Artículos de revistas sobre el tema "Hazardous wastes Biodegradation"

Release of textile effluent into the environment is a matter of health concern. Dyes and pigments that are part of textile effluent generate hazardous wastes which are generally inorganic or organic contaminants. Among the present pollution control strategies, biodegradation of synthetic dyes by microbes is evolving as a promising approach, even more than physico-chemical methods. While both mixed cultures and pure cultures have been used to achieve efficient biodegradation, no conclusive result has been determined. This paper aims at checking the efficiency of mixed culture of sewage and pure isolates in degradation of azo dyes, both simple dyes like methyl red and methyl orange and a more complex dye like Janus green.

Biodegradation of recalcitrant petrochemical sludges was carried out in sealed continuous tank stirred reactors (CSTR's). The specific sludge used in the research contained eight polynuclear aromatics (PNA's) cited by the United States Environmental Protection Agency (USEPA) as hazardous wastes. Benzo(a)pyrene {B(a)P} was selected in this research as the primary target contaminant due to its strong carcinogenic nature and low allowable release concentrations in sludges. Equilibrium conditions in the strongly stirred aerobic 1 litre reactors, were confirmed by daily monitoring of key control parameters which included: sludge oil & solids mass balances, B(a)P mass balances, pH, culture plating, carbon dioxide respiration, and biomass accumulation. B(a)P loadings varied from 285 mg/kg of dry feed solids to 3475 mg/kg and 10 out of 13 reactors produced solid wastes meeting the 1990 USEPA constituent concentration limit (CCL) for B(a)P of 12 mg/kg for allowable land disposal. Anionic surfactants - Triton N-101, Triton X-100 - were added to all petrochemical sludges augmented with B(a)P at mass concentrations of 1600 mg/kg and higher. All sampling and analytical protocols followed USEPA methodologies. Mass balance removals of B(a)P and other similar aromatic hydrocarbons were found to exceed 90 percent. It is concluded that the high removals of B (a) P demonstrated in aerobic bioremediations in high solids environments, will generate better engineered and more economical commercial waste minimization applications.

Amoxicillin is one of penicillin antibiotic groups with active β-lactam which the presence in surface water and wastes not only affects water quality but also causes long-term adverse effects on ecosystems and human health due to their resistance to natural biodegradation. The processing of organic waste electrochemically has the advantages of cheap and efficient cost, waste gas that does not contain toxic and hazardous materials. Have been studied the process of amoxicillin electro-oxidation mediated by a cobalt (III) in a cyclic voltammetry study using a platinum, Pt/Co(OH)2 and Pt/Co as working electrodes in acidic medium HNO3 and H2SO4 as supporting electrolytes solution. The voltammogram of Pt, Pt/Co and Pt/Co(OH)2 electrodes showed that higher current was found in medium of HNO3 0.1 M and it can be used to oxidize the amoxicillin wastes, the two anodic and cathodic peaks can be observed at potential of 200-800 mV (vs Ag/AgCl). The presence of cobalt (III) ions in the system caused the decrease of oxidation current, indicated the presence of degradation to amoxicillin.

<p class="p1">This document presents results of research in which an autochthonous consortium of cyanide-degrading microorganisms was developed for use in the biological treatment of hazardous cyanide waste. </p><p class="p1">These autochthonous microorganisms were lyophilized (freeze dried) in different protective media, such as gelatin and lactose broth, at different temperatures (-35,-45,-55 and -65 <span class="s1">o</span>C). </p><p class="p1">The preliminary treatment of cyanide wastes involved pretreatment of sludge for 3-5 days to leach the waste, and a subsequent treatment in aerated lagoons, where the consortium of lyophilized microorganisms was applied. </p><p class="p1">Eight different lyophilized samples were obtained at different temperatures using two protective media for lyophilization, which produced excellent results six months after lyophilization. </p><p class="p1">The consortium of lyophilized microorganisms showed 70% to 80% viability, with cyanide extraction percentages higher than 95%, and can be kept active for long periods of time (for years). </p><p class="p1">Lyophilized microorganisms can be used for biodegradation of cyanide wastes from gold mines or from any other cyanide waste such as that from metallic electroplating baths, or from the jewelry manufacturing industry. </p>

The scientific community is confronted with a number of significant environmental issues, including the dilemma of how to maintain, safely and effectively, the enormous quantity of organic and inorganic hazardous wastes that are produced in the U.S. alone. Substantial interest in the concept of bioremediation, the use of microorganisms to accelerate the degradation of environmental contaminants, has been generated during the past decade. Bacillus sp., has demonstrated an ability to degrade water dispersible polyurethane, a molecule normally exceedingly difficult for microbial organisms to metabolize. The primary objective of this investigation is to obtain basic ultrastructural information on the physical nature of polyurethane biodegradation conducted by Bacillus.A bacterial suspension of l×l09 cells was placed in one liter of a stock solution of polyurethane (3mg polyurethane/L distilled water). A comparable number of cells was maintained in 1 L of growth media and served as a control. At 2, 8, and 24 h subsequent to the initial exposure, samples were obtained from the experimental and control flasks and processed for phase-contrast microscopy, TEM and SEM.

A method for determination of 2,4,6-trinitrotoluene in geoenvironmental subjects by gas chromatography with mass-spectrometric detection was proposed. The distribution of 2,4,6-trinitrotoluene in wastes and sewage water samples from mining plants was studied. The presence of this compound in surface water was established. Other nitrogen-containing compounds, in particular, 2-amino-4,6-dinitrotoluene and<br />2,4,-dinitrotoluene, were also identified in the studied samples.<br />The 2,4,6-trinitrotoluene (TNT) is the most important shattering explosive used for blasting out. This compound is highly toxic and stable to biodegradation. The TNT belongs to the second hazard class (highly hazardous); its maximum permissible concentration (MPC) in drinking water sources was strongly restricted, from 0.5 to 0.01 mg/L. A method for determination of 2,4,6-trinitrotoluene in surface water, sewage water and wastes by gas chromatography with mass-spectrometric detection has been developed. The TNT calibration curve was shown to be linear over the concentration range of 1.6-160 μg/mL, and the correlation factor of the line was equal to 0.997. The distribution of 2,4,6-trinitrotoluene in sewage water and wastes from mining plants has been studied. Mine water in the case of underground mining has high TNT concentrations, which cannot be decreased by the existing traditional methods of sewage water treatment. TNT is detected also in surface water after mine water disposal. Note that the TNT concentrations can exceed many times the maximum permissible concentrations prescribed for water works system.<br />2-amino-4,6-dinitrotoluene and 2,4,-dinitrotoluene, which can be considered as products of TNT metabolism, were also identified in the studied samples. The developed method and results of the present study make it possible to introduce the quantitative<br />determination of TNT and its metabolites into the programs for monitoring of surface water, sewage water and wastes in the mining plant sites in different countries as well in Russia, namely in Kuzbass.

Background Lack of infrastructure for disposal of effluents in industries leads to severe pollution of natural resources in developing countries. These pollutants accompanied by solid waste are equally hazardous to biological growth. Natural attenuation of these pollutants was evidenced that involved degradation by native microbial communities. The current study encompasses the isolation of pesticide-degrading bacteria from the vicinity of pesticide manufacturing industries. Methods The isolation and identification of biodegrading microbes was done. An enrichment culture technique was used to isolate the selected pesticide-degrading bacteria from industrial waste. Results Around 20 different strains were isolated, among which six isolates showed significant pesticide biodegrading activity. After 16S rRNA analysis, two isolated bacteria were identified as Acinetobacter baumannii (5B) and Acidothiobacillus ferroxidans, and the remaining four were identified as different strains of Pseudomonas aeruginosa (1A, 2B, 3C, 4D). Phylogenetic analysis confirmed their evolution from a common ancestor. All strains showed distinctive degradation ability up to 36 hours. The Pseudomonas aeruginosa strains 1A and 4D showed highest degradation percentage of about 80% for DDT, and P. aeruginosa strain 3C showed highest degradation percentage, i.e., 78% for aldrin whilst in the case of malathion, A. baumannii and A. ferroxidans have shown considerable degradation percentages of 53% and 54%, respectively. Overall, the degradation trend showed that all the selected strains can utilize the given pesticides as sole carbon energy sources even at a concentration of 50 mg/mL. Conclusion This study provided strong evidence for utilizing these strains to remove persistent residual pesticide; thus, it gives potential for soil treatment and restoration.

