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1.
The potential of the autoclaved Tunisian landfill leachate treatment using microalgae (Chlorella sp.) cultivation was investigated in this study. Landfill leachate was collected from Borj Chakir landfill, Tunisia. A full factorial experimental design 22 was proposed to study the effects of the incubation time and leachate ratio factors on the organic matter removal expressed in chemical oxygen demand (COD) and ammoniacal nitrogen (NH4─N) and on the biological response of Chlorella sp. expressed by the cell density and chlorophyll content. All experiments were batch runs at ambient temperature (25 ± 2 °C). The Chlorella sp. biomass and chlorophyll a concentrations of 1.2 and 5.32 mg L?1, respectively, were obtained with 10% leachate spike ratio. The obtained results showed that up to 90% of the ammoniacal nitrogen in landfill leachate was removed in 10% leachate ratio spiked medium with a residual concentration of 40 mg L?1. The maximum COD removal rate reached 60% within 13 days of incubation time indicating that microalgae consortium was quite effective for treating landfill leachate organic contaminants. Furthermore, with the 10% leachate ratio spiked medium, the maximum lipid productivity was 4.74 mg L?1 d?1. The present study provides valuable information for potential adaptation of microalgae culture and its contribution for the treatment of Tunisian landfill leachate.  相似文献   

2.
An electrochemical advanced oxidation process employing a boron-doped diamond anode for the treatment of synthetic waters and secondary effluents of wastewater treatment plants (WWTP) was studied. The efficiency and formation of transformation products (TPs) for this treatment process were investigated at different current densities for bisphenol A (BPA) spiked to synthetic water and WWTP effluents. A complete removal of the parent compound was achieved in WWTP effluents. Higher applied current densities resulted in faster removal. At the same time, a correlation between the applied current density and the ozone concentration measured in the bulk solution was revealed. Hence, the observed transformation of BPA is likely due to the generation of reactive oxygen species such as hydroxyl radicals and ozone. Based on a suspected target screening approach, four known TPs and two unreported (new) TPs were identified by LC–MS analysis. These results suggest a transformation pathway following three steps: hydroxylation of the aromatic ring, followed by oxidation of the isopropylidene bridge and finally a ring opening and formation of organic acids and other small molecules. The presence of chloride ions in WWTP effluents can result in the generation of excessive concentrations of chlorate and perchlorate during electrochemical oxidation. Applying a current density of 208 mA cm?2, a complete elimination of BPA was achievable after 15 min (Q/V = 430 mA h L?1); however, the oxidation resulted in concentrations of chlorate and perchlorate of 2.85 and 5.65 mg L?1, respectively. These values were directly dependent on the exposure time and desired degree of BPA removal.  相似文献   

3.
The present paper undertakes a study of the physico-chemical properties and toxic heavy metals content in the untreated and treated pharmaceutical effluents in order to evaluate the working efficiency of industrial effluent treatment plants. The treatment efficiency achieved for various parameters was conductivity (79.94%), alkalinity (93.91%), hardness (87.70%), chloride (89.24%), cyanide (79.66%), phosphate (99.19%), total dissolved solids (85.89%), total suspended solids (96.87%), salinity (52.41%), dissolved oxygen (27.32%), biochemical oxygen demand (83.39%) and chemical oxygen demand (72.21%). The removal efficiency achieved for different heavy metals was Cu2+ (79.66%), Ni2+ (69.22%), Cr6+ (80.15%), Pb2+ (72.14%), Fe3+ (92.59%) and Zn2+ (90.61%). The level of biochemical oxygen demand (64 mg L?1) in the treated effluents was above the limit of 30.0 mg L?1, chemical oxygen demand level (208 mg L?1) was close to a limit of 250 mg L?1, while average Pb2+ concentration (0.10 mg L?1) was on the borderline of maximum permissible limit of 0.10 mg L?1 set by Central Pollution Control Board for safe discharge of industrial effluent in inland surface water. The average concentration of cyanide (0.01 mg L?1) in the treated industrial effluent of our study is of great concern to the fisheries of freshwater ecosystem in which the effluents finally get discharged. Based on the results of the present study, it is concluded that the pollution level in the discharged pharmaceutical effluent is of the great concern requiring proper treatment and regular scientific monitoring so as to protect the environmental degradation of water resources and facilitate the propagation of the aquatic life.  相似文献   

