Biodegradation Studies Research Articles

BIODEGRADATION OF GLYPHOSATE CONTAINING HERBICIDE BY SOIL FUNGI

Ten fungal isolates were isolated from two herbicide-contaminated soil farms obtained from Amoyo and the University of Ilorin environment in Kwara State after enrichment with mineral salt medium (MSM) supplemented with glyphosate-containing herbicide. The growth of fungal isolates was efficiently stimulated by the organophosphorus herbicide. Fungi isolated were subjected to screening by varying the herbicide concentrations from 0.1 to 3%, which is prepared with MSM. This screening showed that all the fungal isolates had the ability to act in the biodegradation process. However, varying degradative potentials were observed, as some had heavy growth while others had only slight or no growth as the concentrations of the herbicide increased. The ten fungal isolates were characterized and identified as Aspergillus niger, Penicillum spinulosum, Aspergillus terrus, Aspergillus flavus, Fusarium oxysporum, Mucor spp., Aspergillus oryzae, Aspergillus tamari, Rhizopus stolonifer, and Trichoderma koningii, and these were reduced to six after screening with 3% concentration of the herbicide. Four isolates (A. niger, F. oxysporum, Mucor spp., and A. flavus) were selected based on their growth ability on the medium during screening and were used in the biodegradation study. However, there is an increase in fungal dry weights ranging from 8.60 to 18% for 12 days. This shows that these fungi can be employed in the biodegradation of herbicides since they are potentially effective species and are environmentally safer alternative to protect the soil from the contamination of glyphosate-containing herbicide residues.

Metabolic Profiling and Comparative Proteomic Insight in Respect of Amidases during Iprodione Biodegradation.

The fungicide iprodione (IPR) (3-(3,5-dichlorophenyl) N-isopropyl-2,4-dioxoimidazolidine-1-carboxamide) is a highly toxic compound. Although IPR has been restricted, it is still being applied in many places around the world, constituting an environmental risk. The biodegradation of IPR is an attractive option for reducing its residues. In this study, we isolated thirteen IPR-tolerant bacteria from a biopurification system designed to treat pesticides. A study of biodegradation using different strains was comparatively evaluated, and the best degradation rate of IPR was presented by Achromobacter sp. C1 with a half-life (T1/2) of 9 days. Based on a nano-LC-MS/MS analysis for the strains, proteins solely expressed in the IPR treatment were identified by highlighting the strain Achromobacter sp. C1, with 445 proteins primarily involved in the biosynthesis of secondary metabolites and microbial metabolism in diverse environments. Differentially expressed protein amidases were involved in six metabolic pathways. Interestingly, formamidase was inhibited while other cyclases, i.e., amidase and mandelamide hydrolase, were overexpressed, thereby minimizing the effect of IPR on the metabolism of strain C1. The dynamic changes in the protein profiles of bacteria that degrade IPR have been poorly studied; therefore, our results offer new insight into the metabolism of IPR-degrading microorganisms, with special attention paid to amidases.

Bio-based surfactants derived from pectin

Surfactants derived from renewable resources and synthesized using renewable feedstock and sustainable methods have become a major research focus over the past decade in the surfactant industry. This research presents an approach for rapidly converting readily available polysaccharides, like pectin derived from fruit waste, into safely biodegradable surface-active polymers. Commercially available pectin was modified with n-alkyl amines having different alkyl chain lengths using potassium carbonate as a catalyst. The effect of pectin molecular weight, alkyl chain length and degree of substitution (DS) on surface-active properties of the modified pectin derivatives was studied. Surface tension decreased slightly with lowering molecular weight, whereas interfacial tension decreased dramatically. Cytotoxicity evaluations using human dermal fibroblast, HepG2 and Jurkat cells demonstrated that these polysaccharide-based surfactants exhibit lower cytotoxicity compared to the conventional surfactants such as octyl phenol ethoxylates (i.e., Triton™ X-100), and therefore are more environmentally friendly. Biodegradation studies show that all modified pectins are “ultimately biodegradable” except for Pectin-amide C8 (1:10).

