OBJECTIVENitrobenzene extraction enhanced by salting-out effect was employed to recover aniline from wastewater at 25 degrees C.

METHODBatchwise experiments were conducted to elucidate the influence of various operating variables on the extracting performance, including acidity of wastewater, initial aniline concentration, ratios of solvent to wastewater, extraction stages, concentrations and different types of inorganic salts, such as NaCl, KCl, Na(2)SO(4), CaCl(2) and K(2)SO(4).

RESULTSNitrobenzene with a concentration of 20% and a pH value of 9.1 at the temperature of 25 degrees C together with NaCl of a concentration of 14 wt.% realized nearly 100% aniline recovery at the fifth stage of wastewater treatment.

CONCLUSIONSHigh pH values and volume ratios of nitrobenzene/wastewater are more suitable for recovery of aniline. In addition, recovery of aniline is significantly elevated with increase of the concentration of salts, whose promoting effects are in the following order: NaCl>Na(2)SO(4)>K(2)SO(4)>CaCl(2)>KCl on the weight basis of wastewater. Furthermore, aniline in wastewater can be almost completely recovered by five-stage sequential nitrobenzene extraction, which is promoted continuously by the salting-out effect.

Aniline Compounds ; isolation & purification ; Hydrogen-Ion Concentration ; Nitrobenzenes ; chemistry ; Water Pollutants, Chemical ; isolation & purification

OBJECTIVE: To establish the solid phase extraction (SPE) with GC/MS technology for fish poisoning cases to determine five pesticides in fishpond. METHODS: By three solid phase extraction column including Oasis HLB cartridge, Bond Elut C18 and SampliQ C18, the recovery rate was compared to extract and purify five pesticides in fishpond. The effects of different kinds and dosages of eluents on extract rate were also reviewed. RESULTS Using Bond Elut C18 as solid phase extraction column and 3 mL benzene as eluent, the linear range of mass concentration of five pesticides in fishpond was 1-50 μg/mL, and the correlation coefficient was 0.996 2-0.999 6. The limit of detection was 3.4-26 μg/L and the recovery was 61.49%-102.48%. The relative standard deviations was less than or equal to 3.01%. CONCLU-SION: With high sensitivity, good accuracy and precision, SPE-GC/MS has simple and quick operation and less solvent. It can be applied to determination of five pesticides in fishpond.
Gas Chromatography-Mass Spectrometry/methods* ; Pesticides/isolation & purification* ; Solid Phase Extraction ; Solvents ; Water Pollutants, Chemical/isolation & purification*

The flocculating yeast strain SPSC01 is a fusant strain of Saccharomyces cerevisiae and Schizosaccharomyces pombe. The use of SPSC01 to absorb Cr(VI) from Cr(VI) containing aqueous solution would greatly reduce the cost of post-adsorption separation, since the superior flocculating property of SPSC01 would allow easy separation of the Cr(VI)-biomass from the solution. In order to investigate the effects of flocculating proteins on Cr(VI) reduction and absorption by SPSC01, the absorption behaviors of SPSC01 and its parental strains were compared. The results showed that Cr(VI) removal rate of SPSC01 was almost the same as that of S. pombe, which also has flocculating ability, but was faster than that of S. cerevisiae, which has no flocculating ability. When the system reached equilibrium, the amount of total Cr adsorbed by S. pombe, SPSC01 and S. cerevisiae were 68.8%, 48.6% and 37.5%, respectively. This showed that flocculation was beneficial to Cr(VI) reduction and adsorption, and suggested that focculating proteins may play a role in enhancing the Cr(VI) adsorption capacity of SPSC01 and S. pombe. We investigated the mechanism of Cr(VI) adsorption by SPSC01 using chemical modification and FTIR. The results indicated that the major functional groups (amino, carboxyl and amide) of surface proteins may contribute to the absorption of Cr(VI).
Adsorption ; Biodegradation, Environmental ; Chromium ; isolation & purification ; Flocculation ; Saccharomyces cerevisiae ; metabolism ; Schizosaccharomyces ; metabolism ; Surface Properties ; Water Pollutants, Chemical ; isolation & purification

OBJECTIVEThis study was to assess the influence of interaction of combination of immobilized nitrogen cycling bacteria (INCB) with aquatic macrophytes on nitrogen removal from the eutrophic waterbody, and to get insight into different mechanisms involved in nitrogen removal.

METHODSThe aquatic macrophytes used include Eichhornia crassipes (summer-autumn floating macrophyte), Elodea nuttallii (winter-growing submerged macrophyte), and nitrogen cycling bacteria including ammonifying, nitrosating, nitrifying and denitrifying bacteria isolated from Taihu Lake. The immobilization carriers materials were made from hydrophilic monomers 2-hydroxyethyl acrylate (HEA) and hydrophobic 2-hydroxyethyl methylacrylate (HEMA). Two experiments were conducted to evaluate the roles of macrophytes combined with INCB on nitrogen removal from eutrophic water during different seasons.