Background Lack of infrastructure for disposal of effluents in industries leads to severe pollution of natural resources in developing countries. These pollutants accompanied by solid waste are equally hazardous to biological growth. Natural attenuation of these pollutants was evidenced that involved degradation by native microbial communities. The current study encompasses the isolation of pesticide-degrading bacteria from the vicinity of pesticide manufacturing industries. Methods The isolation and identification of biodegrading microbes was done. An enrichment culture technique was used to isolate the selected pesticide-degrading bacteria from industrial waste. Results Around 20 different strains were isolated, among which six isolates showed significant pesticide biodegrading activity. After 16S rRNA analysis, two isolated bacteria were identified as Acinetobacter baumannii (5B) and Acidothiobacillus ferroxidans, and the remaining four were identified as different strains of Pseudomonas aeruginosa (1A, 2B, 3C, 4D). Phylogenetic analysis confirmed their evolution from a common ancestor. All strains showed distinctive degradation ability up to 36 hours. The Pseudomonas aeruginosa strains 1A and 4D showed highest degradation percentage of about 80% for DDT, and P. aeruginosa strain 3C showed highest degradation percentage, i.e., 78% for aldrin whilst in the case of malathion, A. baumannii and A. ferroxidans have shown considerable degradation percentages of 53% and 54%, respectively. Overall, the degradation trend showed that all the selected strains can utilize the given pesticides as sole carbon energy sources even at a concentration of 50 mg/mL. Conclusion This study provided strong evidence for utilizing these strains to remove persistent residual pesticide; thus, it gives potential for soil treatment and restoration.

Petroleum-based plastics are an indispensable part of our daily life now because they are flexible, convenient, light weight, waterproof, and also have good mechanical strength and economical. They are especially suitable in products packaging, but they accumulate in soils, rivers and oceans, resulting in undesirable environmental and ecological hazards. Conventional plastics wastes in landfills occupy a much higher proportion of space because of their light-weight and extremely low biodegradation rate under anaerobic conditions. Composting is a treatment process to deal with biodegradable plastics (BPs) wastes and diverts a fraction of the wastes from landfilling to provide a feasible solution to the waste management problem. Biodegradability and degradation rate of plastics products depend on the fundamental chemical characteristics of the specific plastics mainly while environmental conditions and the establishment of an active degrading population of microorganisms contribute to a small extent of the fate of plastics after disposal. As the biodegradation rate varies among different plastics, a group of testing methods are available for assessing the degradability of different plastics and their products. Plasticizers in plastics and polymeric materials deserve a special attention up on their dispersal and ecological impact because of their endocrine-disrupting activity. The widely used phthalate esters are biodegradable by indigenous microorganisms in the environments, but the large quantity of them used is a serious issue to the environment and ecological health. However, there is an apparent cost difference between biodegradable and synthetic plastics, which hinder the commercialization of biodegradable ones for daily use. Separation of waste collection and education can contribute to the plastic waste management. It is unrealistic that biodegradable plastics are the solution to the problems facing today’s society on waste management. The ultimate goal is to reduce the use by society members so that amount of waste generated can be reduced so that waste products can be reduced from the sources.

Oil sludge from petroleum industry effluent is classified as hazardous waste and requiredspecial treatment before discharge to the environment. Biodegradation using bacterialactivities is a general treatment for oil sludge processing. However, the bacterial abilityin oil sludge biodegradation is blocked by non-aqueous phase liquid of oil sludge. Twopossible ways of enhancing the bioavailability of oil sludge are surfactants application and slurry bioreactors system. The objective of this study is to obtain the surfactant which can increase oil sludge biodegradation using simple slurry bioreactor. The surfactant selection obtained Emulsogen LP (58% effectiveness) which was examined based on HLB value, nonionic character, and surfactant effectiveness. Emulsogen LP is readily biodegradable which reached 93% biodegradability in 15 days. The biodegradation test showed that Emulsogen LP addition on its Critical Micelle Concentration (10 mg/L) enhanced oil sludge biodegradation in 3 bacterial cultures of Pseudomonas aeruginosa, Bacillus subtilis, and Actinobacter baumanni after 48 hours. By surfactant addition, oil sludge biodegradation reached 37-49% whereas without surfactant addition it only reached 28-33%. The highest oil sludge biodegradation was obtained in P. aeruginosa cultures with Emulsogen LP addition (49%). The surfactant addition had no effect on microbial growth. Moreover, P. aeruginosa population was increased by surfactant addition.

Chlorinated organic compounds are hazardous pollutants found in waste water, surface water, and ground water. Our study shows that a combination of ultrasonic pretreatment and biodegradation effectively removes the solvent chlorobenzene and the disinfectant 2,4-dichlorophenol, also reduces Adsorbable Organic Halogens (AOX) and Chemical Oxygen Demand (COD). In our experiments, the ultrasonic dechlorination was not influenced by the presence of other soluble organic compounds like acetate or glucose. Dechlorination of chlorobenzene by ultrasound did not lead to toxic or inhibiting reaction products. More than that, the ultrasonic pretreatment significantly reduced the toxicity of 2,4-dichlorophenol and biological activity was initiated after sonication. Residual organic pollutants after ultrasonic pretreatment were eliminated by biodegradation.

Abstract Purpose of Review In the presented review, we have summarized recent achievements on the use of immobilized oxidoreductases for biodegradation of hazardous organic pollutants including mainly dyes, pharmaceuticals, phenols, and bisphenols. In order to facilitate process optimization and achievement of high removal rates, effect of various process conditions on biodegradation has been highlighted and discussed. Recent Findings Current reports clearly show that immobilized oxidoreductases are capable of efficient conversion of organic pollutants, usually reaching over 90% of removal rate. Further, immobilized enzymes showed great recyclability potential, allowing their reuse in numerous of catalytic cycles. Summary Collected data clearly indicates immobilized oxidoreductases as an efficient biocatalytic tools for removal of hazardous phenolic compounds, making them a promising option for future water purification. Data shows, however, that both immobilization and biodegradation conditions affect conversion efficiency; therefore, process optimization is required to achieve high removal rates. Nevertheless, we have demonstrated future trends and highlighted several issues that have to be solved in the near-future research, to facilitate large-scale application of the immobilized oxidoreductases in wastewater treatment.

Abstract Generally, all petroleum processing industries produce oil sludge or sludge. Polycy-clic Aromatic Hydrocarbons (PAH), one of the components contained in sludge, are hazardous and toxic waste material with toxic, carcinogenic and mutagenic properties. The research objective was to understand the biodegradation mechanism of naphthalene by utilizing a marine sponge symbiotic bacterial isolate. Partial bacteria Bacillus Sp strain AB353f (BC), sponge isolate Neopetrosia sp and Acinetobacter Calcoaceticus strain PHCDB14 (AC) isolate sponge Callyspongia (Aerizusa) as biomaterial for PAH degradation. Biodegradation method integrates bacterial suspension with 10,000 ppm naphthalene for 25 days. Every 5 days, the bio-degradation indicators were observed and the products of the destruction of naphthalene components were measured using FTIR and GC-MS. The results showed that BC isolates and AC isolates from sponge symbionts could degrade naphthalene. The biodegradation performance of BC bacteria tended to be more dominant than AC against naphthalene. Based on the functional groups resulting from FTIR, three types of biodegradation products were identified, namely: alcohol, aldehyde and carboxylic acid and one transition product in the form of a cate-chol. Maximum naphthalene bio-degradation occurs at an interaction period of 20 - 25 days.

Environmental applications of enzymes in biodegradation for preventing pollution by toxic byproducts warrants approaches that can be performed under mild conditions, are economically feasible and can replace the use of chemicals. Technologies involving physico-chemical methods, like incineration, dechlorination and UV oxidation, for waste treatment are not acceptable since they generate a lot of pollutants as by-products. To address these problems, environmental–friendly alternatives are required for bioremediation. In this context, fungal enzymes have emerged as a natural tool to detoxification of pollutants in environment, and the potential to convert toxic substances to less hazardous or non-hazardous forms. However, what are the effective advances by using white-rot fungi for bioremediation? Here, a brief discussion about the application of these fungi to detoxification of pollutants in environment has been considered.

Depositing municipal waste in a responsible and controlled manner in landfills allows their decomposition to stabilized material. However, there are many environmental risks during operation and stabilization after landfill closure. These include: dusts, odors, potential fires associated with the presence of landfill gas and it is microbiological hazards and leachates. The latter are also generated many years after closure and reclamation of the landfill. In the event of a leak trough the anti-filtration shutter, toxic compounds found in the leachates can migrate and contaminate to groundwater. The article presents the quantitative and qualitative analysis of leachates in the final operational period of the landfill and after its closure. In both cases, the chromatographic analysis was carried out using the same conditions, i.e. solvent, extraction time, chromatograph and conditions for chromatographic analysis of samples. Physical and chemical leachate examinations were performed on the basis of valid standards. Their results show that the waste deposit is subject to increasingly advanced biodegradation processes of organic compounds. The values of such indicators as COD and BZT5 are decreasing. However, they remain quite significant, which indicates the presence of hard-to decompose and newly compounds in the leachates.