Polylactic acid/polycaprolactone/sawdust based biocomposites trays with enhanced compostability

The major drawback associated with petroleum-based polymer products is pollution, leading to environmental hazards. Biodegradable polymers and biocomposites have the potential to play a major role in replacing the conventional polymers in specific applications on a case to case basis. In the current study, sawdust reinforced polylactic acid/polycaprolactone (PLA/PCL) biocomposites were developed using the melt extrusion technique. Primary processed fine sawdust was reinforced with PLA/PCL blend in a mini twin screw extruder in different weight fractions (10 %, 20 %, 30 %, and 40 %). The developed biocomposites were subjected to tensile testing, which indicated that the increased weight percent of sawdust reduced the tensile strength. The materials were further characterized, using sophisticated analytical such as field emission scanning electron microscopy, differential scanning calorimetry and thermogravimetry analysis. The composite containing 30 % sawdust concentration presented the best results with tensile strength of 26.5 MPa, tensile strain of 4.4 % and onset degradation temperature of 320 °C. The same formulation was successfully scaled up to the pilot level of 5 kg batch. It was further subjected to secondary processing to produce market ready cutlery items. Biodegradability studies in simulated composting environments revealed that addition of sawdust drastically reduces the lag phase in degradation and total degradation may be obtained in approximately 90 days. Based on the investigation, there is optimism that the PLA/PCL composites, blended with sawdust may ensure commercial application of sustainable polymer blends at affordable prices.

Biodegradability of Cellulose Diacetate in Aqueous Environments

Cellulose acetate with a degree of substitution (DS) of 2.5, commonly referred to as cellulose diacetate, has been discussed as an important source of microplastic in the environment, especially since it is used to produce cigarette filters. According to EU Single-Use Plastics Directive tobacco products are one of the ten most found SUP products in beach litter by number. However, at present only very few biodegradation studies with natural microbial communities in aqueous media have been reported. In the present study aqueous aerobic biodegradation simulation tests were performed on commercial materials according to international standards (ASTM D6691, ISO 14851 and ISO 19679) to address this bias. Cellulose diacetate proved to be biodegradable or showed strong indication to be non-persistent in freshwater (> 90% relative biodegradation after 100 days at 21 °C), seawater (> 90% after 142 days at 30 °C) and seawater/sediment interface (> 70% after 360 days at 25 °C) under defined laboratory conditions. In freshwater, biodegradation of cellulose diacetate was characterized by a prolonged lag phase (75 days), followed by > 90% relative biodegradation in a short time frame (25 days). This indicates that an abiotic degradation or hydrolysis to reduce the DS is not a pre-requisite to initiate the biodegradation of cellulose diacetate. In addition, it was found that the lag phase can be significantly shortened (from 75 to 5 days) by using pre-adapted microorganisms. In contrast to what could have been expected from literature our present study demonstrates that microorganisms can adapt to a DS as high as 2.5 and metabolize the material. This underlines the importance of studies with natural communities of microorganisms to get a more realistic idea of the persistence of a polymer material.

Preparation and characterization of slow-release fertilizers loaded guar gum-g-poly methylmethacrylate-cl-polylactic acid (Gg-g-PMMA-cl-PLA) hydrogel and its effect on wheat growth

In order to reduce the harmful effects of synthetic non-biodegradable hydrogel, biopolymers have attracted attention, particularly for use in slow-release fertilizers. The current attempt intends to develop a hydrogel from biopolymers for sustainable release of water and nutrients in soil. Here, guar gum is used as a polysaccharide, MMA as a monomer, KPS as an initiator, and Polylactic acid as a cross-linker. Further investigation is done to study synthesized hydrogel in the development of wheat crop. Biodegradation study shows that it's environmentally favorable and degradable, contributing nutrients to the soil as it decomposes. Fertilizer release studies in soil and water show that the timing of the nutrient release is delayed, improving soil water holding capacity and retention studies. The agronomic parameters show that fertilizers-loaded hydrogel has a positive effect on physiological, morphological characteristics like shoot length, root length, number of shoots and roots, shoot weight and root weight, chlorophyll content, and most notably, fruiting efficiency is enhanced as compared with commercially available hydrogel. ATR-FTIR, SEM-EDX, TGA-DTA, and XRD analysis used to confirm successful loading of fertilizers and biodegradation of hydrogel. The encouraging findings suggested that this hydrogel could be used as a multifunctional, fertilizers-loaded hydrogel in crop production.

