Removal Of Polychlorinated Biphenyls Research Articles

Kinetic analysis for the interpretation of polychlorinated biphenyls removal mechanism

AbstractRemoving polychlorinated biphenyls (PCBs) from subsurface water, soils, and transformer oil is crucial to save the environment from these pollutant materials. Hydrodechlorination (HDC) of PCBs consists of numerous chemical reactions and the simple kinetic models may not provide details for the process. To gain more awareness of the reaction mechanism, in the proposed approach, the isoconversional methods of the Friedman were investigated paralleling other kinetic models of Langmuir‐Hinshelwood (L‐H), Eley‐Rideal (E‐R), pseudo‐first‐order, and pseudo‐second‐order methods. The analysis was validated by laboratory results of HDC of contaminated transformer oil in front of Pd/MWCNTs. The most reactivity was observed for biphenyls with a higher number of chlorines. Finding a suitable model, Akaike Information Criteria were applied. It was attained that Friedman model was the most suitable for monitoring of HDC of PCBs in front of catalyst. Besides, E‐R reaction was appropriate to elucidate the theoretical interpretations of the adsorption and desorption of reactants and chlorinated benzene.

Strategy for Remediation of Polychlorinated Biphenyls-Contaminated Soil Through Redox Management Based on Electronegativity of the Contaminants.

Literature review reveals that Persistent Organic Pollutants (POPs), such as polychlorinated biphenyls (PCBs), are electron deficient compounds due to the presence of highly electronegative groups. Hence, they are more amenable to anaerobic biodegradation rather than oxidative metabolism. However, the studies on PCBs bioremediation are more inclined towards aerobic treatment. Besides, the past studies are mainly centered on screening and application of PCB-degrading microorganisms. In our opinion the degradative capacity is already present in the native microflora, and choice of electron donor is of paramount importance for faster reductive metabolism of PCBs. In this study, the use of methanol as electron donor with cow dung as the general microbial inoculum resulted in high specific rate of degradation (0.0542-0.0637 /day) for high-chlorinated biphenyls. The % removal of PCBs ranged between 67.7 and 71.7%. It may be the first study on the application of methanol as a cheap electron donor for PCBs biodegradation without bioaugmentation with specifically selected microorganisms.

A novel mechanism of enhanced PCBs degradation associated with nitrogen in the rhizosphere of the wetland plant Myriophyllum aquaticum

Co-contamination of polychlorinated biphenyls (PCBs) and nitrogen (N) is widespread. Here, N removal and PCBs degradation were investigated in constructed wetlands populated with Myriophyllum aquaticum, and the role of N in PCBs degradation was explored as well. Nearly 97% of N was removed in the planted system, whereas less than 40% was removed in the plant-free system. Compared to the treatment with plants and no N amendment, N addition enhanced plant growth by 31.9% and PCBs removal by 9.90%. PCBs attenuation was mainly attributed to microbial degradation rather than plant uptake. Using DNA stable-isotope probing, 26 operational taxonomic units were identified across all treatments, of which 25 were linked to PCBs degradation for the first time. Some PCB-degraders were associated with nitrification/denitrification and were significantly enriched in the treatment that included both plants and N application, indicating that PCBs degradation was promoted by recruiting ammonia-oxidising and denitrifying microbes with PCBs metabolic ability. This was confirmed by the higher A13/A12 ratios for the bphC, amoA, and nirK genes and their significant positive correlations. Overall, the findings clarify the novel mechanism by which N promotes PCBs degradation in constructed wetlands and offers a theoretical basis for efficiently removing inorganic elements and persistent organic pollutants.

