Elimination Of Sulfate Research Articles

Electricity-driven synergistic sulfur recovery and sulfate elimination in seawater

High sulfate (SO42-) concentration inhibits seawater utilization but provides a potential source for elemental sulfur (S0) production. The aim of this study was to investigate the feasibility of SO42- removal with the enhancement of S0 recovery simultaneously using a biotic-abiotic hybrid electrochemical (BAHE) process. Long-term operation (i.e., ∼ 240 d) of the biotic electrochemical unit (i.e., single-chamber bioelectrochemical system) obtained a low S0 recovery of 0.78 ± 0.08 % with high SO42- removal exceeding 95 %. The non-conductive S0 precipitated on the anodic surface inhibited continuous electrochemical oxidation of S2-, resulting in the S2- accumulation in the effluent of the bioelectrochemical process and low S0 recovery. In contrast, efficient S2- oxidation took place on the anode surface of the abiotic electrochemical process with electricity generation. The final S2- concentration in the BAHE process was much lower than that in the individual bioelectrochemical process (3 ± 1 vs. 539 ± 60 mg/L). Efficient S0 recovery (i.e., 71.73 ± 7.17 %) and SO42- reduction (92 ± 5 %) were realized in the BAHE process, mainly attributed to the synergistic effect between the single-chamber bioelectrochemical and abiotic electrochemical cells. Our results may provide a promising way for both seawater utilization and elemental sulfur production.

Assessment of performance and safety of Corneal Chamber hypothermic storage medium and PSS-L corneal rinsing solution in human and porcine corneas

PurposeTo prove the safety and performance of the hypothermic corneal storage medium "Corneal Chamber" and the rinsing solution "PSS-L" in support of the new Conformité Européenne (CE) certification process in...

Influence of konjac glucomannan and its derivatives on the oral pharmacokinetics of antimicrobial agent in antibiotics cocktails: Keep vigilant on dietary fiber supplement

In this study, konjac glucomannan (KGM) and its derivatives were gavaged as dietary fiber supplements, followed by a single dose of antibiotic cocktail (Abx) containing amoxicillin, neomycin, metronidazole and vancomycin in mice. The effects of dietary fiber on the pharmacokinetics and tissue distribution of each antibiotic were investigated. The results showed that the specific effects of KGM and its derivatives on the absorption, distribution, and elimination of certain antibiotics varied and depended on the nature of the fibers and the characteristics of the antibiotics. Explicitly, the ingestion of KGM and its derivatives enhanced the absorption of metronidazole by 1.7 times and hindered that of amoxicillin by nearly 36 % without affecting the absorption of neomycin sulfate and vancomycin. KGM and its derivatives had no effect on the distribution of amoxicillin and metronidazole, but DKGM and KGM hindered the distributions of neomycin sulfate (from 1.25 h to 1.62 h) and vancomycin (from 0.95 h to 1.14 h), respectively. KGM and its derivatives promoted the elimination of amoxicillin by nearly 38 % while prolonging that of metronidazole by >50 %. KOGM boosted the elimination of neomycin sulfate and vancomycin, but KGM differed from DKGM in acting on the elimination of both.

Effect of continuous renal replacement therapy on plasma concentration, clinical efficacy and safety of colistin sulfate

To investigate the effects of continuous renal replacement therapy (CRRT) on plasma concentration, clinical efficacy and safety of colistin sulfate. Clinical data of patients received with colistin sulfate were retrospectively analyzed from our group's previous clinical registration study, which was a prospective, multicenter observation study on the efficacy and pharmacokinetic characteristics of colistin sulfate in patients with severe infection in intensive care unit (ICU). According to whether patients received blood purification treatment, they were divided into CRRT group and non-CRRT group. Baseline data (gender, age, whether complicated with diabetes, chronic nervous system disease, etc), general data (infection of pathogens and sites, steady-state trough concentration, steady-state peak concentration, clinical efficacy, 28-day all-cause mortality, etc) and adverse event (renal injury, nervous system, skin pigmentation, etc) were collected from the two groups. A total of 90 patients were enrolled, including 22 patients in the CRRT group and 68 patients in the non-CRRT group. (1) There was no significant difference in gender, age, basic diseases, liver function, infection of pathogens and sites, colistin sulfate dose between the two groups. Compared with the non-CRRT group, the acute physiology and chronic health evaluation II (APACHE II) and sequential organ failure assessment (SOFA) were higher in the CRRT group [APACHE II: 21.77±8.26 vs. 18.01±6.34, P < 0.05; SOFA: 8.5 (7.8, 11.0) vs. 6.0 (4.0, 9.0), P < 0.01], serum creatinine level was higher [μmol/L: 162.0 (119.5, 210.5) vs. 72.0 (52.0, 117.0), P < 0.01]. (2) Plasma concentration: there was no significant difference in steady-state trough concentration between CRRT group and non-CRRT group (mg/L: 0.58±0.30 vs. 0.64±0.25, P = 0.328), nor was there significant difference in steady-state peak concentration (mg/L: 1.02±0.37 vs. 1.18±0.45, P = 0.133). (3) Clinical efficacy: there was no significant difference in clinical response rate between CRRT group and non-CRRT group [68.2% (15/22) vs. 80.9% (55/68), P = 0.213]. (4) Safety: acute kidney injury occurred in 2 patients (2.9%) in the non-CRRT group. No obvious neurological symptoms and skin pigmentation were found in the two groups. CRRT had little effect on the elimination of colistin sulfate. Routine blood concentration monitoring (TDM) is warranted in patients received with CRRT.

