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1.
A laboratory-scale biological activated carbon (BAC) process was conducted to treat a reactive azo-dye (reactive red 22) by Pseudomonas luteola and the kinetics of azo-dye decolorization was investigated. The BAC-reactor removed 89% of reactive red 22 while P. luteola biofilm and suspended P. luteola reached a maximum growth rate at a steady-state condition. The azo-dye effluent from BAC-reactor met a discharge standard required by Taiwan government. The kinetic BAC-model, based on fundamental mechanisms, including surface diffusion, liquid-film mass transfer, Monod kinetics, growth of biofilm and suspended cells as well as shear loss of biofilm, was developed to describe the performance of biofilm attached on activated carbon in the azo-dye treatment process. The kinetic BAC-model predictions and experimental results for simultaneous adsorption and biodegradation of azo-dye contaminants were compared. It is shown that the fundamental mechanisms of BAC-process for azo-dye decolorization are not the simple addition but the synergetic combination of carbon adsorption and biodegradation of P. luteola strain. The major aspects of such synergism are the bioregeneration of the adsorbent and the reduction of the toxic effect of azo-dye contaminants in textile wastewater on P. luteola strain. The kinetic BAC-model not only provides insights into underlying mechanisms of adsorption and biodegradation but also can be used as a powerful tool to assist the design of a pilot-scale or full-scale BAC-process to treat azo-dye contaminants by P. luteola cells in textile wastewater.  相似文献   

2.
Heavy metal removal is mainly conducted by adjusting the wastewater pH to form metal hydroxide precipitates. However, in recent years, the xanthate process with a high metal removal efficiency, attracted attention due to its use of sorption/desorption of heavy metals from aqueous solutions. In this study, two kinds of agricultural xanthates, insoluble peanut‐shell xanthate (IPX) and insoluble starch xanthate (ISX), were used as sorbents to treat the copper‐containing wastewater (Cu concentration from 50 to 1,000 mg/L). The experimental results showed that the maximum Cu removal efficiency by IPX was 93.5 % in the case of high Cu concentrations, whereby 81.1 % of copper could rapidly be removed within one minute. Moreover, copper‐containing wastewater could also be treated by ISX over a wide range (50 to 1,000 mg/L) to a level that meets the Taiwan EPA's effluent regulations (3 mg/L) within 20 minutes. Whereas IPX had a maximum binding capacity for copper of 185 mg/g IPX, the capacity for ISX was 120 mg/g ISX. IPX is cheaper than ISX, and has the benefits of a rapid reaction and a high copper binding capacity, however, it exhibits a lower copper removal efficiency. A sequential IPX and ISX treatment (i.e., two‐stage xanthate processes) could therefore be an excellent alternative. The results obtained using the two‐stage xanthate process revealed an effective copper treatment. The effluent (Ce) was below 0.6 mg/L, compared to the influent (C0) of 1,001 mg/L at pH = 4 and a dilution rate of 0.6 h–1. Furthermore, the Cu‐ISX complex formed could meet the Taiwan TCLP regulations, and be classified as non‐hazardous waste. The xanthatilization of agricultural wastes offers a comprehensive strategy for solving both agricultural waste disposal and metal‐containing wastewater treatment problems.  相似文献   

3.
Coir pith, a waste biomass, from coconut coir industry was used to prepare activated carbon with ZnCl2 and employed for the removal of 2-chlorophenol (2-CP) from aqueous solution and wastewater. Zinc chloride–activated coir pith carbon (ZnCPC) was prepared by mixing coir pith with ZnCl2 in the ratio 2:1 and carbonized at 700°C for 1 h. ZnCPC was characterized using standard physicochemical methods, Brunaver, Emmett, and Teller (BET) surface area, and scanning electron microscopy (SEM) studies. Batch mode adsorption studies were carried out to evaluate the effect of contact time, initial concentration, adsorbent dose, pH, and temperature. The Langmuir adsorption capacity Q 0 was found to be 149.3 mg g?1. Kinetic studies showed that the adsorption obeyed second-order and Bangham's model. Equilibrium adsorption data fit better into Langmuir, Freundlich, and D-R isotherms. pH effect and desorption studies showed that ion-exchange mechanism was involved in the adsorption process. Effect of temperature was not significant. Quantitative removal of 2-CP from synthetic wastewater was also achieved. ZnCPC is economically effective compared to commercial activated carbon, because the raw material is abundantly and freely available and it can be used effectively in the treatment of water contaminated with 2-CP.  相似文献   