Removal of cadmium and polychlorinated biphenyls by clover and the associated microbial community in a long-term co-contaminated soil

Legumes such as clover are cost-effective and environmentally friendly components of strategies for remediating soils contaminated with heavy metals or organic pollutants. However, the mechanisms by which clover remediates co-contaminated soils are unclear. The present study explored the effects of phytoremediation by clover on pollutant removal and the microbial community in soil co-contaminated with cadmium (Cd) and polychlorinated biphenyls (PCBs). After 18 months of phytoremediation, Cd removal increased from 20.25 % in the control to 40.65 % in soil planted with clover, while PCB removal increased from 29.81 % to 60.02 %. High-throughput sequencing analysis showed that the relative abundances of the bacterial phylum Proteobacteria and the diazotrophic genus Rhizobium increased significantly after phytoremediation. Random forest analysis showed that bacterial and diazotrophic diversity significantly influenced Cd and PCB removal. Furthermore, co-occurrence network and correlation analyses revealed that Rhizobiales and Micromonosporales were the main bacteria associated with Cd removal, while Rhizobiales, Burkholderiales, and Xanthomonadales were identified as the main degraders of PCBs. PICRUSt functional prediction demonstrated that the gene bphC, which is related to PCB degradation, was significantly increased in the rhizosphere soil in the presence of clover. These results provide a better understanding for further studies of remediation efficiency by clover, rhizosphere microbial response and remediation mechanisms of co-contaminated soils under in situ conditions in the field.

Simultaneous adsorption and biodegradation of polychlorinated biphenyls using resuscitated strain Streptococcus sp. SPC0 immobilized in polyvinyl alcohol‑sodium alginate

Enhanced bioremediation of polychlorinated biphenyls (PCBs) is a promising and effective strategy for eliminating the risks posed by PCBs. In the present study, the feasibility of utilizing an immobilization approach to enhance the PCBs degradation performance of a resuscitated strain Streptococcus sp. SPC0 was evaluated. The results indicated that a mixed matrix containing polyvinyl alcohol (PVA) and sodium alginate (SA) used as immobilized carriers provided a porous microstructure space for SPC0 colonization and proliferation. The enhanced removal of PCBs by immobilized SPC0 was attributed to simultaneous adsorption and biodegradation performances of PVA-SA-SPC0 beads. The relative equilibrium adsorption capacity of immobilized beads increased with elevated initial concentration, and the maximum theoretical value calculated was 1.64 mg/g. The adsorption process of PCBs by immobilized beads was well fitted to the quasi-second-order kinetic model, and most suitable for Langmuir isotherm model. Immobilized SPC0 enhanced PCB removal with 1.0–7.1 times higher than free cells. Especially, more effective removal of PCBs at higher concentrations could be achieved, in which 73.9 % of 20 mg/L PCBs was removed at 12 h by immobilized SPC0, whereas only 12.0 % by free cells. Moreover, the immobilized SPC0 with excellent stability and reusability retained almost 100 % of the original PCBs removal activity after reusing four times. These results revealed the application potential of immobilizing resuscitated strains for enhanced bioremediation of PCBs.

Development and microbial characterization of Bio-RD-PAOP for effective remediation of polychlorinated biphenyls

Polychlorinated biphenyls (PCBs) as typical halogenated persistent organic pollutants are widely distributed in natural environments, and can be enriched and magnified in organisms via food webs. It is consequently urgent and necessary to develop techniques to completely remove these persistent organohalides. In this study, we developed a process (Bio-RD-PAOP) by integrating microbial reductive dechlorination (Bio-RD) with subsequent persulfate activation and oxidation process (PAOP) for effective remediation of PCBs. Results showed the synergistic combination of advantages of Bio-RD and PAOP in dechlorination of higher-chlorinated PCBs and of PAOP in degradation/mineralization of lower-chlorinated PCBs, respectively. For the PAOP, both experimental evidences and theoretical calculations suggested that degradation rate and efficiency decreased with the increased PCB chlorine numbers. Relative to the Bio-RD and PAOP, Bio-RD-PAOP had significantly higher PCB removal efficiencies, of which values were PCB congener-specific. For example, removal efficiency of Bio-RD-PAOP in removing PCB88 is 2.50 and 1.86 times of that of Bio-RD and PAOP, respectively. In contrast, the efficiency is 1.66 and 3.35 times of Bio-RD and PAOP, respectively, for PCB180 removal. The PAOP-derived oxidizing species (mainly sulfate free radical) significantly decreased microbial abundance, particularly of the organohalide-respiring Dehalococcoides. Notably, co-existence of other microorganisms alleviated the inhibitive effect of oxidizing species on the Dehalococcoides, possibly due to formation of microbial flocs or biofilm. This study provided a promising strategy for extensive remediation of organohalide-contaminated sites, as well as new insight into impact of PAOP-derived oxidizing species on the organohalide-respiring community.

