Cadmium uptake by non-viable biomass from a marine brown algaEcklonia radiata turn

Biomass of non-viable and dried brown marine algaeEcklonia radiata Turn. was used to examine its cadmium uptake capability. Twelve different pretreatments on the algal biomass were prepared. Among these pretreatments, the algal biomass, which treated with 0.1 M NaOH and kept in water bath (100°C, 18 h) followed by washing with distilled water and squeezing, showed the highest amount of cadmium uptake as 1634±195 mg/g dry biomass at pH 4.0 and 50°C. Adsorption temperatures and pH levels played some important role in cadmium uptake. However, cadmium uptake decreased dramatically at a lower pH than 4.0. Freundlich adsorption isotherm showed potent cadmium uptake capacity of the non-viable biomass. Pretreatments on the nonviable algal biomass shown in this study may enhance the cadmium removal in the industrial wastewater.     

Bioremediation of water contaminated with uranium using Penicillium piscarium

Penicillium piscarium can be indicated as promising in the treatment of sites contaminated with uranium. Thus, this research aimed to analyze the P. piscarium dead biomass in uranium biosorption. This fungus was previously isolated from a highly contaminated uranium mine located in Brazil. Biosorption tests were carried out at pH 3.5 and 5.5 in solutions contaminated with concentrations of 1 to 100 mg/L of uranium nitrate. Our results showed that the dead biomass of P. piscarium was able to remove between 93.2 and 97.5% uranium from solutions at pH 3.5, at the end of the experiment, the pH of the solution increased to values above 5.6. Regarding the experiments carried out in solutions with pH 5.5, the dead biomass of the fungus was also able to remove between 38 and 92% uranium from the solution, at the end of the experiment, the pH of the solution increased to levels above 6.5. The analysis of electron microscopy, Energy-dispersive spectroscopy, and X-ray fluorescence demonstrated the high concentration of uranium precipitated on the surface of the fungal biomass. These results were impressive and demonstrate that the dead biomass of P. piscarium can be an important alternative to conventional processes for treating water contaminated with heavy metals, and we hope that these ecofriendly, inexpensive, and effective technologies be encouraged for the safe discharge of water from industrial activities.     

Biosorption and desorption studies of chromium (III) by free and immobilized Rhizobium (BJVr 12) cell biomass

Experiments with free cell biomass (cells + exopolysaccharides) ofRhizobium BJVr 12 (mungbean isolate) showed that amount ofCr³⁺ ion sorbed is influenced by the amount of biomass toCr³⁺ concentration ratio and time of contact. A ratio of 0.5 gfresh biomass to 10.0 ml 5.03 ppm Cr³⁺ sorbed 0.0275 mg Crequivalent to an uptake of 2.86 mg Cr g-¹ dry biomass and 1.0g: 10.0 ml sorbed 0.0366 mg Cr equivalent to an uptake of 1.9 mg Crg-¹ biomass. Immobilized cell biomass in ceramic beads and inaquacel (a porous cellulose carrier with a charged surface) were moreefficient than free cell biomass in adsorbing Cr(III). A reduction of49.7percnt; of Cr(III) for free cells, 95.6% for cells immobilized inceramic beads and 94.6% for cells in aquacel was achieved after 48hours under shaken conditions. Sorption capacities of immobilized cellbiomass in ceramic beads and aquacel ranged from 5.01 to 5.06 mg Crg^-1 dry cell biomass. The biosorption of Cr³⁺follows generally the Langmuir and Freundlich models of adsorption at lowCr³⁺ concentrations. The Langmuir constant for immobilizedcells in ceramic beads are: Q₀, 0.065 mmol Crg^-1 biomass; b (affinity constant), - 694 lmmol^-1 Cr and for cells in aquacel Q, 0.07 mmol Crg^-1 biomass; b, - 694 l mmol Cr g^-1 Cr. TheFreundlich constants are: K, 0.071 mmol Cr g^-1 biomass; n,0.13 g^-1 biomass l^-1 and for aquacel: K, 0.074mmol g^-1 biomass; n, 0.13 g^-1 biomass. Biotrapsmade up of immobilized cells in ceramic beads and aquacel were tested foradsorbing Cr(III) using two different flow rates: 0.5 ml/min and 1.5 ml/min.A significantly higher amount of Cr(III) was adsorbed at the lower flow rateof 0.5 ml/min. Biosorption of Cr³⁺ is competitive. Thetreatment of a waste water sample containing 6.03 ppm Cr³⁺ andother cations with the biomass reduced the Cr³⁺ concentrationto that much lower than for the test solution containing only Cr. Recoveryof biosorbed Cr(III) was by treatment at a different pH using dilute HClsolution. Recovery was higher for cells imbibed in ceramic beads thanaquacel. Percentage recoveries for cells in aquacel are 46.4% at pH1.0, 33.0% at pH 3.0 and 6.6% at pH 6.0–7.0. For cellsin ceramic beads, percentage recoveries are: 93.1% at pH 1.0,75.6% at pH 3.0 and 16.4% at pH 6.0–7.0. Biosorption ofCr³⁺ by cells immobilized in ceramic beads is reversible butonly partially for cells in aquacel.     