Biodegradation of hazardous waste is often the most cost-effective technique suitable for purifying large quantities of polluted groundwater and industrial effluents. In an effort of optimizing environmental conditions for microorganisms to degrade carbon tetrachloride, culture redox potential (Eh) was demonstrated as having a critical role. The microorganisms tested were isolated from contaminated field sites and included Pseudomonas cepacia and Providencia stuartii. Ti(III) citrate was used as a reducing agent to poise Eh at designed values. Over 99% degradation of carbon tetrachloride was effected in 3 days at −250 mV ≤ Eh ≤ −200 mV. Lesser rates were observed at Eh ≥ 0 mV. Kinetic analysis indicated that the overall degradation rate constant increased from 2.75×10−3 h−1 to 4.75×10−2 h−1 by controlling Eh at about −200 mV compared with Eh at ≥ 0 mV. Results indicated that the implementation of critical redox potential may be effective in optimizing CT biodegradation activity.

A significant increase in the production of plastic materials and the expansion of their areas of application contributed to the accumulation of a large amount of waste of polymeric materials. Most of the polymer composition is made up of plasticizers. Phthalate plasticizers have been recognized as potentially hazardous to humans and the environment due to the long period of their biodegradation and the formation of persistent toxic metabolites. It is known that the industrial plasticizer dioctyl adipate is characterized by reduced toxicity and a short biodegradation period. The paper describes the synthesis of a number of new asymmetric esters based on adipic acid and ethoxylated butanol by azeotropic esterification. The receipt of the products was confirmed by IR spectra. The physicochemical properties of the synthesized compounds were investigated. The glass transition temperatures of PVC composites plasticized with alkyl butoxyethyl adipates were determined using DSC analysis. The ecological safety of esters was assessed by the phytotesting method. Samples of adipates were tested for fungal resistance, and the process of their biodegradation in soil was also studied. It is shown that the synthesized esters have good plasticizing properties and are environmentally safe. When utilized under natural conditions, they can serve as a potential source of carbon for soil microorganisms and do not form stable toxic metabolites; therefore, they are not able to accumulate in nature; when the plasticizers under study are disposed of in the soil, toxic substances do not enter.

Organic contaminants (OCs), such as pharmaceuticals, personal care products, flame retardants, and plasticisers, are societally ubiquitous, environmentally hazardous, and structurally diverse chemical compounds whose recalcitrance to conventional wastewater treatment necessitates the development of more effective remedial alternatives. The engineered application of ligninolytic oxidoreductase fungal enzymes, principally white-rot laccase, lignin peroxidase, and manganese peroxidase, has been identified as a particularly promising approach for OC remediation due to their strong oxidative power, broad substrate specificity, low energy consumption, environmental benignity, and cultivability from lignocellulosic waste. By applying an understanding of the mechanisms by which substrate properties influence enzyme activity, a set of semi-quantitative physicochemical criteria (redox potential, hydrophobicity, steric bulk and pKa) was formulated, against which the oxidoreductase degradation susceptibility of twenty-five representative OCs was assessed. Ionisable, compact, and electron donating group (EDG) rich pharmaceuticals and antibiotics were judged the most susceptible, whilst hydrophilic, bulky, and electron withdrawing group (EWG) rich polyhalogenated compounds were judged the least susceptible. OC susceptibility scores were in general agreement with the removal rates reported for experimental oxidoreductase treatments (R2 = 0.60). Based on this fundamental knowledge, and recent developments in enzyme immobilisation techniques, microbiological enzymic treatment strategies are proposed to formulate a new generation of biological wastewater treatment processes for the biodegradation of environmentally challenging OC compounds.

A priority environmental problem is pollution and disturbance of natural environments by emerging pollutants ‒ substances of various origins and structures and with known and/or potential ecotoxic effects. One of the most dangerous groups of emerging pollutants is pharmaceutical substances due to their highly stable chemical structure and pronounced biological activity. They are found in soil, bottom sediments, surface, sewage, groundwater and drinking water. Uncontrolled release of pharmaceuticals in open ecosystems is potentially dangerous, entailing environmental consequences. Their negative impacts on living organisms are evident. This has driven the search for effective ways to neutralise persistent pollutants. In Russia, pharmaceutical pollution of the environment has commenced recently and is still presented as research with a local focus. In particular, the dynamics and metabolic mechanisms of pharma pollutants by Rhodococcus actinobacteria, outstanding among other microorganisms for their capacity to degrade a great diversity of degradable pollutants, are most intensively investigated. These studies are implemented at the junction of organic chemistry, molecular biology, biotechnology, and pharmacology. They include a set of interrelated fundamental tasks, such as developing drug detection methods in the cultivation media of microorganisms, elucidating the relationships between the systematic affiliation of microorganisms and their ability to degrade chemically different drug substances, as well as studying the degree of biodegradability and toxic effects of new compounds on the degrading microorganisms, and also the features of their decomposition and co-metabolism. Solving these tasks is important to enable understanding of the environmental fate of pharmaceuticals and to create prerequisites for innovative technical solutions in the advanced treatment of pharmaceutical wastewater. It is also essential for the development of environmentally safe approaches to hazardous pharmaceutical waste management.

Nature is the precious gift for every organism on the earth but, only few species are taking benefits and rest are suffering from scarcity of natural resources because of over exploitation. There exist numbers of hazardous pollutants in environment that are required to eradicate for sustainable use of natural resources. To overcome these pollutants researchers introduced bioremediation with microorganisms. This paper has been prepared by collecting data from various research articles to show numerous applications of bacillus species for sustaining environment. The article is unique from other research studies as it elaborates removal of different pollution causing elements such heavy metals, soil contaminants, removal of dye contaminants from the environment. Although there are large numbers of microbial species to degrade pollutants but according to recent researches, Bacillus is more prominent among all bacterial species. Researchers have proved that Bacillus are safer and cheaper source for conserving environment and reduce toxics from environment. Removal of heavy metals such as cadmium, nickel, copper can be done with the help of Bacillus cereus. In waste water treatment, Bacillus licheniformis and Bacillus acidophilus are also responsible for reducing nitrogenous components like phosphates, nitrites and ammonia.

Today, nitrophenols (NPs) represent chemicals highly in demand not only due to their function in synthetic chemistry but also due to their huge applications in several industries. Such diverse requirements and applications has resulted in a widespread abundance of these chemicals. Improper application and waste disposal practice results in the continuous discharge of these compounds into the environment and causes pollution threat to soil, groundwater, river water, etc. These xenobiotic chemicals are hazardous, toxic, carcinogenic, and mutagenic which results in serious health problems. The Nitro group present in the phenol makes them recalcitrant which causes the persistence of these chemicals in the environment. Although several chemicals, electrochemical, physical, and physicochemical methods have been proposed, bioremediation approaches mainly involving bacteria are considered best. To date, very few successful attempts (related to microbe-assisted bioremediation) have been carried out with environmental habitats for the removal of NPs (both in-situ and ex-situ attempts). So, as far as the effectiveness of the bioremediation process for NP decontamination is concerned, we are far away. More explorative studies using efficient aerobic-anaerobic NP degrading bacterial consortium (or combination of microbes- plant systems) and advanced techniques including omics approaches and nanotechnologies may help towards developing better practicable bioremediation approaches, in the future. This review article focuses on the list of nitrophenol degrading microorganisms, biodegradation pathways of NPs, bioremediation by immobilized cell technique, and the advantages and disadvantages of bioremediation. This article will increase our knowledge of the biodegradation of NPs.

Bioremediation uses biological organisms and their metabolic processes in order to degrade contaminants present in water, soil etc. Microbes have the vast potential are the major resource for bioprocess of using microbial enzymes reduces the toxicity of pollutants caused by the waste materials like pesticides, insecticides, plastics, other hydrocarbon-containing substances and obtain novel useful substances for mankind and the environment. Enzymes produced by bacteria, fungi, plants play a key role in the biodegradation of toxic organic compounds. The purpose of bioremediation processes that will an eco-friendly and cost-effective mechanism. The aim is to develop an advanced technique in bioprocesses that will help to minimize toxin risk and thereby acquire new, usable substances. Some of the bioremediation-related compounds like oxidoreductases hydrolases, dioxygenase, peroxidases, and laccase are most widely considered. The aim of the review is to express the role of microbial enzymes on the bioremediation of toxic, hazardous environmental pollutants.