Biological Remediation of Polychlorinated Biphenyl (PCB)-Contaminated Soil Using the Vermicomposting Technology for the Management of Sewage Sludge Containing Eisenia fetida Earthworms

ABSTRACT Biological vermicomposting is an economic and eco-friendly method to remove PCBs from contaminated soils. This study aimed to investigate the effects of biological sewage sludge on contaminated soil in the presence of Eisenia fetida earthworms for the removal of PCBs. For this purpose, different mixtures of contaminated soil and biological sludge were prepared at various mixing ratios in sample containers, followed by the addition of earthworms. The degradation period was 80 days. During the degradation process, the PCBs concentrations, C/N ratio, temperature, and number of earthworms were measured. The highest reduction in PCBs (47.4%) was found in vermicompost pilot D at a contaminated soil-to-biological sludge volume ratio of 1:4, where the PCBs concentration decreased from 18 mg/kg to 9.5 mg/kg. In the control pilot D, which was identical to the vermicompost pilot D, but lacked the earthworms, the removal rate was 34%. This means that earthworms have played an effective role in increasing the removal rate. Degradation mainly occurred by microorganisms; the earthworms increased the degradation efficiency by increasing contact between microorganisms and contaminants. Overall, the vermicomposting process, in which biological sewage sludge is used for feeding E. fetida earthworms to reduce the amount of PCBs in contaminated soil, can be introduced as an innovative approach. The present study proposed a practical method to manage soil PCB contamination, using available and cost-effective raw materials that can be used in a large scale in situ. The present results indicated that the use of biological sludge, in the presence of E. fetida earthworms, could reduce highly chlorinated PCB contamination in soils.

Ultrasound-assisted soil washing processes using organic solvents for the remediation of PCBs-contaminated soils

Ultrasonic soil washing processes using organic solvents were investigated for the development of novel remediation technologies for persistent organic pollutants (POPs)- contaminated soils. Aluminum foil erosion was first tested to understand sonophysical activity in water, methanol (polar) and n-hexane (nonpolar) in a 28 kHz double-bath-type sonoreactor. Significant sonophysical damage on the aluminum foil was observed at the antinodes for all solvents, and the order of degree of sonophysical damage was as follows: water > methanol > n-hexane. Subsequently, conventional (mechanical mixing only) and ultrasonic soil washing (mechanical mixing and ultrasound) techniques were compared for the removal of polychlorinated biphenyls (PCBs) from soil. Two types of contaminated soils, fresh (Soil A, C0 = 2.5 mg/kg) and weathered (Soil B, C0 = 0.5 mg/kg), were used and the applied soil-to-liquid (S:L) ratio was 1:5 and 1:10 for methanol and n-hexane, respectively. The polar solvent significantly increased washing efficiencies compared to the nonpolar solvent, despite the nonpolar nature of the PCBs. Washing efficiency was significantly enhanced in ultrasonic soil washing compared to conventional washing, owing to macro- and micro-scale sonophysical actions. The highest washing efficiencies of 90% for Soil A and 70% for Soil B were observed in the ultrasonic washing processes using methanol. Additionally, a single operation of the ultrasonic washing process was superior to two sequential processes with conventional mixing in terms of washing efficiency, consumption of washing agents, treatment of washing leachate, and operation time. Finally, the removal of PCBs in an organic solvent (methanol) was investigated in photolytic and sonolytic processes for the post-treatment of soil washing leachate. A photolysis efficiency of 80% was obtained within 60 min of UV exposure for intensities of 1.0, 2.0, and 4.0 W/cm2. The primary mechanism of PCBs degradation is photolytic dechlorination. In contrast, no degradation was detected in the sonolytic process, as the excess organic solvent acted as a strong radical scavenger.

