Reduction In Sulfate Concentration Research Articles

Optimization of the electrostatic coal adsorption process for sea-salt production from seawater

High sulfate content in seawater forms sulfate salts, which become impurities in sea salts. This study investigates the influence of lime juice in the adsorption of sulfate ions in seawater using commercial activated carbon. A full factorial experimental design was employed to optimize the level factors of activated carbon type, adsorbent dosage, and concentration of lime juice in response to the percentage reduction in sulfate concentration. Activated carbon (GCB) and acid-washed activated carbon (GCA) were two types of coconut shells granular activated carbon used for the experiment without further modification. The main effect and interaction effects were analyzed using analysis of variance (ANOVA) and p-values to define the influence of variables affecting sulfate ions adsorption. The adsorption of sulfate ions in seawater was affected by the interaction between the activated carbon type and the dosage, and the concentration of lime juice. The lime juice factor significantly enhanced the performance of activated carbon to adsorb the sulfate ions in seawater, and the factor's contribution was 58.2 %. The optimum sulfate ions reduction from seawater was attained at levels of factors activated carbon GCB, the dosage of 50mg, and the concentration of lime juice 50 µl. The interaction between lime juice and activated carbon pores are electrostatic. The impurities are attracted by the revealed polarity of the activated carbon pores. High electronegativity of lime juice acid pulls the negatively charged ions of the impurities. The more economical activated carbon, GCB, which performed better in sulfate ion adsorption, provides an alternative for reducing sea salt impurities. Hence, GCB can directly be mixed with the seawater to produce high quality sea-salt. Therefore, this study is suitable to improve sea salt product quality that processed with activated carbon

Impact of elevated phosphogypsum on soil fertility and its aerobic biotransformation through indigenous microorganisms (IMO's) based technology

Phosphogypsum (PG) is a waste by-product of phosphate fertilizer industry, produced in huge amount during the manufacture of phosphoric acid by economic wet process. Assessment of PG toxicity on soil has been poorly emphasized, therefore an efficient methods needs to be adopted to assess its toxic effect on soil fertility. We also need an effective eco-technological strategies for better waste PG management in order to improve the environmental health. The present study aimed to investigate the impact of PG toxicity on fertile soil and utilization of indigenous microorganisms for aerobic detoxification of PG contaminated soil to evaluate the scope for biostimulation based in situ bioremediation. In this study it is evident that application of PG to fertile soil in certain concentration results highly acidic, sulfate rich, aerobic environment, thus severely weakens the metabolic activity of the indigenous microorganisms. This investigation via microcosm based study further evaluated the intrinsic biotransformation ability of these microorganisms and found that was enhanced significantly (>95% reduction in sulfate concentration in 180 days) with carbon, nitrogen and phosphate amendments. Community level physiological profiling analyses indicated distinct shift in metabolic abilities following carbon amendments. Our study for the first time may help to formulate a strategy in aerobic biotransformation of PG contaminated soil environment, yet appreciable rate by supplying adequate nutrients.

Treatment of paint wastewater by radiation combined with coagulation and adsorption

In this study, attempts were made to examine the efficiency of radiation combined with coagulation with aluminium sulphate and adsorption using granular activated carbon (GAC) for treatment of paint wastewater and its reuse for different purpose. Parameters affecting microorganism disinfection such as radiation dose showed that complete disinfection was obtained at radiation dose 2 kGy. Factors affecting coagulation such as settling time, aluminium sulphate concentration were also studied, it was found that Al2(SO4)3.16H2O at concentration 10 g/L and pH 8 showed the better coagulation at 51 sec compared with other concentrations. A combined treatment of radiation followed by coagulation and adsorption by GAC of a dose (2 g/100 ml supernatant) showed a reduction in sulphate concentration 50%, COD 92% and BOD 98.5%. Also the obtained supernatant can be used for some irrigation purposes, whereas the coagulant was used as filler and showed the same physical parameters compared with the original one. Thus, this study might offer an effective way for wastewater treatment of paint industry.

Rice husk filtrate as a nutrient medium for the growth of Desulfotomaculum nigrificans: characterisation and sulfate reduction studies

The filtrate obtained by interacting a known amount of rice husk with deionised, Milli-Q water was assessed as a carbon source and nutrient medium for the growth of Desulfotomaculum nigrificans, a typical sulfate-reducing bacterium. The filtrate contained essential growth constituents such as magnesium, potassium, phosphorous apart from calcium, sodium, chloride and sulfate ions. Based on the 1H and 13C NMR characterization studies, the organic composition of the components dissolved from the rice husk, was found to be: (i) 66% lignocellulosic material, (ii) 24% xylose + arabinose and (iii) 10% galactose. The growth studies indicated a 15-fold increase in the bacterial cell number in about 20 days. Nearly 81% and 66% reduction in sulfate concentration could be achieved in about 28 days, from the solutions containing initial sulfate concentrations of 550 mg/l and 1200 mg/l respectively. In both the cases studied, the iron concentration could be reduced by over 85%.