Biosorption of Cr, Cu and Al bySargassum biomass

The biosorption and desorption of Cr, Cu and Al were carried out using brown marine algaeSargassum fluitans biomass, known as the good biosorbent of heavy metals. The content of alginate bound to light metals could be changed by physical and chemical pretreatment. The maximum uptake of Cr, Cu and Al was independent of the alginate content. The maximum uptake of Al was two times(mole basis) than those of Cu and Cr. The aluminum-alginate complex was found in the sorption solution of raw and protonated biomass. Most of Cu, Al and light metals sorbed in the biomass were eluted at pH 1.1. However, only 5 to 10% of Cr sorbed was eluted at pH 1.1. The stoichometric ion exchange between Cu and Ca ion was observed on Cu biosorption with Ca-loaded biomass. A part of Cr ion was bound to biomass as Cr(OH)₂ ⁺ or Cr(OH)²⁺. Al was also bound to biomass as multi-valence ion and interfered with the desorbed Ca ion. The behavior of rawS. fluitans in ten consecutive sorption-desorption cycles has been investigated in a packed bed flow-through-column during a continuous removal of copper from a 35 mg/L aqueous solution at pH 5. The eluant used was a 1%(w/v) CaCl/HCl solution at pH3.     

Cellulose and lignin degradation in forest soils: Response to moisture,temperature, and acidity

The concentration of lignin in plant tissue is a major factor controlling organic matter degradation rates in forest ecosystems. Microbial biomass and lignin and cellulose decomposition were measured for six weeks in forest soil microcosms in order to determine the influence of pH, moisture, and temperature on organic matter decomposition. Microbial biomass was determined by chloroform fumigation; lignin and cellulose decomposition were measured radiometrically. The experiment was designed as a Latin square with soils of pH of 4.5, 5.5, and 6.5 adjusted to 20, 40, or 60% moisture content, and incubated at temperatures of 4, 12, or 24°C. Microbial biomass and lignin and cellulose decomposition were not significantly affected by soil acidity. Microbial biomass was greater at higher soil moisture contents. Lignin and cellulose decomposition significantly increased at higher soil temperatures and moisture contents. Soil moisture was more important in affecting microbial biomass than either soil temperature or soil pH.     

Batch studies on the removal of gold(III) from aqueous solution by Azolla filiculoides

Azolla filiculoides removed 86% and 100% of gold(III) from initial metal solutions of 2–10 mg gold l^–1 increasing with increased initial concentrations of gold(III). The biomass gave greater than 95% removal efficiency from solution at all biomass concentrations measured. Complete removal of gold occurred at pH 2, with 42% removal at pH 3 and 4, and 63% and 73% removal at pH 5 and 6, respectively. No temperature-dependence removal was observed.     