4.
The long-term sustainability of an anaerobic ammonium oxidation (anammox) process in a moving bed biofilm reactor (MBBR) treating highly concentrated (mean of 740 mg NH4 +-N L?1) wastewater was demonstrated by 1600 days of efficient operation. A high maximum total nitrogen removal rate (TNRR) of 1.5 g N m?2 d?1 was achieved at the low temperature of 20 °C. For nitrogen removal recovery in cases of nitrite inhibition, anammox intermediate nitric oxide (NO) was tested in batch experiments as an N-removal accelerating agent. The effect of the addition of various NO dosages (8–72 mg NO-N L?1) was studied under inhibitory nitrite concentrations (>100 mg NO2 ?-N L?1) for anammox bacteria. Optimal maintained NO concentration was 58 mg NO-N L?1 and brought about the highest biofilm-specific anammox activity (SAA). Compared to a blank test, the minimum concentration of added NO of 40 mg NO-N L?1 showed a statistically significant (p < 0.05) accelerating effect on SAA. No inhibition of SAA by NO was observed, although at NO concentrations exceeding 72 mg NO-N L?1, the acceleratory effect upon SAA was decreased by 8%. Changes in the bacterial consortia involved in nitrogen conversion were determined concurrently for the different nitrogen removal rates and operational conditions. Quantities of Planctomycetales clone P4 strains, which are the closest (99% similarity) relative to Candidatus Brocadia fulgida, increased from 1 × 103 to 1 × 106 anammox gene copies per g total suspended solids during reactor operation days 568–1600, which was determined by quantitative polymerase chain reaction. During the operation of the MBBR, the abundance of ammonium-oxidizing bacteria (AOB) increased proportionally (up to 30%). The abundance of nitrite-oxidizing bacteria (NOB) did not increase (remaining below 10%) during days 232–860. AOB became predominant over NOBs owing to the inhibition of free ammonia spiking on NOBs.  相似文献   

5.
A simple spectrophotometric method for determination of hydrogen sulfide in wastewater and hot spring samples was developed. The method is based on the reaction between hydrogen sulfide and sodium 1,2-naphthoquinone-4-sulfonate (NQS). The effect of various experimental factors on the reaction between hydrogen sulfide and NQS was investigated and optimized using central composite design. The optimal values of the factors were 5.00 × 10?4 mol L?1 for concentration of NQS and 1.00 × 10?2 mol L?1 for concentration of hydrochloric acid. The wavelength of the maximum absorption of the reaction product was 320 nm. Constructed calibration curve for hydrogen sulfide determination was linear in the range of 0.5–20.0 mg L?1 with the detection limit of 0.16 mg L?1. The method was free from interferences. Percent relative errors below 2 % were obtained for determination of hydrogen sulfide in environmental samples.  相似文献   

6.
The study was designed to quantify cadmium accumulation in different components of sewage treatment ponds during different seasons and to assess risk for human consumption perspective. The study estimated cadmium concentration in water, sludge, Eichhornia, plankton and tilapia fish from anaerobic, facultative, maturation-1 and -4 ponds during pre-monsoon, monsoon and post-monsoon periods. It resulted that cadmium accumulated among different components of anaerobic, facultative, maturation-1 and -4 ponds ranging 0–18, 0–10, 0–7 and 0–15.4 ppb, respectively. During monsoon, highest accumulation was observed in tilapia in both facultative and maturation ponds, but during post-monsoon, plankton community showed highest value in all. The highest bio-magnification of cadmium was recorded during monsoon with varying degrees (facultative pond: 4.39, maturation pond-1: 3.03 and maturation pond-4: 7.08). Cadmium concentration in tilapia lied within WHO’s safe level and may be recommended for human consumption. The concentration of cadmium was estimated by Flame Atomic Absorption Spectrophotometer. The above findings occurred due to chelation, adsorption and sedimentation, absorption and bio-accumulation, ionization, leaching through sediment and rainfall. Water pH (6.7–8.8), dissolved oxygen (0–17 mg L?1), total solids (251–650 mg L?1), iron (Fe2+) concentration (0.61–4.87 mg L?1) and sedimentation rate (278.9–2,409.6 g day?1 m?3) were conducive for the distribution of cadmium into different ecosystem components of treatment ponds. These ponds reclaimed 28.57–61.11 % of sewage-cadmium and may be promoted as a low-cost eco-tech for sewage treatment.  相似文献   

