition needs to be considered further as a standard interval to meet the criteria.

Nowadays, ionic liquids (ILs) have extensive applications in biotechnology and are classified as green solvents. However, there are significant concerns over the effect of ILs on microorganism growth, especially towards mixed microorganisms. This study sets out to investigate the effect of synthesized ILs, particularly imidazolium hydrogen sulfate [IM][HSO4] and morpholinium tetrafluoroborate [MOR][BF4], towards mixed culture microorganisms, mainly identified as Bacillus cereus, Bacillus thuringiensis, and Pseudallescheria boydii. The toxicity effect of both ILs is assessed through the disk diffusion method. Moreover, the ecological effects of mixed culture growth on ILs are analyzed by conducting the growth inhibition test in fermentation liquid media. This study reveals that the growth of mixed culture microorganisms started to decline after 4 and 5 h of injecting the [IM][HSO4] and [MOR][BF4], respectively. This shows that mixed culture microorganisms have a longstanding growth and the least inhibition effect after being exposed to [MOR][BF4] rather than [IM][HSO4]. Similar findings are observed regarding the inhibitory effects, with [MOR][BF4] showing a smaller inhibition zone compared to [IM][HSO4]. This finding clearly indicates that imidazolium based ILs are more toxic than morpholinium based ILs. The present study lays the groundwork for further experimental investigation on [MOR][BF4] towards mixed culture microorganisms through the structural characteristics, explicitly focusing on using ILs without the alkyl chain.

Use of biochar produced from biomass residues may improve physical, chemical, and biological conditions of soil, reduce greenhouse gas emissions, and increase crop yields. This study evaluated production of lettuce (Lactuca sativa L., cv. Babá de Verão) in a dystrophic Yellow Latosol (LAd) by adding biochar from the babassu palm (Attalea speciosa Mart.) rachis at 0, 10, 20, or 30 t∙ha−1 in pot culture, and growth and production of lettuce evaluated. Lettuce grown with 30 t∙ha−1 of biochar improved plant height, number of leaves, and total fresh mass. Rates that promoted greater accumulation of fresh mass of the aerial part, aerial part dry mass, fresh root mass, root dry mass, and total dry mass ranged between 17.3 and 27 t∙ha−1 of biochar. Use of biochar may be an alternative to improve physical and chemical conditions of LAd soil in successive crops of lettuce in pot culture. The correction of the LAd soil with increasing rates of biochar increased growth and yield of lettuce in pot culture.

Risk, N., Snider, D. and Wagner-Riddle, C. 2013. Mechanisms leading to enhanced soil nitrous oxide fluxes induced by freeze–thaw cycles. Can. J. Soil Sci. 93: 401–414. The freezing and thawing of soil in cold climates often produces large emissions of nitrous oxide (N2O) that may contribute significantly to a soil's annual greenhouse gas emission budget. This review summarizes the state of knowledge of the physical and biological mechanisms that drive heightened N2O emissions at spring melt. Most studies of freeze–thaw N2O emissions have concluded that denitrification is the dominant process responsible for the large thaw fluxes. Soil moisture, availability of carbon and nitrogen substrates, and freeze temperature and duration are the major factors identified as controlling freeze–thaw cycle (FTC) N2O emissions. Two mechanisms are proposed to lead to enhanced N2O emissions at thaw: (1) the physical release of N2O that is produced throughout the winter and trapped under frozen surface layers and/or within nutrient-rich water films in the frozen layers, and (2) the emission of newly produced (de novo) N2O at the onset of thaw, which is stimulated by increased biological activity and changes in physical and chemical soil conditions. Early studies implicated the physical release of N2O from subsurface soil layers as the main mechanism contributing to spring thaw emissions, but most current studies do not support this hypothesis. Mounting evidence suggests that most of the emitted N2O is produced de novo. This may be fueled by newly available denitrification substrates that are liberated from dead microbes, fine roots, and/or the disintegration of soil aggregates. The release of N2O trapped in shallow surface layers may represent a small, but important contribution of the total emissions. Application of new techniques to study microbial communities in their natural environments, such as metagenomics and stable isotope studies, have the potential to enhance our understanding of the soil N cycle and its linkages to FTC N2O emissions. Future field studies of N2O emissions ought to quantify both overwinter accumulation/release and the de novo production of N2O so that the contribution of each mechanism to the annual emission budget is known.