Coordination of thin-film nanofibrous composite dialysis membrane and reduced graphene oxide aerogel adsorbents for elimination of indoxyl sulfate

• A novel combination of PVA/PAN TNFC dialysis membrane with rGO aerogel was proposed. • The rGO aerogel exhibited good adsorption performance for indoxyl sulfate. • The coordination of TFNC membrane and rGO lightened conventional hemodialysis. The protein-bound uremic toxins, represented by indoxyl sulfate (IS), have been associated with the progression of chronic kidney disease and the development of cardiovascular disease in the presence of impaired renal function. Herein, we proposed a novel strategy of thin-film nanofibrous composite (TNFC) dialysis membrane combined with reduced graphene oxide (rGO) aerogel adsorbents for clinical removal of IS as well as high retention of proteins. The TFNC membrane was prepared by electrospinning in conjunction with coating-reaction method and proved to have good selectivity and permeability. To further improve the removal rate of toxins, we used a medium hydrothermal method following by freeze-drying treatment to obtain the rGO aerogel adsorbents. It exhibited excellent adsorption for IS with a maximum adsorption capacity of 69.40 mg∙g −1 through π−π interaction and hydrogen bonding interaction based on Langmuir isotherm models. Time-dependent absorption experiments showed that it reached adsorption equilibrium within 4 h, which was matched with the hemodialysis time. The coordination was significantly exhibited by introducing rGO aerogel blocks into the dialysate for absorbing the diffused free IS during hemodialysis. Taking the advantages of the TFNC dialysis membrane and the rGO aerogel, the volume of dialysate for hemodialysis was only one-tenth of that without adsorbent blocks but with very comparable dialysis performance (the clearance of IS at 51.8% and the retention of HSA over 98%), which could lighten conventional hemodialysis effectively and be benefit to realize the miniaturization of the hemodialysis equipment. Therefore, the coordination of the TFNC dialysis membrane and rGO aerogel adsorbents would open a new path for the development of portable artificial kidney.

Molecular Basis for Enzymatic Aziridine Formation via Sulfate Elimination.

Natural products containing an aziridine ring, such as mitomycin C and azinomycin B, exhibit antitumor activities by alkylating DNA via their aziridine rings; however, the biosynthetic mechanisms underlying the formation of these rings have not yet been elucidated. We herein investigated the biosynthesis of vazabitide A, the structure of which is similar to that of azinomycin B, and demonstrated that Vzb10/11, with no similarities to known enzymes, catalyzed the formation of the aziridine ring via sulfate elimination. To elucidate the detailed reaction mechanism, crystallization of Vzb10/11 and the homologous enzyme, AziU3/U2, in the biosynthesis of azinomycin B was attempted, and the structure of AziU3/U2, which had a new protein fold overall, was successfully determined. The structural analysis revealed that these enzymes adjusted the dihedral angle between the amino group and the adjacent sulfate group of the substrate to almost 180° and enhanced the nucleophilicity of the C6-amino group temporarily, facilitating the SN2-like reaction to form the aziridine ring. The present study reports for the first time the molecular basis for aziridine ring formation.