Azo dyes are a popular group of dyes in the printing, food, leather, cosmetic, textile, and pharmaceutical sectors and are the largest and most important group of colored chemicals due to their facile production procedure. It is characterized by the presence of an azo group (-N=N-). The stability of azo dyes makes it recalcitrant. Discharge of untreated waste water that contains colored compounds with azo dye reaches water streams and affects the organisms due to the toxicity of the dyes. Many physicochemical and chemical approaches have been used for the removal of dye from polluted water. Although these procedures effectively treat polluted water but become costly and may result in the formation of hazardous compounds. A microbial enzymatic decolorization is an environment-friendly approach that shows excellent removal efficiency at low operating costs however, it has certain downsides, such as a slow process rate and a longer assimilation phase. Alternatively, enzymes derived from various sources can be employed to biodegrade and decolorize azo dyes. For the treatment of dye-based chemicals, enzymes extracted from plants have benefits over other approaches. They are believed to have a significant potential to degrade the recalcitrant pollutants present in the effluent from industries i.e., laccases, polyphenol oxidases, azoreductases, and different peroxidases like manganese peroxidase, lignin peroxidases, and decolorizing peroxidases, are the common enzymes that are isolated from plants and have the potential in the biodegradation of colored compounds. The importance of these enzymes in the treatment of industrial wastewater is unquestionable.

ABSTRACT Pseudomonas putida strain AJ and Ochrobactrum strain TD were isolated from hazardous waste sites based on their ability to use vinyl chloride (VC) as the sole source of carbon and energy under aerobic conditions. Strains AJ and TD also use ethene and ethylene oxide as growth substrates. Strain AJ contained a linear megaplasmid (approximately 260 kb) when grown on VC or ethene, but it contained no circular plasmids. While strain AJ was growing on ethylene oxide, it was observed to contain a 100-kb linear plasmid, and its ability to use VC as a substrate was retained. The linear plasmids in strain AJ were cured, and the ability of strain AJ to consume VC, ethene, and ethylene oxide was lost following growth on a rich substrate (Luria-Bertani broth) through at least three transfers. Strain TD contained three linear plasmids, ranging in size from approximately 90 kb to 320 kb, when growing on VC or ethene. As with strain AJ, the linear plasmids in strain TD were cured following growth on Luria-Bertani broth and its ability to consume VC and ethene was lost. Further analysis of these linear plasmids may help reveal the pathway for VC biodegradation in strains AJ and TD and explain why this process occurs at many but not all sites where groundwater is contaminated with chloroethenes. Metabolism of VC and ethene by strains AJ and TD is initiated by an alkene monooxygenase. Their yields during growth on VC (0.15 to 0.20 mg of total suspended solids per mg of VC) are similar to the yields reported for other isolates (i.e., Mycobacterium sp., Nocardioides sp., and Pseudomonas sp.).

The purpose of this study is to provide a theoretical mechanism during the degradation of polyolefin plastic waste using phytochemicals. Existing degradation (physical, chemical and biological) methods are ineffective, expensive and notably time consuming during the degradation of polyolefin plastics. During the phytochemical degradation process, initially, polyolefin plastic is oxidized and converted into the hydrophilic nature by photo-oxidation. Thereafter, phyto phenols can be used to cleave the main chains of polyolefin plastics, thereby, small molecular hydrocarbons are formed such as oligomers, monomers and dimers. During this process, primary products like all the reactive hydroperoxides and free radicals might be produced and lead to further chain cleavage via peroxide cross linkage. Besides, the consequences of plastic chain cleavage make the product apparently more susceptible to biodegradation. The phytochemical based degradation mechanism is useful for the researchers in the direction towards plastic hazards reduction and management on the earth's environment.

Lignin is an important commercially produced polymeric material. It is used extensively in both industrial and agricultural activities. Recently, it has drawn much attention from the scientific community. It is abundantly present in nature and has significant application in the production of biodegradable materials. Its wide usage includes drug delivery, polymers and several forms of emerging lignin nanoparticles. The synthesis of lignin nanoparticles is carried out in a controlled manner. The traditional manufacturing techniques are costly and often toxic and hazardous to the environment. This review article highlights simple, safe, climate-friendly and ecological approaches to the synthesis of lignin nanoparticles. The changeable, complex structure and recalcitrant nature of lignin makes it challenging to degrade. Researchers have discovered a small number of microorganisms that have developed enzymatic and non-enzymatic metabolic pathways to use lignin as a carbon source. These microbes show promising potential for the biodegradation of lignin. The degradation pathways of these microbes are also described, which makes the study of biological synthesis much easier. However, surface modification of lignin nanoparticles is something that is yet to be explored. This review elucidates the recent advances in the biodegradation of lignin in the ecological system. It includes the current approaches, methods for modification, new applications and research for the synthesis of lignin and lignin nanoparticles. Additionally, the intricacy of lignin’s structure, along with its chemical nature, is well-described. This article will help increase the understanding of the utilization of lignin as an economical and alternative-resource material. It will also aid in the minimization of solid waste arising from lignin.

Petroleum that is produced from several oil wells produces a fluid containing a mixture of petroleum, natural gas and produced water. The produced water usually contains hazardous chemicals such as hydrocarbons, sulfides, ammonia, phenols and other heavy metals. One of the high pollutants in the water produced is phenol. Through a biodegradation process, the contents of phenolic compounds in the produced water are expected to be reduced so that it meets the quality standards of waste water for oil and gas exploration and production activities. This research is development of the results of previous studies using a bioreactor with a larger scale, namely 3 L. The degradation process of phenolic compounds is carried out in optimal conditions, namely: pH 7, temperature 300C, and selected simple media: NP (5: 1) derived from urea and NPK + 0.1% yeast extract. The results of this study indicated that P. aeruginos and bacterial consortium may degrade phenolic compounds very well, which was 5.3 times faster than the previous studies. The biodegradation percentage was 98.40% in P. aeruginosa and 99.03% in bacterial consortium respectively. The monod kinetics model approach was successfully carried out and gave the value of parameters ?Max, Km, YS/X, and ?d respectively of 0.6305 hours-1, 0.0280 mg/L, 7 10-7 mg/L/ CFU/mL, and 0.00575 hours-1 in P. aeruginosa and 0.3272 hours-1, 0.0355 mg/L, 6.63 10-7 mg/L/CFU/ mL, and 0.00279 hours-1 in bacterial consortium. Based on the valuesof these parameters, P. aeruginosa has better affinity and growth.

Plastics have long been overruling the environment affecting the living systems by entering into the food chain. Negligent and erroneous disposal supports plastic for wide distribution and extensive use in day to day life. The durability and non-degradability encourage the persistent accumulation of plastic waste as an active and major pollutant of the biosphere. Plastic pollution is ubiquitous and solicitude issue that need to be heeded in a war footing. Microorganisms are used as major stimulant for degradation; biodegradation is eco-friendly and cost effective approach. In order to increase the microbial degradation process, novel strains need to be identified and explored for effective degradation of plastics. This review is intended to exhibit the impacts of plastics on environment, associated health hazards and the current status of microbial degradation, challenges and scope for improvement.

Abstract Spent mineral oil-based metalworking fluids are waste products of the machining processes and contribute substantially to the global industrial pollution with petroleum oil products. Wastewaters containing oily emulsions are ecologically hazardous and thus a variety of methods have been implemented to prevent these effluents from affecting the natural environment. Most of these methods rely upon physical-chemical treatment and phase separation; however, none of them proved to be effective enough to meet tightening environmental regulations. Therefore, novel technologies need to be elaborated and there is growing interest in implementing biological treatment methods based on microbial bioremediation. In this study an oil/water emulsion obtained from a waste stream of the metal-processing industry was tested for biodegradability of its organic constituents. This liquid waste was found non-toxic to bacterial consortia and was colonized with indigenous microorganisms (approx. 107 cfu · cm−3). The total load of organic content was determined as a chemical oxygen demand (COD) value of 48 200 mg O2 · dm−3. Emulsion treatment was carried out using a threefold wastewater dilution and employing two variants of biostimulated aerobic bacterial communities: (1) uninoculated emulsion, where bioremediation was carried out by the autochthonous bacteria alone, and (2) wastewater samples inoculated with a ZB-01 microbial consortium which served as a source of specialized bacteria for process bioaugmentation. Biodegradation efficiency achieved in a 14-day test was monitored by measuring both the COD parameter and the concentration of high-boiling organic compounds. Both approaches yielded satisfactory results showing significant reduction of the emulsion organic fraction; however, the resultant decrease of wastewater load tended to be more efficient for the case where the process was bioaugmented with the inoculated consortium. Gas chromatography analyses coupled with mass spectrometric detection (GC-MS) confirmed high degradation yields obtained for both cases studied (58 and 71%, respectively) in a 28-day test. It is concluded that oil-based metalworking emulsions can undergo efficient biological treatment under conditions enabling aerobic bacterial proliferation and that xenobiotic biodegradation kinetics can be accelerated by bioaugmenting the process with allochthonous microbial consortia.

