Structural performance of the finger-jointed strength of some wood species with different joint configurations

This study was conducted to evaluate the effects of adhesive type, wood species, and finger joint configurations on structural performance of the finger joint. The wood species studied were oriental beech (Fagus orientalis lipsky.), oak (Quercus robur), Scots pine (Pinus sylvestris lipsky.), poplar (Populus tremula lipsk.) and Uludağ fir (Abies bormülleriana Matff.) and adhesives were poly(vinyl acetate) (PVAc), Desmodur-VTKA (D-VTKA). However, there is little information available concerning the bending strength and modulus of elasticity for finger joints in these field. In this study, it was aimed to determine the bending strength and modulus of elasticity for finger joints. For this purpose, samples were tested according to the TS EN 310 standard. It was observed that the highest bending strength and modulus of elasticity were obtained in beech control (solid wood) samples. As for the finger joints, after the control samples, the highest bending strength value (57.4 N/mm²) was obtained from Oriental beech wood samples having a 21 mm finger length and bonded with PVAc adhesive, the highest modulus of elasticity (8885.3 N/mm²) was obtained from beech wood samples having a 21 mm finger length and bonded with PVAc adhesive. As a result of the effects of finger joints on bending strength and modulus elasticity test, if the length of finger joints increases up to 21 mm, the properties of bending strength increase.     

Impacts of impregnation with Imersol-Aqua on the compression strength of some solid wood materials

The aim of this study was to investigate the effects of impregnation with Imersol-Aqua on the compression strength of some solid wood materials. For this aim, Oriental beech (Fagus orientalis Lipsky), European oak (Quercus petrea Liebl.), Scotch pine (Pinus sylvestris Lipsky), Uludag fir (Abies Bornmülleriana Mattf.), Oriental spruce (Picea orientalis Lipsky) and Lombardy poplar (Populus nigra Lipsky) wood samples were prepared according to TS 2595 and impregnated with Imersol-Aqua, commonly being used in construction wood materials by the method of short, medium and long-term of dipping according to ASTM D 1413 and producers’ definition. After the impregnation process, compression strength was measured according to TS 2595. Consequently, among the non-impregnated wood materials, the highest compression strength was obtained in beech and pine samples. Compression strength at this situation from the highest to lowest can be enumerated beech, pine, oak, spruce, fir and poplar. With regard to the impregnation period, the sequence form the highest to lowest was as long-term, medium-term and short-term dipping. In the interaction of wood material and impregnation period, the highest compression strength values were obtained in Scotch pine (71.220 N mm⁻²) impregnated with long-term dipping method whereas the lowest in Lombardy poplar (35.710 N mm⁻²) impregnated with short-term dipping method.

In consequence, in the massive constructions and furniture elements that the compression strength after the impregnation is of great concern, long-term impregnation of solid wood material could be recommended.     

CS/h-BN/APP层层自组装涂层阻燃杨木的研究

为提高杨木的阻燃性能,利用带正电性的壳聚糖/六方氮化硼(CS/h-BN)聚电解质溶液,以及带负电性的聚磷酸铵(APP)溶液,基于层层自组装(LBL)技术,通过两聚电解质溶液之间的静电吸附作用,在木材表面成功制备出具有良好阻燃性能的CS/h-BN/APP薄膜涂层.结果表明:所制备的涂层均匀分布在木材表面,且具有良好的附着力;涂层阻燃木材试件的热释放速率、烟释放速率显著降低,第2放热峰出现时间晚于未处理木材试件,且在燃烧过程中的残余物质量始终高于未处理木材试件,完全燃尽时间则比未处理木材试件多出约100s,阻燃效果随着自组装涂层数的增加而逐渐增强;涂层阻燃木材试件的CO、CO_2气体生成量明显降低,表明阻燃涂层能有效降低木材烟气及毒性气体释放;涂层阻燃木材试件较未处理木材试件更好地保持了木材本身的结构,显示出了良好的抵抗火灾能力.     