Degradable and Recyclable Polyesters from Multiple Chain Length Bio‐ and Waste‐Sourceable Monomers

AbstractMonomers sourced from waste or biomass are often mixtures of different chain lengths; e.g. catalytic oxidation of polyethylene waste yields mixtures of dicarboxylic acids (DCAs). Yet, polyesters synthesized from such monomer mixtures have rarely been studied. We report polyesters based on multiple linear aliphatic DCAs, present in chain length distributions that vary in their centers and ranges. We demonstrate that these materials can adopt high‐density polyethylene‐like solid state structures, and are ductile (e.g. Et 610 MPa), allowing for injection molding, or film and fiber extrusion. Melting and crystallization points of the polyesters show no odd‐even effects as dipoles cannot favorably align in the crystal, similar to traditional odd carbon numbered, long‐chain DCA polyesters. Biodegradation studies of 13C‐labelled polyesters in soil reveal rapid mineralization, and depolymerization by methanolysis indicates suitability for closed‐loop recycling.

Degradable and Recyclable Polyesters from Multiple Chain Length Bio- and Waste-Sourceable Monomers.

Monomers sourced from waste or biomass are often mixtures of different chain lengths; e.g. catalytic oxidation of polyethylene waste yields mixtures of dicarboxylic acids (DCAs). Yet, polyesters synthesized from such monomer mixtures have rarely been studied. We report polyesters based on multiple linear aliphatic DCAs, present in chain length distributions that vary in their centers and ranges. We demonstrate that these materials can adopt high-density polyethylene-like solid state structures, and are ductile (e.g. Et 610 MPa), allowing for injection molding, or film and fiber extrusion. Melting and crystallization points of the polyesters show no odd-even effects as dipoles cannot favorably align in the crystal, similar to traditional odd carbon numbered, long-chain DCA polyesters. Biodegradation studies of 13C-labelled polyesters in soil reveal rapid mineralization, and depolymerization by methanolysis indicates suitability for closed-loop recycling.

Biodegradation Studies of Phenol, Diclofenac, and Pentachlorophenol in a Packed Bed Reactor Loaded with Immobilized White Rot Fungus Lentinus sajor-caju Biomass

Biodegradation Studies of Phenol, Diclofenac, and Pentachlorophenol in a Packed Bed Reactor Loaded with Immobilized White Rot Fungus Lentinus sajor-caju Biomass

Biodegradability of bacterial cellulose polymer below the soil and its effects on soil bacteria diversity

The increasing demand for sustainable materials has led to a surge in research on biodegradable polymers. This study evaluated the weight and visual changes of bacterial cellulose (BC) polymers and nylon membranes during an eight-week biodegradation study below soil. Scanning electron microscope (SEM) images were taken to investigate morphological changes from decomposition. Changes in soil microbial communities and the relationship between microbial abundance and BC biodegradation were investigated. BC was produced from the fermentation of coffee kombucha using 15 % d-dextrose C6H12O6 (DE) as the nutrient carbohydrate substrate. BCs were purified with 0.5 mol/L aqueous NaOH solution and 1.5 % (v/v) aqueous NaOCl and then freeze-dried. The biodegradation study was conducted using seedling pots and nylon membrane filters inside a greenhouse over eight weeks, with sample points taken at various intervals. Soil characteristics such as pH, nutrient content, texture, organic matter, and soil moisture were analyzed. Results showed that BC polymers underwent significant weight losses and visual decomposition, while nylon membranes did not show any weight or visual losses. Approximately 75 % of the BC polymers were decomposed by the end of the study. Fatty acid methyl ester (FAMEs) analysis showed increased microbial absolute abundance (nmol/g) for BC treatments over biodegradation time. FAMEs principal component analysis (PCA) ordination plots showed the relative abundance of fungi increased in BC microbial communities suggesting fungi's attraction to cellulose. Soil bacterial DNA analysis revealed the dominance of Proteobacteria for all treatments. PCA plots and Faith-pd index Alpha Diversity results showed significant bacterial community variations for week 2 of the biodegradation study compared to the other weeks. Adonis microbial community Beta Diversity analysis showed significant differences between treatments (p = 0.001). PCA plots also showed a slight differentiation of the bacterial communities with BC compared to bacterial communities with nylon and soil (control). This study confirms that BC is easily decomposed in soil and that its biodegradability is likely driven by fungal communities.