7.
Enhancing of the efficient tissue culture protocol for somatic embryos would facilitate the engineered breeding plants program. In this report, we describe the reproducible protocol of Malaysian rice (Oryza sativa L.) cultivar MR219 through somatic embryogenesis. Effect of a wide spectrum of exogenesis materials was assessed in three phases, namely callogenesis, proliferation and regeneration. Initially, rice seeds were subjected under various auxin treatments. Secondly, the effect of different concentrations of 2,4-D on callus induction was evaluated. In the next step, the efficiency of different explants was identified. Subsequently, the effects of different auxins, cytokinins, l-proline, casein hydrolysate and potassium metasilicate concentrations on the callus proliferation and regeneration were considered. For the callogenesis phase, 2 mg L?1of 2,4-D and roots were chosen as the best auxin and explant. In the callus proliferation stage, the highest efficiency was observed at week eight in the MS media supplemented with 2 mg L?1 of 2,4-D, 2 mg L?1 of kinetin, 50 mg L?1 of l-proline, 100 mg L?1 of casein hydrolysate and 30 mg L?1 of potassium metasilicate. In the last phase of the research, the MS media added with 3 mg L?1 of kinetin, 30 mg L?1of potassium metasilicate and 2 mg L?1 of NAA were selected. Meanwhile, to promote the roots of regenerated explants, 0.4 mg L?1 of IBA has shown potential as an appropriate activator.  相似文献   

8.
Diazinon is a widely applied agricultural pesticide whose effect importantly on the environment and the possible contamination of surface waters has led to increased interest in toxicological studies. Crayfish, as an ecologically important benthic macroinvertebrate, seems to be an appropriate model organism for such assessments. Acute toxicity tests were carried out on three crayfish age groups: young-of-the-year (total length = 25.0 ± 4.9 mm), juvenile (total length = 56.5 ± 3.8 mm) and adult (total length = 83.5 ± 5.7 mm). Young-of-the-year crayfish were found to be the most sensitive to diazinon (96 h LC50 = 0.15 mg L?1), followed by juvenile crayfish (96 h LC50 = 0.27 mg L?1), and adults (96 h LC50 = 0.51 mg L?1). Crayfish were highly sensitive to diazinon. A delayed effect of Diazinon 60EC on adults was detected (144 h LC50 = 0.44 mg L?1) suggests functional damage from the use of sublethal concentrations.  相似文献   

9.
Processes that control the distribution and natural attenuation (NA) of petroleum hydrocarbons dissolved from the released diesel fuel in a bench-scale model aquifer were evaluated. The experimental results obtained in two-dimensional aqueous-phase petroleum hydrocarbon concentrations indicated that the total petroleum hydrocarbon (TPH) in the aquifer migrated in longitudinal and lateral directions. The TPH plume of 2 mg L?1 spread to the entire area of the aquifer, and the maximum concentration at the center of the plume was 44.15 mg L?1 after 90 days of release. After diesel fuel release, the NA of TPH was evaluated and quantified. Experimental data indicated that the NA of TPH was immediately implemented to prevent migration of the plume into the downgradient of the aquifer, but controlling the TPH plumes using NA mechanisms requires a long time.  相似文献   

10.
A phenanthrene-degrading strain PHE3, identified as the genus of Sphingobium, was isolated using a two-liquid-phase partitioning bioreactor. More than 96 % of the initial amount (up to 100 mg l?1 silicone oil) of phenanthrene was removed within 77 h by PHE3. Degradation of phenanthrene by PHE3 at pH 7 was also observed in the presence of Cu (II), Zn (II) and Cd (II) ions. Cu (II) showed the highest toxicity to PHE3, followed by Cd (II) and Zn (II). Tolerance to Cu (II) by PHE3 was up to 20 mg l?1 in terms of total aqueous concentration, and up to 40 mg l?1 for both Zn and Cd. Interestingly, 20 mg l?1 of Zn (II) stimulated phenanthrene degradation after 20 h incubation. Its high tolerance to toxic metals and phenanthrene degradation ability of PHE3 highlights its significance in the study of microbial remediation in soils co-polluted by PAHs and metals.  相似文献   