Microorganisms and their application in mining and allied industries

Mining activities cause significant damage to nature but it is inevitable. The nature of ore along mining method not only guide the volume of waste generation but also the nature of waste. Bioremediation is considered as an alternative and economically viable technique compared to conventional remediation techniques. It is found to be suitable alternative in treating mine wastes and recovery of toxic heavy metals. Out of all the waste generated during and after mining operation, Acid mine drainage/ acid rock drainage is the most dangerous one laden with heavy and toxic metals, remain untreated. Use of microorganisms not only help in detoxification but also facilitates extraction. Sulfate-reducing microorganisms have been applied for the treatment of acid mine waste Amongst all the known microorganisms, SRB plays a vital role in mine waste treatment, neutralizing acidity & reviving alkalinity. Due to simultaneous elimination of sulfate and metals, and the possibility to reuse, bioreactors with SRB represent a promising option for remediation of mine waste..Such a technique picked up its momentum due to its low cost, easy availability of ingredients, and eco-friendly nature. Considering the dependency of microorganisms on other factors for their survival, such a treatment system may/ may not be used alone. Therefore, it advisable to use the same along with other techniques depending upon site conditions, nature of deposit and availability of essential requisites. In this paper, attempts were made to highlight the potential thrust areas requiring applying this technique, limiting factors.

Development of a Community-scale Autonomous Water Purifier (AWP) Prototype to Remove Heavy Metals

In this paper, we present the design and evaluation of a prototype Autonomous Water Purifier (AWP) for removing heavy metals from contaminated water. The AWP prototype uses solar energy for its operation; the autonomous photovoltaic system is designed to operate up to 8 hours per day and to generate a water flow of 112 liters per day. The prototype was designed to remove biological and chemical agents. It was achieved the elimination of total coliforms, fecal coliforms, total alkalinity, total hardness, total solids, chloride and sulfate from 50 to 100%, as well as the removal of heavy metals. The Pb2+, Hg2+, Cd2+ and Cu2+ were eliminated from 80 to 99%. This wide range of contaminant removal shows a unique way to treat contaminated water in comparison to existing purification systems. The prototype was evaluated with river and spring water from different rural communities of Chiapas, Mexico. The results indicate that the prototype is able to completely remove contaminants in natural waters and get water that meets the guidelines that mark the Mexican official standards. This work helps to solve problems in marginalized communities and natural disaster areas where they have no access to clean water, electricity and suffer from waterborne diseases

Wet Process Phosphoric Acid Purification Using Functionalized Organic Nanofiltration Membrane

The utilization of phosphoric acid in various sectors, e.g., food industry, is controlled by the authorized concentration limit of impurities. However, industrial phosphoric acid is contaminated with undesirable impurities (such as F, Al, Fe, Mg, etc.). Herein, this study aimed to evaluate the efficiency of the membrane purification process of pretreated industrial phosphoric acid using a premodified nanofiltration membrane. We demonstrated that the prior pretreatment steps for industrial phosphoric acid allowed the elimination of sulfate, fluorine and arsenic. Further purification of the obtained pretreated phosphoric acid using membrane cells reduced the concentrations of Cd, Al, Fe and rare earth elements by 94.81, 99.30, 99.63 and 96.67%, respectively. The membrane is functionalized by a deposit of a high molecular weight polycationic polymer of polyethyleneimines in order to produce a highly charged membrane surface to enhance the separation efficiency, selectivity and stability of the membrane. We found that the purification process relies on electrostatic repulsion between the functionalized membrane and highly charged ions, and the reduction rate of metals is a cation charge-dependent parameter. The laboratory and industrial pilot scale results showed that this process allows the production of food-grade phosphoric acid.

Binding ability of methylene blue with heparin dependent on its sulfate level rather than its sulfation location or basic saccharide structure.

Methylene blue (MB) is one of the most common cationic dyes to detect heparin. As the sulfate residue presented in heparin was the main contributor to bind with MB, the UV performance of the MB with selectively desulfated heparin derivatives was investigated. It was found that the sulfate residue in different heparin analogues did not show the equal ability to attract MB binding. The stoichiometry of sulfate with MB among the heparin and derivatives was verified as a non-constant number. For the two selectively desulfated heparin derivatives: sulfate elimination at 6-O (6-OdeS) and N-acetylated heparin (N-deS-Acetyl), the MB to sulfate ratios were significantly higher than for heparin. For the not fully diminished sulfate at 2-O heparin derivative (2-OdeS), the MB-SO3- ratio of 2-OdeS was between 6-OdeS, N-deS-Acetlyl and heparin. Although in a distinct sulfation position, the MB-SO3- ratio of 6-OdeS and N-deS-Acetyl was almost equal, which agreed with the comparable total desulfation degree between 6-OdeS and N-deS-Acetyl. In addition, compared to heparin groups, the non-desulfated gs-HP showed no significantly different MB-SO3- ratio with heparin. The above results demonstrated that compared with the sulfate location and glycan composition of heparin, the content of sulfate was the most essential factor for the MB binding.