Effect of scale and fuel type on the characteristics of pool fires for fire fighting training

This paper examines the effects of pool size and fuel type on the characteristics of pool fires. The fuels studied include hydrocarbon solvents, alcohol and their blends. The large-scale experiments were conducted on 0.445 and 1 m diameter pools in two enclosures: 41 m long×5.4 m wide×2.4 m high and 25 m long×2.7 m wide×2.4 m high, under a ventilation rate of 1–1.2 m/s. In these tests, measurements of the fuel pyrolysis mass loss rate, heat release rate (from CO₂ and CO concentrations as well as oxygen depletion), smoke extinction area (from laser attenuation), total heat flux emanating from the flame, and the yields of CO₂ and CO were made. Bench-scale tests were conducted using the same fuels and fuel blends on 100 mm× 100 mm pool fires in a Cone Calorimeter—a well-known fire test method.

The hydrocarbon+alcohol fuel blends are used to create large pool fires for fire fighting training. The aim of this study was to: (1) Formulate a fuel blend which will produce a “hot” fire for realistic fire fighting training while generating a minimal quantity of smoke to comply with the pollution regulations. (2) Investigate the effect of fuel type and scale on the properties of the pool fires. (3) Make comprehensive measurements on pool fires in tunnels which can be used for validating mathematical fire models.

This study has resulted in the formulation of a fuel blend which satisfies the requirements of fire fighting training as well as Environment Protection Authority of New South Wales. The bench and the large-scale results correlate well showing good agreement between the heat of combustion, smoke extinction area (SEA) and the yields of CO₂ and CO. The SEA increases with the CO and CO₂ yields which in turn increase with the carbon fraction and the aromatic content of the fuel/fuel blend. The SEA correlates strongly with the CO and CO₂ yields and in both the correlations, the entire data collapse on a single curve. These correlations indicate that the SEA and the CO₂ and CO yields vary mainly with the fuel type, and not so much with the pool size. The flame heat flux increases with the carbon content in the fuel.     

The impact of ferrous ion reduction of chlorite ion on drinking water process performance

The use of chlorine dioxide (ClO₂) as a primary disinfectant and pre-oxidant in drinking water treatment is being explored as an alternative to chlorine for reducing disinfection by-product formation and to assure compliance with United States Environmental Protection Agency's Stage 1 Disinfection/Disinfection By-Products Rule. However, the ClO₂ by-product chlorite ion (ClO₂⁻) is also regulated by the same regulation. Ferrous iron (Fe(II)) has been shown to effectively reduce chlorite ion to chloride ion (Cl⁻) and this study was conducted to evaluate the impact on overall treatment process performance due to the ferric hydroxide solids that form from the reaction. Ferrous iron application was explored at three different points in a pilot-scale water treatment system: pre-rapid mix, pre-settling and pre-filter. Chlorite ion concentrations were effectively reduced from 2 mg/L to less than 0.3 mg/L using an Fe(II) dose of approximately 6 mg/L for all trials. Fe(II) addition at the rapid mix caused no adverse effects and, in fact, allowed for reduction of the alum dose due to the newly formed ferric hydroxide acting as a supplemental coagulant. An increase of 241 and 247% of total suspended solids influent to the filter process was observed when Fe(II) was applied at the pre-settling and pre-filter locations. Pilot-scale filter runs during these trials were less than 2 h and never obtained true steady state conditions. Jar testing was performed to better understand the nature of the ferric hydroxide solids that are formed when Fe(II) was oxidized to Fe(III) and to explore the effectiveness of Fe(II) addition at intermediate stages in the flocculation process.     

