The ability of Azolla caroliniana to remove heavy metals (Hg(II), Cr(III), Cr(VI)) from municipal waste water

The aim of this paper was to investigate the capacity of a small water fern, Azolla caroliniana Willd. (Azollaceae), to purify waters polluted by Hg and Cr. Many plants are capable of accumulating heavy metals (called hyperaccumulators) and one of them is the water fern A. caroliniana. During 12 days of the experiment the fern was grown on the nutrient solution containing Hg2+, Cr3+ and CrO4(2-) ions, each in a concentration 0.1, 0.5 and 1.0 mg dm(-3). The presence of these ions caused a 20-31% inhibition of A. caroliniana growth, the highest in the presence of Hg(II) ions, in comparison to the control. After day 12 of the experiment, metal contents the solution decreased to 0-0.25 mg dm(-3), and this decrease comprised between 74 (Cr3+ 1.0 mg dm(-3) treatment) and 100% (CrO4(2-) 0.1 mg dm(-3) treatment). The fern took a lesser quantity of the metals from 0.1 mg dm(-3) treatments compared to 0.5 and 1.0 mg dm(-3) treatments. In the A. caroliniana tissues the concentration of heavy metals under investigation ranged from 71 to 964 mg kg(-1) dm; the highest level being found for Cr(III) containing nutrient solution.     

Response of growth, photosynthesis and photoinhibition of the edible cyanobacterium Nostoc sphaeroides colonies to thiobencarb herbicide

Effects of thiobencarb on growth, photosynthesis and photoinhibition of Nostoc sphaeroides colonies were examined. Thiobencarb concentrations higher than 2 mg/l led to a significant decrease in phycoerythrin, phycocyanin and allophycocyanin content, but no significant effect on chlorophyll a (chl a) content. Biomass yield, protein content and photosynthetic rate were reduced only in the highest thiobencarb concentration (10 mg/l). Colonies exposed to high thiobencarb dose (10 mg/l) were more sensitive to high light than those exposed to the control and 4 mg/l thiobencarb. Dim light induced recovery from photoinhibition to more great extent in colonies grown in the control and 4 mg/l thiobencarb than 10 mg/l thiobencarb. Darkness resulted in a insignificant recovery regardless of thiobencarb treatments.     

The effect of zeolite on the toxicity of lead to fungi

In order to determine whether clinoptilolite, a naturally occurring zeolite, had any ameliorative effect on lead (Pb) toxicity to fungi, a series of growth experiments were performed. Three fungi, Aspergillus niger, Botrytis cinerea, and Fusarium culmorum, were grown on appropriately amended solid agar media, and their linear extension rates determined. B. cinerea was 25% inhibited, as compared to a control, at 100 mg dm(-3) Pb, and completely inhibited at 1000 mg dm(-3) Pb. F. culmorum was completely inhibited, and A. niger 97% inhibited at 1000 mg dm(-3) Pb. The addition of 3% clinoptilolite partially removed this inhibition in the case of A. niger and B. cinerea and almost completely removed it for F. culmorum. At a constant 500 mg dm(-3) Pb, increasing concentrations of clinoptilolite increased the linear extension rate of F. culmorum and B. cinerea, close to the rates achieved by the untreated controls. A. niger was not inhibited markedly at this Pb concentration. The evidence suggests that the Pb is adsorbed by the clinoptilolite which reduces the availability, and hence toxicity, of the metal to the fungi.     

Calcium chloride and calcium bromide aqueous solutions of technical and analytical grade in Lemna bioassay

Saturated water solutions of calcium chloride, calcium bromide and their 1:1 mixture are commonly used as "high density brines" for pressure control in oil wells. To compare the effect of these chemicals of technical grade with the effect of the chemicals of analytical grade the Lemna test was used. The multiplication rate, fresh weight, dry to fresh weight ratio, area covered by plants and chlorophyll content were measured as toxicity parameters. The concentrations of tested chemicals were 0.025, 0.05. 0.075 and 0.1 mol dm(-3). Generally, the chemicals of both technical and analytical grade in concentrations of 0.025 mol dm(-3) stimulated the Lemna minor growth, while tested chemicals in concentrations of 0.05 mol dm(-3) did not affect the growth significantly. The exceptions were results obtained by measuring fresh weight. Most of tested chemicals in concentrations of 0.075 mol dm(-3) and all chemicals in concentrations of 0.1 mol dm(-3) reduced the growth. No major differences between effects of tested chemicals of technical and analytical grade on plant growth were observed, except that tested chemicals of analytical grade in concentrations of 0.1 mol dm(-3) increased dry to fresh weight ratio much stronger than chemicals of technical grade. All tested chemicals in all concentrations increased chlorophyll content. After treatment with chemicals of analytical grade much higher increase of chlorophyll a concentration in comparison to increase of chlorophyll b was noticed, while chemicals of technical grade caused more prominent increase of chlorophyll b.     