RESULTSEichhornia crassipes and Elodea nuttallii had different potentials in purification of eutrophic water. Floating macrophyte+bacteria (INCB) performed best in improving water quality (during the first experiment) and decreased total nitrogen (TN) by 70.2%, nitrite and ammonium by 92.2% and 50.9%, respectively, during the experimental period, when water transparency increased from 0.5 m to 1.8 m. When INCB was inoculated into the floating macrophyte system, the populations of nitrosating, nitrifying, and denitrifying bacteria increased by 1 to 2 orders of magnitude compared to the un-inoculated treatments, but ammonifying bacteria showed no obvious difference between different treatments. Lower values of chlorophyll a, COD(Mn), and pH were found in the microbial-plant integrated system, as compared to the control. Highest reduction in N was noted during the treatment with submerged macrophyte+INCB, being 26.1% for TN, 85.2% for nitrite, and 85.2% for ammonium at the end of 2nd experiment. And in the treatment, the populations of ammonifying, nitrosating, nitrifying, and denitrifying bacteria increased by 1 to 3 orders of magnitude, as compared to the un-inoculated treatments. Similar to the first experiment, higher water transparency and lower values of chlorophyll a, COD(Mn) and pH were observed in the plant+ INCB integrated system, as compared to other treatments. These results indicated that plant-microbe interaction showed beneficial effects on N removal from the eutrophic waterbody.

Biodegradation, Environmental ; Eutrophication ; physiology ; Magnoliopsida ; metabolism ; Nitrogen ; isolation & purification ; pharmacokinetics ; Systems Integration ; Water Microbiology ; Water Pollutants, Chemical ; isolation & purification ; pharmacokinetics ; Water Purification ; methods

The process performance of simultaneous anaerobic sulfide and nitrate removal was studied. The results showed that the process held a high sulfide and nitrate removal loading rate of 3.73kg/(m3 x d) and 0.80kg/(m3 x d), respectively, under steady state. It was capable of tolerating high influent substrate concentration (580mg/L and 110mg/L) with the optimum substrate concentration of 280mg/L and 67.5mg/L. It was capable of tolerating short hydraulic retention time (HRT) with the optimum HRT of 0.13d. Careful operation was needed when HRT was shortened because the process performance was deteriorated abruptly.
Anaerobiosis ; Bioreactors ; Nitrates ; isolation & purification ; Sulfides ; isolation & purification ; Time Factors ; Waste Disposal, Fluid ; methods ; Water Pollutants, Chemical ; isolation & purification ; Water Purification ; methods

OBJECTIVETo investigate the removal of cadmium from aqueous solution by waste fungal biomass of Aspergillus niger, originated from citric acid fermentation industry.

METHODSBatch adsorption test was used to study the biosorption equilibrium and isotherm. The Cd2+ concentration was measured with atomic adsorption spectrophotometer (AAS) HITACHI 180-80.

RESULTSThe biosorption achieved equilibrium within 30 min. The adsorption isotherm could be described by Freundlich adsorption model, and the constants K(F) and 1/n were determined to be 2.07 and 0.18, respectively, and the correlation efficiency was 0.97. The optimal pH for Cd adsorption was 6.0. The cadmium-laden biomass could be effectively regenerated using 0.1 N HCl.

CONCLUSIONThe waste biomass of Aspergillus niger, a by-product of fermentation industry, is a potential biosorbent for the removal of cadmium from aqueous solution.

Adsorption ; Aspergillus niger ; Biomass ; Cadmium ; isolation & purification ; Citric Acid ; Hydrogen-Ion Concentration ; Industrial Waste ; Waste Disposal, Fluid ; Water Pollutants, Chemical ; isolation & purification ; Water Purification ; methods

We studied simultaneous removal of sulfide and nitrite by an anaerobic process in an upflow anaerobic sludge blanket (UASB) reactor. The process could remove sulfide and nitrite 13.4 kg/(m3 x d) and 2.3 kg/(m3 x d), respectively, of the reactor tolerated high influent substrate concentration (880.0 mg S/L and 252.7 mg N/L) with the optimum substrate concentration (460.0 mg S/L and 132.3 mg N/L). It tolerated short hydraulic retention time (HRT) with the optimum HRT of 4 h. The apparent half inhibition concentrations of sulfide and nitrite were 403.9 mg S/L and 120.8 mg NL, respectively, under different influent substrate concentrations. The combined effect between sulfide and nitrite was antagonistic effect.
Anaerobiosis ; Bioreactors ; microbiology ; Nitrites ; isolation & purification ; metabolism ; Sewage ; microbiology ; Sulfides ; isolation & purification ; metabolism ; Waste Disposal, Fluid ; methods ; Water Pollutants, Chemical ; isolation & purification ; metabolism