Sequential sulfur-based denitrification/denitritation and nanofiltration processes for drinking water treatment

Efficient and cost-effective solutions for nitrogen removal are necessary to ensure the availability of safe drinking water. This study proposes a combined treatment for nitrogen-contaminated groundwater by sequential autotrophic nitrogen removal in a sulfur-packed bed reactor (SPBR) and excess sulfate rejection via nanofiltration (NF). Autotrophic nitrogen removal in the SPBR was investigated under both denitrification and denitritation conditions under different NO3− and NO2− loading rates (LRs) and feeding strategies (NO3− only, NO2− only, or both NO3− and NO2− in the feed). Batch activity tests were carried out during SPBR operation to evaluate the effect of different feeding conditions on nitrogen removal activity by the SPBR biofilm. Bacteria responsible for nitrogen removal in the bioreactor were identified via Illumina sequencing. Dead-end filtration tests were performed with NF membranes to investigate the elimination of excess sulfate from the SPBR effluent. This study demonstrates that the combined process results in effective groundwater treatment and evidences that an adequately high nitrogen LR should be maintained to avoid the generation of excess sulfide.

Continuous photocatalytic set-up assisted with nano TiO2 plate for tannery wastewater treatment.

A novel photocatalytic continuous system has been proposed for the treatment of tannery waste water, which has high levels of environmental pollutants. The purification process was performed by passing wastewater on a titanium dioxide (TiO2)-coated surface, which is continuously activated by irradiation of ultraviolet light. To improve the yield of the process, ferric chloride (FeCl3) was used as a coagulation agent. The organic and inorganic compounds, as well as the microorganisms in the tannery wastewater media, were degraded through a photocatalytic process. The results revealed that total dissolved solids and total suspended solids contents were significantly decreased from 8,450 and 8,990 mg·L-1 to 4,032 and 4,127 mg·L-1, respectively. Furthermore, the chemical oxygen demand content of the sample was reduced from 370 to 50 mg·L-1 after the addition of 100 mL of FeCl3 and 4 h of treatment. The same results were observed for the elimination of sulfate and chromium ions, which led to a decline in electrical conductivity. This suggests that introducing 100 mL of FeCl3 as the coagulation agent and continuous treatment with photocatalityc set-up could be considered as an effective method for the purification of tannery wastewaters.

Plasma concentrations of syndecan-1 are dependent on kidney function.

Elevated plasma concentrations of syndecan-1 and heparan sulfate in studies of trauma, sepsis, and major surgery are commonly assumed to indicate acute glycocalyx degradation. We explored a possible role of the kidneys for these elevations. Plasma and urine concentrations of syndecan-1, heparan sulfate, and biomarkers of inflammation were measured over 5hours in 15 hospital patients treated for post-burn injury. The renal clearances of syndecan-1 and heparan sulfate (CLR ) were calculated and their influence on the plasma concentration predicted by simulation. The urine/plasma concentration ratio was 0.9 (0.3-3.0) for syndecan-1 and 2.8 (2.0-4.3) for heparan sulfate. The CLR varied 250-fold for syndecan-1 and 10-fold for heparan sulfate. Multiple linear regression analysis showed that CLR for syndecan-1 was positively associated with the creatinine clearance (P<.0032) and the urine flow (P<.015). CLR for heparan sulfate increased with interleukin-6 (P<.003) and the urine flow (P<.01). Simulations suggested that a change in CLR from the mean of the highest 3 to the lowest three values would double plasma syndecan-1 within 4hours and cause a 7-fold rise after 24hours. A similar change in CLR for heparan sulfate would triple the plasma level within 24hours, even if no increased shedding of the glycocalyx takes place. The renal elimination of syndecan-1 and heparan sulfate varied greatly. A change in kidney function, which is common after trauma and major surgery, might alone induce several-fold changes in their plasma concentrations.

