scholarly journals The removal of turbid materials from AMD using bentonite clay, Fe or Al salt, MgCO3 and flocculent with varying agitations

2020 ◽  
Vol 15 (3) ◽  
pp. 580-597
Author(s):  
I. O. Ntwampe
Keyword(s):  
Removal Efficiency ◽  
Mine Drainage ◽  
Bentonite Clay ◽  
Jar Test ◽  
Oxidation Reduction ◽  
Treated Effluent ◽  
Oxidation Reduction Potential ◽  
Changing Trend ◽  
Series Of Experiments ◽  
Slow Mixing

Abstract A series of experiments was conducted using 200 mL of acid mine drainage (AMD) collected from Krugersdorp, South Africa, to determine turbid materials removal efficiency of a combination of bentonite clay, Fe or Al salt and MgCO3. The sample was poured into five 500 mL glass beakers using bentonite clay, FeCl3, AlCl3 and MgCO3 dosage respectively. The samples were treated in jar test at rapid and slow mixing, allowed to settle for 1 hour, then the pH, conductivity, total suspended solids (TSS), dissolved oxygen (DO) and oxidation reduction potential (ORP) were measured (exp A). A second and third similar sets of experiments were conducted with a combination of bentonite clay and MgCO3 (flocculent) dosage (exp B), and FeCl3 with slow mixing only (exp C). Experimental results revealed that the pH of treated effluent with bentonite clay does not exhibit significant increasing trend because of insignificant hydrolysis, whereas the pH of samples with FeCl3, AlCl3 and MgCO3 exhibit a slight decreasing trend, showing a low rate of hydrolysis. The DO and ORP of treated effluent does not show a significant changing trend compared to the untreated AMD sample. Residual TSS of the AMD samples treated with a flocculent is lower than the samples treated with bentonite clay, FeCl, AlCl3 and MgCO3. Residual turbidity of the samples with rapid mixing is identical to that of the corresponding samples with slow mixing. TSS removal efficiency of a flocculent is higher compared to other reagents. The results show that synthetic flocculent is an ideal replacement for inorganic coagulants. The scanning electron microscopy (SEM) micrographs exhibit slides with dense-sponge like flocs showing high adsorption capacity.

scholarly journals The effect of saw dust in a flocculent with bentonite clay and FeSO4 in AMD treatment without addition of a neutralizer

2019 ◽  
Vol 14 (3) ◽  
pp. 633-644 ◽  
Author(s):  
I. O. Ntwampe
Keyword(s):  
Reduction Potential ◽  
Mine Drainage ◽  
Bentonite Clay ◽  
Similar Treatment ◽  
Saw Dust ◽  
Jar Test ◽  
Oxidation Reduction ◽  
Oxidation Reduction Potential ◽  
Removal Efficiencies ◽  
Synthetic Acid

Abstract 200 mL of synthetic acid mine drainage (AMD) was poured into five 500 mL glass beakers and treated in a jar test. The samples were dosed with 1.0–2.5 g bentonite clay, 20–60 mL of 0.025 or 0.05 M FeSO4 and 1.0–2.5 g saw dust respectively. The samples were mixed at 250 rpm for 2 minutes and reduced to 100 rpm for 10 minutes. The samples were allowed to settle for 1 hour, after which the pH, oxidation-reduction potential (ORP) and turbidity were measured (exp. A). Two other similar sets of experiments were conducted by dosing the samples with a combination of bentonite clay and FeSO4 with and without saw dust, similar treatment and measurements (exp. B and exp. C), similar treatment and measurements were conducted. The pH and the efficiencies of the flocculants containing 0.025 and 0.05 M Fe3+ in FeSO4 are similarly identical. The removal of turbid materials from the samples with FeSO4 is the lowest, followed by a combination of bentonite clay and FeSO4, whereas a combination of bentonite clay, FeSO4 and saw dust the highest. Comparative removal efficiencies between the two flocculants show that the presence of FeSO4 is relatively insignificant. The removal efficiency of a combination of bentonite clay, FeSO4 and saw dust from AMD sample is low with for Cu2+, and optimal for both Ni2+ and Fe2+ ions.