Plastics are available in different shapes nowadays in order to enhance the living standard. But unfortunately, most of these plastics are synthetic in nature that is why they show resistance to physical and chemical degradation processes and enhance environmental hazards. The aim of the present research study was to isolate and identify beneficial fungal species from soil that have the capability to degrade plastic. Soil samples from a waste disposal site at Peshawar district were diluted and inoculated on sabouraud dextrose agar (SDA) and potato dextrose agar (PDA) for fungus isolation. After isolation, the identifications of fungal species were done using standard identification techniques such as colony morphology and microscopic examination. The isolated fungal species that were identified were Aspergillus Niger, Aspergillus flavus, Penicillium, white rot, and brown rot fungi. After isolation, a degradation experiment was conducted to evaluate the capability of fungal isolates towards degradation of plastic. For this purpose, a 2 cm2 plastic piece was treated with fungal isolates for one month in a liquid culture system. The weight loss percentage was estimated at 22.9%, 16.1%, 18.4%, and 22.7% by Aspergillus Niger, Aspergillus flavus, brown rot, and white rot, respectively, which was confirmed by the Fourier transform analysis. The obtained FTIR peaks revealed the C–H bond deformation in alkenes, ketones, and esters. It has been concluded from the study that fungal species play a significant role in the degradation of synthetic plastic which can be used in bioreactors in future studies for the degradation of complex plastic materials.

ABSTRACT1,2-Dichloroethane (1,2-DCA) and 1,2-dibromoethane (ethylene dibromide [EDB]) contaminate groundwater at many hazardous waste sites. The objectives of this study were to measure yields, maximum specific growth rates (μ̂), and half-saturation coefficients (KS) in enrichment cultures that use 1,2-DCA and EDB as terminal electron acceptors and lactate as the electron donor and to evaluate if the presence of EDB has an effect on the kinetics of 1,2-DCA dehalogenation and vice versa. Biodegradation was evaluated at the high concentrations found at some industrial sites (>10 mg/liter) and at lower concentrations found at former leaded-gasoline sites (1.9 to 3.7 mg/liter). At higher concentrations, theDehalococcoidesyield was 1 order of magnitude higher when bacteria were grown with 1,2-DCA than when they were grown with EDB, while μ̂'s were similar for the two compounds, ranging from 0.19 to 0.52 day−1with 1,2-DCA to 0.28 to 0.36 day−1for EDB.KSwas larger for 1,2-DCA (15 to 25 mg/liter) than for EDB (1.8 to 3.7 mg/liter). In treatments that received both compounds, EDB was always consumed first and adversely impacted the kinetics of 1,2-DCA utilization. Furthermore, 1,2-DCA dechlorination was interrupted by the addition of EDB at a concentration 100 times lower than that of the remaining 1,2-DCA; use of 1,2-DCA did not resume until the EDB level decreased close to its maximum contaminant level (MCL). In lower-concentration experiments, the preferential consumption of EDB over 1,2-DCA was confirmed; both compounds were eventually dehalogenated to their respective MCLs (5 μg/liter for 1,2-DCA, 0.05 μg/liter for EDB). The enrichment culture grown with 1,2-DCA has the advantage of a more rapid transition to 1,2-DCA after EDB is consumed.

<p>Amoxicillin is one of β-lactam antibiotic in penicillin groups which their presence in surface water and wastewater not only affects water quality but also causes long-term adverse effects on ecosystems and human health due to their resistance to natural biodegradation. The processing of organic waste electrochemically has the advantage of cheap and efficient cost, exhaust gas that does not contain toxic and hazardous materials. We have studied the process of amoxicillin electro-oxidation mediated by a cobalt (III) ion called an electrochemical oxidation process mediated (MEO) in a voltammetry study using a platinum working electrode, Pt/Co(OH)₂ and Pt/Co in various supporting electrolytes such as KNO₃, NaClO₄, Na₂SO₄ and phosphate buffer solution with concentrations 0.10 M. The results show that the amoxicillin oxidation peaks using the above-mentioned working electrode in various electrolyte solutions are in the potential range of 500-670 mV (Ag/AgCl). The presence of cobalt ions forming complex compounds with amoxicillin causes the oxidation current decreasing that indicates the presence of degradation to amoxicillin.</p>

The use of fossil fuels (methane, oil, etc.) is undergoing an unprecedented crisis now. There is the urgent need to search for alternative energy sources. A wide range of degraded organic materials can be effectively used to provide energy together with environmental protection. Soapstock is a hazardous waste containing a high concentration of toxic organic compounds of man-made origin (fatty acids, surfactants, dyes, etc.). To prevent environmental contamination such substances require an effective treatment approach. The goal of the study was to isolate the adapted-to-fatty-acids methanogenic microbiome and investigate the patterns of sodium acetate and soapstock degradation with simultaneous biomethane synthesis. The effectiveness of the degradation of sodium acetate and soapstock by non-adapted and adapted microbiomes was evaluated by decreasing the concentration of dissolved organic compounds. The effectiveness of the fermentation process was determined by the biogas (mixture of CH4 and CO2) yield. The most effective degradation occurred in the variant with sodium acetate and adapted methanogens and amounted to 77.9%. In other variants, the patterns and the efficiency of purification were similar ranging from 60.6 to 68.0%. The biomethane was mostly synthesized by adapted methanogens on the soapstock and sodium acetate as substrates. Thus, the CH4 yield was 368.4 L/kg of dissolved organic compounds or 127.5 L/kg of soapstock. The results of this study demonstrated the potential of methanogenic microorganisms in the biodegradation of soapstock with simultaneous biogas synthesis. The results can serve as a basis to reduce the reliance on fossil fuels by generating biomethane via the fermentation of toxic organics.

Polyurethanes (PUs) are an exceedingly heterogeneous group of plastic polymers, widely used in a variety of industries from construction to medical implants. In the past decades, we have witnessed the accumulation of PU waste and its detrimental environmental impacts. PUs have been identified as one of the most toxic polymers leaching hazardous compounds derived both from the polymer itself and the additives used in production. Further environmental impact assessment, identification and characterization of substances derived from PU materials and establishing efficient degradation strategies are crucial. Thus, a selection of eight synthetic model compounds which represent partial PU hydrolysis products were synthesized and characterized both in terms of toxicity and suitability to be used as substrates for the identification of novel biocatalysts for PU biodegradation. Overall, the compounds exhibited low in vitro cytotoxicity against a healthy human fibroblast cell line and virtually no toxic effect on the nematode Caenorhabditis elegans up to 500 µg ml−1, and two of the substrates showed moderate aquatic ecotoxicity with EC50 values 53 µg ml−1 and 45 µg ml−1, respectively, on Aliivibrio fischeri. The compounds were successfully applied to study the mechanism of ester and urethane bond cleaving preference of known plastic-degrading enzymes and were used to single out a novel PU-degrading biocatalyst, Amycolatopsis mediterranei ISP5501, among 220 microbial strains. A. mediterranei ISP5501 can also degrade commercially available polyether and polyester PU materials, reducing the average molecular number of the polymer up to 13.5%. This study uncovered a biocatalyst capable of degrading different types of PUs and identified potential enzymes responsible as a key step in developing biotechnological process for PU waste treatment options.

Treatment of wastewater containing nitrocellulose (NC) fines is a significant hazardous waste problem currently facing manufacturers of energetic compounds. Previous studies have ruled out the use of biological treatment, since NC has appeared to be resistant to aerobic and anaerobic biodegradation. The objective of this study was to examine NC biotransformation in a mixed methanogenic enrichment culture. A modified cold-acid digestion technique was used to measure the percentage of oxidized nitrogen (N) remaining on the NC. After 11 days of incubation in cultures amended with NC (10 g/L) and methanol (9.9 mM), the % N (w/w) on the NC decreased from 13.3% to 10.1%. The presence of NC also caused a 16% reduction in methane output. Assuming the nitrate ester on NC was reduced to N2, the decrease in CH4 represented almost exactly the amount of reducing equivalents needed for the observed decrease in oxidized N. An increase in the heat of combustion of the transformed NC correlated with the decrease in % N. There was no statistically significant decrease in % N when only NC was added to the culture, or in controls that contained only the sulfide-reduced basal medium. The biotransformed NC has a % N comparable to nonexplosive nitrated celluloses, suggesting that anaerobic treatment may be a technically feasible process for rendering NC nonhazardous.