Priority organic pollutant assessment of sludges for agricultural purposes

A comprehensive characterization of five of the seven priority organic pollutants listed in the draft of the "Working document on sludge" [EU, 2000. Working Document on Sludge 3rd Draft. Unpublished, 19 p] has been carried out during 2001-2003 in sludge samples from Catalonia (NE Spain). One hundred and thirty-nine samples belonging to 20 Waste Water Treatment Plants (WWTPs), seven sludge treatment (thermal drying) and three composting sludge plants were taken in order to determine the concentration of polychlorinated dibenzo-p-dioxins and -furans (PCDD/Fs), di-2-(ethyl-hexyl)-phthalate (DEHP), nonylphenol and nonylphenol ethoxylates with one or two ethoxy groups (NPE), polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs). PCDD/F concentrations were in general lower than the 100 ng I-TEQ/kg limit suggested in the above-mentioned document. In the same way, 98.5% for PCBs, 97% for PAH and 92.8% for DEHP of the samples presented concentrations lower than 0.8 mg/kg dm, 6 mg/kg dm and 100 mg/kg dm, respectively. In contrast, the vast majority of samples contained NPE concentrations much higher than 50mg/kg dm limit. The values ranged from 14.3 to 3150 mg/kg dm (median value=286.6 mg/kg) being composted sludge samples the less contaminated ones (17.9-363.4 mg/kg dm; median value=89.3 mg/kg). Special attention should be paid to the Catalan sludge NPE contamination owing to the high levels detected.     

Effects of SO2 on the photosynthetic and respiration rates in scots pine seedlings

Exposure to moderate concentrations (90-500 microg SO(2) m(-3)) of SO(2) for 5-30 days caused a decrease in the photosynthetic rate. Only the lowest concentration (30 microg SO(2) m(-3)) increased photosynthesis. There was hardly any recovery in photosynthesis after the exposure. All exposure concentrations increased dark respiration. However, the lowest concentration had the smallest effect. Exposure to high concentration (2320 microg SO(2) m(-3)) of SO(2) for 5 h caused a strong decrease in the photosynthetic rate but there was a complete recovery within 2 weeks.     

Nutrient run-off following application of livestock wastes to grassland

Three types of farm waste (cattle slurry, dirty water and farm yard manure (FYM)) were applied to hydrologically isolated grassland plots on a sloping poorly draining soil. Two applications were made, the first in October and the second in February. Application rates were 50 m(3) ha(-1) of slurry and dirty water and 50 t ha(-1) of FYM. Volumes of run-off following rainfall events and concentrations of N, P and K in run-off were measured. Losses of nutrients were higher following applications made with the soil at field capacity and rainfall soon after application. In terms of percentage loss of applied nutrients, losses were generally low. Concentration of N in run-off from the dirty water and FYM treated plots following the first application and the slurry treated plots following the second application exceeded 11.3 mg dm(-3) (a recommended limit for drinking water) although the maximum concentration recorded was 15 mg dm(-3) following FYM application. Concentration of P in run-off only exceeded 1 mg dm(-3) following the second application of cattle slurry. Concentration of K exceeded 10 mg dm(-3) following the first application of FYM and the second application of cattle slurry.     

