|
Juby, G. J. G., & Schutte, C. F. (2000). Membrane Life in a Seeded-slurry Reverse Osmosis System. Water Sa, 26(2), 239–248.
Abstract: Membrane replacement can be a major operating cost of a membrane plant. During the development of a novel desalination technique (the SPARRO process) for treating calcium sulphate scaling mine waters the expected life of tubular cellulose acetate membranes operating in the seeded-slurry mode was investigated.During four operating phases of the plant over a five-year period more than 9 000 h of operating data were obtained. Performance data showed that each operating phase was dominated by either membrane fouling or membrane hydrolysis. Membrane fouling was observed to begin near the front-end of the membrane stack and proceed towards the back. Hydrolysis, on the other hand, occurred first in the tail end of the stack and moved backwards towards the Front end modules. Although two detailed membrane autopsies were carried out no definitive statement can be made in respect of the causes of either membrane hydrolysis or membrane fouling. However, suggestions are presented to explain the observed fouling phenomenon in relation to the turbidity of the pretreated feed water and the presence of chlorine. It is proposed that the presence of radioactive isotopes in the mine water which become concentrated in the process contributes to the observed membrane hydrolysis. A membrane life of up to two years is projected for an improved pretreatment arrangement.
|
|
|
Burt, R. A., & Caruccio, F. T. (1986). The effect of limestone treatments on the rate of acid generation from pyritic mine gangue. Environmental geochemistry and health, 8, 8.
Abstract: Surface water enters the Haile Gold Mine, Lancaster County, South Carolina by means of a small stream and is ponded behind a dam and in an abandoned pit. This water is affected by acidic drainage. In spite of the large exposures of potentially acid producing pyritic rock, the flux of acid to the water is relatively low. Nevertheless, the resulting pH values of the mine water are low (around 3.5) due to negligible buffering capacity. In view of the observed low release of acidity, the potential for acid drainage abatement by limestone ameliorants appears feasible. This study investigated the effects of limestone treatment on acid generation rates of the Haile mine pyritic rocks through a series of leaching experiments. Below a critical alkalinity threshold value, solutions of dissolved limestone were found consistently to accelerate the rate of pyrite oxidation by varying degrees. The oxidation rates were further accelerated by admixing solid limestone with the pyritic rock. However, after a period of about a month, the pyrite oxidation rate of the admixed samples declined to a level lower than that of untreated pyrite. Leachates produced by the pyrite and limestone mixtures contained little if any iron. Further, in the mixtures, an alteration of the pyrite surface was apparent. The observed behaviour of the treated pyrite appears to be related to the immersion of the pyrite grains within a high alkalinity/high pH environment. The high pH increases the rate of oxidation of ferrous iron which results in a higher concentration of ferric iron at the pyrite surface. This, in turn, increases the rate of pyrite oxidation. Above a threshold alkalinity value, the precipitation of hydrous iron oxides at the pyrite surface eventually outpaces acid generation and coats the pyrite surface, retarding the rate of pyrite oxidation.
|
|
|
Bochkarev, G. R., Beloborodov, A. V., Kondrat'ev, S. A., & Pushkareva, G. I. (1994). Intensification of Aeration in treating Natural-Water and Mine Water. J. Min. Sci., 30(6), 5.
|
|
|
Erten-Unal, M., & Wixson, B. G. (1999). Biotreatment and Chemical Speciation of Lead and Zinc Mine/Mill Wastewater Discharges in Missouri, USA. Water Air Soil Pollut., 116(3-4), 501–522.
Abstract: Continued mining development in the world's largest lead producing area has generated and increased concern over effective mine water treatment in Missouri's New Lead Belt. A new type of mine/mill wastewater treatment system was constructed which consisted of a tailings pond followed by a series of artificially constructed meandering biotreatment channels and a polishing lagoon. This system provided additional retention time and distance for the removal of heavy metals by abundant aquatic plants and sedimentation. Seasonal field sampling and analytical testing that evaluated the present system confirmed that it provided good treatment for removal of heavy metals within the company property and produced a final effluent within the state and federal regulatory guidelines. On average, greater than 95% of zinc and manganese in the drainage water were removed by the biotreatment system, while lead and copper were 50 to 60%. A chemical equilibrium model, MINTEQ, was also used to identify various species of lead and zinc in the biotreatment system. The model predicted that the major species of carbonates and hydroxides would be the predominant complexes of lead and zinc for the pH and alkalinity values reported in the biotreatment system. These results were also supported by the literature.
|
|
|
Chen, M., Li, L., Grace, J., Tazaki, K., Shiraki, K., Asada, R., et al. (2007). Remediation of acid rock drainage by regenerable natural clinoptilolite. Water, Air, Soil Pollut., 180(1-4), 11–27.
Abstract: Clinoptilolite is investigated as a possible regenerable sorbent for acid rock drainage based on its adsorption capacity for Zn, adsorption kinetics, effect of pH, and regeneration performance. Adsorption of Zn ions depends on the initial concentration and pH. Adsorption/Desorption of Zn reached 75% of capacity after 1-2 h. Desorption depended on pH, with an optimum range of 2.5 to 4.0. The rank of desorption effectiveness was EDTAEDTA > NaCl > NaNO3 > NaOAc > NaHCO3 > Na2CO3 > NaOH > CeCa(OH)(2). For cyclic absorption/desorption, adsorption remained satisfactory for six to nine regenerations with EDTA and NaCl, respectively. The crystallinity and morphology of clinoptilolite remained intact following 10 regeneration cycles. Clinoptilolite appears to be promising for ARD leachate treatment, with significant potential advantages relative to current treatment systems.
|
|