Anaerobic biological treatment of phenol at 9.5-15 degrees C in an expanded granular sludge bed (EGSB)-based bioreactor

The aims of this study were to demonstrate the (1) feasibility of psychrophilic, or low-temperature, anaerobic digestion (PAD) of phenolic wastewaters at 10–15 °C; (2) economic attractiveness of PAD for the treatment of phenol as measured by daily biogas yields and (3) impact on bioreactor performance of phenol loading rates (PLRs) in excess of those previously documented (1.2 kg phenol m⁻³ d⁻¹). Two expanded granular sludge bed (EGSB)-based bioreactors, R1 and R2, were employed to mineralise a volatile fatty acid-based wastewater. R2 influent wastewater was supplemented with phenol at an initial concentration of 500 mg l⁻¹ (PLR, 1 kg m⁻³ d⁻¹). Reactor performance was measured by chemical oxygen demand (COD) removal efficiency, CH₄ composition of biogas and phenol removal (R2 only). Specific methanogenic activity, biodegradability and toxicity assays were employed to monitor the physiological capacity of reactor biomass samples. The applied PLR was increased to 2 kg m⁻³ d⁻¹ on day 147 and phenol removal by day 415 was 99% efficient, with 4 mg l⁻¹ present in R2 effluent. The operational temperature of R1 (control) and R2 was reduced by stepwise decrements from 15 °C through to a final operating temperature of 9.5 °C. COD removal efficiencies of c. 90% were recorded in both bioreactors at the conclusion of the trial (day 673), when the phenol concentration in R2 effluent was below 30 mg l⁻¹. Daily biogas yields were determined during the final (9.5 °C) operating period, when typical daily R2 CH₄ yields of c. 3.3 l CH₄ g⁻¹ COD_removed d⁻¹ were recorded. The rate of phenol depletion and methanation by R2 biomass by day 673 were 68 mg phenol g VSS⁻¹ d⁻¹ and 12–20 ml CH₄ g VSS⁻¹ d⁻¹, respectively.     

Effect of temperature on porosity and on chloride diffusion in cement pastes

This paper is related to the effect of temperature upon the diffusive properties and the microstructural features of cementitious materials. Our experimental studies aim at linking the transport properties to the porosity and the cracks network of the microstructure.

The studied materials were three cement pastes having different water to cement (W/C) ratios (W/C = 0.35, 0.45 and 0.60). Rise of temperature in concrete structures was simulated by heating at different temperatures (45 °C, 80 °C and 105 °C). Evolution of microstructure was essentially characterized by mercury intrusion porosimetry (MIP). Diffusion tests in non-steady-state regime were carried out in order to characterize the diffusive properties. Apparent diffusion coefficients were determined from colorimetric method to follow the ingress of chloride and an analytical solution of Fick’s second law.

Our results showed that rise of temperature induced macroscopic cracking network and modification of pore size distribution. As a consequence, the transport properties were modified by thermal treatment. These modifications were mostly explained by the increase of capillary porosity.     

Quantitative study of the effect of electromagnetic field on scale deposition on nanofiltration membranes via UTDR

Ultrasonic time-domain reflectometry (UTDR) as an in situ, non-invasive real-time technique has been successfully utilized to quantify membrane fouling and cleaning. This study describes an existing ultrasonic technique for quantitative study of the effect of magnetic fields on CaCO₃ scale deposition on the membrane surface during crossflow nanofiltration (NF). The fouling experiments were conducted with CaCO₃ solution containing Ca²⁺ of 1.8 and 3 mmol/L. The experimental electromagnetic field (EMF) was 0.02 T. A commercial NF membrane and a highly sensitive ultrasonic sensor were used in all the experiments. Results show a good relationship between the ultrasonic measurements and the development of CaCO₃ scale on the NF membrane surface. An increase in the amplitude of differential signal with operation time results from the deposition of the CaCO₃ scale layer. In addition, the movement of the differential signal in the time domain observed is associated with an increase in the thickness of the fouling layer. The UTDR technique is capable of measuring the rate of fouling layer formation under different treatment conditions, i.e. with non-magnetic field (NMF) and EMF. Scale layer of deposited CaCO₃ obtained in the experiment with NMF is denser and thicker than that with EMF. The scanning electron microscopy (SEM) and X-ray diffraction (XRD) analyses imply that the magnetic treatment suppresses the formation of calcite crystals and prefers vaterite and aragonite. Furthermore, the ultrasonic technique is sensitive to the different fouling rate between experiments carried out with 1.8 and 3 mmol/L CaCO₃ solutions. The thickness of the fouling layer measured by weight measurement is consistent with that obtained by UTDR in real time. The thinner and less dense scale layer is the main reason for the slower flux decline. Overall, independent measurements such as the flux-decline data, SEM analysis and weight measurement corroborate the ultrasonic measurements.     