Face masks have become an essential commodity during the COVID-19 pandemic, and their use rises daily. Excessive face mask use will likely continue to combat the virus and bacterial impacts in the long term. Afterward, used face masks are hazardous to the environment since most are made of nonbiodegradable porous polymeric fibrous materials. Thus, finding new ways to recycle waste face masks is urgently needed. Similarly, managing agricultural water for irrigation is a crucial challenge in saving water. This study demonstrates an approach for recycling face masks as bag- or small-sized pillows filled with superabsorbent polymers (SAPs) for the slow release of water near plant roots. Previous studies have reported that SAPs or hydrogel could boost soil’s water retention capacity, mixed with hydrogel/SAP. However, mixing SAPs into soil is improper because biodegradation generates low toxic organic molecules and contaminates soil and surface water. The objective of this research was to develop a face mask reuse approach, reduce irrigation water using polymers, and reduce toxic contamination in the soil. Here, swollen SAPs were taken inside the pillow and buried near plants, and the growth of the plants was studied. The moisture of the inner soil was constant for a long time, boosting plant growth. Afterward, the face mask pillows could be removed from the soil and maintained for further use. This new approach could be helpful in pot farming. This approach could contribute to the circular economy and the development of environmental sustainability.

Contamination of groundwater by petroleum-hydrocarbons is a widespread environmental problem. Generally in plumes of petroleum-hydrocarbon contamination, the dissolved oxygen (DO) demand imposed by biodegradation of organic contaminants exceeds the DO available creating anaerobic conditions within the plume core and mid-plume areas. The objectives of this bench-scale study were to (1) develop oxygen-releasing materials for continuous oxygen supplement, (2) determine the optimal components of the studied oxygen release material, and (3) evaluate the oxygen release rate and lifetime of this material. Moreover, the potential of using a passive oxygen release material to clean up aquifers contaminated by petroleum hydrocarbons was also studied. Bench experiments were conducted to design and identify the components of the oxygen-releasing materials. The mixtures of the oxygen release material were prepared by blending gypsum, calcium peroxide (CaO2), sand, and water together at a ratio of 1：0.5：0.14：0.75 by weight. Cement was used as a binder and regular medium filter sand was used to increase the permeability of the mixture. Calcium peroxide releases oxygen upon contact water (2CaO2 + 2H2O → O2 + 2Ca(OH) 2). The designed material with a density of 1.1 g/cm3 was made of 3.5-cm cube for the batch experiment. Results show that the oxygen release rate of the material is 0.025 mg/day/g. The oxygen release material is able to remain active in oxygen release for more than three months. With the application of this developed oxygen release material, the contaminated subsurface can remain an aerobic environment for subsequent aerobic bioremediation. For the future field application, the developed materials can be placed in remediation wells, trenches, horizontal wells, or barriers. Thus, the passive biobarrier system has advantages over conventional system including less maintenance, cost-effectiveness, no above-ground facilities, no groundwater pumping and reinjection, no air pollution problems, and groundwater remediation in situ. The proposed treatment system would be expected to provide a more cost-effective alternative to remediate petroleum-hydrocarbon contaminated aquifers. This technology can also be applied for other hazardous waste contaminated sites.

The present research work has clearly denoted as initially estimation of physic-chemical properties of the experimental hydrocarbon contaminated soil. The texture of the soil plays a very important role in microbial and plant species establishment and development and also influences physical parameters of the soil. The current results are clearly showed experimental soil of the hydrocarbon contaminated soil possessed totally eight different autochthonus bacterial strains were provably identified viz., Acinetobacter, Mycobacterium sp., Bacillus sp., Pseudomonas sp., and Aeromonas sp., observed by Bergy’s Manual. When this experimental soil was remediated with two biological sources such as four allothonus bacterial strains named as Enterobacter sp., Flavobacter sp., Shigella sp., and Bacillus sp., along with agronomic wastes also addition with neem juice. From the present result showed that Enterobacter sp., subjected polluted soil was remediated maximum than other treated sources assessed by spectrometric data. While, the biofilm formation experiment also been definitely expressed biodegradation potential enriched allothonus bacterial strain was the following order Enterobacter sp., Flavobacter sp., Shigella sp., and Bacillus sp.,. Moreover, other interesting finding also had been profounded such as dominant Antagonistic activity potential possessed autochthonus bacterial strain from the hydrocarbon contaminated soil. It has been identified through the molecular identification those typical organism expressed the named as ‘’Pseudomonas aeruginosa PA96’’by 16sr RNA sequence analysis. Additionaly maximum and maximum antagonistic activity has been noticed on E.coli, more or less similar zone of inhibition showed on other bacterial species of Shijella sp., and K. pneumonia. Moreover, HPLC results were almost elucidated fractions of hydrocarbon compounds thoroughly replied total illustrated chemical compounds are gradually minimized, when the heavy contaminated soils subjected with other bacterial sources along with various agronomic wastes. It has been significantly reduced the spectrum of the total hydrocarbon derivatives when it compared with before treatment of the contaminated soils. Therefore, these allothonous bacterial organism Enterobacter sp., strains could be considered for future use for bioremediation of oil contaminated land. However, further studies are needed to evaluate the potential of the isolated strains to degrade hydrocarbons in situ, in natural environmental conditions. This could be equally applicable for any allothonously present or other bacterial strains ubiquitously available in nature, and the technology could be further developed for targeting of any pollutants present on earth creating enormous environmental and health hazards.

