Displaying publications 1 - 20 of 363 in total

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  1. Lam WK, Dharmaraj D
    Med J Malaysia, 1982 Jun;37(2):114-23.
    PMID: 6127601
    A survey on mosquito breeding in septic tanks in several residential areas was carried out on 211 septic tanks in the Ipoh Municipality. The septic tanks inspected comprised two types; the contact filter-bed with pump sump and pump motor type (Type A) and the subsoil [ilter trench type (Type B). Mosquito breeding occurred in. both types of septic tanks, with Type A septic tanks showing heavier breeding, Seventy-two (55.4 percent) of the 130 Type A septic tanks inspected had Aedes albopictus breeding. Besides being a nuisance, mosquito breeding is a potential threat to public health, as Ae. albopictus is a vector of dengue fever. Prolific breeding by Ae. albopictus was encountered in areas where Type A septic tanks were used. Other mosquitoes encountered in the survey were Culex qusnquefasciatus, Armigeres subabaltus and Uranotaenia spp. Analysis of effluent samples from Type A and Type B septic tanks revealed that of the 4 parameters measured (PH, chloride, BOD5 and Free Ammonia}, only pH was not significantly different at the 95 percent level of confidence. Chloride, BOD5 and Free Ammonia levels in. the Type B septic tanks were significantly higher than that in Type A septic tanks. Turbidity of the effluent in Type B septic tanks probably deters Ae. albopictusfrom breeding. Several methods to prevent breeding of mosquitoes in septic tanks were discussed. The easiest method is to mosquito-proof the septic tanks but this has been tried not too successfully. A method using expanded polystyrene balls is suggested. Other methods include the use of parasitic nematodes and the use of insecticides but these are not favourable.
    Matched MeSH terms: Waste Disposal, Fluid*
  2. Singhal A, Gomes J, Praveen VV, Ramachandran KB
    Biotechnol Prog, 1998 Jul;14(4):645-8.
    PMID: 9694688
    Fluid flow in UASB reactors is usually described by multicompartment models consisting of separate ideally mixed zones, plug flow zones, and stagnant zones linked with bypassing flows and back-mixing flows. A closer look at UASB reactor behavior indicates that this complexity is unnecessary. Our study on the startup and steady-state operation of a UASB reactor shows that its fluid flow can be explained just as well with a simple axial dispersion model. The physical transitions, which occur in different zones of the UASB reactor as the microorganisms acclimate to the wastewater, are adequately described by the model. Further, the number of parameters, which is six in standard UASB reactor models, is reduced to four in the case of the axial dispersion model.
    Matched MeSH terms: Waste Disposal, Fluid
  3. Haron MJ, Yunus WM
    PMID: 11460327
    A cerium-loaded poly(hydroxamic acid) chelating ion exchanger was used for fluoride ion removal from aqueous solution. The resin was effective in decreasing the fluoride concentration from 5 mM down to 0.001 mM in acidic pH between 3 and 6. The sorption followed a Langmuir model with a maximum capacity of 0.5 mmol/g. The removal is accomplished by an anion exchange mechanism. The rate constant for the sorption was found to be 9.6 x 10(-2) min-1. A column test shows that the fluoride ion was retained on the column until breakthrough point and the fluoride sorbed in the column can be eluted with 0.1 M NaOH. The column can be reused after being condition with hydrochloric acid at pH 4. The resin was tested and found to be effective for removal of fluoride from actual industrial wastewater.
    Matched MeSH terms: Waste Disposal, Fluid/methods*
  4. Lim PE, Wong TF, Lim DV
    Environ Int, 2001 May;26(5-6):425-31.