Biodegradation of Oxide Nanoparticles in Apoferritin Protein Media: A Systematic Electrochemical Approach

AbstractFunctional oxide nanoparticles are extensively utilized in the last decades for biomedical purposes due to their unique functional properties. Nevertheless, their biodegradation mechanism by biological species, particularly by proteins at oxide/protein interfaces, still remains limited. Here, a systematic approaches is provided to investigate electrochemical behavior, electronic properties, and biodegradation mechanism of cobalt ferrite (CFO) and cobalt ferrite‐bismuth ferrite (CFO‐BFO) core‐shell nanoparticles in apoferritin‐containing media. Scanning Kelvin probe force microscopy results indicate that the presence of a thin shell (≈5 nm) of BFO on CFO causes a significant increase in surface potential. The potentiodynamic polarization measurements in different solutions showed higher anodic current densities for both samples when decreasing pH and increasing apoferritin concentration. Notably, CFO‐BFO exhibits lower anodic current densities than CFO due to a slightly higher flat band potential and lower donor density distribution on CFO‐BFO than on CFO, which results in lower electrochemical activity. Long‐term monitoring reveals that biodegradation of both nanoparticles is accelerated by high apoferritin concentrations and acidic media, resulting in the decrease of electrochemical potentials and impedance values, and enhancement of metal ion release. Thus, this systematic biodegradation study can help to predict the lifespan and toxicity of these functional nanoparticles in biological environments.

Dissolved organic nitrogen removal from reclaimed water by enhanced coagulation, ozonation, and biodegradation

The presence of dissolved organic nitrogen (DON) in reclaimed water can pose adverse effects in water reuse practices, serving as a precursor of carcinogenic nitrogenous disinfection by-products (N-DBPs) and promoting membrane fouling. This study investigated DON removal by enhanced coagulation, ozonation, and ozonation/biodegradation at the lab and pilot scales. In the lab, enhanced coagulation by polyaluminum chloride (PACl) (60 mg/L) resulted in 46 ± 4 % DON removal. Lab-scale ozonation resulted in about 50 % reduction in DON over 2 h with a constant total nitrogen concentration. Biodegradation studies revealed <15 % DON removal, but ozonation combined with biodegradation achieved >30 % DON removal. At the pilot scale, enhanced coagulation by 56 mg/L of PACl plus 4 mg/L aluminum chlorohydrate resulted in 36 ± 8 % and 27 ± 9 % DON removal from secondary and filter effluent, respectively. Pilot-scale ozonation followed by biological active carbon (BAC) removed DON by 40 ± 6 % and 42 ± 5 %, respectively, from secondary and filter effluent. Dissolved organic carbon was also significantly removed by enhanced coagulation (23 ± 7 % and 20 ± 13 % from secondary and filter effluent, respectively) and by ozonation/BAC (39 ± 6 % and 39 ± 3 % from secondary and filter effluent, respectively) treatment.