11.
A sandwich domestic wastewater-fed dual-chamber microbial fuel cell (MFC) was designed for energy generation and wastewater treatment. The generated power density by the MFC was observed to increase with increasing chemical oxygen demand (COD) of the domestic wastewater. The maximum power density was 251 mW m?2 when the COD was 3400 mg L?1 at a current density of 0.054 mA cm?2 and external resistance of 200 Ω. These values dropped to 60 mW m?2 (76 % lower) and 0.003 mA cm?2 using wastewater 91 % diluted to 300 mg L?1 COD. Maximum removals were: COD, 89 %; nitrite, 60 %; nitrate, 77 %; total nitrogen, 36 %; and phosphate, 26 %. Coulombic efficiency ranged from 5 to 7 %. The use of full-strength domestic wastewater reduces cost, and with improved reactor design, the ultimate goal of large-scale operation could be achieved.  相似文献   

12.
Greenhouse tests were conducted to study the effect of chelates on the phytoextraction of cadmium and lead, and the rhizodegradation of used engine oil present as a mixed contaminant in a sandy soil. Indian mustard plants were grown in test pot soil for 30 days and chelates ethylenediamine tetraacetic acid (EDTA) and ethylenediaminedisuccinic acid (EDDS) were individually applied to the test soil. The soil was spiked earlier with 50 mg kg?1 of CdCl2, 500 mg kg?1 of PbCl2 and 500 mg kg?1 of used engine oil to form the mixed soil contaminant. At the same concentration of chelates, EDTA was found to be more effective than EDDS in increasing the concentration of metal contaminants Cd and Pb in the plant. Compared to EDDS, EDTA was also more effective in promoting rhizodegradation of the organic contaminant formed by used engine oil. The study demonstrated that the application of chelates to soils containing mixed contaminants such as heavy metals (Cd and Pb) and organics (used engine oil) can simultaneously assist metal accumulation at higher concentrations in the biomass of Indian mustard plant and also reduce the amount of used engine oil in the soil through rhizodegradation.  相似文献   

13.
Bisphenol-A is one of the highest volumes of chemicals produced worldwide and released into the atmosphere each year. Recent extensive literature has raised concerns about its possible endocrine-disrupting effect in animals and humans. A bacterium having high tolerance of bisphenol-A (1000 mg L?1) was isolated from agriculture soil of Coimbatore District, Tamil Nadu, India, and identified as Virgibacillus sp. KU4 by 16S ribosomal RNA sequence analysis. Bisphenol-A removal efficiency of this strain was measured as greater than 92% at seventh day of incubation in a basal mineral medium supplemented with 1000 mg L?1 at seventh day. Gas chromatography analysis showed that 1000 mg L?1 BPA in distilled water was degraded by the Virgibacillus sp. KU4 in an efficient way. A 70 ± 3% bisphenol-A degradation was observed in the suspended cell pellet-mediated degradation study, where distilled water supplemented with 1000 mg L?1 bisphenol-A was sole carbon and energy source for bacterial growth. Further, Virgibacillus sp. KU4 is expected to be a candidate as a biological cleaner of BPA in the environment.  相似文献   

14.
This study examined the cell growth rate, lipid contents, lipid productivity, chlorophyll a concentration, and carbon dioxide tolerance of Chlorella vulgaris under various cultivation conditions. The pH, concentration of carbon dioxide in media, and light intensity variables were manipulated to obtain high lipid productivity. The optimum conditions were at pH 7.0, 2,930 lux, and 30 % carbon dioxide. Biomass concentration reached 1,288, 1,130, and 1,083 mg L?1 at 15, 30, and 50 % CO2 after 6 days, respectively, implying that this strain has appreciable tolerance to carbon dioxide. The highest concentration of chlorophyll a occurred at 2,930 lux and decreased with increasing light intensity gradually. The maximum specific growth rate was 3.25 day?1 based on the dry weight and 4.63 day?1 based on the cell number. The lipid content (45.68 %) and lipid productivity (86.03 mg day?1 L?1) obtained in this study are higher than reported values in literatures. Hence, C. vulgaris is a good candidate for subsequent research in biodiesel production under elevated carbon dioxide concentration by microalgae.  相似文献   

