Iron and manganese removal and membrane fouling during UF in conjunction with prechlorination for drinking water treatment

Integration of a kraft pulping mill into a forest biorefinery: pre-extraction of hemicellulose by steam explosion versus steam treatment.

Rejection and modeling of arsenate by nanofiltration: Contributions of convection, diffusion and electromigration to arsenic transport

Acid mine drainage (AMD) is recognized as one of the more critical environmental problems in the mining industry, with the potential of severe contamination of surface and groundwater, as well as soils. Different conventional methods are used to treat AMD such as lime neutralization, in which lime is added to AMD to raise pH and then precipitate the dissolved toxic heavy metals. In addition to a high concentration of sulphate, the sludge produced by this process has no economic value and has to be disposed of in large areas of land. Nanofiltration (NF) membranes are a new alternative method employed to treat AMD in this work. First, neutralization of AMD collected from the copper mine in Chile using both sodium hydroxide and lime will be investigated to find the optimum formed sludge. Then, three commercial NF membranes (NF99, DK, GE) have been used to filter AMD at two different pressures of 20 and 30 bar and at two different concentrations. The results showed that NF membranes successfully treated AMD w...

Nanofiltration of Acid Mine Drainage

Although ferrous iron removal from drinking water by aeration has been studied for a while, there is still an uncertainty on the performance and the physicochemical mechanisms of iron(II) oxidation [S.K. Sharma, B. Petrusevski, J.C. Schippers, J. Water . Supply Res . Technol. Aqua, 54 (2005) 239–247]. A possible reason is the autocatalytic effect of ferric hydroxide particles, but this assumption is never validated quantitatively in practice because this catalytic effect has been investigated only under batch laboratory-controlled conditions. In this work, iron(II) oxidation has been studied on synthetic waters in a 63 L split-rectangular airlift reactor, the hydrodynamics and the mass transfer properties of which were described previously [N. El Azher, B. Gourich, C. Vial, M. Belhaj Soulami, A. Bouzidi, M. Ziyad, Biochem. Eng. J., 23 (2005) 161–167]. Experiments were carried out both under semi-batch and continuous flow conditions. The kinetic parameters derived from the experiments were consistent with the literature both under unsteady and steady-state conditions. Experimental results showed that the airlift reactor allowed simultaneously good mixing, mass transfer and pH control despite the strong sensitivity of the oxidation kinetics to pH. Data confirmed that recycling about 50 mg/L of ferric hydroxide particles in a slurry phase could decrease drastically the time necessary to reach the minimum admissible concentration of iron(II). For example, residence time could be reduced by a factor six at pH 7.0 under steady-state conditions, which may avoid the need for a further pH increase.

Study of ferrous iron oxidation in Morocco drinking water in an airlift reactor

Removal of metal complexes by nanofiltration in a TCF pulp mill: technical and economic feasibility

To assess the feasibility of implementing hemicellulose recovery stages in kraft mills, Eucalyptus globulus wood samples were subjected to aqueous treatments with hot, compressed water (autohydrolysis processing) to achieve partial dissolution of xylan. Autohydrolyzed solids were subjected to kraft pulping under selected conditions to yield a pulp of low kappa number, and to an optimized TCF bleaching sequence made up of three stages (alkaline oxygen delignification, chelating, and pressurized hydrogen peroxide), with minimized additions of pulping and bleaching chemicals. The final product had a relatively low kappa number (1.4), 641 mL/g ISO intrinsic viscosity, and 86.4% brightness.

https://ojs.cnr.ncsu.edu/index.php/BioRes/article/download/BioRes_07_3_4179_Vila_RFSP_Recovery_Hemicellulose_Kraft_Pulping/1670

José Luis Francisco

Papers

Removal of metal complexes by nanofiltration in a TCF pulp mill: technical and economic feasibility

On the recovery of hemicellulose before kraft pulping