    PMID: 11392762
    This study was conducted to: (1) assess the role of wetland vegetation in the removal of oxygen demand and nitrogen under tropical conditions, (2) estimate the uptake of nitrogen and copper by wetland plants and (3) investigate the speciation of Cu in wetland media among four operationally defined host fractions, namely exchangeable, carbonate, reducible and organically bound. Four laboratory-scale wetland units, two free-water-surface (FWS) and two subsurface-flow (SF) with one of each planted with cattails (Typha augustifolia), were fed with primary-treated sewage and operated at nominal retention times of 0.6-7 days. The influent and effluent BOD/COD and nitrogen concentrations were monitored to assess the performance of the wetland units for various mass loading rates. At the end of the study, all cattail plants were harvested and analyzed for total Kjeldahl nitrogen (TKN). Four other wetland units, which were identical to the first four, were fed with domestic wastewater spiked with copper in increasing concentrations. Copper speciation patterns in the sand layer were determined at the end of the study. The results showed that wetland vegetation did not play an important role in oxygen demand removal but were capable of removing about 22% and 26% of the nitrogen input in the FWS and SF wetland units, respectively. Mass balance analysis indicated that less than 1% of copper introduced was taken up by the cattails. Copper speciation patterns in the sand media showed that the exchangeable fraction contributed 30-57% and 63-80% of the nonresidual copper in the planted and unplanted FWS wetlands, respectively. For SF units, the percentages were 52-62% and 59-67%, respectively. This indicates that large amount of copper in the media were potentially remobilizable.
    Matched MeSH terms: Waste Disposal, Fluid
  5. Aziz HA, Othman N, Yusuff MS, Basri DR, Ashaari FA, Adlan MN, et al.
    Environ Int, 2001 May;26(5-6):395-9.
    PMID: 11392757
    This paper discusses heavy metal removal from wastewater by batch study and filtration technique through low-cost coarse media. Batch study has indicated that more than 90% copper (Cu) with concentration up to 50 mg/l could be removed from the solution with limestone quantity above 20 ml (equivalent to 56 g), which indicates the importance of limestone media in the removal process. This indicates that the removal of Cu is influenced by the media and not solely by the pH. Batch experiments using limestone and activated carbon indicate that both limestone and activated carbon had similar metal-removal efficiency (about 95%). Results of the laboratory-scale filtration technique using limestone particles indicated that above 90% removal of Cu was achieved at retention time of 2.31 h, surface-loading rate of 4.07 m3/m2 per day and Cu loading of 0.02 kg/m3 per day. Analyses of the limestone media after filtration indicated that adsorption and absorption processes were among the mechanisms involved in the removal processes. This study indicated that limestone can be used as an alternative to replace activated carbon.
    Matched MeSH terms: Waste Disposal, Fluid/methods*
  6. Ariff AB, Rosfarizan M, Sobri MA, Karim MI
    Environ Technol, 2001 Jun;22(6):697-704.
    PMID: 11482390
    Research was undertaken to investigate the treatment of fishery washing water using Bacillus sphaericus, and to recover the spores for subsequent use as bioinsecticide to control the population of mosquitoes. This treatment method could reduce pollution due to organic matter by decreasing the value of Chemical Oxygen Demand (COD) and Biological Oxygen Demand (BOD) by about 85% and 92%, respectively. The maximum concentration of spores (83.3 x 10(7) spores ml(-1)) using normal concentration of filtered fishery washing water was only about 27% lower than that obtained in fermentation using 0.25% (w/v) yeast extract. The larvicidal activity of the spores produced in fermentation using fishery washing water to Culex quinquefaciatus, as measured by LD50 after 48 h, was almost the same as the larvicidal activity of spores obtained from fermentation using yeast extract.
    Matched MeSH terms: Waste Disposal, Fluid/methods*
  7. Azad SA, Vikineswary S, Ramachandran KB, Chong VC
    Lett Appl Microbiol, 2001 Oct;33(4):264-8.
    PMID: 11559398
    AIMS: Rhodovulum sulfidophilum was grown in sardine processing wastewater to assess growth characteristics for the production of bacterial biomass with simultaneous reduction of chemical oxygen demand.

    METHODS AND RESULTS: Growth characteristics were compared in diluted and undiluted, settled and non-settled wastewater growing in anaerobic light and aerobic dark conditions; and also at different agitation speeds. The highest biomass (8.75 g l(-1)) and a reduction in chemical oxygen demand of 71% were obtained in unsettled, undiluted wastewater after 120 h culture with 15% inoculum. In settled wastewater, highest biomass (7.64 g l(-1)) and a COD reduction of 77% was also obtained after 120 h. Total biomass was higher (4.34 g l(-1)) after 120 h culture in anaerobic light compared to (3.23 g l(-1)) in aerobic dark growth.