'Cry-for-help' in contaminated soil: a dialogue among plants and soil microbiome to survive in hostile conditions.

SummaryAn open question in environmental ecology regards the mechanisms triggered by root chemistry to drive the assembly and functionality of a beneficial microbiome to rapidly adapt to stress conditions. This phenomenon, originally described in plant defence against pathogens and predators, is encompassed in the ‘cry‐for‐help’ hypothesis. Evidence suggests that this mechanism may be part of the adaptation strategy to ensure the holobiont fitness in polluted environments. Polychlorinated biphenyls (PCBs) were considered as model pollutants due to their toxicity, recalcitrance and poor phyto‐extraction potential, which lead to a plethora of phytotoxic effects and rise environmental safety concerns. Plants have inefficient detoxification processes to catabolize PCBs, even leading to by‐products with a higher toxicity. We propose that the ‘cry‐for‐help’ mechanism could drive the exudation‐mediated recruitment and sustainment of the microbial services for PCBs removal, exerted by an array of anaerobic and aerobic microbial degrading populations working in a complex metabolic network. Through this synergistic interaction, the holobiont copes with the soil contamination, releasing the plant from the pollutant stress by the ecological services provided by the boosted metabolism of PCBs microbial degraders. Improving knowledge of root chemistry under PCBs stress is, therefore, advocated to design rhizoremediation strategies based on plant microbiome engineering.

Effects of iron-carbon materials on microbial-catalyzed reductive dechlorination of polychlorinated biphenyls in Taihu Lake sediment microcosms: Enhanced chlorine removal, detoxification and shifts of microbial community

Nano zero-valent iron particles (nZVI, 0.09 wt%), micro zero-valent iron particles (mZVI, 0.09 wt%), granular activated carbon (GAC, 3.03 wt%), GAC supported nZVI (nZVI/GAC, 3.12 wt%) and nZVI&GAC (nZVI 0.09 wt%, GAC 3.03 wt%) were evaluated for their effects on polychlorinated biphenyls (PCBs) anaerobic reductive dechlorination, detoxification, as well as microbial community structure in Taihu Lake (China) sediment microcosms. The results showed that all of these five materials could stimulate PCBs reductive dechlorination, especially for dioxin-like PCB congeners, and nZVI&GAC had the best removal effect on PCBs. The reduction of total PCBs increased from 13.5% to 33.2%. H2 generated by zero-valent iron corrosion was utilized by organohalide-respiring bacteria (OHRB) to enhance the dechlorination of PCBs predominantly via meta chlorine removal in the short term. The addition of ZVI had little impact on the total bacterial abundance and the microbial community structure. The adsorption of GAC and potential bioremediation properties of attached biofilm could promote the long-term removal of PCBs. GAC, nZVI/GAC, nZVI&GAC had different influences on the microbial structure. These findings provide insights into the biostimulation technique for in situ remediations of PCBs contaminated sediments.

Comparative study of single cultures and a consortium of white rot fungi for polychlorinated biphenyls treatment.

To evaluate the mycoremediation of polychlorinated biphenyls (PCBs) by either single cultures or binary consortia of Pleurotus pulmonarius LBM 105 and Trametes sanguinea LBM 023. PCBs tolerance, removal capacity, toxicity reduction and ligninolytic enzyme expression were assessed when growing single culture and binary consortium of fungus in 217mgl-1 of a technical mixture of Aroclor 1242, 1254 and 1260 in transformer oil. A decrease in tolerance and variation in ligninolytic enzyme secretion were observed in PCB-amended solid media. Pleurotus pulmonarius LBM 105 mono-culture was able to remove up to 95·4% of PCBs, whereas binary consortium and T. sanguinea LBM 023 could biodegrade about 55% after 24days. Significant detoxification levels were detected in all treatments by biosorption mechanism. Pleurotus pulmonarius LBM 105 in single culture had the best performance regarding PCBs biodegradation and toxicity reduction. Ligninolytic enzyme secretion changed in co-culture. The evaluation of PCBs bioremediation effectiveness of basidiomycetes consortium in terms of PCB removal, toxicity and ligninolytic enzyme production to unravel the differences between using individual cultures or consortium has not been reported. The results from this study enable the selection of P. pulmonarius LBM 105 mono-culture to bioremediate PCBs as it showed higher efficiency compared to binary consortium with T. sanguinea LBM 023 for potential decontamination of PCB-contaminated transformer oil.