Anatomic-radiographic aspects and gastrointestinal transit time in boa constrictor amarali stull, 1932 (Squamata, Boidae)

ABSTRACT The goal of this study was to describe the gastrointestinal transit technique in the Boa constrictor amarali. For that purpose, we obtained simple radiographic images of seven serpents, subsequently administering a 25mL/kg dose of barium sulfate and establishing a radiographic sequence at the following times: 5 minutes; 1, 2, 3, 6, 9, 24, 48, 72 and 96 hours, extending to 120 and 126 hours for one animal. The mean esophageal transit was 26.71±19.48 hours; the mean gastric filling time was 28.57±27.22 minutes and the emptying time was 60±12 hours; the mean filling time of the contrast medium in the small intestine was 3±2.16 hours and the emptying time was 97±15.65 hours. We also obtained the mean filling time of the large intestine, which was 40±11.31 hours. We found that the mean passage time of the contrast medium through the cranial gastrointestinal tract - until the complete elimination of barium sulfate from the small intestine -was 97±15.65 hours. In addition to determining the gastrointestinal transit time, the technique used allowed for the morphological identification of the alimentary canal.

Effect of processing time on removal of harmful emerging salt pollutants from saline-sodic soil during electrochemical remediation

The recent climate change has spawned a new emerging environmental hazard known as soil salinity. The lacks of rainfall and global warming have drastically increased the concentration of harmful emergent salt pollutants (HESPs) to toxic levels for natural and human assets. Electrochemical remediation (ECR) has been successfully used in remediation of contaminated soils. This research aims to investigate the effect of processing time (PT) on the removal of HESPs during ECR. The experiments were operated in a designed laboratory cell, using two different PT of 3 and 5 days with a voltage gradient of 1.5 V/cm. The results show that the increase of PT enhances the removal of monovalent cations, including sodium (Na+) and potassium (K+), reaching an efficiency of 63 and 83%, respectively. However, calcium (Ca2+) and magnesium (Mg2+) have exhibited irreversible behavior, where the increase of PT seems hindering their removal, namely near the cathode. Longer periods induce sharp increase in the basic front, which curb their desorption and mobilization. For the anionic salts, the raises of PT lead to better elimination of monovalent anions, with a removal of 92 and 63% for nitrate (NO3−) and chloride (Cl−), respectively. Nevertheless, the effect of PT was less significant on the elimination of sulfate (SO42-), due to their chemical nature. It can be concluded that the removal rate is an intrinsic parameter, strongly related to set of parameters, including the soil pH, chemical nature, ionic valence of the targeted salts and their selectivity on clay particles in clay-water-electrolyte system.

Direct Fermentative Hydrogen Production from Cellulose and Starch with Mesophilic Bacterial Consortia.

Hydrogen produced from lignocellulose biomass is deemed as a promising fuel of the future. However, direct cellulose utilization remains an issue due to the low hydrogen yields. In this study, the long-term effect of inoculum (anaerobic sludge) heat pretreatment on hydrogen production from untreated cellulose and starch was evaluated during repeated batch processes. The inoculum pretreatment at 90°C was not sufficient to suppress H2 consuming bacteria, both for starch and cellulose. Although hydrogen was produced, it was rapidly utilized with simultaneous accumulation of acetic and propionic acid. The pretreatment at 100°C (20 min) resulted in the successful enrichment of hydrogen producers on starch. High production of hydrogen (1.2 l H2/lmedium) and H2 yield (1.7 mol H2/molhexose) were maintained for 130 days, with butyric (1.5 g/l) and acetic acid (0.65 g/l) as main byproducts. On the other hand, the process with cellulose showed lower hydrogen production (0.3 l H2/lmedium) with simultaneous high acetic acid (1.4 g/l) and ethanol (1.2 g/l) concentration. Elimination of sulfates from the medium led to the efficient production of hydrogen in the initial cycles – 0.97 mol H2/molhexose (5.93 mmol H2/gcellulose). However, the effectiveness of pretreatment was only temporary for cellulose, because propionic acid accumulation (1.5 g/l) was observed after 25 days, which resulted in lower H2 production. The effective production of hydrogen from cellulose was also maintained for 40 days in a repeated fed-batch process (0.63 mol H2/molhexose).

Serum Sulphate Levels in Hemodialysis Patients.