Relating fish biomass to habitat and chemistry in headwater streams of the northeastern United States

Stream pH and stream habitat have both been identified as important environmental features influencing total fish biomass in streams, but few studies have evaluated the relative influence of habitat and pH together. We measured total fish biomass, stream habitat, and stream pH in sixteen sites from three tributary systems in the northeastern United States. The habitat metrics included total pool area, a cover score, large wood frequency, and stream temperature. We created and compared nine linear models relating total fish biomass in summer to stream pH and stream habitat using Akaike’s Information Criterion (AIC) analysis. The best (most parsimonious) models included pool area and stream pH. These results and a separate comparison of three regressions (low-flow pH, pool area, and these two metrics together versus total fish biomass) suggest that both habitat and stream buffering capacity affect the total biomass of fish in northeastern US headwater streams. When stream pH is adequate (low-flow pH greater than at least 5.7), physical habitat is likely to be more important, but under lower pH conditions, habitat is likely to be less effective in accounting for the total biomass of fish in these streams. This work demonstrates the continued effects of stream acidification in the northeastern US and more generally, it illustrates the importance of considering both physical and chemical conditions of a stream when evaluating the factors influencing fish communities.     

Biomass and Production of Lake Charr During the Acidification and PH Recovery of A Small Ontario Lake

The biomass and production of lake charr, Salvelinus namaycush, was studied in Lake 223, a lake that was intentionally acidified to pH 5.0 and then allowed to gradually recover, and in Lake 224, a natural lake of neutral pH. During the first 6 years pH decreased, biomass of Lake 223 lake charr increased, primarily due to high recruitment during the initial years of acidification. Biomass then decreased the final year of acidification. Biomass of Lake 223 lake charr remained low during the subsequent 10 years of pH recovery and 5 additional years after lake pH had returned to neutral pH. Production of lake charr decreased during acidification and increased during pH recovery. Production was still at least an order of magnitude lower at the end of this study than 22 years earlier before lake pH was lowered. The continued low production was caused primarily by low abundance during the years of pH recovery and following years. Production per individual fish in Lake 223 decreased during acidification and quickly increased during pH recovery to values similar to that prior to acidification. Production, biomass, and production per individual varied little between years for lake charr in Lake 224.     

Biosorption of uranium and thorium

Selected samples of waste microbial biomass originating from various industrial fermentation processes and biological treatment plants have been screened for biosorbent properties in conjunction with uranium and thorium in aqueous solutions. Biosorption isotherms have been used for the evaluation of biosorptive uptake capacity of the biomass which was also compared to an activated carbon and the ion exchange resin currently used in uranium production processes. Determined uranium and thorium biosorption isotherms were independent of the initial U or Th solution concentration. Solution pH affected the exhibited uptake. In general, lower biosorptive uptake was exhibited at pH 2 than at pH 4. No discernible difference in uptake was observed between pH 4 and pH 5 where the optimum pH for biosorption lies. The biomass of Rhizopus arrhizus at pH 4 exhibited the highest uranium and thorium biosorptive uptake capacity (g) in excess of 180 mg/g. At an equilibrium uranium concentration of 30 mg/liter, R. arrhizus removed approximately 2.5 and 3.3 times more uranium than the ion exchange resin and activated carbon, respectively. Under the same conditions, R. arrhizus removed 20 times more thorium than the ion exchange resin and 2.3 times more than the activated carbon. R. arrhizus also exhibited higher uptake and a generally more favorable isotherm for both uranium and thorium than all other biomass types examined.     

Bryophyte biomass and species richness on the Park Grass Experiment,Rothamsted, UK

The relationships between bryophyte biomass and species richness and soil pH, nutrient applications and vascular plant biomass and species richness were analyzed for the Park Grass Experiment (Rothamsted, UK). The study examined the abundance of bryophytes in relation to long-term fertilizer and lime application and to fertilizer treatments recently being ceased on some plots. The probability of bryophytes being present on a plot increased with increasing soil pH, and on plots at soil pH 3.3–4.5, the lowest values in this experiment, there were virtually no mosses present. Total bryophyte biomass decreased with increasing vascular plant biomass and vascular plant richness. Both bryophyte biomass and species richness showed a curvilinear response to soil pH. Bryophyte biomass was markedly increased on plots where nitrogen (N) fertilization had recently been ceased. The abundance of the common bryophyte species showed individualistic responses to treatments. N had a negative effect on the abundance of Brachythecium rutabulum. Increasing soil pH, and the application of phosphorus (P) and potassium (K) fertilizer together, had a positive effect on Eurhynchium praelongum. This species was also negatively affected by N, but tolerated larger amounts of it (100–150 kg ha^–1 N) than B. rutabulum. An ephemeral moss, Bryum subapiculatum, had a unimodal response to soil pH but showed no response to N, P, K or other explanatory variables.     