    CONCLUSIONS, SIGNIFICANCE AND IMPACT OF THE STUDY: Better performance, mean of total biomass (6.97 g l(-1) after 96 h), total carotenoids (4.24 mg g(-1) dry cell from 24 h) and soluble protein (431 microg ml(-1) after 96 h) were obtained from aerobic dark culture at 300 rev min(-1). The COD reduction, however, was lower (69%) after 96 h culture. Thus, the benefits in the production of bacterial biomass in non-sterilized sardine processing wastewater with the reduction of chemical oxygen demand could be achieved.

    Matched MeSH terms: Waste Disposal, Fluid
  8. Alam MZ, Fakhru'l-Razi A, Molla AH, Roychoudhury PK
    PMID: 11545349
    This study was conducted to evaluate the effect of an eminent decay fungus, Phanerocheate chrysosporium of organic residues on wastewater sludge for its improvement through decomposition and separation of waste particles by Liquid State Bioconversion (LSB). The effect of fungal treatment was compared to uninoculated (Control) at three different harvests 7, 14 and 21 days after inoculation (DAI). The observed results showed that the weight loss and solid content of wastewater sludge were significantly influenced by Phanerocheate chrysosporium. Both parameters were highly influenced at 7 DAI. The COD and pH of wastewater sludge were also highly influenced by fungal treatment.
    Matched MeSH terms: Waste Disposal, Fluid/methods*
  9. Hussein MZ, Zainal Z, Yaziz I, Beng TC
    PMID: 11413839
    Layered double hydroxide of Mg-Al-carbonate system (MACH) was prepared and its heat-treated product (MACHT) was obtained by calcination at 500 degrees C. The resulting materials were used as an adsorbent for removal of color from synthetic textile wastewater (STW) and textile wastewater (TWW). Batch kinetic study showed that these materials are an efficient adsorbent for textile dye. The maximum adsorption capacities between 16 to 32 mg of dyes per g of adsorbent was obtained by fitting the adsorption data to the Langmuir adsorption Isotherm. It was found that the adsorption capacity of MACHT is higher than MACH.
    Matched MeSH terms: Waste Disposal, Fluid*
  10. Lim PE, Ong SA, Seng CE
    Water Res, 2002 Feb;36(3):667-75.
    PMID: 11827329
    The application of simultaneous adsorption and biodegradation processes in the same reactor is known to be effective in the removal of both biodegradable and non-biodegradable contaminants in various kinds of wastewater. The objective of this study is to evaluate the efficacy of the two processes under sequencing batch reactor (SBR) operation in treating copper and cadmium-containing synthetic wastewater with powdered activated carbon (PAC) as the adsorbent. The SBR systems were operated with FILL, REACT, SETTLE, DRAW and IDLE periods in the ratio of 0.5: 3.5: 1.0: 0.75 :0.25 for a cycle time of 6 h. In the presence of 10 mg/L Cu(II) and 30 mg/L Cd(II), respectively, the average COD removal efficiencies were above 85% with the PAC dosage in the influent solution at 143 mg/L compared to around 60% without PAC addition. Copper(II) was found to exert a more pronounced inhibitory effect on the bioactivity of the microorganisms compared to Cd(II). It was observed that the combined presence of Cu(II) and Cd(II) did not exert synergistic effects on the microorganisms. Kinetic study conducted for the REACT period showed that the addition of PAC had minimized the inhibitory effect of the heavy metals on the bioactivity of microorganisms.
    Matched MeSH terms: Waste Disposal, Fluid/methods*
  11. Fakhrul-Razi A, Alam MZ, Idris A, Abd-Aziz S, Molla AH
    PMID: 11929070
    A study was carried out to isolate and identify filamentous fungi for the treatment of domestic wastewater sludge by enhancing biodegradability, settleability and dewaterability of treated sludge using liquid state bioconversion process. A total of 70 strains of filamentous fungi were isolated from three different sources (wastewater, sewage sludge and leachate) of IWK's (Indah Water Konsortium) sewage treatment plant, Malaysia. The isolated strains were purified by conventional techniques and identified by microscopic examination. The strains isolated belonged to the genera of Penicillium, Aspergillus, Trichoderma, Spicaria and Hyaloflorae The distribution of observed isolated fungi were 41% in sewage sludge followed by 39% in wastewater and 20% in leachate. The predominant fungus was Penicillium (39 strains). The second and third most common isolates were Aspergillus (14 strains) and Trichoderma (12 strains). The other isolates were Spicaria (3 strains) and Hyaloflorae (2 strains). Three strains (WWZP1003, LZP3001, LZP3005) of Penicillium (P. corylophilum, P. waksmanii, and P. citrinum respectively), 2 strains (WWZA1006 and SS2017) of Aspergillus (A. terrues and A. flavus respectively) and one strain (SSZT2008) of Trichoderma (T. harzianum) were tentatively identified up to species level and finally verified by CABI Bioscience Identification Services, UK.