Sorption of cadmium(II) and zinc(II) ions from aqueous solutions by cassava waste biomass (Manihot sculenta Cranz)

The sorption of two divalent metal ions, Cd(II) and Zn(II), onto untreated and differentially acid-treated cassava waste biomass over a wide range of reaction conditions was studied at 30°C. The metal ion removal from the spent biomass was also measured. The batch experiments show that pH 4.5–5.5 was the best range for the sorption of the metal ions for untreated and acid-treated biomass. Time-dependent experiments for the metal ions showed that for the two metals examined, binding to the cassava waste biomass was rapid and occurred within 30 min and completed within 1 h. High sorption capacities were observed for the two metals. The binding capacity experiments revealed the following amounts of metal ions bound per gram of biomass: 86.68 mg/g Cd, 55.82 mg/g Zn and 647.48 mg/g Cd, 559.74 mg/g Zn for untreated and acid-treated biomass, respectively. It was further found that the rate of sorption was particle-diffusion controlled, and the sorption rate coefficients were determined to be 2.30×10⁻¹ min⁻¹ (Cd²⁺), 4.0×10⁻³ min⁻¹ (Zn²⁺) and 1.09×10⁻¹ min⁻¹ (Cd²⁺), 3.67×10⁻² min⁻¹ (Zn²⁺) for 0.5 and 1.00 M differential acid treatment, respectively. Desorption studies showed that acid treatment inhibited effective recovery of metal ions already bound to the biomass as a result of stronger sulfhydryl-metal bonds formed. Less than 25% of both metals were desorbed as concentration of acid treating reagent increases. However, over 60% Cd and 40% Zn were recovered from untreated biomass during the desorption study. The results from these studies indicated that both untreated and acid-treated cassava waste biomass could be employed in the removal of toxic and valuable metals from industrial effluents.     

Development of an advanced biological treatment system applied to the removal of nitrogen and phosphorus using the sludge ceramics

To develop a method of forming lake sediment into sludge ceramics with porosity and good biological adhesion for use as a medium for microorganisms in wastewater treatment, a study of the effects of forming conditions was conducted by adjusting the water content of sludge and compounding some additives. By adjusting the water content of the raw material at the kneading/pelletizing step to 40–42% and adding 3% waste glass to the raw materials to make up for the lack of flux, a sludge ceramic with a density in terms of specific gravity of saturated surface dry aggregate of about 1400 kg m⁻³ was formed. In addition, to develop a small-scale wastewater treatment system capable of removing nitrogen and phosphorus, a sludge ceramic was applied as a medium for biological filtration. The results indicated that the BOD removal nitrification rate were superior to those of conventional ceramic media, reached at 95.3% and 87.4%, respectively. The introduction of iron electrolysis resulted in high treatment performance achieving BOD levels of 10 mg L⁻¹ or less, T-N of 10 mg L⁻¹ or less and T-P of 1 mg L⁻¹ or less.     

Influence of inter-annual variations in climatic factors on fecal coliform levels in Mississippi Sound

Information on the effects of inter-annual variations in climatic factors on fecal coliform levels in coastal waters is scarce. We used 11 years (1990–2001) of rainfall, water temperature, Pearl River stage and salinity data to assess the effects of the 1991–1992 and 1997–1998 El Niño events on fecal coliform levels in Mississippi Sound. El Niño-Southern Oscillation had major effects on Pearl River stage and water quality in the Sound. The geometric mean fecal coliform number differed among years (P=0.0001), being highest during 1991–1992 El Niño years (14.22 MPN per 100 ml) and lowest during 1999–2000 La Niña years (<1.8 MPN per 100 ml). Mean salinity varied among years (P=0.0001) from 9 ppt (1991–1992) to 21 ppt (1999–2000). Mean water temperature was lowest in 1997–1998 (14.5 °C) and highest in 1998–2000 (19.4 °C). Pearl River stage differed among years (P=0.0001), ranging from 1.96 m (1999–2000) to 3.57 m (1997–1998). Inverse relationships were observed between fecal coliform levels and salinity (r²=0.74; P=0.001) and water temperature (r²=0.69; P=0.001), whereas positive relationships were obtained with total rainfall (r²=0.52; P=0.013) and Pearl River stage (r²=0.90; P=0.0001). These relationships are useful for evaluating the potential effects of climate change on water quality and classification of shellfish growing waters in order to protect humans from consuming contaminated shellfish in shallow river-influenced estuaries.     