Unraveling the Potential of Innovative Eco‐friendly Thermoplastic Starch/SEBS‐g‐MA/Graphene Oxide Bionanocomposites

AbstractThe increasing focus on bionanocomposites as environmentally friendly solutions for sustainable applications forms the crux of this study. This study explores the influence of incorporating 2% graphene oxide (GO) on the mechanical and thermal characteristics of blends containing glycerol plasticized thermoplastic starch (TPS) and polystyrene‐block‐poly(ethylene‐ran‐butylene)‐block‐polystyrene‐graft‐maleic anhydride (SEBS‐g‐MA), based matrix films through a solution casting method. Starch is successfully obtained from three varied sources: corn, cassava, and potato, with confirmation via fourier transform infrared spectroscopy (FTIR) and X‐ray diffraction (XRD) analysis. The authors formulate and examine varying proportions of TPS/SEBS‐g‐MA (ranging from 10 to 50 wt.%), focusing on their biodegradability, and find that a 10 wt.% SEBS‐g‐MA concentration yields optimal degradation rates, thus this is kept constant. The bionanocomposite films are probed using techniques such as FTIR, XRD, mechanical strength testing, thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), water absorption, and biodegradability studies. These results indicate that GO incorporation results in a robust hydrogen bonding network within the cassava starch‐based bionanocomposite films, enhancing their mechanical strength while decreasing their moisture absorption. Upgraded thermal properties of these films are also evident from the results. Consequently, these materials show promising utility, particularly in the realm of food packaging.

Purification and characterization of extracellular PHB depolymerase enzyme from Aeromonas caviae Kuk1-(34) and their biodegradation studies with polymer films.

PHB depolymerase enzymes are able to breakdown the PHB polymers and thereby get significant economic value in the bioplastics industry and for bioremediation as well. This study shows the purification of novel extracellular PHB depolymerase enzyme from Aeromonas caviae Kuk1-(34) using dialysis followed by gel filtration and HPLC. The purification fold and yield after HPLC were 45.92 and 27.04%, respectively. HPLC data showed a single peak with a retention time of 1.937min. GC-MS analysis reveals the presence of three compounds, of which 1-Dodecanol was found to be most significant with 54.48% area and 8.623-min retention time (RT). The molecular weight of the purified enzyme was obtained as 35kDa with Km and apparent Vmax values of 0.769mg/mL and 1.89 U/mL, respectively. The enzyme was moderately active at an optimum temperature of 35 °C and at pH 8.0. The stability was detected at pH 7.0-9.0 and 35-45 °C. Complete activity loss was observed with EDTA, SDS, Tween-20 at 5 mM and with 0.1% Triton X 100. A biodegradation study of commercially available biodegradable polymer films was carried out in a liquid medium and in soil separately with pure microbial culture and with purified enzyme for 7, 14, 28, and 49 consecutive days. In a liquid medium, with a pure strain of Aeromonas caviae Kuk1-(34), the maximum degradation (89%) was achieved on the PHB film, while no changes were observed with other polymer films. With purified enzyme in the soil, 71% degradation of the PHB film was noticed, and it was only 18% in the liquid medium. All such weight analysis were confirmed by SEM images where several holes, pits, grooves, crest, and surface roughness are clearly observed. Our results demonstrated the potential utility of Aeromonas caviae Kuk1-(34) as a source of extracellular PHB depolymerase capable of degrading PHB under a wide range of natural/ lab conditions.

Valorization of custard apple (Annona squamosa) waste through polyhydroxybutyrate (PHB) production by Bacillus megaterium MAPCS4: optimization, characterization, and biodegradation studies

Valorization of custard apple (Annona squamosa) waste through polyhydroxybutyrate (PHB) production by Bacillus megaterium MAPCS4: optimization, characterization, and biodegradation studies

Facile synthesis of novel interpenetrating polymeric network (IPN) from semi-IPN: comparative analysis of biodegradation studies for environmental remediation

Abstract This paper reports the novel synthesis of an interpenetrating polymer network (IPN) from semi-IPN. This semi-IPN is based on naturally occurring Colocasia esculenta corn starch. The toxicity levels were compared through various biodegradation methods. The polymer network was synthesised from the corresponding semi-IPN via a green pathway by using green solvent (water) and polyvinyl alcohol (PVA) as secondary monomer. The biodegradability of synthesized IPN was tested by vermi-composting, composting and soil burial methods. The study was divided into three stages that lasted up to 70 days. The synthesised IPN degraded 78.94 %, 69.23 % and 67.24 % within 70 days by vermi-composting, composting and burying in the soil, respectively. This was confirmed by Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy with electron dispersion analysis (SEM-EDX) for each stage. Therefore, the system could be considered for agrochemical release without affecting soil fertility.