Pentachlorophenol is used as an industrial wood preservative for utility poles, crossarms, fence posts, and other purposes (79%);for NaPCP (12%); and miscellaneous, including mill uses, consumer wood preserving formulations and herbicide intermediate (9%) (CMR, 1980). As a wood preservative, pentachlorophenol acts as both a fungicide and insecticide (Freiter, 1978). The miscellaneous mill uses primarily involve the application of pentachlorophenol as a slime reducer in paper and pulp milling and may constitute ∼6% of the total annual consumption of pentachlorophenol (Crosby et al., 1981). Sodium pentachlorophenate (NaPCP) is also used as an antifungal and antibacterial agent (Freiter, 1978). Pentachlorophenol also is used as a general herbicide (Martin and Worthing, 1977). Photolysis and microbial degradation are the important chemical removal mechanisms for pentachlorophenol in water. In surface waters, pentachlorophenol photolyzes rapidly (ECETOC, 1984; Wong and Crosby. 1981; Zepp et al., 1984); however, the photolytic rate decreases as the depth in water increases (Pignatello et al., 1983). Pentachlorophenol is readily biodegradable in the presence of accli-mated microorganisms; however, biodegradation in natural waters requires the presence of microbes that can become acclimated. A natural river water that had been receiving domestic and industrial effluents significantly biodegraded pentachlorophenol after a 15-day lag period, while an unpolluted natural river water was unable to biodegrade the compound (Banerjee et al., 1984). Even though pentachlorophenol is in ionized form in natural waters, sorption to organic particulate matter and sediments can occur (Schellenberg et al., 1984), with desorption contributing as a continuing source of pollution in a contaminated environment (Pierce and Victor, 1978). Experimentally determined BCFs have shown that pentachlorophenol can significantly accumulate in aquatic organisms (Gluth et al., 1985; Butte et al., 1985; Statham et al., 1976; Veith et al., 1979a,b; Ernst and Weber, 1978), which is consistent with its widespread detection in fish and other organisms. Direct photolysis may be an important environmental sink for pen tachlorophenol present in the atmosphere. The detection of pen tachlorophenol in snow and rain water (Paasivirta et al., 1985; Bevenue et al., 1972) suggests that removal from air by dissolution is possible. Soil degradation studies indicate that pentachlorophenol is biodegrad able; microbial decomposition is an important and potentially domin ant removal mechanism in soil (Baker et al., 1980; Baker and Mayfield, 1980; Edgehill and Finn, 1983; Kirsch and Etzel, 1973; Ahlborg and Thunberg, 1980). The degree to which pentachlorophenol leaches in soil is dependent on the type of soil. In soils of neutral pH, leaching may be significant, but in acidic soils, adsorption to soil generally increases (Callahan et al. , 1979; Sanborn et al. , 1977). The ionized form of pentachlorophenol may be susceptible to adsorption in some soils (Schellenberg et al., 1984). In laboratory soils, pen tachlorophenol decomposes faster in soils of high organic content as compared with low organic content, and faster when moisture content is high and the temperature is conducive to microbial activity. Half- lives are usually ∼2-4 weeks (Crosby et al., 1981). Monitoring studies have confirmed the widespread occurrence of pentachlorophenol in surface waters, groundwater, drinking water and industrial effluents (see Table 2). The U.S. EPA's National Urban Runoff Program and National Organic Monitoring Survey reported frequent detections in storm water runoff and public water supplies (Cole et al., 1984; Mello, 1978). Primary sources by which pen tachlorophenol may be emitted to environmental waters may be through its use in wood preservation and the associated effluents and its pesticidal applications. Pentachlorophenol can be emitted to the atmosphere by evaporation from treated wood or water surfaces, by releases from cooling towers using pentachlorophenol biocides or by incineration of treated wood (Skow et al., 1980; Crosby et al., 1981). Pentachlorophenol has been detected in ambient atmospheres (Caut reels et al., 1977), in snow and rain water (Paasivirta et al,. 1985; Bevenue et al., 1972) and in emissions from hazardous waste incinera tion (Oberg et al., 1985). The U.S. Food and Drug Administration's Total Diet Study (conducted between 1964 and 1977) found pen tachlorophenol residues in 91/4428 ready-to-eat food composites (See Tables 4 and 5). The average American dietary intake of pen tachlorophenol during 1965-1969 was estimated to range from <0.001-0.006 mg/day (Duggan and Corneliussen, 1972). The most likely source of pentachlorophenol contamination in many food prod ucts may be the exposure of the food to pentachlorophenol-treated wood materials such as storage containers (Dougherty, 1978). Acute toxicity data indicated that salmonids are more sensitive to the toxic effects of pentachlorophenol than other fish species, with LC50 values of 34-128 μ g/l for salmonids and 60-600 μ g/l for other species. More recent data showed that carp larvae, bluegills, channel catfish and knifefish also had LC50 values < 100 μ gl (see Table 10). The most sensitive marine fishes were pinfish larvae, the goby, Gobius minutus, and eggs and larvae of the flounder, Pleuronectes platessa, all with LC50 values <100 μ g/l (Adema and Vink, 1981). The most sensitive freshwater invertebrate species were the chironomid, Chironomus gr. thummi (Slooff, 1983) and the snail, Lymnaea luteola (Gupta et al., 1984). The most sensitive marine invertebrates were the Eastern oyster (Borthwick and Schimmel, 1978), larvae of the crusta ceans, Crangon crangon and Palaemon elegans (VanDijk et al. , 1977), and the copepod, Pseudodiaptomus coronatus (Hauch et al., 1980), all with LC50 values <200 μ g/l. In chronic toxicity tests, the lowest concentration reported to cause adverse effects was 1.8 μ g/l (NaPCP), which inhibited growth of sockeye salmon (Webb and Brett, 1973). The marine species tested displayed similar thresholds for chronic toxicity. Both acute and chronic toxicity increased at lower pH, probably because a lower pH favors the un-ionized form of pentachlorophenol, which is taken up more readily and is therefore more toxic than ionized pentachlorophenol (Kobayashi and Kishino, 1980; Spehar et al., 1985). Data concerning the effects of pentachlorophenol on aquatic plants were highly variable. Therefore, it was difficult to draw conclusions from these data. Pentachlorophenol did not appear to bioaccumulate in aquatic or ganisms to very high concentrations. BCFs for pentachlorophenol were <1000 for most species tested. The highest BCF was 3830 for the polychaete, Lanice conchilega (Ernst, 1979). Some species appear to have an inducible pentachlorophenol-detoxification mechanism, as evidenced in several experiments in which pentachlorophenol tissue levels peaked in 4-8 days and declined thereafter despite continued exposure (Pruitt et al., 1977; Trujillo et al., 1982). A study by Niimi and Cho (1983) indicated that uptake of waterborne pentachlorophenol from gills was much greater than uptake from food, indicating that bioconcentration of pentachlorophenol through the food chain is unlikely. Biomonitoring data of Lake Ontario fishes showed that similar pentachlorophenol levels were found in predators andforage species. Studies with experimental ecosystems have indicated that ecological effects may occur at pentachlorophenol levels as low as those causing chronic toxicity in sensitive species in single-species tests. The lowest concentration that caused adverse effects in these studies was 15.8 μ g/l, which caused a reduction in numbers of individuals and species in a marine benthic community (Tagatz et al., 1978). Pentachlorophenol is readily absorbed from the gastrointestinal tract of rats, mice, monkeys and humans (Braun et al. , 1977, 1978; Ahlborg et al., 1974; Braun and Sauerhoff, 1976). Peak plasma concentrations are reached within 12-24 hours after oral administration to monkeys (Braun and Sauerhoff, 1976), but 4-6 hours after oral administration to rats (Braun et al., 1977). After oral administration, the highest concentration of radioactivity was found in the liver and gastrointesti nal tract of monkeys (Braun et al., 1977). In rats and mice, tet rachlorohydroquinone was identified in the urine (Jakobson and Yllner, 1971; Braun et al., 1977; Ahlborg et al., 1974) as well as unmetabolized pentachlorophenol and glucuronide-conjugated pen tachlorophenol. Although Ahlborg et al. (1974) reported that oxidative dechlorination of pentachlorophenol occurs in humans, as evidenced by the presence of tetrachlorohydroquinone in the urine of workers occupationally exposed (probably by inhalation), analysis of human urine after ingestion of pentachlorophenol revealed the presence of conjugated pentachlorophenol and unmetabolized pentachlorophenol (Braun et al., 1978). The primary route of excretion after oral administrtation of all species studied is in the urine (Braun et al. , 1977, 1978; Ahlborg et al., 1974; Larsen et al., 1972; Braun and Sauerhoff, 1976). Although urinary excretion followed second-order kinetics in rats (Larsen et al., 1972; Braun et al., 1977) except in females receiving a single high dose (100 mg/kg) of pentachlorophenol, urinary excretion of pentachlorophenol in humans and monkeys followed first-order kinetics (Braun and Sauerhoff, 1976; Braun et al., 1978). Enterohepatic circulation played an importation role in the pharmacokinetics of pen tachlorophenol. The half-life of pentachlorophenol in the plasma is longer in female rats and monkeys than it is in male rats and monkeys (Braun et al. , 1978; Braun and Sauerhoff, 1976). Because many preparations of pentachlorophenol are contaminated with small but measurable amounts of highly toxic substances, such as dibenzodioxins, special attention must be paid to the composition of the pentachlorophenol solution tested. In studies where technical and purified pentachlorophenol have been evaluated (Schwetz et al., 1974; Goldstein et al., 1977; Kimbrough and Linder, 1978; Knudsen et al., 1974; Johnson et al., 1973; Kerkvliet et al., 1982), only the results of the experiments using purified pentachlorophenol were reported in detail. Oral exposure to pentachlorophenol was not carcinogenic in mice (BRL, 1968; Innes et al., 1969) or rats (Schwetz et al., 1977), regardless of the composition of the pentachlorophenol solution tested. Although there are a few studies that suggest pentachlorophenol may be mutagenic in B. subtilis (Waters et al., 1982; Shirasu, 1976), in yeast, Saccharomyces cerevisiae (Fahrig et al., 1977) and in mice, as evidenced by the coat-color spot test (Fahrig et al., 1977), no evidence of mutagenicity was reported in S. typhimurium (Anderson et al. , 1972; Simmon et al., 1977; Lemma and Ames, 1975; Moriya et al. , 1983; Waters et al., 1982; Buselmaier et al., 1973) or in E. coli (Simmon et al., 1977; Fahrig, 1974; Moriya et al., 1983; Waters et al., 1982) with or without metabolic activation. Three teratogenicitylreproductive toxicity studies (Schwetz et al., 1974, 1977; Courtney et al., 1976) indicate that pentachlorophenol is fetotoxic in rats at oral dose levels ≥5 mg/kg/day. At the highest dose tested (500 ppm) in a fourth teratogenicity/reproductive toxicity study (Exon and Koller, 1982), there was a statistically nonsignificant decrease in litter size. The lowest dose tested (5 mg/kg/day) by Schwetz et al. (1977) was the lowest dose at which any evidence offetotoxicity, as indicated by delayed ossification, was observed. No adverse fetal or reproductive effects were reported at ≤3 mg/kg/day (Schwetz et al., 1977; Exon and Koller, 1982). In subchronic and chronic toxicity studies, adverse effects occurred primarily in the liver (Kerkvliet et al., 1982; Johnson et al., 1973; Knudsen et al. , 1974; Goldstein et al. , 1977; Kimbrough and Linder, 1978; Schwetz et al., 1977), the kidney (Johnson et al., 1973; Kimbrough and Linder, 1978; Schwetz et al., 1977) and the immune system (Kerkvliet et al., 1982). Knudsen et al. (1974) reported increased liver weights in female rats and centrilobu lar vacuolization in male rats exposed to diets containing ≧50 ppm commercial pentachlorophenol, which contained 282 ppm dioxins. In the remaining studies, increased liver weight (Johnson et al., 1973) and increased pigmentation of hepatocytes (Schwetz et al., 1977) were observed at oral doses of≥10 mg/kg/day (∼90%), and SGPT levels significantly increased in rats ingesting 30 mg/kg/day pentachloro phenol (∼90%) for 2 years (Schwetz et al., 1977). Increased kidney weight unaccompanied by renal histopathology was reported in rats exposed to dietary concentration ≧20 ppm of pentachlorophenol (>99%) for 8 months (Kimbrough and Linder, 1978) and in rats ingesting 30 mg/kg/day (∼90%) for 90 days (Johnson et al., 1973). Increased pigmentation of the renal tubular epithelial cells was re ported in rats ingesting 10 or 30 mg/kg/day pentachlorophenol for 2 years (Schwetz et al., 1977). Although decreased immunocompetence was reported in mice exposed to dietary levels of 50 or 500 ppm of pentachlorophenol (>99%) for 34 weeks (Kerkvliet et al., 1982), the decrease was statistically significant only at the higher dose. An ADI of 0.03 mg/kg/day or 2.1 mg/day for a 70 kg human was derivedfrom the NOAEL of 3 mg/kg/day in rats in the chronic dietary study by Schwetz et al. (1977). An uncertainty factor of 100 was used. An RQ of 100 was derived based on the fetotoxic effects of pen tachlorophenol in rats in the study by Schwetz et al. (1974). Based on guidelines for carcinogen risk assessment (U.S. EPA, 1984b) and inadequate evidence for animal carcinogenicity or absence of human cancer data, pentachlorophenol is classified as Group D, meaning that it is not classified as a human carcinogen.