Effects of distillery waste on the performance of Cicer arietinum L

The impact of distillery effluent in various concentrations (1, 2.5, 5, 10, 25, 50, 75 and 100%) on the seed germination, Speed of Germination Index, growth behaviour, leaf area, biomass, net primary productivity, pigment content, reproductive capacity, seed output, seed weight, seed density and the seed protein content of Cicer arietinum L. plants was investigated. The percentage and speed of germination of seeds were increasingly retarded with increase in effluent concentration and at 100% concentration there was no germination. The seedlings exhibited maximum shoot length at 5% concentration and maximum root length at 2.5% concentration. The values of root and shoot lengths, leaf area, biomass, net primary productivity, pigment content, reproductive capacity, seed output, seed weight, seed density and seed protein content in pot plants exhibited a gradual increase from the control up to 5% concentration and decreases at higher concentrations. The very high BOD load and the presence of excessive concentrations of soluble salts could be responsible for the toxicity of the effluent. The effluent at up to 5% concentration was, however, beneficial for the overall growth parameters studied and can thus be used as a liquid fertilizer.     

The changes in common carp blood after short-term zinc exposure

Blood zinc level, hematological parameters and blood cell morphology were evaluated in common carp immediately after 3 h exposure to 20 mg dm(-3) of zinc (Zn0), and in 24, 48 and 96 hours after the end of it (Zn24, Zn48, Zn96). Blood zinc level in the non-exposed fish was 8 mg dm(-3), reached a maximum of 20 mg dm(-3) in Zn48, while it dropped to 9 mg dm(-3) in Zn96. Zinc caused a stress reaction in fish indicated by an increase in hematocrit value in Zn0, and elevated plasma glucose level and trombocytosis which persisted until the end of the experiment. Zinc-exposed fish showed an increased frequency of abnormal erythrocytes, and a compensatory release of immature erythrocytes to the blood stream. In zinc-treated fish, leukocyte count initially increased and subsequently decreased significantly below the control level due to a drop in lymphocyte number. Lymphocyte viability was reduced, and abnormal lymphocytes appeared. A decreased count of juvenile neutrophiles, and reduced phagocyte activity also occurred. The results indicate possible zinc-induced disturbances in both specific and non-specific immune mechanisms.     

Visual determination of nitrite and nitrate in waters by color band formation method

A spot test for aqueous nitrate and nitrite for controlling nitrogen removal performance in small-scale wastewater treatment facilities is proposed. In this method, NO(2)(-) ion in water samples was allowed to react with sulfanilic acid and 1-naphthol to form an anionic azo dye. The resulting colored solution was introduced onto a mini column (similar to a gas detecting tube) packed with PVC particles coated with benzyl cetyl dimethyl ammonium chloride (BCDMA) and biphenyl. The NO(2)(-)-N concentration was determined visually by measuring the color band length (CBL) in the column. The CBL correlates linearly with nitrite concentration in the 4-20 mg-N l(-1) range. The concentration of nitrite+nitrate was determined after reduction to nitrite with zinc. The concentration of NO(3)(-)-N species was calculated by difference. This method was used to visually determine the concentrations of NO(2)(-)-N and (NO(2)(-)+NO(3)(-))-N in domestic wastewater samples with maximum suspended solid (SS) and chemical oxygen demand (COD) concentrations of 114 mg l(-1) and 73.9 mg l(-1), respectively.     

Effect of arsenic on photosynthesis, growth and yield of five widely cultivated rice (Oryza sativa L.) varieties in Bangladesh

A glass house experiment was conducted to investigate the effect of soil arsenic on photosynthetic pigments, chlorophyll-a and -b, and their correlations with rice yield and growth. The experiment was designed with three replications of six arsenic treatments viz. control, 10, 20, 30, 60, 90 mg of As kg(-1) soil. Arsenic concentration in initial soil, to which the above mentioned concentrations of arsenic were added, was 6.44+/-0.24 mg kg(-1). Both chlorophyll-a and -b contents in rice leaf decreased significantly (p<0.05) with the increase of soil arsenic concentrations. No rice plant survived up to maturity stage in soil treated with 60 and 90 mg of As kg(-1). The highest chlorophyll-a and -b contents were observed in control treatment (2.62+/-0.24 and 2.07+/-0.14 mg g(-1) were the average values of chlorophyll-a and -b, respectively of the five rice varieties) while 1.50+/-0.20 and 1.04+/-0.08 mg g(-1) (average of five rice varieties) of chlorophyll-a and -b, respectively were the lowest. The content of photosynthetic pigments in these five rice varieties did not differ significantly (p>0.05) from each other in control treatment though they differed significantly (p<0.05) from each other in 30 mg of As kg(-1) soil treatment. Among the five rice varieties, chlorophyll content in BRRI dhan 35 was found to be mostly affected with the increase of soil arsenic concentration while BRRI hybrid dhan 1 was least affected. Well correlations were observed between chlorophyll content and rice growth and yield suggesting that arsenic toxicity affects the photosynthesis which ultimately results in the reduction of rice growth and yield.     