Experimental criteria of sequential continuous ozonation and semi-continuous biodegradation for the decomposition of 4-chlorophenol

This study presents experimental criteria for developing a sequential treatment that couples continuous ozonation with aerobic biodegradation to degrade 4-chlorophenol (4-CP). The ozonation of 4-CP (60, 120, and 240 mg L−1) was carried out in semi-continuous and continuous modes to select suitable experimental conditions in terms of the decomposition efficiency (DE) of 4-CP and its toxic ozonation products (for continuous mode). Complete degradation of 4-CP (98–100% DE) was achieved within 10–30 min of ozonation in the semi-continuous mode and with hydraulic retention times (HRT) of 30, 45, and 60 min in the continuous system. Continuous ozonation resulted in 46.7% and 36.8% reduction of total organic carbon (TOC) for 4-CP initial concentrations of 120 and 240 mg L−1 at 60 min of HRT, respectively. Based on these results, the combination of ozonation and biological treatment was evaluated. Biodegradation experiments were conducted in batch, fed-batch, and continuous operation modes using a microbial consortium adapted to the pre-ozonized 4-CP. In this step, the TOC of pre-ozonized solutions was reduced by 93%. The global efficiency of ozonation followed by biodegradation system reached up to 96% of mineralization. Suitable experimental conditions were obtained through mathematical modeling of continuous ozonation and biodegradation data. The mineralization achieved was the target result of the proposed treatment scheme, with the maximum mineralization of ozonation products in the bioprocess serving as a critical criterion for its efficacy. Based on a proposed mathematical model, the experimental results were used to conduct kinetic studies of ozonation and biodegradation in continuous mode.

PVA free-radical diblock copolymer for nanoencapsulation with enhanced biodegradability in the environment

The synthesis of readily biodegradable amphiphilic polyvinyl alcohol diblock copolymers (poly(VA-b-MDO)) was achieved through the combination of radical ring-opening polymerization (rROP) and reversible addition-fragmentation chain-transfer (RAFT)-living radical polymerization using 2-methylene-1,3-dioxepane (MDO) and vinyl acetate (VAc) monomers in three steps. The chemistry features solvent-free conditions (bulk polymerization) and subsequent deprotection of the acetyl group under mild conditions. With this optimized method, various lengths of poly(VA) and poly(MDO) in poly(VA-b-MDO) were synthesized by controlling the molecular weight distribution of both blocks. The self-assembly of diblock copolymers to nanoparticles with narrow size distribution and subsequent encapsulation of personal care and pharma active ingredients (e.g., curcumin and fenofibrate) and their controlled release were investigated. In vitro release experiments demonstrated that encapsulated nanoparticles release the actives at a slow and consistent rate compared to free actives. Stability experiments showed that the particle size distribution and purity of curcumin and fenofibrate remained unchanged after being exposed to light for ten months. More importantly, our environmental biodegradability studies revealed that the degradable poly(VA-b-MDO) (6b), consisting of 35 mol% poly(VA) and 65 mol% poly (MDO) blocks, achieves a biodegradability of 78% in 28 days. This is owing to the higher mole ratio of degradable polyester units in the polymer backbone as compared to poly(VA-b-MDO) (6c), which contains 64 mol% poly(VA) and 36 mol% poly(MDO) blocks (33% in 28 days). Our results provide insights into the potential applicability of these polymers in personal care and pharmaceutical products where biodegradability is a crucial factor. By developing a sustainable methodology from synthesis to application, our work helps to harness the potential of biodegradable diblock copolymers in the consumer care and medical fields.