A novel strategy using persulfate activated with thiosulfate for strong enhancement of trace 2,2′-dichlorobiphenyl removal: Influencing factors, and mechanisms

Efficient and environmentally friendly methods for the remediation of polychlorinated biphenyls (PCBs)-contaminated wastewater have become an important issue. In this study, persulfate (PS) was activated with sodium thiosulfate (TS) to degrade 2,2′-dichlorobiphenyl (DCB) at an extraordinarily high rate at pH ≤ 4.0 at room temperature. The PS/TS system exhibited much higher activity than systems with PS or TS alone at pH 2.0: 90.3% DCB was removed within 120 min, a much higher removal rate than those of the latter systems. Sulfate radical (SO4−) was verified to be the main reactive substance through scavenging and trapping experiments; sulfate radicals can decompose and detoxify DCB by dechlorination and hydroxylation processes. The removal efficiency of DCB (58.5% in 120 min) was also satisfactory in the TS system, in which TS could perform nucleophilic substitution on the DCB molecule at pH ≤ 4.0, followed by DCB dechlorination and the generation of hydroxy-biphenyl. Plausible mechanisms and reaction pathways involving nucleophilic substitution in the TS system and the formation of reactive oxygen species (ROS) in the PS/TS system to attack the carbon atom on DCB were proposed and calculated by density functional theory (DFT). The presence of Cl−, NO3−, HCO3− and humic acid (HA) may have inhibited the removal of DCB in the PS/TS system, while the effect was not significant in the TS system. Our work introduces novel and rapid removal methods for the removal of PCBs and may be significant for the development of efficient strategies for halogenated pollutant control in real water.

Strategies for mitigation of polychlorinated biphenyls (PCBs): A review

Polychlorinated Biphenyls or PCBs belong to a broad family of chlorinated hydrocarbons and find use across industrial and commercial applications including hydraulic and electrical equipments, plastics, paints, rubber products, dyes, pigments and carbonless copy paper etc. PCB residues persist in the ecosystem and bioaccumulate in food chain due to their persistent nature and resistance against natural breakdown agents. Global case studies suggest widespread contamination of the toxicant. So it becomes the need of an hour to remove polychlorinated biphenyls entirely from the environment. Stepwise, physical, chemical and ecological remediation strategies have been applied but some lacuna in efficient mitigation was felt by various researchers in each of the methods. Therefore, combination of multiple technologies have been suggested. The current review provides the detailed descriptions on the different physical and chemical methods used for removal of PCBs including incineration, natural attenuation, supercritical water oxidation, ultrasonic radiation, bimetallic systems, nZVI, etc as well as the combination of multi techniques that have been used till date e.g. nZVI with metal combo and bimetallic metal combination etc. It also depicts the future prospects and acceptability of these methods for removal of the polychlorinated biphenyls from the ecosystem to help us achieve a green sustainable world.