Effects of the triazine herbicide, simetryn, on freshwater plankton communities in experimental ponds

The effects of a triazine herbicide, simetryn, on freshwater phyto- and zooplankton communities and water chemistry were investigated using outdoor experimental ponds. Simetryn was applied at a concentration of 0.1 or 1.0 mg l(-1) 18 days after the start of the experiment. Simetryn treatments reduced pH, dissolved oxygen concentration, chlorophyll a concentration and photosynthetic rate in the pond water, whereas they increased the dissolved nutrient concentration. In the phytoplankton community Volvocales and Cryptophyceae were clearly reduced by the herbicide application. In the 0.1 mg l(-1) simetryn-treated ponds, photosynthetic rate of the phytoplankton community recovered slightly about two weeks after the treatment, which coincided with recovery of centric diatoms and Cryptophyceae, whereas it was completely suppressed until the end of the experiment in the 1.0 mg l(-1) simetryn-treated ponds. The decrease in zooplankton density in the treated ponds was not due to the direct toxic effects of simetryn but to indirect effects resulting from reduced algal productivity which in turn reduced the food supply.     

Activated carbon from industrial solid waste as an adsorbent for the removal of Rhodamine-B from aqueous solution: kinetic and equilibrium studies

The activated carbon was prepared using industrial solid waste called sago waste and physico-chemical properties of carbon were carried out to explore adsorption process. The effectiveness of carbon prepared from sago waste in adsorbing Rhodamine-B from aqueous solution has been studied as a function of agitation time, adsorbent dosage, initial dye concentration, pH and desorption. Adsorption equilibrium studies were carried out in order to optimize the experimental conditions. The adsorption of Rhodamine-B onto carbon followed second order kinetic model. Adsorption data were modeled using both Langmuir and Freundlich classical adsorption isotherms. The adsorption capacity Q0 was 16.12 mg g(-1) at initial pH 5.7 for the particle size 125-250 microm. The equilibrium time was found to be 150 min for 10, 20 mg l(-1) and 210 min for 30, 40 mg l(-1) dye concentrations, respectively. A maximum removal of 91% was obtained at natural pH 5.7 for an adsorbent dose of 100mg/50 ml of 10 mg l(-1) dye concentration and 100% removal was obtained when the pH was increased to 7 for an adsorbent dose of 275 mg/50 ml of 20 mg l(-1) dye concentration. Desorption studies were carried out in water medium by varying the pH from 2 to 10. Desorption studies were performed with dilute HCl and show that ion exchange is predominant dye adsorption mechanism. This adsorbent was found to be both effective and economically viable.     

Profenofos induced modulation in physiological indices,genomic template stability and protein banding patterns of Anabaena sp. PCC 7120

To understand the mechanism underlying organophosphate pesticide toxicity, cyanobacterium Anabaena PCC 7120 was subjected to varied concentrations (0, 5, 10, 20 and 30 mg L^?1) of profenofos and the effects were investigated in terms of changes in cellular physiology, genomic template stability and protein expression pattern. The supplementation of profenofos reduced the growth, total pigment content and photosynthetic efficiency of the test organism in a dose dependent manner with maximum toxic effect at 30 mg L^?1. The high fluorescence intensity of 2′, 7′ –dichlorofluorescin diacetate and increased production of malondialdehyde confirmed the prevalence of acute oxidative stress condition inside the cells of the cyanobacterium. Rapid amplified polymorphic DNA (RAPD) fingerprinting and SDS-PAGE analyses showed a significant alteration in the banding patterns of DNA and proteins respectively. A marked increase in superoxide dismutase, catalase, peroxidase activity and a concomitant reduction in glutathione content indicated their possible role in supporting the growth of Anabaena 7120 up to 20 mg L^?1. These findings suggest that the uncontrolled use of profenofos in the agricultural fields may not only lead to the destruction of the cyanobacterial population, but it would also disturb the nutrient dynamics and energy flow.     