4.
Abstract

The technical feasibility of removing chromium(III) from contaminated tannery wastewater by adsorption on naturally available marl, referred to as HEWAR in Palestine, has been investigated by batch experiments. The effects of various parameters on the percentage relative adsorption concentration were carried out by UV-vis spectrophotometry. Percentage relative concentration curves showed an increase with time until approaching a plateau (adsorption capacity). The adsorption capacity increased with the marl-to-liquid ratio, providing complete removal of chromium above 0.003g mL?1 accomplished within 7 hours, while the marl particles were kept in suspension by stirring. The adsorption capacity increased with pH above 5.0, and decreased below this value. One sample of marl can be used for adsorbing chromium from various batches of wastewater until the adsorption sites are full.  相似文献   

5.
Jatropha seed press cake (JPC), a biodeisel waste, was investigated for its use as biosorbent for Cr(VI) removal from wastewater. The acid-pretreated biomass exhibited 1.9-fold higher biosorption efficiency for Cr(VI). The Cr(VI) biosorption efficiency was found to increase with decrease in pH of aqueous medium. The adsorption capacity of biosorbent for Cr(VI) increased with increasing concentration of Cr(VI). The biosorption of Cr(VI) by acid-treated JPC followed a pseudo-second-order kinetics. The results of equilibrium studies showed that the biosorption process fitted the Langmuir isotherm model, with a maximum adsorption capacity of 22.727 mg of Cr(VI)/g of biosorbent at 30°C. The activation energy was found to be 27.114 kJ/mol, suggesting that the adsorption process was mainly a physical process. The important thermodynamic parameters of adsorption (ΔG, ΔH, andΔS) were determined, which indicated that the Cr(VI) sorption by JPC is a spontaneous and endothermic process.  相似文献   

6.
The risk of heavy metal contamination in domestic water causes serious health and environmental problems. Biosorption has been considered as an efficient and alternative way for treatment of heavy metal–contaminated wastewater. The potentials of dried charophytes, Chara aculeolata and Nitella opaca, to biosorb lead (Pb), cadmium (Cd), and zinc (Zn) from synthetic solutions and municipal wastewater were investigated. The efficiency of metal removal was studied under varied conditions in different sorbent dosages, pH, and contact times. Biosorption isotherm and kinetics were used to clarify heavy metal preference and biosorption mechanism. C. aculeolata and N. opaca performed well in the biosorption of all three metal ions, with preference towards Pb, followed by Cd and Zn, in the single-metal solutions. Pb adsorption onto algal biomass followed first-order rate kinetics (N. opaca) and intraparticle diffusion (C. aculeolata and N. opaca). These results indicated physical adsorption process between Pb ions and both algal biomasses. Cd and Zn biosorption kinetics fitted the second-order rate model, indicating chemical adsorption between metal ions and both algae. The experimental data of three-metal biosorption fitted well to Langmuir isotherm model, suggesting that the metal ion adsorption occurred in a monolayer pattern on a homogeneous surface. C. aculeolata exhibited slightly higher maximum uptake of Pb, Cd, and Zn (105.3 mgPb/g, 23.0 mgCd/g, 15.2 mgZn/g) than did N. opaca (104.2 mgPb/g, 20.5 mgCd/g, 13.4 mgZn/g). In multi-metal solutions, antagonistic effect by metal competition was observed. The ability of charophytes to remove Pb and Zn was high in real municipal water (81–100%). Thus, the charophytic biomass may be considered for the treatment of metal contamination in municipal wastewater.  相似文献   