scholarly journals Destabilization dynamics of clay and acid-free polymers of ferric and magnesium salts in AMD without pH adjustment

2016 ◽  
Vol 74 (4) ◽  
pp. 861-875 ◽  
Author(s):  
I. O. Ntwampe ◽  
F. B. Waanders ◽  
J. R. Bunt
Keyword(s):  
Removal Efficiency ◽  
Suspended Solids ◽  
Reduction Potential ◽  
Mine Drainage ◽  
Jar Test ◽  
Oxidation Reduction ◽  
Oxidation Reduction Potential ◽  
Predominant Process ◽  
Magnesium Salts ◽  
Treat Acid Mine Drainage

The physicochemical treatment was employed to treat acid mine drainage (AMD) in the removal of turbid materials using clay only (exp A) and a combination of clay, FeCl3 and Mg(OH)2 (exp B) to form a polymer. A 5 g sample of clay (bentonite) was added to 1.2 L of AMD and treated in a jar test at 250 rpm for 2 min and reduced to 100 rpm for 10 min. A 200 mL sub-sample from the 1.2 L mother liquor was poured into five 500 mL glass beakers, and 20 mL dosages of a polymer of 0.1 M Fe3+ in (FeCl3) and 0.1 M Mg2+ in (Mg(OH)2) was added to the beakers. The samples were allowed to settle for 1 h, after which the supernatant was analyzed for pH, total suspended solids (TSS), dissolved oxygen (DO) and oxidation-reduction potential (ORP) (exp A). A similar set of experiments was conducted where 200 mL of the AMD sample was poured into 500 mL glass beakers and (20–60 mL) dosages of a combination of 5 g clay, 0.1 M Fe3+ (FeCl3) and Mg2+ (Mg(OH)2) polymer was added and similar mixing, settling time and measurements were conducted (exp B). The polymers used in exp A exhibited TSS removal efficiency (E%) which was slightly lower compared with the polymer used in exp B, above 90%. Clay has a high TSS removal efficiency in the treatment of the AMD, indicating that adsorption was a predominant process in exps A and B. The scanning electron microscope (SEM) micrographs of the AMD sludge of both exps A and B, with a rigid and compacted structure consisting of dense flocs surrounded by the smaller flocs bound together, corroborate the fact that adsorption is a predominant process.

scholarly journals The removal of pollutants and natural organic compounds from acid mine drainage using a combination of bentonite clay and MgSO4

2021 ◽  
Vol 16 (2) ◽  
pp. 490-503
Author(s):  
I. O. Ntwampe
Keyword(s):  
Acid Mine Drainage ◽  
Organic Compounds ◽  
Removal Efficiency ◽  
Mine Drainage ◽  
Bentonite Clay ◽  
Small Scale ◽  
Acid Mine ◽  
Jar Test ◽  
Oxidation Reduction ◽  
Natural Organic Compounds

Abstract 200 mL of synthetic acid mine drainage (AMD) sample was poured into five 500 mL glass beakers and treated in a jar test and a shaker in sets of experiments, respectively. The samples were treated in small-scale laboratory experiments using synthetic AMD sample dosed with bentonite clay and MgSO4 respectively, and a flocculant consisting of the same reagents. The pH, EC, turbidity and oxidation reduction potential were measured. The removal of turbid materials in the samples dosed with a flocculant is higher compared to those of the samples dosed with each reagent alone. The samples with flocculant dosage show high removal efficiency of natural organic compounds and toxic metals, slightly higher compared to those with a dosage of a combination of bentonite clay and MgSO4. The removal efficiency of the samples treated in a shaker is better than those with rapid mixing. The SEM micrographs show sorption is a physico-chemical phenomenon.

