Browsing by Author "Fan, Linhua"

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    High rate algal systems for treating wastewater: A comparison
    (Elsevier, 2022-06-07) Kube, Matthew; Fan, Linhua; Roddick, Felicity; Whitton, Rachel; Pidou, Marc; Jefferson, Bruce
    Algal systems can remove nitrogen (N) and phosphorus (P) from wastewater while producing valuable biomass. The microalga Chlorella vulgaris in three concentrated forms (suspended, entrapped in Ca-alginate gel beads and as a biofilm on supports and the macroalga Oedogonium cardiacum were compared for treating secondary effluent containing 15 mg/L of ammonium (N-NH4+), 6 mg/L of nitrate (N-NO3−), and 7 mg/L of total phosphorus (TP) with a hydraulic retention time of 12 h. Identical conditions and reaction vessels enabled a direct comparison of growth systems. The biofilm system was the most effective of the microalgal systems, decreasing concentrations to 1.9 mg/L TP and 0.5 mg/L N-NO3− on average from day 3 to 24, and like the other microalgal systems, was not as effective for N-NH4+ removal (average of 9.0 mg/L). The macroalgal system decreased TP to 1.3 mg/L and N-NH4+ to ≤0.5 mg/L on average from day 16 to 30 and operated for longer than the other systems, but was not effective for N-NO3− removal (average of 4.8 mg/L). Hence the minimum TN concentration of the effluent from the macroalgal system (7.1 mg/L) was lower than for the biofilm system (10.6 mg/L) from the feed of 24 mg/L. The biofilm system produced 56 mg/L/d and the macroalgae 102 mg/L/d of biomass. The production of the highest quality effluent for longer and of more biomass than the microalgal systems, combined with their larger cell size which facilitates reactor operation, demonstrates that macroalgae can compete with microalgae for wastewater remediation.
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    The impact of wastewater characteristics, algal species selection and immobilisation on simultaneous nitrogen and phosphorus removal
    (Elsevier, 2018-02-01) Kube, Matthew; Jefferson, Bruce; Fan, Linhua; Roddick, Felicity
    Nutrient removal from wastewater reduces the environmental impact of its discharge and provides opportunity for water reclamation. Algae can accomplish simultaneous nitrogen and phosphorus removal while also adding value to the wastewater treatment process through resource recovery. The application of algae to wastewater treatment has been limited by a low rate of nutrient removal and difficulty in recovering the algal biomass. Immobilising the algal cells can aid in overcoming both these issues and so improve the feasibility of algal wastewater treatment. Trends for nutrient removal by algal systems over different wastewater characteristics and physical conditions are reviewed. The impact that the selection of algal species and immobilisation has on simultaneous nutrient removal as well as the interdependence of nitrogen and phosphorus are established. Understanding these behaviours will allow the performance of algal wastewater treatment systems to be predicted, assist in their optimisation, and help to identify directions for future research.
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    Recovery and reuse of alginate in an immobilised algae reactor
    (Taylor and Francis, 2019-09-27) Murujew, Olga; Whitton, Rachel; Kube, Matthew; Fan, Linhua; Roddick, Felicity; Jefferson, Bruce; Pidou, Marc
    The use of microalgae for nutrients removal from wastewater has attracted more attention in recent years. More specifically, immobilized systems where algae cells are entrapped in beads in a matrix of a polysaccharide such as alginate have shown a great potential for nutrients removal from wastewater to low levels with reduced retention times and hence smaller footprint. However, a significant operational cost in the up-scaling of alginate-immobilized algae reactors will be the gelling agent alginate. To reduce expenditure of this consumable a proof-of-concept is given for an alginate recycling method using sodium citrate as a dissolving agent. Using algae beads made from virgin and recycled alginate yielded comparable removal rates for both phosphorus and nitrogen compounds from wastewater. At labscale, an alginate recovery of approximately 70% can be achieved which would result in a net operational cost reduction of about 60%.