7.
The genetic identity of Ixodes granulatus ticks was determined for the first time in Taiwan. The phylogenetic relationships were analyzed by comparing the sequences of mitochondrial 16S ribosomal DNA gene obtained from 19 strains of ticks representing seven species of Ixodes and two outgroup species (Rhipicephalus sanguineus and Haemaphysalis inermis). Four major clades could be easily distinguished by neighbour-joining analysis and were congruent by maximum-parsimony method. All these I. granulatus ticks of Taiwan were genetically affiliated to a monophyletic group with highly homogeneous sequences (92.2–99.3% similarity), and can be discriminated from other Ixodes species and other genera of ticks with a sequence divergence ranging from 11.7 to 30.8%. Moreover, intraspecific analysis revealed that two distinct lineages are evident between the same species of I. granulatus ticks collected from Taiwan and Malaysia. Our results demonstrate that all these I. granulatus ticks of Taiwan represent a unique lineage distinct from the common vector ticks (I. ricinus complex) for Borrelia burgdorferi spirochetes.  相似文献   

8.
In wastewater treatment microbial cultures immobilised on various matrices are used to protect the microbes from confronting shock loads of organic pollutants. Because of the beneficial effect of activated carbon, it is generally used as a carrier material in comparison to other matrices. In this study mutant strain of P. pictorum (MU 174) was immobilised on ricebran based activated carbon. The effect of contact time, pH, particle size, mass of activated carbon, temperature and ionic strength on adsorption of MU 174 on activated carbon were investigated. The adsorption kinetic parameters like K p , K ad and H were also determined.Authors are grateful to Dr. K.V. Raghavan, Director, CLRI for his keen interest in publishing this work. Financial assistance by CSIR/UGC is gratefully acknowledged by Miss S. Chitra.  相似文献   

9.
This study was conducted in order to understand the mechanism of Cd and Pb adsorption in aqueous solutions by raw and modified saw dust (SD) of Alstonia macrophylla. The biosorbent was characterized by Boehm titration, specific surface area, scanning electron microscopy (SEM), X-ray energy dispersion (EDAX), and Fourier transform infrared (FTIR) analyses. SD was treated using organic acids and bases. Batch studies were conducted for raw and modified SD to determine the effect of initial concentration, pH, ionic strength, and contact time on metal adsorption. The specific surface area and total basic and acidic groups of SD were 77 m2/g and 1521 and 2312 μmol/g, respectively. The adsorption of both metals onto SD was pH dependent. No ionic strength dependency was observed in adsorption of Cd and Pb at pH >6, indicating inner sphere surface complexation. Monolayer adsorption is dominant in both metal sorptions by SD. Furthermore, there is no competition between metals on adsorption and raw SD was found to be suitable for removal of Cd and Pb as compared to organic acid– or base-treated SD. Maximum adsorption capacity of SD for Cd and Pb were 30.6 and 204.2 mg/g, respectively. Results indicate that the A. macrophylla SD can be considered as a potential material for metal ion removal from wastewater.  相似文献   

10.
Borrelia valaisiana-related spirochetes were detected for the first time in Ixodes granulatus ticks collected in Taiwan. The genetic identities of these detected spirochetes were determined by analyzing the gene sequences amplified by a genospecies-specific polymerase chain reaction assay based on the outer surface protein A (OspA) gene of B. burgdorferi sensu lato. Phylogenetic relationships were analyzed by comparing the sequences of OspA gene obtained from 35 strains of Borrelia spirochetes representing six genospecies of Borrelia. Eight major clades can be easily distinguished by neighbour-joining analysis and were congruent by maximum-parsimony method. Except one strain (KH-74), all these Borrelia spirochetes of Taiwan were genetically affiliated to the same clade with highly homogeneous sequences (97.8–100% similarity), and can be discriminated from other groups of B. valaisiana and other genospecies of Borrelia spirochetes with a sequence divergence ranging from 3 to 19.6%. Moreover, intraspecific analysis also revealed that three distinct groups are evident between the same species of B. valaisiana spirochetes detected in Taiwan. Our results provide the first evidence of B. valaisiana spirochetes detected in I. granulatus ticks collected in Taiwan and demonstrate that all these B. valaisiana spirochetes of Taiwan represent three major groups distinct from the European group of B. valaisiana spirochetes.  相似文献   