scholarly journals The removal of turbidity and toxic metals in the AMD using a combination of saw dust, bentonite clay and synthetic CaMg.2(OH)2

2021 ◽  
Author(s):  
I. O. Ntwampe
Keyword(s):  
Toxic Metals ◽  
Mine Drainage ◽  
Bentonite Clay ◽  
Lower Percentage ◽  
Turbidity Removal ◽  
Saw Dust ◽  
Oxidation Reduction ◽  
Oxidation Reduction Potential ◽  
Sem Micrograph ◽  
Oxygen Oxidation

Abstract Sets of experiments were conducted using 200 mL of synthetic acid mine drainage(AMD) into five 500 mL glass beaker, dosed with varying quantities of bentonite clay, saw dust and CaMg.2(OH)2 respectively and as a flocculent (bentonite clay, saw dust and CaMg.2(OH)2), mixed at 250 and 100 rpm for 2 and 10 mns respectively. The samples settled for 1 hour after which the pH, conductivity, turbidity, dissolved oxygen, oxidation reduction potential and toxic metals were measured. The turbidity removal of treated AMD samples treated with a flocculent (0–23 NTU) is lower compared to that of the samples treated with bentonite clay and saw dust (27–32 NTU). Results show 100% removal of Ni, moderate percentage removal of Fe and slightly lower percentage of Cu in treated AMD using a flocculent. Turbidity removal in treated AMD using a flocculent is higher compared to that of the samples treated with bentonite clay, saw dust or CaMg.2(OH)2. Treated AMD using flocculent has low Ca, Mg, Cl− and SO42− content (>84.8%). The SEM micrograph of the sludge of the sample with a combination of 1.5 bentonite clay, 1.5 g saw dust and 20 mL 0.025 M CaMg.2(OH)2 dosage shows optimal sorption of turbid materials.

scholarly journals The efficiency of a flocculent consisting of saw dust and bentonite clay in the removal of Fe and Ni from AMD

2020 ◽  
Vol 15 (1) ◽  
pp. 188-200
Author(s):  
I. O. Ntwampe ◽  
R. Mthembu
Keyword(s):  
Crystal Morphology ◽  
Mine Drainage ◽  
Bentonite Clay ◽  
High Sorption Capacity ◽  
Saw Dust ◽  
Oxidation Reduction ◽  
Oxidation Reduction Potential ◽  
Removal Of Heavy Metals ◽  
High Sorption ◽  
Synthetic Acid

Abstract Sets of experiments were conducted by pouring 200 mL of synthetic acid mine drainage (AMD) into five 500 mL glass beakers, dosed with varying quantities of bentonite clay and saw dust interchangeably, mixed at 250 and 100 rpm for 2 and 10 mns respectively. The samples settled for 1 hour after which the pH, concentration, oxidation reduction potential (ORP) and percentage removal of heavy metals were measured. The results show that the removal efficiency of a flocculent on Ni and Fe is effective. The results show that saw dust does not affect the conductivity of a solution. The ORP of the samples with a flocculent with increasing bentonite clay exhibits a higher rate oxidation than that of a flocculent with increasing saw dust. The crystal morphology of the SEM micrographs with 1.5 g bentonite clay and 1.5 g saw dust show three types of structures, i.e. round flocs, elongated and clustered agglomerates which is indicative of high sorption capacity.

Enhanced Nitrogen Removal of Low C/N Wastewater in a Subsequent Denitrifying Reactor Fed by Endogenous Carbon Source Generated from Primary Sludge Fermentation

2011 ◽  
Vol 281 ◽  
pp. 101-105
Author(s):  
Cheng Cheng Wu ◽  
Yong Zhen Peng ◽  
Liang Zhang ◽  
Shu Ying Wang
Keyword(s):  
Carbon Source ◽  
Removal Efficiency ◽  
Nitrogen Removal ◽  
High Performance ◽  
Reduction Potential ◽  
Biological Nitrogen Removal ◽  
Primary Sludge ◽  
Oxidation Reduction ◽  
Oxidation Reduction Potential ◽  
Biological Nitrogen