    Matched MeSH terms: Waste Disposal, Fluid*
  12. Alam MZ, Fakhru'l-Razi A, Idris A, Abd-Aziz S
    PMID: 12227649
    The bioconversion of domestic wastewater sludge by immobilized mixed culture of filamentous fungi was investigated in a laboratory. The potential mixed culture of Penicillium corylophilum WWZA1003 and Aspergillus niger SCahmA103 was isolated from its local habitats (wastewater and sludge cake) and optimized on the basis of biodegradability and dewaterability of treated sludge. The observed results in this study showed that the sludge treatment was highly influenced by the effect of immobilized mixed fungi using liquid state bioconversion (LSB) process. The maximum production of dry filter cake (DFC) was enriched with fungal biomass to about 20.05 g/kg containing 23.47 g/kg of soluble protein after 4 days of fungal treatment. The reduction of COD, TSS, turbidity (optical density against distilled water, 660 nm), reducing sugar and protein in supernatant and filtration rate of treated sludge were influenced by the fungal mixed culture as compared to control (uninnoculated). After these processes, 99.4% of TSS, 98.05% of turbidity, 76.2% of soluble protein, 98% of reducing sugar and 92.4% of COD in supernatant of treated sludge were removed. Filtration time was decreased tremendously by the microbial treatment after 2 days of incubation. The effect of fungal strain on pH was also studied and presented. Effective bioconversion was observed after 4 days of fungal treatment.
    Matched MeSH terms: Waste Disposal, Fluid/methods*
  13. Molla AH, Fakhru'l-Razi A, Hanafi MM, Abd-Aziz S, Alam MZ
    PMID: 12369641
    Ten filamentous fungi adapted to domestic wastewater sludge (DWS) were further studied to evaluate their potential in terms of adaptation to higher sludge supplemented growing media and phytopathogenicity (induction of diseases to plants) to three germinating crop (Corn: Zea mays, Mung bean: Phaseolus aureus and Mustard: Brassica napus) seeds. The performances of the fungi in seed germination were evaluated based on percent germination index (GI) and infected/spotted seeds on direct fungal biomass (FBM) and fungal metabolite (FM). Significantly the highest biomass production was achieved with RW-P1 512 and Penicillium corylophilum (WW-P1003) at the highest (25%) sludge supplemented growing media that implied its excellent potentiality of adaptation and multiplication to domestic wastewater sludge. Significantly encouraging results of percent GI and spotted/infected seedlings were observed in FM than FBM by all fungi except the strain Aspergillus niger. A. niger gave the poorest percent of GI (24.30, 26.98 and 00.00%) and the highest percent of infected/spotted seeds (70, 100, and 100%) using FBM for corn, mung bean and mustard, respectively. On the other hand, comparatively the highest percent of GI (107.99, 106.25 and 117.67%) and the lowest percent of spotted/infected seedlings (3.3, 3.3 and 3.3%) were achieved with the isolate RW-P1 512 using FM. In FBM, the superior results of percent GI (86.61, 95.92 and 83.87%) and spotted/infected seedlings (3.3, 63.3 and 43.3%) were obtained by A. versicolor. Several crop seeds were responded differently for different fungal treatments. Hundred percent infected/spotted seeds in FM were recorded only for mustard with Trichoderma family that implied its strong sensitiveness to its metabolites.