Тhe article presents the results of studies to determine the amount of bacterial ATP in pure and mixed cultures of microorganisms. The level of ATP-bioluminescence was determined using the HY-LiTE®2 (Merk, Germany) luminometer in accordance with the manufacturer's instructions using special test systems. In the course of the experiments, the numerical values of bacterial ATP of Escherichia coli and Staphylococcus aureus have been determined. It was found that at the concentration of E. coli (1,5 ± 0,1)∙102…(2,1 ± 0,2)∙106 CFU / cm3, the level of ATP was 323,9 ± 16,2…22666,8 ± 906,7 RLU. At equal number of bacteria, the level of ATP St. aureus exceeded the level of ATP escherichia by 1,4…1,8 times. It was noted that in mixed cultures of Escherichia coli and staphylococcus, the values of ATP were average values between ATP escherichia and staphylococcal ATP and were within 423,4 ± 29,6…28334,1 ± 2550,1 RLU with the number of microorganisms (1,75 ± 0, 1) ∙ 102…(1,5 ± 0,1)∙106 CFU/cm3. It was found that in pure and mixed cultures of microorganisms between the level of bacteria and the parameters of ATP there is a linear dependence: the more the number of bacteria, the higher the level of ATP.

In literature, the environmental applications of green rust (GR) have mainly been pointed out through the reduction of inorganic contaminants and the reductive dechlorination of chlorinated organics. However, reactions involving GR for the oxidation and mineralization of organic pollutants remain very scantly described. In this study, the ability of three synthetic Fe(II)-Fe(III) green rusts, GR(CO (3)(2-)), GR(SO(4)(2-)), and GR(Cl(-)), to promote Fenton-like reaction was examined by employing phenol as a model pollutant. Unlike the traditional Fenton's reagent (dissolved Fe(II) + H(2)O(2)), where the pH values have to be lowered to less than 4, the proposed reaction can effectively oxidize the organic molecules at neutral pH and could avoid the initial acidification which may be costly and destructive for the in situ remediation of contaminated groundwater and soils. The green rust reactivity towards the oxidative transformation of phenol was thoroughly evaluated by performing a large kinetic study, chemical analyses, and spectroscopic investigations. The kinetics of phenol removal was studied at three initial phenol concentrations for three green rusts under similar conditions (pH = 7.1; 1 g L(-1) of GR; 30 mM H(2)O(2)) and reaction rates were calculated based on mass and surface area. The oxidation rate constants are compared with that of magnetite, a well-known mixed iron (II, III) oxide. The mineralization of phenol was investigated at various H(2)O(2) doses and GR concentrations. In order to describe the phenol transformation in GR/H(2)O(2) system, several investigations were performed including HPLC and ion exclusion chromatography analysis, TOC, dissolved iron, and H(2)O(2) concentration measurements. Finally, X-ray powder diffraction and Raman spectroscopy were used to identify the oxidation products of GRs. In GR/H(2)O(2) system, the kinetics of phenol removal at neutral pH was very fast and independent of the initial phenol concentration. No aromatic intermediates were detected and final by-products are mainly of short chain organic acids (oxalic acid and formic acid). Green rusts exhibit different reactivity toward Fenton-like oxidation of phenol. Both on mass and surface area basis, the reactivity of Fe(II)-Fe(III) species toward the oxidation of phenol was highest for GR(Cl(-)), little less for GR(SO(4)(2-)) or GR(CO(3)(2-)), and even less for magnetite (Fe(3)O(4)). Phenol degradation pseudo-first order rate constants (k(surf)) values were found to be: 13 x 10(-4), 3.3 x 10(-4), 3.5 x 10(-4), and 0.4 x 10(-4) L m(-2) s(-1) for GR(Cl(-)), GR(SO(4)(2-)), GR(CO(3)(2-)), and Fe(3)O(4), respectively. The mineralization yield of phenol as well as the decomposition rate of H(2)O(2) was higher for GR(Cl(-)) than for GR(SO(4)(2-)) or GR(CO(3)(2-)), mainly due to the higher Fe(II) content of GR(Cl(-)). Both X-ray diffraction analysis and Raman spectroscopy showed that the oxidation of GR with H(2)O(2) may lead to feroxyhyte (delta-FeOOH), with possible formation of poorly crystallized goethite (alpha-FeOOH), depending on GR type. This original work shows that the heterogeneous Fenton-like reaction using GR/H(2)O(2) is very effective toward degradation and mineralization of pollutants. In summary, this study has demonstrated that the green rust-promoted oxidation reaction could contribute to the transformation of water contaminants in the presence of H(2)O(2.) These results could serve as the basis for the understanding of the transformation of organic pollutants in iron-rich soils in the presence of chemical oxidant (H(2)O(2)) or for the development of wastewater treatment process. However, some experimental parameters should be optimized for a high-scale application. Further work needs to be done for the reactive transport and transformation of organic compounds in a green rust-packed column. The reusability of GR in mineral-catalyzed reaction should be also investigated.