A novel post-denitrification system fed by carbon source from primary sludge (PS) was used for enhancing biological nitrogen removal (BNR) of low C/N wastewater. This system included one anoxic/oxic (AO) reactor and a special reactor for simultaneous sludge fermentation and denitrification (Sifeden). Ammonia was nitrified to nitrate in AO and then the nitrate was reduced to dinitrogen in Sifeden , into which PS was added intermittently. Results showed that this system had high performance on nitrogen removal. Total nitrogen (TN) removal efficiency was higher than 85% and the effluent TN≤10mg/L in the condition of influent C/N≤2. In Sifeden, volatile fatty acid (VFA) produced from PS fermentation provided electron donor for nitrate reduction, and PS was preliminarily stabilized simultaneously. Oxidation-Reduction Potential (ORP) had a significant correlation with the denitrification performance. TN removal efficiency could be further improved if adopting proper PS addition strategy according to the ORP profiles.

scholarly journals Treatment of AMD using a combination of saw dust, bentonite clay and phosphate in the removal of turbid materials and toxic metals

2021 ◽  
Author(s):  
I. O. Ntwampe
Keyword(s):  
South Africa ◽  
Particle Size ◽  
Removal Efficiency ◽  
Toxic Metals ◽  
Laboratory Experiments ◽  
Mine Drainage ◽  
Bentonite Clay ◽  
Small Scale ◽  
Saw Dust ◽  
Natural Organic Compounds

Abstract Acid mine drainage collected from the western decant in South Africa was treated in a series of small-scale laboratory experiments. 200 mL of the sample was poured into five 500 mL glass beakers using flocculants formed by mixing size-optimized 1.5 g of bentonite clay with 3.5 g saw dust and 1.0 g of Na3PO4 in triplicates (experiment A). Four similar sets of control experiments were conducted using the same amount of bentonite clay and saw dust with varying Na3PO4, contents in AMD treatment; the rationale being to determine the efficiency of Na3PO4 (experiments B, C and D). The results show that conductivity has an influence in the removal of the turbid materials. The removal efficiency of toxic metals using a flocculant containing 220 μm bentonite clay particle size and 0.012 or 0.25 M of Na3PO4 is higher than 96% when compared to that of the samples dosed with a flocculant containing 0.05 M Na3PO4, which is less than 91%. The flocculent also showed optimal removal efficiency of both turbid materials and toxic metals, i.e. removal efficiency within a range 96.5–99.3%. The flocculants containing 0.025 M Na3PO4 showed optimal removal efficiency of turbidity, colour, toxic metals and natural organic compounds.

Study on SO2, NO Removal from Flue Gas Using an Aqueous NaClO2 Solution with Oxidation Reduction Potential and pH Control

2014 ◽  
Vol 955-959 ◽  
pp. 2221-2225 ◽  
Author(s):  
Ye Sun
Keyword(s):  
Removal Efficiency ◽  
Flue Gas ◽  
Feeding Rate ◽  
Ph Value ◽  
Ph Control ◽  
Sodium Chlorite ◽  
Regression Equations ◽  
Oxidation Reduction ◽  
Oxidation Reduction Potential ◽  
Optimized Conditions

Removal of SO2 and NO from the flue gas using an aqueous sodium chlorite solution was achieved in a bubbling reactor, ORP and pH were used as monitoring parameter. The effect of pH, NaClO2 feeding rate and SO2 concentration on simultaneous removal of SO2 and NOx efficiencies were systematical investigated. The results showed that SO2 removal efficiency was always 100% and NOx removal efficiency could achieve 65% at optimized conditions, the optimized pH value of 5-5.5 was observed. The correlation analysis among ORP, original pH, NaClO2 feeding rate and input SO2 concentration was established using multiple regression equations.

scholarly journals Effects of azo dye on simultaneous biological removal of azo dye and nutrients in wastewater