Optimization using the response surface methodology for adsorption of polychlorinated biphenyls (PCBs) from transformer oil by magnetic CMCD-Fe3O4@SiO2 nanoparticles

The main objective of this work was to synthesis a novel magnetic nanoparticles functionalized with β-cyclodextrin and use it to refine transformer oil contaminated with high concentration of PCBs. Carboxymethyl-β-cyclodextrin modified Fe3O4@SiO2 magnetic nanoparticles (CMCD-Fe3O4@SiO2) were fabricated by grafting onto the core-shell silica magnetic nanoparticles surface using carbodiimide. The successful synthesis of nanocomposites was characterized by FTIR, XRD, VSM, SEM, TEM, VSM, TGA and EDX analysis. Hereinafter, the application of response surface methodology (RSM) based on the central composite design (CCD) was employed for optimization of the interactive effects of the three main variables on the removal efficiency of PCBs. A quadratic model was applied as a final model to measure the adequacy and the significance of the individual and interactive effects of variables via analysis of variance. The design matrix under the optimum conditions exhibited that the maximum PCBs removal of 82% was attained to be at adsorbent dosage, contact time and temperature of 10 mg/mL, 30 min, and 50 °C, respectively. The obtained results revealed that the adsorbent dosage is known as the key operating parameter (P < 0.0001) affecting PCB removal efficiency. Thermodynamic parameters (ΔH0 > 0, ΔG0 > 0, ΔS0 > 0) were confirmed that the adsorption process was nonspontaneous and endothermic and assess physical phenomena occurring on the surface of adsorbent. The experimental results were proposed that the as-synthesized β-cyclodextrin -modified magnetic nanoparticles could be an ideal candidate for purification of PCB compounds from contaminated transformer oil owing to its simple process and rapid separation and good reusability after five times.

Nanotechnology to remove polychlorinated biphenyls and polycyclic aromatic hydrocarbons from water: a review

Persistent pollutants cause adverse effects to human and environmental health. Most polychlorinated biphenyls (PCB) and polycyclic aromatic hydrocarbons (PAH) are toxic and stable in the environment, yet their removal is rarely targeted by conventional remediation methods. Alternatively, nanotechnology appears promising for contaminant removal. Indeed, nanomaterials have unique size-dependent properties due to their high specific surface area. Nanomaterials also possess fast dissolution properties, strong sorption, supermagnetic characteristics and quantum confinement. This manuscript reviews the application of nanotechnologies for the removal of PCB and PAH from contaminated water sources.

Polychlorinated biphenyls in the tributaries of Southern Baikal

In the aquatic ecosystem of Lake Baikal, global atmospheric transport is regarded as the dominant source of polychlorinated biphenyls (PCBs). Relatively high level of PCB concentration in the southern basin of the lake is associated with PCB influx from local sources. The waters of the tributaries of Southern Baikal, which have watershed basins on the slopes of the Khamar-Daban ridge, possess significant potential as a source of pollutants. The article presents the results of monitoring PCBs in the waters of the rivers Utulik, Solzan, Khara-Murin, Snezhnaya, and Pereeemnaya in 2017 and 2019. PCB concentrations in the waters of the tributaries were estimated by the total concentration of seven indicator congeners Nos. 23, 28, 101, 118, 138, 153, and 180 (ƩPCB7) in water samples taken at the estuaries of the rivers. The ƩPCB7 level in the waters - from 0.02 to 1.5 ng/L can be comparable to or exceed that in the littoral zone of the lake. An assessment of the removal of PCBs to the southern part of Lake Baikal indicates a minimal influx of pollutants of this class with tributary waters. In 2017, the number of PCB indicator congeners that entered Baikal with water runoff was estimated to be between 1.7 and 3.1 g in May and between 7.7 and 26 g in September. In extreme conditions, the stock of PCBs can reach 40-170 g per month, September 2019.