Content and bioconcentration factors of mercury by Parasol Mushroom Macrolepiota procera

The carpophores of Parasol Mushroom and underlying soil substrate collected from several unpolluted and spatially distant sites across Poland were examined to know content and bioconcentration potential of mercury by this species. The total mercury content of the caps of Parasol Mushroom for the particular sites ranged from 1.1 +/- 1.0 to 8.4 +/- 7.4 microg/g dry matter (total range from 0.05 to 22 microg/g dm), while in the stalks were from 0.53 +/- 0.27 to 6.8 +/- 7.1 microg/g dm (total range from 0.078 to 20 microg/g dm). A top soil layer (0-10 cm) showed baseline mercury concentration from 0.022 +/- 0.011 to 0.36 +/- 0.16 microg/g dm (total range from 0.010 to 0.54 microg/g dm). Parasol Mushroom is an effective mercury accumulator in the carpophores and bioconcentration factor (BCF) values of this element in the caps and depending on the sampling site ranged from 16 +/- 6 to 220 +/- 110 (total range from 0.52 to 470), while for the stalks were from 7.6 +/- 2.6 to 130 +/- 96 (total range from 0.52 to 340). It seems reasonable to state that tolerance (maximum allowable concentration) of the total mercury in a single cap of Parasol Mushroom at unpolluted areas should not exceed 25 microg/g dm. A value greater then 25 mu g/g dm will imply an elevated content due to site pollution problems. Nevertheless, knowledge on highly toxic methylmercury content and its fraction in the total mercury content of Parasol Mushroom is lacking.     

A combination of ion exchange and electrochemical reduction for nitrate removal from drinking water. Part I: nitrate removal using a selective anion exchanger in the bicarbonate form with reuse of the regenerant solution.

The process of selective nitrate removal from drinking water by means of ion exchange was studied. A commercial strong base anion exchanger with triethylammonium (-N+Et3) functional groups was used in the bicarbonate (HCO3-) and carbonate (CO3(2-)) form. The aim of this study was to optimize ion-exchanger regeneration in view of the subsequent electrochemical reduction of nitrates in the spent regenerant solution. The effects of ion-exchanger form, concentration of regenerant solution, and presence of nitrates, chlorides, and sulphates in the regenerant solution were studied. The strong base anion exchanger in HCO3- form that was investigated was able to treat 270 bed volumes of model water solution containing 124 mg dm(-3) nitrates. To achieve adequate regeneration of the saturated anion exchanger, it is necessary to use approximately 30 bed volumes of fresh 1-M sodium bicarbonate (NaHCO3) regenerant solution. The presence of residual 50-mg dm(-3) nitrates in the regenerant solution, treated by electrolysis, resulted in an increase in the dose of regenerant solution to 35 bed volumes and a decrease in the subsequent sorption run of approximately 13%. The volume of applied regenerant solution was high, but the consumption of NaHCO3 for regeneration was low.     

Decolorization and biodegradation of dye wastewaters by a facultative-aerobic process

BACKGROUND: Dye wastewater is one of the main pollution sources of water bodies in China. Conventional biological processes are relatively ineffective for color removal, the development of alternative treatment methods will become important. Our subjective was that of introducing a new biotreatment technology which combined a facultative biofilm reactor (FBR) with an aerobic reactor (AR) to treat a dye wastewater. The efficiencies of color and chemical oxygen demand (COD) removal and the mechanism of dye degradation were investigated. METHODS: The anthraquinone acid dye (acid blue BRLL) concentration, organic loading rate (OLR) and hydraulic retention time (HRT) were varied in the experiments to evaluate the treatment efficiency and process stability. The biodegradation products were detected by infrared (IR) and high performance liquid chromatography and mass spectrometry (HPLC-MS). RESULTS AND DISCUSSION: The results demonstrated that the facultative biofilm process was more effective for decolorization than the anaerobic stage of an anaerobic-aerobic process. Most color removal occurred in the facultative reaction (maximum to 88.5%) and the BOD (biochemical oxygen demand): COD of the FBR effluent increased by 82.2%, thus improving the biodegradability of dyes for further aerobic treatment. The dye concentration, OLR and HRT will be the factors affecting decolorization. Color removal efficiency falls as the influent dye concentration increases, but rises with increased HRT. The infrared and HPLC-MS analyses of the effluents of FBR and AR reveal that the dye parent compound was degraded in each reactor during the process. CONCLUSION: The Facultative-aerobic (F-A) system can effectively remove both color and COD from the dye wastewater. The FBR played an essential role in the process. The average overall color and COD in the system were removed by more than 93.9% and 97.1%, respectively, at an OLR of 1.1 kg COD m(-3) d(-1) and at the HRT of 18-20 hours in the FBR and 4-5 hours in the AR. The color removal mechanism in each reactor was not only a sort of biosorption on the floc materials, but even more an effect of biodegradation, especially in the facultative process. Recommendation and Outlook. In applying the F-A system to treat a dye wastewater, the control of facultative processes and the set up of appropriate operation conditions appear to be critical factors. Also, it is suggested a moderate COD loading rate and about a 24-hour HRT will favor the F-A system.     