11.
The phylogenetic relationship among freshwater crab species of Geothelphusa from northern Taiwan and the Yaeyama Group of islands (including Iriomote and Ishigaki) in the southern Ryukyus was studied using the mitochondrial genes 16S rRNA and COI. Our results support the hypothesis that speciation of Geothelphusa among these islands was the result of cyclic glaciations and interglaciations during the Pleistocene. Two main clades, one the Taiwan Group (containing several clades, including most Taiwanese Geothelphusa species except Geothelphusa miyazakii but including Geothelphusa minei from Yaeyama), was estimated to be separated from its sister group, the southern Ryukyus-northern Taiwan (SRN) clade (including G. miyazakii, Geothelphusa shokitai, Geothelphusa fulva and G. marginata from northern Taiwan, the Pinnacle Islands [=Diaoyutai Islands or Senkaku Islands] and Yaeyama) at about 5.3 million years ago (mya). G. shokitai was separated from others within the SRN clade at 2.4 mya, but was probably derived from G. miyazakii in northern Taiwan. The ancestor of G. miyazakii is hypothesised to have dispersed from ancestors in Yaeyama and then isolated at 2.0 mya during the Pleistocene interglaciations. This is similar to the speciation of G. minei in Yaeyama at 1.5 mya, except that its ancestors originated from north-eastern Taiwan. Four clades of freshwater crabs are present in the Fushan Botanical Garden, located in the mountainous area of north-eastern Taiwan, which might be due to the historical rearrangements of the drainage and proximity of the various river origins.  相似文献   

12.
The work deals with the removal of textile dyes from wastewater using cyanobacteria and integrating the dye removal ability of the organism with the ability to produce hydrogen. Phormidium valderianum, a marine cyanobacterium, has been shown to remove more than 90% of textile dyes Acid red, Acid red 119 and Direct black 155 from the solutions in the pH range higher than 11. Presence of phenolic compounds and metal chelators drastically reduced the dye adsorption capacity of the organisms. The mechanism involved in the dye adsorption has been investigated. Hydrogen production by cells grown in presence of dyes in any phase of their growth was found to be less in comparison to that of control (grown without dye). A laboratory scale reactor was designed to integrate the hydrogen production and dye removal ability of P. valderianum.  相似文献   

13.
Horseradish peroxidase (HRP) is a highly specific enzyme with great potential for use in the decolorization of synthetic dyes. A comprehensive study of HRP immobilization using various techniques such as adsorption and covalent immobilization on the novel carrier Purolite® A109 with a special focus on enzymatic decolorization and toxicity of artificially colored wastewater. The immobilized preparations with an activity of 156.21 ± 1.41 U g−1 and 85.71 ± 1.62 U g−1 after the HRP adsorption and covalent immobilization, respectively, were obtained. Stability and reusability of the immobilized preparations were also evaluated. A noteworthy decolorization level (~90%) with immobilized HRP was achieved. Phytotoxicity testing using Mung bean seeds and acute toxicity assay with Artemia salina has confirmed the applicability of the obtained immobilized preparation in industrial wastewater plants for the treatment of colored wastewater.  相似文献   

14.
Abstract

Adsorption of dyes onto natural materials like polysaccharides is considered a green chemistry approach for remediation of wastewater. In this work, the polysaccharide isolated from the corm of Colocasia esculenta (L.) Schott or taro tuber (CEM) was utilized for removing methylene blue (MB) from aqueous solution by batch adsorption method. The CEM adsorbent was characterized by FTIR spectroscopy, Brunauer–Emmett–Teller (BET), and scanning electron microscopy (SEM). The solution pH and adsorbent dose have been found to have a significant positive correlation with the adsorptive removal efficiency of CEM for MB dye. The removal efficiency of CEM was found to be 72.35% under the optimum conditions; 20?mg/L initial concentration of dye, 120?mg of adsorbent dose, solution pH 8.5, 311.2?K temperature and 80?min contact time. The adsorption of MB onto CEM followed best the Freundlich isotherm and pseudo-second-order kinetics. The adsorption was thermodynamically favorable and was endothermic in nature. The desorption/adsorption data justifiably indicated the reuse capability of CEM adsorbent for MB adsorption. Hence, CEM may be regarded as an eco-friendly and cost-effective natural adsorbent for MB dye removal from aqueous solution.  相似文献   