Objective Sulphur, similar to phosphorus, is easily attached to organic compounds. The inadequate elimination of sulphate may cause high sulphate concentrations in hemodialysis (HD) patients because sulphate is low in free form in plasma. Although we are well aware of the accumulation of phosphorus in chronic dialysis patients, we do not have an adequate knowledge database about the sulphur compounds. This study was designed to determine the level of sulphate in hemodialysis patients. Materials and Methods Ninety-four prevalent HD patients and 33 patients without renal failure were included in the study. The serum inorganic sulphate levels were measured by turbidimetric technique. Moreover, the serum level of urea, creatinine, albumin, calcium, phosphorus, and parathyroid hormone concentrations was simultaneously recorded. Results Mean levels of plasma sulphate were significantly higher (0.56 ± 0.17 mM vs 0.31 ± 0.13 mM, p < 0.001) in HD patients. Serum sulphate level correlated with patient's age, serum albumin, serum BUN and creatinine, and serum phosphorus level in HD patients. Serum sulphate levels were not associated with serum parathyroid hormone levels. Conclusion Serum sulphate levels were approximately twofold higher in HD patients than in the normal control group. Inorganic sulphate does not seem to accumulate in long-term dialysis patients, and mild increased serum levels of sulphate has no poor clinical outcome in these patients.

Investigation of the parameters affecting the treatment of mining waters by electrocoagulation

Recently electrochemical methods have been studied as an alternative to conventional methods to treat industrial and municipal waters. One such water, the mining water, has been mainly treated previously by electrocoagulation (EC) to remove metals. Few studies have been performed on the removal of sulfate, nitrate and cyanide from mining waters. In this paper, results from 39 lab-scale experiments on the elimination of sulfate by electrocoagulation with iron electrodes are presented. Significance of parameters affecting the removal of sulfate by EC was studied using response surface methodology (RSM). Also, results from kinetic studies and comparison of synthetic and real mining waters are reported. According to kinetics studies, it was suggested that both physical and chemical mechanisms are involved in sulfate removal. At the same test conditions, sulfate removal from both synthetic and real mining waters followed the same pattern. The study concludes that the most significant parameters in sulfate removal are initial sulfate concentration and applied current when initial pH was insignificant in batch operation. From a technology development perspective, this study enhances knowledge about the significance of process parameters and their interactions as well as allows further scale-up of the process

Exploring the performance limits of a sulfidogenic UASB during the long-term use of crude glycerol as electron donor

SOx contained in flue gases and S-rich liquid effluents can be valorized to recover elemental sulfur in a two-stage bioscrubbing process. The reduction of sulfate to sulfide is the most crucial stage to be optimized. In this study, the long-term performance of an up-flow anaerobic sludge blanket (UASB) reactor using crude glycerol as electron donor was assessed. The UASB was operated for 400 days with different sulfate and organic loading rates (SLR and OLR, respectively) and a COD/S-SO42− ratio ranging from 3.8 g O2 g−1 S to 5.4 g O2 g−1 S. After inoculation with methanogenic, granular biomass, the competition between sulfate-reducing and methanogenic microorganisms determined to what extent dissolved sulfide and methane were produced. After the complete washout of methanogens, which was revealed by next-generation sequencing analysis, the highest S-EC was reached in the system. The highest average sulfate elimination capacity (S-EC = 4.3 kg S m−3d−1) was obtained at a COD/S-SO42− ratio of 5.4 g O2 g−1 S and an OLR of 24.4 kg O2 m−3d−1 with a sulfate removal efficiency of 94%. The conversion of influent COD to methane decreased from 12% to 2.5% as the SLR increased while a large fraction of acetate (35% of the initial COD) was accumulated. Our data indicate that crude glycerol can promote sulfidogenesis. However, the disappearance of methanogens in the long-term due to the out competition by sulfate reducing bacteria, lead to such large accumulation of acetate.

Design of a bioprocess for metal and sulfate removal from acid mine drainage

The high levels of sulfate and the metals in acid mine drainages generate important environmental problems. This paper describes the synergistic combination of a biosorption process and a new sulfate removal process. The treatment for the elimination of metals by biosorption with a Bacillus strain allowed reducing the high metal concentrations that had a toxic effect on the sulfate-reducing bacteria (SRB). On the other hand, the sulfate removal process used a microbial sulfate-reducing halotolerant consortium, which was able to reduce the sulfate concentration using low-cost organic substrates such as spirulina, cellulose and industrial starch. Independent of substrate present in the culture medium, the SRB was the predominant group. The sulfate-reducing consortium was cultured on a bench-scale upflow anaerobic packed bed bioreactor filled with Celite R-635. It was possible to reduce the concentration of sulfate in the culture medium in batch or semi-continuous operation. This integrated process is an inexpensive alternative for the elimination of metals by biosortion and the elimination of sulfate using a sulfate-reducing consortium.