高压电弧放电处理偶氮染料废水

用高压电弧放电产生的低温等离子体对含偶氮染料的废水进行了处理,以甲基橙为例研究了电压幅值、处理时间、溶液初始浓度、溶液初始pH值、投加Fe^2＋和Fe^3＋对染料脱色的影响。实验结果表明,甲基橙浓度为50mg／L时其降解率随时间和电压幅值的增加而增加。溶液初始浓度对染料去除效果影响较为明显,同等条件下初始浓度越低降解率越高。酸性条件下有利于低温等离子体处理甲基橙。Fe^2＋和Fe^3＋对低温等离子体降解甲基橙有一定的催化作用。电压8kV处理3min,Fe^2＋为20mg／L时去除率由89．64％增至99．72％。Fe2（SO4）,的最佳投加量为5mg／L（以Fe^3＋计）,而FeCl,的最佳投加量为80mg／L（以Fe^3＋计）。     

Remazol Brilliant Blue R decolourization by the laccase from Trametes trogii

The decolourization of the recalcitrant dye RBBR by the culture filtrate of Trametes trogii and its isolated laccase was investigated. Both filtrates from Cu-induced cultures as well as purified laccase decolourized the dye RBBR. The purified laccase decolourized the dye down to 97% of 100 mg l(-1) initial concentration of RBBR when only 0.2U ml(-1) of laccase was used in the reaction mixture. The effects of different physicochemical parameters were tested and optimal decolourization rates occurred at pH 5 and at a temperature of 50 degrees C. Decolourization of RBBR occurred in the presence of metal ions which could be found in textile industry effluents. Of all the metal ions tested, FeCl2 was the most inhibiting for the decolourization. HBT was shown to have no effect on the decolourization of RBBR at low concentration, while at a concentration of 5 mM it slightly inhibited decolourization. The presence of aromatic compounds was found to be inhibiting for the decolourization at a concentration of 10 mM, but not at 0.1 mM, while at 1 mM only ortho-diphenols were inhibiting. Probing the effect of methanol it was found that higher concentrations caused a decrease in the decolourization rate of RBBR. The effect of laccase inhibitors on the decolourization of RBBR was tested with L-cysteine, SDS and EDTA. It was demonstrated that L-cysteine was the most inhibiting substrate for the decolourization while SDS was only inhibiting at 10 mM concentration and ETDA was not inhibiting at all tested concentrations.     

Comparative study of responses in four Datura species to a zinc stress

The effects of zinc toxicity on the growth and the photosynthetic activities of four Datura species (Datura metel, Datura innoxia, Datura sanguinea, Datura tatula) were studied using various ZnSO4 concentrations (0, 1, 2.5 and 5 mM) added in the Coic Lessaint solution. Growth, photosynthesis, chlorophyll fluorescence and chlorophyll concentration were measured after 20 days of zinc stress. These parameters were severely reduced by this heavy metal. The zinc excess involves the stomate closing, the increase of CO2 concentration in the leaves, the inhibition of certain enzyme of the Calvin cycle, a degradation of photosystem and the chlorophyll decomposition. These phenomena allow the decrease of the net photosynthesis to be partially explained. These key parameters to assess photosynthetic performance allow the plants to be classified according to their resistance to zinc. Compared with the three other species, D. innoxia showed a very strong capacity to protect itself against toxic zinc concentrations; a large amount of ZnSO4 (5 mM) was required to inhibit 43% of the photosynthesis.