15.
Spider-Mite Problems and Control in Taiwan   总被引:3,自引:0,他引:3  
Problems with spider mites first appeared in Taiwan in 1958, eight years after the importation of synthetic pesticides, and the mites evolved into major pests on many crops during the 1980s. Of the 74 spider mite species recorded from Taiwan 10 are major pests, with Tetranychus kanzawai most important, followed by T. urticae, Panonychus citri, T. cinnabarinus, T. truncatus and Oligonychus litchii. Most crops suffer from more than one species. Spider mites reproduce year-round in Taiwan. Diapause occurs only in high-elevation areas. Precipitation is the most important abiotic factor restricting spider-mite populations. Control is usually accomplished by applying chemicals. Fifty acaricides are currently registered for the control of spider mites. Acaricide resistance is a serious problem, with regional variation in resistance levels. Several phytoseiid mites and a chrysopid predator have been studied for control of spider mites with good effect. Efforts to market these predators should be intensified so that biological control can be a real choice for farmers.  相似文献   

16.
Adsorption techniques are widely used to remove industrial wastewater contaminants, especially non-biodegradable colourants. In this study, Iranian zeolite clinoptilolite was synthesised using magnetic iron oxide as an inexpensive and efficient adsorbent. The results showed that using natural zeolite, the removal efficiency of 26.8.6% at pH?=?3 reached 48% at pH?=?9. However, the adsorption capacity of the modified clinoptilolite did not change by increasing pH; it ranged from 96.4% to 98.6%. Moreover, increase in the initial concentration of the dye did not have any effects on the removal efficacy of the modified clinoptilolite. Using natural zeolite, on the other hand, the adsorption capacity showed a significant decrease and reached less than 10% at the 200?mg/l dye concentration. At the optimal contact time of 45?min, the dye removal rate by the modified zeolite was more than 98% at the optimal dose of 0.5?g. Indeed, the adsorption isotherm complied with Freundlich equation. Overall, the results showed that in comparison to the natural zeolite, the adsorption capacity of the clinoptilolite modified by iron nanoparticles increased significantly due to the uniformity of the cavities and increase in the surface of the adsorbent.  相似文献   

17.
The genus Reinboldiella essentially consists of tiny, membranous blades, epiphytic on benthic red algae, with a wide distribution in the north-western Pacific Ocean (Taiwan, Korea and Japan). In this study, we re-examined the generitype R. schmitziana from Taiwan and neighbouring islands. Two new species of Reinboldiella, R. orientalis sp. nov. and R. taiwanensis sp. nov. are recognized from Taiwan based on comparative morphological studies and molecular analyses of RuBisCO large subunit (rbcL) gene sequences. Reinboldiella orientalis is characterized by its rosette-like appearance, with both erect and prostrate, membranous flat blades whereas R. taiwanensis is distinguishable by mainly consisting of erect, membranous blades with few, short prostrate blades in basal parts of the thalli. Thalli of R. schmitziana also have a rosette-like appearance, but their erect flat blades have cylindrical bases or stipes. The rbcL phylogenetic analyses also support the separation of R.schmitziana’ from Taiwan and R. schmitziana from Japan and Korea.  相似文献   