    Matched MeSH terms: Waste Disposal, Fluid/methods*
  14. Fakhru'l-Razi A, Alam MZ, Idris A, Abd-Aziz S, Molla AH
    PMID: 12369644
    Bioconversion of higher strength of domestic wastewater biosolids (sludge) (4% w/w of TSS) by mixed fungal culture of Aspergillus niger and Penicillium corylophilum was studied in a laboratory. The effect of potential mixed fungi on domestic wastewater sludge accelerated the liquid state bioconversion (LSB) process. The highest production of dry sludge cake (biosolids) was enriched with fungal biomass to about 85.66 g/kg containing 25.23 g/kg of protein after 8 days of treatment. The results presented in this study revealed that the reduction of chemical oxygen demand (COD), total suspended solid (TSS), and specific resistance to filtration (SRF) of treated sludge were highly influenced by the fungal culture as compared to control (uninnoculated). The maximum removal rates in treated sludge (biosolids) supernatant recorded were 92% of COD and 98.8% of TSS. Lower SRF (1.08 x 10(12) m/kg) was perceived in microbially treated sludge after 6 days of fermentation. The observed parameters were highly influenced after 8 days of treatment. The influence of pH was also studied and presented in the paper.
    Matched MeSH terms: Waste Disposal, Fluid/methods*
  15. Molla AH, Fakhru'l-Razi A, Abd-Aziz S, Hanafi MM, Roychoudhury PK, Alam MZ
    Bioresour Technol, 2002 Dec;85(3):263-72.
    PMID: 12365494
    Twenty seven filamentous fungal strains representing five genera; Aspergillus, Penicillium, Trichoderma, Myriodontium and Pleurotus were isolated from four sources; domestic wastewater sludge cake (SC) from IWK (Indah Water Konsortium) wastewater treatment plant, palm oil mill effluent compost from Sri Ulu palm Oil Processing Mill, compost of plant debris, and fungal fruiting bodies from a rotten wood stump. Thirty-three strains/isolates were tested for their ability to convert domestic wastewater sludge into compost by assessing biomass production and growth rate on sludge enriched media. The strains/isolates Aspergillus niger, SS-T2008, WW-P1003 and RW-P1 512 produced the highest dry biomass at higher sludge supplemented culture media from their respective group (Aspergillus, Trichoderma, Penicillium and Basidiomycetes, respectively). This implied these strains are better adapted for growth at higher sludge rich substances, and subsequently may be efficient in bioconversion/biodegradation of sludge. The fungi isolated from ecological closely related sources were more amendable to adaptation in a sludge rich culture media.
    Matched MeSH terms: Waste Disposal, Fluid/methods*
  16. Ramasamy P, Periathamby A, Ibrahim S
    Waste Manag Res, 2002 Dec;20(6):536-40.
    PMID: 12549665
    Carbide sludge (10.4-11.5 tonnes day(-1)) is generated from the reaction of calcium carbide (900 kg) and water (6,000 L) in the production of acetylene (2,400 m3), in three selected acetylene manufacturing plants. The sludge (of pH 12.2 and containing Cu, Pb, Fe, Mn, Ni and Zn ions whose concentrations exceed the Department of Environment limits for industrial wastewater) was treated by vacuum filtration as a substitute for the ponding system, which is environmentally less acceptable. A similar system by flocculation was also developed. The filtration system represents an improvement over the ponding method, as shown by a pH of 7 for the clear filtrate; the solid cake, which contains 98% of the metals, can be conveniently disposed at an integrated scheduled waste treatment centre.
    Matched MeSH terms: Waste Disposal, Fluid/methods*
  17. Ujang Z, Wong CL, Manan ZA
    Water Sci Technol, 2002;46(11-12):77-84.
    PMID: 12523736
    Industrial wastewater minimization can be conducted using four main strategies: (i) reuse; (ii) regeneration-reuse; (iii) regeneration-recycling; and (iv) process changes. This study is concerned with (i) and (ii) to investigate the most suitable approach to wastewater minimization for an old textile industry plant. A systematic water networks design using water pinch analysis (WPA) was developed to minimize the water usage and wastewater generation for the textile plant. COD was chosen as the main parameter. An integrated design method has been applied, which brings the engineering insight using WPA that can determine the minimum flowrate of the water usage and then minimize the water consumption and wastewater generation as well. The overall result of this study shows that WPA has been effectively applied using both reuse and regeneration-reuse strategies for the old textile industry plant, and reduced the operating cost by 16% and 50% respectively.
    Matched MeSH terms: Waste Disposal, Fluid/methods*
  18. Salim MR, Othman F, Imtiaj Ali M, Patterson J, Hardy T
    Water Sci Technol, 2002;46(9):339-46.