15.
A laboratory-scale sequencing airlift bioreactor continuously treating high-level 4-chloroaniline (4-ClA) wastewater was used for studying the effect of 4-ClA on the characteristics and microbial community of aerobic granular sludge. The granulation of aerobic sludge and efficient pollutant removal performance were developed via shortening sludge settling time and gradually increasing influent 4-ClA concentration to around 400 mg L?1. However, the granular sludge reactor deteriorated with the 4-ClA loading rate above 0.8 kg m?3 d?1. Denaturing gradient gel electrophoresis and real-time quantitative PCR were applied to investigate the microbial community succession during the start-up and recovery of bioreactor. The results showed that the performance of granular reactor was significantly influenced by the microbial community of aerobic granule, and stable aerobic granule was dominated with β-Proteobacteria (61.28 %), Flavobacteriales, Planctomycetales, Clostridiales, and Acidobacteria. Since Thauera (21.55 %) related to the genus β-Proteobacteria was abundant in the stable 4-ClA-degrading granular sludge, it was speculated as the main 4-ClA-degrading bacteria. Under high chloroaniline level, the sludge granulation may maintain the stability of the bioreactor via adjusting the composition of microbial community and abundance of functional microorganism. This paper provided useful information for better understanding the change of microbial community characteristics under high-level toxic organic pollutants and process optimizing.  相似文献   

16.
In this study, we investigated the possible effects of paraquat and micro-plastics on blood biochemical parameters in common carp (Cyprinus carpio). We exposed C. carpio for 21 days to sublethal concentrations of paraquat (0.2 and 0.4 mg L?1) and micro-plastics (1 and 2 mg L?1), alone or in combination. Blood biochemical analysis indicated that exposure to 0.4 mg L?1 paraquat and mixture of paraquat and micro-plastics was followed by an increase in aspartate aminotransferase (AST), alkaline phosphatase (ALP), and creatine phosphokinase (CPK) activities and glucose levels. The activity of ALP and CPK showed a significant increase in fish treated with 2 mg L?1 micro-plastics. No significant changes were observed in glucose level, AST, ALT, and LDH activities in fish exposed to micro-plastics. Exposure to paraquat and/or micro-plastics resulted in a significant decrease in total protein, globulin, cholesterol, and triglyceride levels and γ-glutamyl transferase activity. When fish were exposed to paraquat or paraquat and micro-plastics, alanine aminotransferase (ALT) and lactate dehydrogenase (LDH) activities increased significantly compared to the control group. Treating fishes with a mixture of paraquat and 2 mg L?1 micro-plastics caused a significant increase in albumin levels. However, a significant decrease in the albumin level was observed after exposure to paraquat or micro-plastics. Creatinine levels increased after exposure to paraquat and/or micro-plastics. The results indicate that increased doses of micro-plastics in water significantly increased toxic effects of paraquat in fish. Finally, these data support the hypothesis that changes in blood biochemical parameters were induced by exposure to paraquat and/or micro-plastics.  相似文献   

17.
Lead (Pb) dust exposure can have detrimental environmental and human health effects. Improperly enclosed stockpiles of Pb concentrates can cause dust emissions, subsequent pollution of the soil and environmental risk. The aim of this work was to study Pb form, distribution and immobilization (by using eggshell and seashell) in an industrial arid soil near a storage area of Pb mineral concentrates in northern Chile. High amounts of sulfur (S; 9900 mg kg?1) and Pb (6530 mg kg?1) were found in the polluted soil. The energy-dispersive X-ray spectroscopy analysis revealed a lead sulfide (PbS: galena). Metallic Pb particles, which were between 41 and 46 µm, were identified in the soil. After eggshell and seashell (20%) were applied, the soil pH increased from 6.0 to 7.84 and 8.07, respectively. In the studied soil, the leaching test showed a 59 mg L?1 average Pb extractable concentration. After 240 days, extractable Pb by toxicity characteristics leaching procedure decreased to 4.79 mg L?1 (93.3%) with the application of seashell at 20% compared with a decrease of 33.33 mg L?1 (53.6%) using eggshell. Pb in the polluted soil was mainly found in the exchangeable fraction (66%), followed by the reducible (24%), residual (7%) and oxidizable (6%) fractions. According to the risk assessment code, the contaminated soil before treatment was classified as very high risk. Adding eggshell (20%) and seashell (20%) decreased the exchangeable fractions to 39 and 35%, respectively. Applying these liming materials achieved Pb immobilization in the soil, but the soil remained in the high environmental risk category. We conclude that the application of seashell waste, resulting from high aquaculture activity, opens an interesting window to the treatment of contaminated arid soils.  相似文献   