Nanoscale zero-valent iron supported on carbon nanotubes for polychlorinated biphenyls removal

Nanoscale zero-valent iron supported on carbon nanotubes for polychlorinated biphenyls removal

Biodegradation of PCBs in contaminated water using spent oyster mushroom substrate and a trickle-bed bioreactor

Due to their persistence, polychlorinated biphenyls (PCBs) represent a group of important environmental pollutants, but conventional physicochemical decontamination techniques for their removal are usually expensive. The main aim of this work was to develop a cost-effective method for PCB bioremediation, focusing on contaminated water and utilizing the well-known degradation capability of Pleurotus ostreatus (the oyster mushroom). For this purpose, the conditions of several laboratory-scale reactors (working volume 1 L) were optimized. Spent oyster mushroom substrate obtained from a commercial farm was used as a fungal inoculum and growth substrate. The highest degradation efficiency (87%) was recorded with a continuous low-flow setup, which was subsequently scaled up (working volume 500 L) and used for the treatment of 4000 L of real contaminated groundwater containing 0.1–1 μg/L of PCBs. This trickle-bed pilot-scale bioreactor was able to remove 82, 80, 65, and 30–50% of di-, tri-, tetra- and pentachlorinated PCB congeners, respectively. No degradation was observed for hexa- or heptachlorinated congeners. Multiple mono- and dichlorobenzoic acids (CBAs) were identified as transformation products by mass spectrometry, confirming the role of biodegradation in PCB removal. A Vibrio fischeri bioluminescence inhibition test revealed slight ecotoxicity of the primary reactor effluent (sampling after 24 h), which was quickly suppressed once the effluent passed through the reactor for the second time. Moreover, no other effluent exhibited toxicity for the rest of the experiment (71 days in total). Microbial analyses (phospholipid fatty acid analysis and next-generation sequencing) showed that P. ostreatus was able to degrade PCBs in the presence of an abundance of other fungal species as well as aerobic and anaerobic bacteria. Overall, this study proved the suitability of the use of spent oyster mushroom substrate in a bioremediation practice, even for pollutants as recalcitrant as PCBs.

Mycoremediation of high concentrations of polychlorinated biphenyls with Pleurotus sajor-caju LBM 105 as an effective and cheap treatment

Polychlorinated biphenyls (PCBs) are exceptionally stable organic pollutants. An effective and economically feasible process is essential for their removal. Mycoremediation using white-rot fungal strains proved as a highly effective approach that has not been thoroughly investigated. The aim of this work was to evaluate PCBs remediation efficacy applying Pleurotus sajor-caju LBM 105. Axenic cultures of the fungus, either in complex or N-limited liquid media, were spiked with 217 mg L−1 of a technical mixture of Aroclor 1242, 1254 y 1260 in oil transformer. PCBs removal capacity, toxicity reduction, changes in fungal morphology and laccase expression caused by pollutant addition and the cost-effectiveness of the remediation treatment were assessed when growing the fungus under two different nutritional conditions. P. sajor-caju LBM 105 could remove 97.7% and 91.7% of the PCBs mixture and reduced the toxicity in complex and mineral media respectively after 35 days of incubation. The addition of PCBs to P. sajor-caju LBM 105 culture media resulted in an increase in hyphal diameter, changes in biomass, glucose consumption, proteins and laccase secretion. A 3-fold rise in laccase activity was detected in both media at 28 day. Laccase mRNA augmented 16% and 91% at 21 and 28 days respectively when PCBs were added to the N-limited liquid media. Mycoremediation of PCBs with P. sajor-caju LBM 105 cultivated in N-limited liquid medium is an effective low-cost (0.69 $ g-1d-1) alternative technique for PCBs treatment.

Mycoremediation of PCBs by Pleurotus ostreatus: Possibilities and Prospects

With the rising awareness on environmental issues and the increasing risks through industrial development, clean up remediation measures have become the need of the hour. Bioremediation has become increasingly popular owing to its environmentally friendly approaches and cost effectiveness. Polychlorinated biphenyls (PCBs) are an alarming threat to human welfare as well as the environment. They top the list of hazardous xenobiotics. The multiple effects these compounds render to the niche is not unassessed. Bioremediation does appear promising, with myco remediation having a clear edge over bacterial remediation. In the following review, the inputs of white-rot fungi in PCB remediation are examined and the lacunae in the practical application of this versatile technology highlighted. The unique abilities of Pleurotus ostreatus and its deliverables with respect to removal of PCBs are presented. The need for improvising P. ostreatus-mediated remediation is emphasized.