Phosphatase activity in relation to phytoplankton composition and pH in Swedish lakes

SUMMARY. 1. Potential phosphatase activity and phytoplankton from several lakes of different character were compared in order to evaluate the importance of lake water pH and phytoplankton composition for the activity and pH optimum of lake water phosphatases.
2. In oligotrophic lakes, in which phytoplankton biomass was most often dominated by Ochromonadaceae spp., optimum phosphate activity was found at pH values <6. In eutrophic lakes, where species of Cyanophyceae and Bacillariophyceae dominated the phytoplankton biomass, optimum phosphatase activity was found at pH 7.5 or 8.5.
3. The pH optimum of phosphatase activity often differed from the corresponding lake water pH.
4. Experimental variation in phosphorus availability resulted in predictable changes in phosphatase activity. However, specific phosphatase activity, calculated per biomass of phytoplankton, was dependent on plankton species composition.     

Cr6+ bioremediation efficiency of Oscillatoria laete-virens (Crouan & Crouan) Gomont and Oscillatoria trichoides Szafer: kinetics and equilibrium study

Two species of cyanobacteria, Oscillatoria laete-virens (Crouan & Crouan) Gomont and Oscillatoria trichoides Szafer, were isolated from a polluted environment and studied for their Cr⁶⁺ removal efficiency from aqueous solutions. The parameters studied included the solution pH, contact time, initial concentration of Cr⁶⁺ and culture density. Living biomass is more efficient than dead biomass in Cr⁶⁺ removal. Removal by living biomass involves bioreduction and biosorption. Below pH 3.1, bioreduction is favored and biosorption is dominant at higher pH. The highest removal through biosorption for living biomass was achieved between pH 5 and 5.9 and for dead biomass at pH 2. The maximum removal was on the tenth day of exposure for both the species. Cr⁶⁺ removal increased from 0.2 to 0.4 g L^?1 of culture biomass with a decrease with further increase in biomass. Increased Cr⁶⁺ concentration decreases growth of both the species over time. Both species tolerate a concentration as high as 30 mg L^?1 Cr⁶⁺. There was no evidence of bioreduction in the case of dead biomass. Living biomass of O. laete-virens followed both Langmuir and Freundlich models with maximum sorptive capacity (q _max) of 21.88 mg g^?1. The results of dead biomass were well fitted only to Langmuir isotherm. O. trichoides living biomass did not follow either of the isotherms, but removed the metal to a maximum extent of 38.7mg g^?1. The removal was better described by Freundlich isotherm in case of dead biomass. The pseudo-first-order model describes the kinetics better than the pseudo-second-order model in the case of living biomass. Participation of carboxylic, carbonyl, and amino groups in Cr⁶⁺ removal was confirmed by FTIR analysis. Both species seem to be promising biosorbents for Cr⁶⁺.     

Polygalacturonase,biomass and ascospore production by Byssochlamys fulva. II. Effects of sugars found in fruits

Polygalacturonase, biomass, and ascospore production by four strains of Byssochlamys fulva cultured in laboratory media supplemented with glucose, sucrose, or fructose was studied over a 20-day incubation period at 30° C. The production of polygalacturonase was variable, but most activity was detected between 4 and 8 days in 1% sugar media at an initial pH of 4 or 5. The rate of biomass production was retarded early in the incubation period in media initially at pH 3 or 4 as compared to pH 5, but the amount of growth was about the same in media containing the test sugars after 20 days. Large numbers of ascospores were produced between 8 and 10 days in media containing 5% sugar initially at pH 5 and 4. Production of ascospores was retarded at pH 3 in media containing 5% sugar as compared to media initially at pH 5 and 4.     