Solid wastes generation is a ginormous and ever-expanding problem affecting the world, majorly developing countries. This is because the world populace produces million tonnes of municipal solid wastes each day and this number has been projected to triple in the next few years. Drastic increase in wastes especially solid wastes could be directly proportional to increase in pollution and this could pose deleterious effect to mankind in general. Cellulose which is a chief constituent of solid wastes could be degraded by cellulase, a hydrolytic enzyme presents in the genetic make-up of giant African snail. In this study, cellulase was isolated from the hemolymph of Archachatina marginata and partially purified by draining the hemolymph into a sterilized beaker. The drained hemolymph was centrifuged at 4000g for 20 min to obtain a crude fraction of the enzyme. The actions of isolated cellulase on different agricultural and industrial wastes were examined using standard procedure. The enzyme had a specific activity of 1.39U/mg. Biodegradation study showed that the enzyme has highest activities on agricultural and industrial wastes such as; Leaves (approximately 125.32-426.40%), Plastics (2.95-91.14%), Wrappers (21.29-72.65%), Kitchen wastes (3.89-65.71%), Woods (12.34-40.77%) and the lowest activity was recorded on Nylons (3.26-9.64%). The degree of biodegradation of solid wastes signifies that the enzyme could play a key role in efficient, reliable and non-hazardous means of waste management and material recycling.

Plastic is a synthetic polymer that is widely used in almost every field of life. The massive use of this synthetic polymer has led to the accumulation of this polymer in the environment thus polluting the environment. The general techniques in preventing plastic waste as landfill, incineration, recycling are considered less effective as they release some hazardous materials to the environment. Thus, the appropriate technique is needed to overcome this problem. Biodegradation is an enzymatic degradation involving some microorganisms including bacteria. This technique can be used to prevent the plastic waste problem. Plastic waste biodegradation occurred through several steps, including biodeterioration, depolymerization, and assimilation. Within this process, bacteria will secrete many enzymes that will degrade and convert plastic polymers into microbial biomass and gases. Thus, this process has fewer even no side effect.

Nowadays, constantly increasing plastic pollution is the primary area of scientific research worldwide. The excessive use of this synthetic polymer has led to its accumulation in the environment. A large number of marine organisms are at risk because of plastic debris jeopardizing their survival and many are already at the stake of endangerment. The conventional plastic waste management techniques are inadequate as their by-products are also hazardous to environment and oceans. Microbes exposed to plastic waste and producing catalytic enzyme have proved to be one of the finest approaches to tackle this ever-increasing problem of plastic waste. This biodegradation occurs through various steps including biodeterioration and depolymerization. Recent advances in system biology and genetic engineering techniques can pave path towards better plastic degradation. This review highlights the toxic impact of nano and microplastic on environment and ocean and how futuristic research in biodegradation can solve the issue of plastic pollution.

Dye is a chemical substance which is used for coloring of a substance. For better coloration of substance it is made chemically stable and persistence to light, and biodegradation process. After applied to a substrate the waste generated in water causes very toxic effect and hazardous for aquatic ecosystem so it is necessary to degrade or decolorize dyes from waste water. In present review degradation of different dyes using Fe3O4 based nanoparticles were cited and their catalytic properties for degradation studied in this review.

AbstractCleaning the oil industry's fuel storage and management facilities generates high levels of hazardous waste. This research aims to assess the use of biological bioremediation treatments, most commonly used for decontaminating soil, by applying them to hydrocarbon-contaminated waste. Turned pile composting using food-derived sludge as a co-substrate and the necessary proportion of bulking agent enabled the bioremediation of the initial mixture via the succession of microbial populations (PLFAs), with a 70% lower TPH concentration obtained 6 months after the start of the process. Subsequent bioassays using the composted material showed survival rates of over 80% with earthworms (Eisenia andrei) and a larger decrease in TPH in the joint treatment with earthworms and plants (Pennisetum clandestinum). The composting process reduces the concentration of hazardous organic compounds, allowing for the proper development of fauna and flora in the compost by improving the biodegradation rate. Graphical Abstract

<p>This research study analyses the life cycle assessment of different waste management techniques and sanitary drawings in landfilled waste treatment units' biotechnology at Community Health Centres design for the protection of Public Health from biogas emissions, leachate hazardous toxic acids and landfill biomass biodegradation stages. The environmental impact assessment is examined of associative pollution spaces of Community Health Centres minimising the relative public health's risks. Moreover, it examines the significance of phytobioremediation techniques for landfills' heavy metal concentrations and associated risks minimisation. Reclamation works are examined in associated risks minimisation of toxic hazardous concentrations that could enter in water resources, food chain and agricultural resources. A useful geoinformatics utility is presented in this research study for project management of associated infrastructures in green sustainable construction designs; the optimum operation of Health Centres and associated infratructures for the protection of Public Health.</p>

Organic chemical mixtures are prevalent in waste waters from industrial and municipal sources as well as in contaminated groundwater. Phenols are pollutants found in wastewaters from oil refineries, chemical plants, explosives, resins and coke manufacture, coal conversion, pesticide and textile industries. The main contaminants of refinery wastewater include phenols, polycyclic aromatic hydrocarbons (PAHs) as well as heavy metals. Among these toxic pollutants, phenols are considered to be the most hazardous ones, and they are certainly the most difficult to remove. Phenolic compounds are toxic at relatively low concentration. Because of these low concentrations the most suitable methods for their removal are the microbial ones. The present work is a review of biodegradation of phenol. Degradation of phenol occurs as a result of the activity of a large number of microorganisms including bacteria, fungi and actinomycetes. There are reports on ma33ny microorganisms capable of degrading phenol through the action of variety of enzymes. These enzymes may include oxygenases, hydroxylases, peroxidases, tyrosinases, oxidases etc. Batch experiments were carried out in a different bioreactors. Biodegradation of organic chemicals by microbes using pure cultures can produce toxic intermediates. This problem may be overcome by the use of mixed cultures that have a wider spectrum of metabolite degradation properties. In this revew we described also some new technology for biodegradation of phenol like: different immobilization, FISH (Fluorescence in-situ hybridization) analysis, nanobiotechnologies and etc. Key words: phenol, biodegradation, microorganisms, enzymes, immobilization, FISH analysis, nanobiotechnologies