Micronutrient supplements for optimisation of the treatment of industrial wastewater using activated sludge

The process performance and metabolic rates of several samples of activated sludge which were dosed with micronutrient supplements have been compared in this study. Six trace metals and six vitamins were used as chemical additives dosed into the mixed liquor. It was confirmed experimentally that a wastewater stream from a chemicals manufacturing plant did not contain a sufficient supply of micronutrients for efficient biological treatment. This was concluded from the observation that control sludge batches (receiving no micronutrient supplements) attained an average chemical oxygen demand (COD) removal rate of 1.94 kg COD kg MLSS⁻¹ d⁻¹. Dosing micronutrients into the mixed liquor produced COD removal rates of up to 2.24 kg COD kg MLSS⁻¹ d⁻¹. Some of the supplements increased the metabolic rate of the sludge while some decreased it, indicating a range of stimulatory and inhibitory effects. Complex interactions between micronutrients that were dosed simultaneously were evident. Several positive effects led to the conclusion that micronutrient supplements have the potential to optimise the process performance of activated sludge plants treating industrial wastewater.     

Removal of metal ions by modified Pinus radiata bark and tannins from water solutions

Pinus radiata bark and tannins, chemically modified with an acidified formaldehyde solution were used for removing metal ions from aqueous solutions and copper mine acidic residual waters. The adsorption ability to different metal ions [V(V), Re(VII), Mo(VI), Ge(IV), As(V), Cd(II), Hg(II), Al(III), Pb(II), Fe(II), Fe(III), Cu(II)] and the factors affecting their removal from solutions were investigated. Effect of pH on the adsorption, desorption, maximum adsorption capacity of the adsorbents, and selectivity experiments with metal ion solutions and waste waters from copper mine were carried out. The adsorbents considerably varied in the adsorption ability to each metal ion. The adsorption depends largely upon the pH of the solution. Modified tannins showed lower adsorption values than the modified bark. For the same adsorbent, the maximum capacity at pH 3 for the different ions were very different, ranging for modified bark from 6.8 meqg⁻¹ for V to 0.93 meqg⁻¹ for Hg. Waste waters were extracted with modified bark as adsorbent and at pH 2. The ions Cu(II) (35.2 mgL⁻¹), Fe(III) (198 mgL⁻¹), Al(III) (83.5 mgL⁻¹) and Cd(II) (0.15 mgL⁻¹) were removed in 15.6%, 46.9%, 83.7% and 3.3%, respectively, by using 1 g of adsorbent/10 mL of waste water. In general, a continuous adsorption on a packed column gave higher adsorbed values than those observed in the batchwise experiment.     

Removal of saxitoxins from drinking water by granular activated carbon, ozone and hydrogen peroxide--implications for compliance with the Australian drinking water guidelines

In a laboratory-scale trial, we studied the removal of saxitoxins from water by ozone, granular activated carbon (GAC) and H₂O₂, and considered the implications of residual toxicity for compliance with the Australian drinking water standards. Cell-free extracts of Anabaena circinalis were added to raw, untreated drinking water obtained from a water supply reservoir to provide a toxicity of 30 μg (STX equivalents) l⁻¹. Ozone alone, or in combination with H₂O₂, failed to destroy the highly toxic STX and GTX-2/3, and only partially destroyed dc-STX, and the low-toxicity C-toxins and GTX-5. In all cases, the toxicity of the water was reduced by less than 10%. GAC removed all of the STX, dc-STX and GTXs, but only partially removed the C-toxins. However, the residual toxicity was reduced to the suggested Australian drinking water guideline concentration of 3 μg (STX equivalents) l⁻¹ without O₃ pre-treatment. Modelling the spontaneous chemical degradation of residual C-toxins following treatment shows that residual toxicity could increase to 10 μg l⁻¹ after 11 d due to formation of dc-GTXs and would then gradually decay. In all, residual toxicity would exceed the Australian drinking water guideline concentration for a total of 50 d.     