2018 ◽  
Vol 5 (8) ◽  
pp. 180795 ◽  
Author(s):  
Aihui Chen ◽  
Bairen Yang ◽  
Yuanqiang Zhou ◽  
Yuze Sun ◽  
Cheng Ding
Keyword(s):  
Removal Efficiency ◽  
Azo Dye ◽  
Oxygen Demand ◽  
Cod Removal ◽  
Batch Reactors ◽  
Biological Removal ◽  
Oxidation Reduction ◽  
Alizarin Yellow ◽  
Oxidation Reduction Potential ◽  
Alizarin Yellow R

The potential disrupting effects of Azo dye on wastewater nutrients removal deserved more analysis. In this study, 15 days exposure experiments were conducted with alizarin yellow R (AYR) as a model dye to determine whether the dye caused adverse effects on biological removal of both the dye and nutrients in acclimated anaerobic–aerobic–anoxic sequencing batch reactors. The results showed that the AYR removal efficiency was, respectively, 85.7% and 66.8% at AYR concentrations of 50 and 200 mg l −1 , while higher AYR inlet (400 mg l −1 ) might inactivate sludge. Lower removal of AYR at 200 mg l −1 of AYR was due to the insufficient support of electron donors in the anaerobic process. However, the decolorized by-products p -phenylenediamine and 5-aminosalicylic were completely decomposed in the following aerobic stage at both 50 and 200 mg l −1 of AYR concentrations. Compared with the absence of AYR, the presence of 200 mg l −1 of AYR decreased the total nitrogen removal efficiency from 82.4 to 41.1%, and chemical oxygen demand (COD) removal efficiency initially decreased to 68.1% and then returned to around 83.4% in the long-term exposure time. It was also found that the inhibition of AYR, nitrogen and COD removal induced by a higher concentration of AYR was due to the increased intracellular reactive oxygen species production, which caused the rise of oxidation–reduction potential value and decreased ammonia monooxygenase and nitrite oxidoreductase activities.

scholarly journals Dynamic Experimental Study on Treatment of Acid Mine Drainage by Bacteria Supported in Natural Minerals

Energies ◽  
2020 ◽  
Vol 13 (2) ◽  
pp. 439 ◽  
Author(s):  
Yanrong Dong ◽  
Junzhen Di ◽  
Xianjun Wang ◽  
Lindan Xue ◽  
Zhenhua Yang ◽  
...  
Keyword(s):  
Acid Mine Drainage ◽  
Treatment Effect ◽  
Mine Drainage ◽  
Ph Value ◽  
Oxygen Demand ◽  
Sulfate Reducing ◽  
Acid Mine ◽  
Oxidation Reduction ◽  
Oxidation Reduction Potential ◽  
Geographic Origins

In order to solve the problem of pollution of acid mine drainage (AMD), such as low pH value and being rich in SO42−, Fe and Mn pollution ions, etc., immobilized particles were prepared by using sugar cane-refining waste (bagasse), a natural composite mineral (called medical stone in China) and sulfate-reducing bacteria (SRB) as substrate materials, based on microbial immobilization technology. Medical stone is a kind of composite mineral with absorbability, non-toxicity and biological activity. The adsorption capacity of medical stone is different according to its geographic origins. Two dynamic columns were constructed with Column 1 filled by Fuxin’s medical stone-enhanced SRB immobilized particles, and Column 2 filled by Dengfeng’s medical stone-enhanced SRB immobilized particles as fillers. The treatment effect on AMD with SRB-immobilized particles enhanced by medical stone from different areas was compared. Results showed that Column 2 had better treatment effect on AMD. The average effluent pH value of Column 2 was 6.98, the average oxidation reduction potential (ORP) value was −70.17 mV, the average removal percentages of SO42−, Fe2+ and Mn2+ were 70.13%, 83.82% and 59.43%, respectively, and the average chemical oxygen demand (COD) emission was 555.48 mg/L.

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