Process optimization of batch biosorption of lead using <Emphasis Type="Italic">Lactobacillius bulgaricus</Emphasis> in an aqueous phase system using response surface methodology

Response surface methodology (RSM) based on central composite rotatable design was used to investigate the effects of operating variable, mainly, pH, weight of biomass, and initial lead ion concentration on the lead adsorption capacity at ambient temperature using dried cells of Lactobacillius bulgaricus. Using RSM, quadratic polynomial equation was obtained for predicting the percent of lead ion removal. Analysis of variance showed that the effects of pH and weight of dried biomass were concluded to be the key factors influencing the capacity of lead ion removal. At pH lower than 2 (high acidic condition) and in alkaline condition, there is no significant biosorption. The optimum percent of lead ion removal was found at pH of 6.78, biomass concentration of 6.58 g/l and initial lead concentration 36.22 ppm. In this condition, percent of lead ion removal was 86.21%. This study showed RSM effectiveness for modeling of biosorption process.     

Studies on the biosorption of uranium by Talaromyces emersonii CBS 814.70 biomass

Residual biomass, produced by the thermophilic fungus, Talaromyces emersonii CBS 814.70, following growth on glucose-containing media, was examined for its ability to take up uranium from aqueous solution. It was found that the biomass had a relatively high observed biosorption capacity for the uranium (280 mg/g dry weight biomass). The calculated maximum biosorption capacity obtained by fitting the data to a Langmuir model was calculated to be 323 mg uranium/g dry weight biomass. Pretreatment of the biomass with either dilute HCl or NaOH brought about a significant decrease in biosorptive capacity for uranium. Studies on the effects of variation in temperature on the biosorptive capacity demonstrated no significant change in binding between 20°C and 60°C. However, a significant decrease in biosorptive capacity was observed at 5°C. Binding of uranium to the biomass at all temperatures reached equilibrium within 2 min. While the routine binding assays were performed at pH 5.0, adjustment of the pH to 3.0 gave rise to a significant decrease in biosorption capacity by the biomass. The biosorptive capacity of the biomass for uranium was increased when extraction from solution in sea-water was examined.     

Influence of pH on the culture of Scenedesmus obliquus in olive-mill wastewater

Olive-mill wastewater (OMW), an agro-industrial by-product from olive-oil milling (with the three-phase extraction method), was used experimentally as 5% (v/v) of the medium to culture Scenedesmus obliquus CCAP 276/3A. The characterization of the wastewater indicated a nitrogen deficiency. The highest specific growth rate of S. obliquus μ_m = 0.022 h⁻¹ was found when the medium was maintained at a constant pH value of 7.0. The biomass productivity, P_b was determined by the influence of pH on the speciation of the dissolved CO₂. The greatest elimination of BOD₅ occurred at extreme pH values. The protein and chlorophyll contents presented a maximum value close to pH = 7.0. The highest crude-protein content in the biomass was 25.6%. The polyunsaturated and essential fatty acids presented a clear trend to increase with the pH, at pH 9.0, representing 26.2 and 19.4%, respectively, of the total fatty-acid content of the biomass.     

Characteristics of Aluminum Biosorption by Sargassum fluitans Biomass

Biomass of nonliving brown seaweed Sargassum fluitans pretreated by different methods is capable of taking up more than 10% (11 mEq/g) of its dry weight in aluminum at pH 4.5. There are indications that the biomass hydroxyl groups were involved in sequestering the aluminum in the form of polynuclear aluminum species. Aluminum-alginate complex (like cotton candy) was formed in the aluminum sorption solution as alginate was partially released from the biomass. Aluminum uptake of S. fluitans biomass was independent of residual alginate content in the biomass. Sodium ion added for pH adjustment was not adsorbed at all in the presence of aluminum ion. Received March 11, 1998; accepted October 9, 1998.     

