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

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.

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

Water Practice & Technology ◽

10.2166/wpt.2019.051 ◽

2019 ◽

Vol 14 (3) ◽

pp. 633-644 ◽

Cited By ~ 1

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.

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

Water Practice & Technology ◽

10.2166/wpt.2021.075 ◽

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.

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

Water Practice & Technology ◽

10.2166/wpt.2020.040 ◽

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.

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Derivation of Optimum Study Factors for Samples Contaminated with Cd Using Electric/Magnetic Field and ORP

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.813.519 ◽

2013 ◽

Vol 813 ◽

pp. 519-524

Author(s):

Sang An Ha ◽

Jei Pil Wang

Keyword(s):

Magnetic Field ◽

Heavy Metals ◽

Removal Rate ◽

Underground Water ◽

Liquid Electrode ◽

Oxidation Reduction ◽

Oxidation Reduction Potential ◽

Removal Of Heavy Metals ◽

High Removal Rate ◽

Membrane Treatment

A purpose of the present study is to derive optimum study factors for removal of heavy metals using combined alternating current electric/magnetic field and electric membranes for the area contaminated with heavy metals in soil or underground water. ORP (Oxidation Reduction Potential) analysis was conducted to determine an intensity of tendency for oxidation or reduction of the samples contaminated with heavy metals, and electrical membrane treatment was used with adjustment of concentrations and voltages of liquid electrode (Na2SO4) to derive a high removal rate. Removal constants were analyzed to be 0.0417, 0.119, 0.1594 when the voltages were 5V, 10V, 15V, respectively, and treatment efficiency was shown to increase as the liquid electrode concentration was increased. Keywords: heavy metals, electric/magnetic field, ORP, electrical membrane

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

Water Practice & Technology ◽

10.2166/wpt.2021.014 ◽

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.

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

Energies ◽

10.3390/en13020439 ◽

2020 ◽

Vol 13 (2) ◽

pp. 439 ◽

Cited By ~ 7

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

Water Science & Technology ◽

10.2166/wst.2016.259 ◽

2016 ◽

Vol 74 (4) ◽

pp. 861-875 ◽

Cited By ~ 2

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.

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

Water Practice & Technology ◽

10.2166/wpt.2021.015 ◽

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.

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