Soil macrofungi and some soil biological, biochemical and chemical investigations on the upper and lower slope of a spruce forest

Although microbial remediation has been widely used in the bioremediation of various contaminants, in practical applications of biological remediation, pure cultures of microorganisms are seriously limited by their adaptability, efficiency, and capacity to handle multiple contaminants. Mixed cultures of microorganisms involve the symbiosis of two or more microorganisms. Such cultures exhibit a collection of the characteristics of each microorganism species or strain, showing enormous potential in the bioremediation of organic or heavy metal pollutants. The present review focuses on the mixed cultures of microorganisms, demonstrating its importance and summarizing the advantages of mixed cultures of microorganisms in bioremediation. Furthermore, the internal and external relations of mixed culture microorganisms were analyzed with respect to their involvement in the removal process to elucidate the underlying mechanisms.

Sonochemical oxidation of organic pollutants in an aqueous environment is considered to be a green process. This mode of degradation of organic pollutants in an aqueous environment is considered to render reputable outcomes in terms of minimal chemical utilization and no need of extreme physical conditions. Indiscriminate discharge of toxic organic pollutants in an aqueous environment by anthropogenic activities has posed major health implications for both human and aquatic lives. Hence, numerous research endeavours are in progress to improve the efficiency of degradation and mineralization of organic contaminants. Being an extensively used advanced oxidation process, ultrasonic irradiation can be utilized for complete mineralization of persistent organic pollutants by coupling/integrating it with homogeneous and heterogeneous photocatalytic processes. In this regard, scientists have reported on sonophotocatalysis as an effective strategy towards the degradation of many toxic environmental pollutants. The combined effect of sonolysis and photocatalysis has been proved to enhance the production of high reactive-free radicals in aqueous medium which aid in the complete mineralization of organic pollutants. In this manuscript, we provide an overview on the ultrasound-based hybrid technologies for the degradation of organic pollutants in an aqueous environment.

This review is devoted to oxidative water treatments, with emphasis on catalytic ozonation. The approach tackled herein resides in exposing a wide variety of oxidative treatments attempts as a basis for summarizing the main findings that allow envisaging improvements aiming towards total mineralization of organic pollutants. Comparison between specific operating conditions for specific pollutant-catalyst-oxidizing systems is quite difficult, and is not targeted in the present work. However, when deeply and judiciously analyzed, such a comparison allows demonstrating that, except for some works, most of these attempts seldom took into accounts basic requirements such as the parameter interactions, the role of cation mobility around a solid surface, if any, the multiple pollutant-catalyst-oxidizing species interactions and the significant contribution of adsorption, etc. Otherwise, how to explain that many experiments are still conducted with unsuitable catalysts under totally inadequate operating conditions? A better understanding of the essential requirements for a catalyst to achieve total mineralization of any organic molecules is the main objective of this work. The data summarized herein allow devoting a special interest to ozone, which is a powerful oxidizing agent and probably the most easily handleable, in spite of its low solubility in water. The use of catalysts is an ultimate strategy to improve the ozonation performance, by reducing the chemical oxygen demand (COD), even until total disappearance. However, solid catalysts, more particularly those developing high specific surface areas, such as silicates, aluminosilicates, zeolites, pseudozeolites, and clay minerals and derivatives are expected to display appreciable performances in ozonation. The latest findings show strong dependency of their catalytic activity on the chemical and physical characteristics of their surface, their concentration in the liquid media, the pH level of the reaction mixture and other parameters. The effects of these factors will be systematically examined in this review paper. The state-of-the-art in the catalytic ozonation of organic pollutants may be useful to understand the contribution of both surface and bulk ozonation reaction in the vicinity of the surface of a solid catalyst, and more particularly the role of the catalytic agent and its mobility near the solid surface. A rigorous data synthesis, made available in the present paper, allows understanding the ozone scavenging by the very species present in water, and correlating the highest effectiveness of ozone in the presence of optimum catalyst concentration at optimum pH. This supposes strong interactions between the main factors, which remain to be elucidated for each type of catalyst. The structure of this review makes emphasis on montmorillonite, which exhibits most of the required properties for effective ozonation catalysts. These are common features of natural clay minerals and zeolites, which appear as interesting candidates for large-scale water treatments, targeting complete mineralization of organic pollutants without generating persistent toxins.

Mineralization of organic pollutants by anodic oxidation using reactive electrochemical membrane synthesized from carbothermal reduction of TiO2.