18.
The state of Punjab—a part of the Indus basin of the Indian subcontinent has an excellent net work of irrigation facilities. However, due to intensive cultivation it is facing a major problem with respect to quality of groundwater for irrigation. In the present investigation, geo-referenced groundwater samples were analysed to map water quality using geographical information system. Electrical conductivity varied from 0.418 to 5.754 dS m?1 with an average of 1.365 dS m?1. The carbonate ranged between 0 and 120 mg L?1, whereas bicarbonate ranged from 5 to 1,000 mg L?1. Chloride varied from 7 to 2,347 mg L?1. Calcium plus magnesium ranged from 12 to 1,216 mg L?1 with a mean value of 169 mg L?1. Sodium adsorption ratio ranged between 0.0 and 34.78 with an average of 2.66 meq L?1/2. Residual sodium carbonate varied from 0 to 21.30 meq L?1 with a standard deviation of 2.24. The Geographic Information System (GIS)-based mapping indicated that water in suitable category spatially covered 45.7 % of the state which is located mostly in the sub-mountain (Siwalik Hills), north-eastern undulating and piedmont and alluvial plain agro-eco-subregions. Marginally suitable groundwater spatially covered 46.1 % in the central alluvial plain and south-western alluvial plain agro-eco-subregions. Unsuitable groundwater covered 8.2 % of the state, mostly in the erstwhile sodic soils areas in the central alluvial plain and south-western alluvial plain agro-eco-subregions. GIS-based maps are effective in identifying hot spots which need immediate attention and call for strategic planning for sustainable management.  相似文献   

19.
The role of rhizospheric microbes of giant reed (Arundo donax L.) in Cr uptake from hydroponic culture was investigated. The control group was exposed to Cr in range of 25–100 mg L?1 containing a control itself (with no metal addition). The experimental group received same Cr treatments, but in addition was exposed to antibiotic treatment in order to inhibit rhizospheric bacteria. The range of Cr accumulated in the roots was 3–7.65 mg L?1; in stem it ranged 2.15–42.4 mg kg?1; while in leaves, the range of Cr content was 13.7–15 mg kg?1. Overall, Cr uptake in A. donax (without rhizobacterial inhibition) was root < leaf < stem. However, the amount of Cr uptake in plants with rhizobacterial inhibition was significantly less (~4.6-folds in 100 mg L?1 Cr treatment) than those without such inhibition clearly highlighting that rhizobacterial inhibition decreased the Cr uptake. The experimental results clearly demonstrated that the inhibition of the rhizobacterial populations had great influence on the Cr uptake. However, Cr uptake could not be completely inhibited as some metal uptake was observed after the rhizobacterial inhibition although it was significantly less than the Cr uptake of plants without such inhibition.  相似文献   

20.
In order to reduce the cost of the microbial-induced carbonate precipitation, mixotrophic growth of Sporosarcina pasteurii was carried out at different yeast extract/sodium acetate concentrations and constant chemical oxygen demand for optimal production of urease enzyme. Optimization of cultivation conditions was also investigated using a 3-level central composite design approach based on the response surface methodology. A good agreement between predicted values of enzyme activity and experimental results was observed (R 2 value of 0.973). All three chosen independent variables had statistically great effects on the efficiency of urease activity. The maximum activity of 2.98 mM urea min?1 was achieved at yeast extract concentration of 5 g L?1, NH4 concentration of 9.69 g L?1, and incubation time of 60 h as the optimal conditions. Thereafter, a novel injection procedure as sequencing batch mode injection has been proposed for bacteria and cementation fluid injection at obtained optimal urease activity. After fourth injection of bacteria and cementation fluid, uniform CaCO3 distribution with unconfined compression strength of 795 kPa was obtained even for poorly graded sand. The presented experimental approach for optimizing urease activity and strength production in porous media can be used to design the treatment protocol for practical engineering applications.  相似文献   

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