Response of acid lakes in the UK to reductions in atmospheric deposition of sulfur

United Kingdom emissions of sulfur dioxide declined by 82% between 1970 and 2000. This decline has been accompanied by reductions in the atmospheric deposition of anthropogenic sulfur. A further expected response, possibly delayed, is a reduction in sulfur concentrations, as sulphate, in upland surface waters. Associated water quality changes, including an increase in alkalinity and reduction in acidity are also anticipated. We examine annual data from 1988 to the present from 10 lakes in the UK acid waters monitoring network for evidence of changes in water chemistry as a response to reductions in the atmospheric deposition of sulfur. We show that there is a close association between reduction in sulfur deposition and reduction in lake water concentrations of sulphate and this provides some supporting evidence for the efficacy of the international agreements to reduce S emissions. However, only 3 of the 10 lakes show an upward trend in alkalinity, and this is not related in a simple fashion to reductions in sulphate concentrations. This suggests that recovery from acidification, measured as an increase in pH and alkalinity, while requiring a reduction in sulphate concentration, may not occur over the same time scale.

Removal of sulfate and heavy metals by sulfate reducing bacteria in short-term bench scale upflow anaerobic packed bed reactor runs

Mildly acidic metal (Cu, Zn, Ni, Fe, Al and Mg), arsenic and sulfate contaminated waters were treated, over a 14 day period at 25°C, in a bench-scale upflow anaerobic packed bed reactor filled with silica sand and employing a mixed population of sulfate-reducing bacteria (SRB). The activity of SRB increased the water pH from ∼4.5 to 7.0, and enhanced the removal of sulfate and metals in comparison to controls not inoculated with SRB. Addition of organic substrate and sulfate at loading rates of 7.43 and 3.71 kg d −1 m −3, respectively, resulted in >82% reduction in sulfate concentration. The reactor removed more than 97.5% of the initial concentrations of Cu, Zn and Ni, while only >77.5% and >82% of As and Fe were removed, respectively. In contrast, Mg and Al levels remained unchanged during the whole treatment process. The removal patterns for Cu, Zn, Ni and Fe reflected the trend in their solubility for their respective metal sulfides, while As removal appeared to coincide with decreasing Cu, Zn, Ni and Fe concentrations, which suggests adsorption or concomitant precipitation with the other metal sulfides.

Methanol as a carbon source for microbiological treatment of acid mine drainage

Sulfate reducing passive bioreactors are increasingly being used to remove metals and raise the pH of acidic waste streams from abandoned mines. These systems commonly use a variety of organic substrates (i.e. manure, wood chips) for sulfate reduction. The effectiveness of these systems decreases as easily accessible reducing equivalents are consumed in the substrate through microbial activity. Using column studies at room temperature (23–26°C), we investigated the addition of lactate and methanol to a depleted manure substrate as a method to reactivate a bioreactor that had lost >95% of sulfate reduction activity. A preliminary experiment compared sulfate removal in gravity fed, flow through bioreactors in which similar masses of each substrate were added to the influent solution. Addition of 148 mg/l lactate resulted in a 69% reduction in sulfate concentration from 300 to 92 mg/l, while addition of 144 mg/l methanol resulted in an 88% reduction in sulfate concentration from 300 to 36 mg/l. Because methanol was found to be an effective sulfate reducing substrate, it was chosen for further experiments due to its inherent physical properties (cost, low freezing point and low viscosity liquid) that make it a superior substrate for remote, high elevation sites where freezing temperatures would hamper the use of aqueous solutions. In these column studies, water containing sulfate and ferrous iron was gravity-fed through the bioreactor columns, along with predetermined methanol concentrations containing reducing equivalents to remove 54% of the sulfate. Following an acclimation period for the columns, sulfate concentrations were reduced from of 900 mg/l in the influent to 454 mg/l in the effluent, that reflects a 93% efficiency of electrons from the donor to the terminal electron acceptor. Iron concentrations were reduced from 100 to 2 mg/l and the pH increased nearly 2 units.