Bioremediation of crystal violet using air bubble bioreactor packed with Pseudomonas aeruginosa

Seven water and sediment samples were collected and tested for decolorizing crystal violet. Pseudomonas aeruginosa was the most effective isolate for dye decolorization. The LC₅₀ of the crystal violet (115 mg/l) was measured using Artemia salina as a biomarker. The effect of different heavy metals on crystal violet decolorization was investigated. Cd²⁺ and Fe³⁺ ions showed marginal enhancement of the decolorization process, the rate was 1.35 mg/l/h compared to (1.25 mg/l/h) for the control. Phenol and m-cresol showed no effect on crystal violet decolorization, meanwhile p-cresol and p-nitrophenol reduced the decolorization rate to 1.07 and 0.01 mg/l/h, respectively. P. aeruginosa cells were immobilized by entrapment in agar-alginate beads. The beads were cultivated and reused in Erlenmeyer flask and in an air bubble column bioreactor and they enhanced the crystal violet decolorization rate to 3.33 and 7.5 mg/l/h, respectively.     

A computational fluid dynamics study of wood fire extinguishment by water sprinkler

A Computational Fluid Dynamics (CFD) model is developed to predict extinguishment times of an array of wood slats by water sprinkler. The model predicts flow field, combustion of wood volatiles and radiation transfer. The gas-phase model is coupled with the wood pyrolysis model to predict a volatile release rate. A sprinkler water spray is modelled using a Lagrangian particle tracking procedure, coupled with the gas flow model by a Particle-Source-In-Cell algorithm. A simple model of instant droplet evaporation at the burning surface is employed.

The experimental program includes full-scale experiments in a fire gallery with a commercial sprinkler system installed in the roof. In some tests a water restrictor is used to vary the water flow rates. Water droplet size and velocity distributions are measured to serve as inputs to the spray model. A vertical array of wood slats is ignited uniformly in a slight draft of about 0·7 m/s. A few minutes after self-sustained burning is developed, the sprinkler is activated. Thermocouple and heat flux measurements in the vicinity of the flame, as well as a video record, are used to determine flame shape and to provide data for validation of the CFD model. Burning rates are measured by load cell and by CO₂ measurements.

Extinguishment happens primarily due to fuel cooling, which is indicated by long extinguishment times (two orders of magnitude longer than for plastic materials).

The predictions of burning rate and flame shape are reasonably accurate. Extinguishment times are modelled for different water flow rates. The dependence on water flow rate is found to be weak because the extinguishment process is controlled by the thermal time constant of the whole wood sample.     

Use of boron waste as a fluxing agent in production of red mud brick

The study was directed towards determining the usability of clay and fine wastes (CW and FW) of boron from the concentrator plant in Kirka (Turkey) as a fluxing agent in production of red mud (RM) brick. Both laboratory studies on the characterization of materials and industrial-scale tests for production of bricks were carried out. CW and FW, which have similar chemical composition but include different types and amounts of oxides, were added in amounts of 5, 10 and 15 wt% to RM, which consists of high amounts of Fe₂O₃, Al₂O₃, SiO₂ and alkalies. Six different sets of samples have been produced and fired at 700, 800 and 900 °C. Dry shrinkage of green body, bending and compressive strength, firing shrinkage, water absorption, frost resistance and harmful magnesia and lime tests on heat-treated bodies have been performed. The mineralogical and mechanical tests showed that usability of boron wastes as a fluxing agent in the production of RM bricks was possible. In addition, the samples obtained by adding 15 wt% CW and FW to RM showed the best mechanical characteristic.     