Biosorption of chromium (Cr(III)/Cr(VI)) on the residual microalga Nannochloris oculata after lipid extraction for biodiesel production

In order to increase the economic feasibility of biodiesel production from microalgae, the residual biomass after biodiesel production can be utilized as biosorbent for heavy metal removal. In this study, biosorption of chromium by residual Nannochloris oculata after lipid extraction was investigated. Increased surface area of N. oculata was observed after lipid extraction. Cr(III) removal increased as the pH increased from 2 to 6, while Cr(VI) removal was highest at pH 2 and it decreased with the increase in pH. Cr(VI) was reduced to Cr(III) in the presence of biomass under acidic conditions; X-ray photoelectron spectroscopy revealed that the converted Cr(III) was bound to the biomass. Chromium removal was significantly enhanced at high chromium concentrations, which indicates that surface reactions may occur at high chromium/biomass ratios. FTIR study indicated that phosphate and carboxyl functional groups of the biomass were mainly responsible for chromium binding.     

pH effects on the removal of Cu2+, Cd2+ and Pb2+ from aqueous solution by waste brewery biomass

An industrial strain of Saccharomyces cerevisiae collected from the waste of a brewing industry was used to remove lead, cadmium and copper from aqueous solutions (1?mm). Metal removal efficiency by using either biomass suspension directly diluted into the metal solutions or biomass previously incubated and washed in distilled water was compared. In all experiments with unwashed biomass a shift in the medium pH from 4.5 to a final value in the 7.0–8.0 range occurred. This pH increase was responsible for a metal precipitation effect associated to the metal biosorption. A very different pH profile was observed when washed biomass was used leading to different removal profiles for Cd²⁺ and Pb²⁺ and a similar one for Cu²⁺. In the absence of biomass, medium components and/or the excreted intracellular products proved to interfere in the metal removal and to be responsible for 80% Pb²⁺ precipitation, in the pH 4.5–5.0 range. To initial metal solution pH, leading to the lowest residual ion concentrations, after 96?h of contact with unwashed biomass and in the absence of pH adjustment, was 4.5–5.0. Continuous or stepwise adjustment of medium pH to this range during the process was unfavourable for metal removal, being the continuous adjustment the worst procedure. In this case, Cd²⁺ was not biosorbed and Cu²⁺ removal decreased from 76 to 33%. However, Pb²⁺ was always extensively removed (89%) and only slightly affected by pH control. The global results suggest different removal mechanisms for each cation. Cu²⁺ was removed by both metal sorption and precipitation, due to the pH shift that occurred during the process, while Cd²⁺ removal showed to be completely dependent of this pH shift. Pb²⁺ was totally and quickly removed, by precipitation, in the presence of the biomass suspension and at pH 4.5. Moreover, the biosorbent changes occurring during the process played an important role in the metal removal when non-viable microbial biomass is used.     

Removal of hexavalent chromium by fungal biomass of <Emphasis Type="Italic">Mucor racemosus</Emphasis>: influencing factors and removal mechanism

This study reported the hexavalent chromium removal by untreated Mucor racemosus biomass and the possible mechanism of Cr (VI) removal to the biomass. The optimum pH, biomass dose, initial Cr (VI) concentration and contact time were investigated thoroughly to optimize the removal condition. The metal removal by the biomass was strongly affected by pH and the optimum pH ranged from 0.5 to 1.0. The residual total Cr was determined. It was found that dichromate reduction occurred at a low very low pH value. At biomass dose 6 g/l, almost all the Cr (VI) ions were removed in the optimum condition. Higher removal percentage was observed at lower initial concentrations of Cr (VI) ions, while the removal capacity of the biomass linearly depended on the initial Cr (VI) concentration. More than half of Cr (VI) ions were diminished within 1 h of contact and removal process reached a relative equilibrium in approximately 8 h. Almost all of the Cr (VI) ions were removed in 24 h when initial concentrations were below 100 mg/l. The equilibrium data were fitted in to the Langmuir and the Freundlich isotherm models and the correlated coefficients were gained from the models. A Fourier transform infrared spectra was employed to elucidate clearly the possible biosorption mechanism as well.