Reduction of nitrate by zero-valent iron is a highly exergonic reaction that has long been known to occur. Use of scrap iron filings (SIF) as the PRB (Permeable Reactive Barrier) material can be used to recycle certain by-products, and identify cheaper replacements for expensive conventional PRB materials, especially pure metallic iron. The feasibility of reductive denitrification of nitrate by SIF was studied by batch experiments. Operational parameters such as pH value, SIF dosage and initial concentration of nitrate were investigated. The removal efficiency of nitrate reached 80% under the conditions of pH of 2.5, nitrate initial concentration of 45 mg/L and SIF dosage of 100 g/L within 4 h. Results indicated that nitrate removal is inversely related to pH. Low pH value condition favors for the nitrate transformation. Different from the results of others who studied nitrate reduction using iron powder, we found that there was a lag time before nitrate reduction occurs, even at low pH. Finally, the possible mechanism of nitrate reduction by Fe0 is discussed.
Computer Simulation ; Feasibility Studies ; Hydrogen-Ion Concentration ; Iron ; chemistry ; Models, Chemical ; Nitrates ; chemistry ; isolation & purification ; Nitrogen ; chemistry ; isolation & purification ; Oxidation-Reduction ; Water Pollutants, Chemical ; isolation & purification ; Water Purification ; methods

The objective of this work was to develop a valuable adsorbent for recovery of platinum by studying the properties of Pt4+ -adsorption with immobilized Citrobacter freudii XP05 biomass. Five methods for immobilization of Citrobacter freudii XP05 biomass were compared. The method with gelatin-alginate sodium as entrapment matrix was considered to be the optimal. Spherical and uniform beads were produced and the SEM micrograph indicated that the cell of strain XP08 were uniformly dispersed within the matrix. The adsorption of Pt4+ by immobilized XP05 biomass was affected with adsorptive time, pH value of the solution, immobilized biomass concentration, Pt4+ initial concentration The adsorption was a rapid process. The optimal pH value for Pt4+ adsorption was 1.5, and its adsorptive capacity increased linearly with increasing Pt4+ initial concentrations in the range of 50 - 250 mg/L. The experimental data could be fitted to Langmuir and Freundlich models of adsorption isotherm. The adsorptive capacity reached 35.2 mg/g under the conditions of 250 Pt4+ mg/L, 2.0 g/L immobilized biomass, pH 1.5 and 30 degrees C for 60 min. 98.7% of Pt4+ adsorbed on immobilized biomass could be desorbed with 0.5 mol HC1/L. The characteristics of dynamic adsorption and desorption of immobilized XP05 biomass in packed-bed reactor were investigated. The saturation uptake was 24.66 mg Pt4+ /g under the conditions of flow rate 1.2 mL/min, pH 1.5, 50 mg Pt4+/L and 1.85 g biomass(dry weight) . Adsorptive efficiency of Pt4 + by the immobilized XP05 biomass was above 78% for 4 cycles of adsorption and desorption. The recovery of platinum from waste platinum catalyst was studied. The adsorptive capacity was 20.94 mg Pt4+/g immobilized biomass under the conditions of 4.0 g/L immobilized XP05 biomass, 117.76 mg Pt4+/L and pH 1.5 for 60 min. The immobilized XP05 biomass is potentially applicable to the recovery of platinum from waste and wastewater containing platinum.
Biomass ; Bioreactors ; microbiology ; Citrobacter ; metabolism ; Microscopy, Electron, Scanning ; Microspheres ; Platinum ; isolation & purification ; metabolism ; Waste Disposal, Fluid ; methods ; Water Pollutants, Chemical ; isolation & purification ; metabolism

We prepared the nano-sized magnetic fluid in aqueous phase solution to modify the killed yeast cells (Saccharomyces cerevisiae). Subsequently, the yeast cells with good magnetic response was obtained.The infrared spectroscopy analysis showed that the modified yeast cells increased obviously the absorption at the Fe-O characteristic peak of 581 cm(-1). Moreover, the transmission electron microscopy picture indicated the magnetic nanoparticles presented individually or aggregately on the yeast cell surface. Under the experimental conditions, the magnetically labeled yeast with 160 microL showed the adsorption percentage up to 100% in 1 mL direct scarlet dye solution with the concentration of 0.4 mg/mL, and arrived at the adsorption equilibrium within 8 min. Besides, the adsorbed dyes can be eluted in 70% alcohol with a desorption percentage of 99.18%. Because of the strong adsorption capacity, the high adsorption speed and easy of magnetic separation, the magnetically modified yeast cells are the promising biosorbent candidates for removal of water-soluble dyes.
Adsorption ; Azo Compounds ; isolation & purification ; metabolism ; Biodegradation, Environmental ; Coloring Agents ; isolation & purification ; metabolism ; Magnetics ; Nanoparticles ; Saccharomyces cerevisiae ; genetics ; metabolism ; Waste Disposal, Fluid ; methods ; Water Pollutants, Chemical ; isolation & purification ; metabolism ; Water Purification ; methods