Bioremediation of Aluminium from the Waste Water of a Conventional Water Treatment Plant Using the Freshwater Macroalga Oedogonium

Abstract

Abstract:Conventional water treatment processes use aluminium sulphate (alum) as a coagulant in the production of potable water. While alum is an inexpensive and reliable means of treating water, the process generates waste water containing dissolved Al. This waste water is primarily dealt with via on-site retention. In this study we investigate the cultivation of the freshwater macroalga Oedogonium as a means to sequester dissolved Al from waste water from a conventional water treatment plant. Furthermore, we examine the use of CO 2 to manipulate the pH of cultivation as a means of enhancing the sequestration of Al by either increasing the productivity of Oedogonium or increasing the bioavailability of Al in the waste water. The relative bioavailability of Al under conditions of CO 2 and no-CO 2 provision was contrasted by comparing Al uptake by Diffusive Gradients in Thin Films (DGTs). Oedogonium was able to grow rapidly in the waste water (12 g dry weight m −2 day −1 ) while consistently sequestering Al. The Oedogonium-treated waste water had a sufficiently low Al concentration that it could be used in unrestricted irrigation in the surrounding region. When CO 2 was added to the waste water containing concentrations of Al up to 8 mg L −1 , there was a slight increase (~10%) in the rate of sequestration of Al by Oedogonium relative to waste water not receiving CO 2 . This was due to two concurrent processes. The provision of CO 2 increased the productivity of Oedogonium by 15% and the bioavailability of Al by up to 200%, as measured by the DGTs. Despite this strong effect of CO 2 on Al bioavailability, the increase in Al sequestration by Oedogonium when CO 2 was provided was modest (~10%). Al was sequestered by Oedogonium to concentrations below permissible limits for discharge without the need for the addition CO 2 . The cultivation of Oedogonium in waste water from conventional treatments plants can simultaneously treat waste water for re-use and provide a biomass source for value-added applications.

Use of Acorn Leaves as a Natural Coagulant in a Drinking Water Treatment Plant

“…This process is aimed at reducing the concentration of suspended solids (SS) and non-settling colloidal particles, thus lowering turbidity and improving water quality [6]. The effectiveness of this process is known to be dependent on the nature of the particles, the type and dosage of the coagulant and the pH of the water [7,8].…”

Adding Value to Wastewater Bioremediation by Lipid Extraction from Oedogonium intermedium

“…Additionally, the ability of macroalgae to biotransform the arsenic from inorganic to organic form makes them an attractive option to treat arseniccontaining wastewater, with the former being far more toxic than the latter [16][17][18][19]. Recently, some kinds of green macroalgae have been reported as an effective bioremediation species for wastewater, such as the genus of Oedogonium and Cladophora [8,[20][21][22][23][24][25].…”

Freshwater Macroalgae, Oedogonium, Grown in Wastewater Reduce Diet-Induced Metabolic Syndrome in Rats

“…This then allows the reuse or discharge of clean freshwater, an increasingly rare resource [21], as well as a generation of new products from macroalgae such as biostimulants and soil conditioners [22][23][24]. Species of Oedogonium are effective in removing metals from the wastewater of commercial coalfired power stations [25] and nutrients in municipal wastewater treatment plants [26][27][28]. Growing freshwater macroalgae for bioremediation of wastewater will likely produce biomass that is a potential functional food for metabolic syndrome as similar benefits have already been shown for marine macroalgal biomass.…”