18.
To investigate the genetic specificity of Ixodes granulatus ticks collected from Taiwan, the genetic identities and phylogenetic relationships were analyzed by comparing the sequences of the internal transcribed spacer 2 (ITS2) region obtained from 27 strains of ticks representing twelve species of Ixodes. Five major clades can be easily distinguished by neighbour-joining analysis and were congruent by maximum-parsimony method. All these I. granulatus ticks collected from Taiwan and Japan were genetically affiliated to a monophyletic group with highly homogeneous sequences (95.8–99.5% similarity), and can be discriminated from other species and subgenera of Ixodes ticks with a sequence divergence ranging from 13.6% to 62.9%. Moreover, interspecific analysis revealed that four distinct lineages are evident between Ixodes ticks, and all these I. granulatus ticks collected from Taiwan and Japan belong to the same lineage. Our results provide the first investigation on the genetic specificity of I. granulatus ticks, and demonstrate that all these I. granulatus ticks represent a unique lineage distinct from other species and subgenera of Ixodes ticks. The feasibility of ITS2-based genetic analysis for species-specific identification of I. granulatus ticks around East Asia was highly anticipated.  相似文献   

19.
Mitochondrial DNA cytochrome b sequences (1140 bp) in 61 specimens of Chinese spiny loach Cobitis sinensis from 12 drainages in Taiwan were identified as two major clades, exhibiting a southern and a northern distribution, north of TzengWen and south of TzengWen (including TzengWen), respectively. The divergence time between these two phylogroups was estimated at 7·34–9·06 million years before present (b.p. ), but these two phylogroups were formed c. 3·41–4·23 and 2·22–2·75 M b.p. , respectively. Moreover, geological events have been recalculated that Taiwan Island emerged above sea level at an estimate of c. 4–5 M b.p. , and quickly became its present shape at c. 2 M b.p. through mountain building. These results suggest that these two major clades of C. sinensis in Taiwan might originate from two different continental populations, since the island's initial isolation in the Pliocene. Within southern Taiwan, the initial colonization was hypothesized to be in KaoPing River, followed by its northward dispersal. The high divergence between KaoPing and TzengWen was influenced by glaciations and landforms. Within north Taiwan, the colonization was from the Miaoli Plateau through western Taiwan to north‐eastern and northern Taiwan. This dispersal pattern is concordant with the previously proposed hypothesis. Apparently, both geological and phylogeographic evidence suggested that river capture of the upper Takia River by the LanYang River promoted range expansion in freshwater fishes and also indicated that the Central Range within Taiwan did not act as a barrier to the dispersal of C. sinensis.  相似文献   

20.
A novel type of magnetic molecularly imprinted polymers (MMIP) as the solid‐phase extraction sorbent was prepared, which can extract effectively the allocryptopine from the waster of Macleaya cordata (Willd) R. Br. In this study, MMIP was synthesized by using Fe3O4@SiO2, 4‐vinyl‐pyridine, ethylene glycol dimethacrylate, and allocryptopine, and these ingredients worked as magnetic core, functional monomer, cross‐linker, and template, respectively. Concluded by the calculation of Gaussian 09 software, different ratio models of 4‐vinyl‐pyridine and allocryptopine were simulated, and the optimal ratio was 1:5 and the energy was ?2205.34 kJ/mol. Transmission electron microscopy, vibration sample magnetometry, X‐ray diffraction, Fourier transform infrared spectroscopy, and thermogravimetric analysis were used to determine the morphology and structure of MMIP. Furthermore, the results of adsorption experiments indicated that MMIP had high selectivity, excellent recyclability, and good adsorption performance (9.86 mg/g, 298 K). The adsorption process was consistent with the Langmuir adsorption isotherm (R2 > 0.98, 298 K) and pseudo‐second‐order kinetics model (R2 > 0.99, 298 K). After six times adsorption‐desorption experiments, the adsorption amount of MMIP only reduced to 8.5%. In the experiments of selective adsorption, MMIP has better adsorption properties for allocryptopine (ALL, C21H23NO5) than those having the same functional group. The limit of detection (LOD) was 0.4 μg/mL. The relative standard deviation ranged from 0.09% to 0.72%. The recovery of allocryptopine in samples ranged from 93.60% to 106.19%. In addition, the synthesized complex had a certain adsorption effect on allocryptopine separating from the wastewater of Macleaya cordata (Willd) R. Br.  相似文献   

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