Stabilization of zirconia nanoparticles by collagen protein and calcium carbonate extracted from eggshell and its biodegradation, radical scavenging and mineralization activity

In this current study,collagen protein extracted from eggshell membrane and calcium carbonate (a main component of eggshell) are used as additive to enhance the stability and hardness of the zirconia crystals. Five different samples are prepared by adding membrane containing eggshell content as, 1 g, 2 g, 3 g, 4 g and 5 g in aqueous zirconium oxychloride sol. Phase purity is confirmed by XRD and FTIR. Phase pure and dense particles divulges the high hardness (∼1389 HV) and fracture toughness (12.89 MPa m1/2).FESEManalysis illustrates the formation of dense, well separated, non-agglomerated and spherical nanoparticles at 5 g of eggshell content. Eggshell works as a surfactant and stabilizer for formation of phase pure tetragonal spherical nanoparticles. Biodegradation study of optimized tetragonal zirconia (t-ZrO2)in phosphate buffered saline (PBS) presents that minor change in weight and hardness after 72 h of immersion. Antioxidant study shows the 96% of radical scavenging activity (RSA). In vitro bio-mineralization study shows the formation of new bone after 5 weeks. After 5 weeks all pores were filled and minerals were deposited on the surface of the scaffolds. SEM images confirms that eggshell-zirconia composite form new bone. So eggshell addition results in formation of phase pure t-ZrO2 nanoparticles with well-defined boundaries which exhibit higher hardness, fracture toughness, stability and enhanced antioxidant properties.

The use of Lotus corniculatus in the study of biodegradation of TPH and PAHs assisted by phytoremediation

W artykule przedstawiono zagadnienia związane z etapową bioremediacją gleby zanieczyszczonej substancjami ropopochodnymi. Badania procesu bioremediacji gleby G6 wykonywano w dwóch etapach. W etapie I przeprowadzono biodegradację zanieczyszczeń ropopochodnych na drodze inokulacji biopreparatem B1, opracowanym na bazie niepatogennych mikroorganizmów autochtonicznych. Badania prowadzono metodą pryzmowania ex situ przez okres 3 miesięcy w ściśle kontrolowanych warunkach temperaturowych. W II etapie badań wstępnie oczyszczoną glebę poddano procesowi biodegradacji (inokulacja biopreparatem B2) wspomaganej fitoremediacją w warunkach ex situ (metoda wazonowa) przez okres 6 miesięcy. W badaniach fitoremediacji wykorzystano komonicę zwyczajną (Lotus corniculatus), należącą do grupy naftofitów. Eksperymenty prowadzono w trzech układach: układ 1 – gleba G6-3 + komonica zwyczajna, układ 2 – gleba G6-3 + biopreparat B2 + komonica zwyczajna, układ 3 – gleba G6-3 + biopreparat B2 z dodatkiem γ-PGA (kwas γ-poliglutaminowy) + komonica zwyczajna. Oceny efektywności I i II etapu bioremediacji dokonano na podstawie przeprowadzonych analiz chromatograficznych i testów toksykologicznych. Zrealizowane badania wykazały, że efektywność I etapu bioremediacji gleby G6 wynosiła 41,67% dla TPH (całkowita zawartość węglowodorów) i 34,73% dla WWA (wielopierścieniowe węglowodory aromatyczne). Największą efektywność II etapu bioremediacji odnotowano w układzie 3, natomiast najniższą – w układzie 1. W wyniku II etapu bioremediacji wspomaganego fitoremediacją za pomocą komonicy zwyczajnej po 6 miesiącach badań osiągnięto spadek stężenia TPH w badanych układach o: 13,32% (układ 1), 39,65% (układ 2) oraz 51,79% (układ 3), natomiast efektywność II etapu biodegradacji WWA wynosiła 8,00% w glebie G6-3(1), 37,10% w glebie G6-3(2) oraz 51,34% w glebie G6-3(3). Wykonane testy toksykologiczne z zastosowaniem Phytotoxkit™, Ostracodtoxkit F™ oraz Microtox®SPT wykazały spadek właściwości toksycznych gleby po przeprowadzeniu procesu oczyszczania. Uzyskane wyniki analiz chromatograficznych i toksykologicznych wykazały, że wykorzystanie fitoremediacji w II etapie remediacji pozwala na zwiększenie efektywności procesu biodegradacji TPH i WWA.