Browsing by Author "Duncan, J R"

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    An integrated algal sulphate reducing high rate ponding process for the treatment of acid mine drainage wastewaters
    (Springer, 1998) Rose, P D; Boshoff, G A; van Hille, R P; Wallace, L C M; Dunn, K M; Duncan, J R
    Acid mine drainage pollution may be associated with large water volume flows and exceptionally long periods of time over which the drainage may require treatment. While the use and role of sulphate reducing bacteria has been demonstrated in active treatment systems for acid mine drainage remediation, reactor size requirement and the cost and availability of the carbon and electron donor source are factors which constrain process development. Little attention has focussed on the use of waste stabilisation ponding processes for acid mine drainage treatment. Wastewater ponding is a mature technology for the treatment of large water volumes and its use as a basis for appropriate reactor design for acid mine drainage treatment is described including high rates of sulphate reduction and the precipitation of metal sulphides. Together with the co-disposal of organic wastes, algal biomass is generated as an independent carbon source for SRB production. Treatment of tannery effluent in a custom-designed high rate algal ponding process, and its use as a carbon source in the generation and precipitation of metal sulphides, has been demonstrated through piloting to the implementation of a full-scale process.The treatment of both mine drainage and zinc refinery wastewaters are reported. A complementary role for microalgal production in the generation of alkalinity and bioadsorptive removal of metals has been utilised and an Integrated ‘Algal Sulphate Reducing Ponding Process for the Treatment of Acidic and Metal Wastewaters’ (ASPAM) has been described.
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    Removal and recovery of zinc from solution and electroplating effluent using Azolla filiculoides
    (IWA Publishing, 1999) Zhao, M; van Hille, R P; Duncan, J R
    The removal of zinc ions from aqueous solutions and electroplating rinse effluent by Azolla filiculoides on batch and column studies was investigated. The maximum zinc uptake by Azolla in batch systems at an optimum pH of 6.0 was found to be 45.2 mg/g. The dried Azolla filiculoides showed good mechanical stability and flow-permeability in repeated column operations. The zinc uptake in column operation at pH 6.2 and 60% breakthrough was between 25.8–30.4 mg/g with varying flow rates (from 32 to 160 ml/h.g). Complete desorption of bound zinc was accomplished with 120 ml of either 0.2 N H2S04 or HCl. The data from regeneration efficiencies for six cycles, evidenced that the reusability of Azolla in the treatment of Zn2+-laden wastewater is viable. An effluent-free, closed loops of zinc treatment system, with Azolla biomass as the sorbent, is proposed.
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    Removal of lead from solution by the non-viable biomass of the water fern Azolla filiculoides
    (Springer, 1998) Sanyahumbi, D; Duncan, J R; Zhao, M; van Hille, R P  
    Non-viable biomass of the aquatic fern, Azolla filiculoides, removed up to 93 mg lead/g biomass from solution. Lead removal varied from 30% of the initial lead concentration at pH 1.5 to approximately 95% at pH values of 3.5 and 4.5. Lead removal decreased to 30% of the initial lead concentration if the lead concentration was initially over 400 mg/l. Lead removal remained at approximately 90% between 10 °C and 50 °C. Biomass concentration (4–8 mg/l) had little effect on lead removal.