Acidification in Norway ? Status and trends

Surface and ground water monitoring in Norway is designed to give a regional coverage with most of the stations in areas with acidification and some stations in unpolluted areas that give background values. Surface water (weekly sampling) and precipitation (daily measurement) are monitored at 6 calibrated catchments, 5 located in southern Norway and 1 in northernmost Norway close to the Russian border. Ground water (weekly sampling) is monitored in 4 reservoirs in Southern Norway. 73 lakes located all over Norway are surveyed each fall. Nineteen rivers in western and southern Norway are monitored by monthly sampling. All sites are considered sensitive to acidification and are chosen to minimise the effects of anthropogenic catchment based impacts. Results from the monitoring over the period 1980–1994 show that there is a reduction of sulphate of about 25–35% in surface waters which is related to a 30–45% reduction in sulphate concentration in precipitation. An improvement in water quality as measured as increase in ANC has only been apparent since 1990. Due to heavy seasalt episodes in the most coastal catchments like Birkenes and the rivers in western Norway, there has been no improvement of ANC since 1980. Deposition of nitrogen has not changed over the last 10 years, and there is no change in the levels of nitrate in the monitored surface waters.

Formation of substrate and transition-state analog complexes in crystals of phosphoglucomutase after removing the crystallization salt

Crystals of phosphoglucomutase, grown in 2.1 M ammonium sulfate, "desalted", and suspended in a 30% polyoxyethylene-8000/1 M glycine solution as described in the accompanying paper [Ray, W. J., Jr., Puvathingal, J. M., Bolin, J. T., Minor, W., Liu, Y., & Muchmore, S. W. (1991) Biochemistry 30 (preceding paper in this issue)], were treated with glucose phosphates to form an equilibrium mixture of the catalytically active substrate/product complexes. However, this treatment extensively fractured the crystals, even when very dilute solutions of glucose phosphates were used. But formation of the desired complexes was achieved, without fracturing, by introducing the glucose phosphates at high salt concentration, where they do not bind significantly to the enzyme, and maintaining their presence during subsequent sulfate-removal steps, in order to obtain essentially uniform binding throughout the crystal at all times. Although this procedure produced unfractured crystals of the catalytically active complexes, an adjustment in water activity was required to prevent the crystals from slowly liquefying in the presence of the added glucose phosphates. After this adjustment, the quality of diffraction-grade crystals subjected to this treatment was not significantly altered. An even larger adjustment in water activity was required to stabilize crystals that had been largely converted into a mixture of vanadate-based transition-state analogue complexes [cf. Ray, W. J., Jr., & Puvathingal, J. M. (1990) Biochemistry 29, 2790-2801] by means of an analogous procedure. The rationale for, and the implications of, this adjustment of water activity are discussed. The phenomenon of lattice-based binding cooperativity also is discussed together with a possible role for such cooperativity in the fracturing of protein crystals during formation of ligand complexes and possible ways to circumvent such fracturing based on the annealing of crystals at fractional saturation. An assay for quantifying the extent of formation of the vanadate-based transition-state analogue complexes in crystals of phosphoglucomutase is described. A solution to problems associated with producing and maintaining a steady-state in treated crystals is discussed within the context of maximizing the fraction of the crystalline enzyme present as a complex with one such inhibitor, glucose alpha-1-phosphate-6-vanadate. One of these problems, achieving a substantial reduction in sulfate concentration, could not be successfully addressed by employing the desalting procedure used to produce the substrate/product complexes, because of reduced diffusional rates in the final solution.(ABSTRACT TRUNCATED AT 400 WORDS)

The relationship between hydrogen and sulphate ions in precipitation-A numerical analysis of rain and snowfall chemistry.

Acidic rain has been identified as potentially harmful to the aquatic and terrestrial components of the ecosystem. Sulphate measured in rain and snow has been used as a surrogate indicator of acidic deposition. If sulphur dioxide controls are the means to limit acidic deposition, then the association between sulphate and hydrogen ion concentrations in precipitation is an important factor in establishing such limits. Selected data on rain and snowfall chemistry from the National Atmospheric Deposition Program (NADP), the Electric Power Research Institute's SURE, the utility industries' UAPSP, and the Department of Energy's MAP3S were reviewed. Numerical analyses were performed to assess the relationship between hydrogen and sulphate ion concentrations. The strength of the association between hydrogen and sulphate ions varied from site to site. In the Midwestern and Eastern regions, the Pearson correlation coefficient was over 0.50 while in the Central and Upper Midwestern parts of the United States, the correlation coefficients were less than 0.25. Regardless of the strength of the association between hydrogen and sulphate ions, all but one of the NADP/NTN sites used in our analysis exhibited at least 30% of the anions (sulphate, nitrate, and chloride) associated with cations other than hydrogen. For sites where the strength of the association was weak, between 65% and 98% of the anions appeared to be associated with cations other than hydrogen. Because a large percentage of the anions (i.e. sulphate, nitrate, and chloride) appear to be associated with cations other than hydrogen even at those sites where the association between hydrogen and sulphate ions was strong, the complex chemistry controlling the acidity in precipitation may make it difficult to predict the impact of a reduction in sulphate concentration.