    PMID: 12448487
    Several types of water treatment technologies including adsorption are now being used to treat polluted water. In this paper the removal of phenol by adsorption will be discussed. Activated carbons are successfully applied for purification of potable water and the removal of organic pollutants in wastwater. This paper is concerned with a low cost approach to treating waste water that is significant especially for those countries where oil palm is an available agricultural product like Malaysia, Ivory Coast, Nigeria, Thailand, Papua New Guinea. In the coastal region coconut is an available agricultural product and activated carbon prepared using coconut shell is also an economical method of water treatment. The materials used in this study were Commercial Activated Carbon (CAC), prepared from coconut shell and Modified Oil Palm Shell (MOPAS) of 1 to 2 mm diameters. The surface area of CAC and MOPAS was 38.5 m2/g and 38.2 m2/g respectively and the iodine number was determined as 674 and 454 for CAC and MOPAS, respectively. From the study the result shows above 70% removal efficiency for 5 mg/L and 40% removal efficiency for 20 mg/L of phenol solution. The performance efficiency will be discussed based on batch test, following Freundlich adsorption isotherm. The results indicate that CAC exhibits a higher adsorptive capacity (Kf of 0.079) as compared to MOPAS (Kf of 0.048). Hence a better removal efficiency for CAC at lower concentration of phenol. Results from column tests show a better adsorptive capacity for CAC (2.73) as compared to MOPAS (2.48).
    Matched MeSH terms: Waste Disposal, Fluid/methods*
  19. Noor MJ, Muyibi SA, Ahmed T, Ghazall AH, Jusoh A, Idris A, et al.
    Water Sci Technol, 2002;46(9):331-8.
    PMID: 12448486
    A laboratory study was conducted on an Extended Aeration-Microfiltration (EAM) reactor in treating a food industry wastewater. The reactor contained horizontally laid hollow fibre microfiltration (MF) units that were fully submerged. The MF units were connected to a peristaltic pump that was used to extract permeate continuously under suction pressure. Continuous aeration from beneath the modules provided the crossflow effect to the MF units. Active activated sludge was used in the start-up where the sludge was mixed together with the feed water at a Food/Microorganisms (F/M) value of about 0.1. Primary effluent with Chemical Oxygen Demand (COD) values ranged between 1,500 and 3,000 mg/l was used as feed water. The EAM reactor was operated for nearly three months without initiating cleaning of the MF units. A suction pressure of 0.9 bar and Mixed Liquor Suspended Solids (MLSS) of over 5,500 mg/l were reached when nearing the end of the three month operation period. Permeate COD and turbidity reduction of over 97% and 99% respectively, were achieved. Prior to this, the MF module arrangements were studied; where vertically arranged modules were found to perform poorly as compared to the horizontally laid modules, in terms of clean water permeate flux.
    Matched MeSH terms: Waste Disposal, Fluid
  20. Idris A, Yen OB, Hamid MH, Baki AM
    Water Sci Technol, 2002;46(9):279-86.
    PMID: 12448479
    A sludge lagoon has been adopted as a simple and cost effective method for dewatering of sludge. The processes occurring in a sludge lagoon include thickening, dewatering, storage and stabilization; all happening simultaneously. The objective of this study is to determine the dewatering and drying rates at pilot-scale which occur in a lagoon having different design configurations. Two types of sludge lagoons with different initial sludge depth (0.75 m and 0.375 m) were investigated to measure the drying behavior and drying efficiency. The first design is a sludge lagoon with a clay bottom where the dewatering mechanisms are decanting supernatant and evaporation. The second design is a sludge lagoon installed with a sand and underdrains system, where the dewatering mechanisms are filtration or draining and evaporation. Sludge drying kinetic models with high fitness were plotted to describe the sludge drying behavior. Drying of sludge in a sludge lagoon with a clay bottom can best be described by an exponential function. Whereas, drying of sludge in a sludge lagoon with sand and underdrains system followed a logarithmic function. A lagoon designed with sand and underdrains system and having shallower sludge depth was the most efficient. The reduction in volatile solids was lower than 4% during the study period. The drying process proceeded with an increase in dryness and decline in pH value.
    Matched MeSH terms: Waste Disposal, Fluid/methods*
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