Uptake and release of zinc by aquatic bryophytes (Fontinalis antipyretica L. ex. Hedw.)

The zinc uptake and posterior release by an aquatic bryophyte—Fontinalis antipyretica L. Ex Hedw.—was experimentally studied in laboratory exposing the plants to different zinc concentrations in the range, 1.0–5.0 mg l⁻¹, for a 144 h contamination period, and then exposed to metal-free water for a 120 h decontamination period. The experiments were carried out in perfectly mixed contactors at controlled illumination, using mosses picked out in February 1997, with a background initial zinc concentration of 263 mg g⁻¹ (dry wt.). A first-order mass transfer kinetic model was fitted to the experimental data to determine the uptake and release constants, k₁ and k₂, the zinc concentration in mosses at the end of the uptake period, C_mu, and at the equilibrium, for the contamination and decontamination stages, C_me and C_mr, respectively. A bioconcentration factor, BCF=k₁/k₂ (zinc concentration in the plant, dry wt./zinc concentration in the water) was determined. A biological elimination factor defined as BEF=1−C_mr/C_mu was also calculated. BCF decreases from about 4500 to 2950 as Zn concentration in water increases from 1.05 to 3.80 mg l⁻¹. BEF is approximately constant and equal to 0.80. Comparing Zn and Cu accumulation by Fontinalis antipyretica, it was concluded that the uptake rate for Zn (145 h⁻¹) is much lower than for Cu (628 h⁻¹) and the amount retained by the plant decreased by a factor of about seven.     

Bioremediation of crystal violet using air bubble bioreactor packed with Pseudomonas aeruginosa

Seven water and sediment samples were collected and tested for decolorizing crystal violet. Pseudomonas aeruginosa was the most effective isolate for dye decolorization. The LC₅₀ of the crystal violet (115 mg/l) was measured using Artemia salina as a biomarker. The effect of different heavy metals on crystal violet decolorization was investigated. Cd²⁺ and Fe³⁺ ions showed marginal enhancement of the decolorization process, the rate was 1.35 mg/l/h compared to 1.25 mg/l/h for the control. Phenol and m-cresol showed no effect on crystal violet decolorization, meanwhile p-cresol and p-nitrophenol reduced the decolorization rate to 1.07 and 0.01 mg/l/h, respectively. P. aeruginosa cells were immobilized by entrapment in agar–alginate beads. The beads were cultivated and reused in Erlenmeyer flask and in an air bubble column bioreactor and they enhanced the crystal violet decolorization rate to 3.33 and 7.5 mg/l/h, respectively.     

Removal of As(III) and As(V) from water using a natural Fe and Mn enriched sample

The arsenic removal capacity of a natural oxide sample consisting basically of Mn-minerals (birnessite, cryptomelane, todorokite), and Fe-oxides (goethite, hematite), collected in the Iron Quadrangle mineral province in Minas Gerais, Brazil, has been investigated. As-spiked tap water and an As-rich mining effluent with As-concentrations from 100 μg L⁻¹ to 100 mg L⁻¹ were used for the experiments. Sorbent fractions of different particle sizes (<38 μm to 0.5 mm), including spherical material (diameter 2 mm), have been used. Batch and column experiments (pH values of 3.0, 5.5, and 8.5 for batch, and about pH 7.0 for column) demonstrated the high adsorption capacity of the material, with the sorption of As(III) being higher than that of As(V). At pH 3.0, the maximum uptake for As(V) and for As(III)-treated materials were 8.5 and 14.7 mg g⁻¹, respectively. The Mn-minerals promoted the oxidation of As(III) to As(V), for both sorbed and dissolved As-species. Column experiments with the cFeMn-c sample for an initial As-concentration of 100 μg L⁻¹ demonstrated a very efficient elimination of As(III), since the drinking water limit of 10 μg L⁻¹ was exceeded only after 7400 BV total throughput. The As-release from the loaded samples was below the limit established by the toxicity characteristic leaching procedure, thus making the spent material suitable for discharge in landfill deposits.