Browsing by Author "Roddick, Felicity"

Now showing 1 - 6 of 6
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    Effectiveness of grease interceptors in food service establishments for controlling fat, oil and grease deposition in the sewer system
    (Elsevier, 2023-12-20) Sultana, Nilufa; Roddick, Felicity; Jefferson, Bruce; Gao, Li; Bergmann, David; Papalois, Jim; Guo, Mike; Tzimourtas, Kyriakos; Pramanik, Biplob Kumar
    The water industry worldwide experiences numerous sewer blockages each year, partially attributed to the accumulation of fat, oil and grease (FOG). Managing this issue involves various strategies, including the requirement for installation of grease interceptors (GIs) installation. However, the claimed efficacy of commercial GIs of eliminating 99 % of FOG has been questioned for many years because FOG deposit formation occurs despite food service establishments (FSEs) using GIs, therefore detailed understanding of FOG wastewater compositions and its removal by GIs is required. This study provides an insight into the key FOG components such as FOG particle size, metals and fatty acid (FA) profile in GI influent and effluent, and within the GI, at three different FSEs. Analysis of FAs identified substantial proportions of extra-long-chain FAs in the effluents, including arachidic (C20:0), behenic (C22:0), mead (C20:3), lignoceric (C24:0), and nervonic (C24:1) acids. In contrast, the household kitchen released palmitic (C16:0), oleic (C18:1) and linoleic (C18:2) acids. It was further observed that scums effectively remove the larger FOG particles, leaving only 10 % below 75.4 μm. Notably, FSEs which employed automatic dishwashers produced up to 80.4 % of particles ≤45 μm, whereas FSEs and household kitchen which used handwash sinks generated only 36.9 % and 26.3 % of particles ≤45 μm, respectively. This study demonstrated that the commercial GIs do not remove FOG entirely but clearly demonstrated that they discharge high concentrations of FOG with extra-long FFAs which were attributed to the occurrence of microbial activity and hydrolysis of triglycerides within the GI, potentially contributing to FOG deposition.
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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%.
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    Tertiary nutrient removal from wastewater by immobilised microalgae: impact of wastewater nutrient characteristics and hydraulic retention time (HRT)
    (IWA Publishing, 2018-03-15) Whitton, Rachel; Santinelli, Martina; Pidou, Marc; Ometto, Francesco; Henderson, Rita; Roddick, Felicity; Jarvis, Peter; Villa, Raffaella; Jefferson, Bruce
    Immobilising microalgal cells has been proposed as a process solution to overcome the barriers associated with the implementation of microalgae for wastewater remediation. This work evaluated the performance and remediation mechanisms of immobilised microalgae for continuous wastewater treatment under varying hydraulic retention times (HRT). Three domestic secondary wastewaters with differing concentrations of orthophosphate (PO4-P), ammonium (NH4-N) and nitrate (NO3-N) were treated by Scenedesmus obliquus immobilised within 2% calcium alginate. Trials were run in continuous operation at HRTs of 3, 6, 12 and 20 h. Removal rates for PO4-P improved with increasing HRT, with minimum residual concentrations of 0.3–3.1 mg·L−1 observed at 3 h and 0.01–0.2 mg·L−1 at 20 h. Ammonium remediation was not linked to HRT or NH4+ concentration with minimum residual concentrations of <0.001 mg·L−1. Reduction in NO3-N improved with increasing HRT, with minimum residual concentrations of ≤19.3 at 3 h and ≤0.4 mg·L−1 at 20 h. Remediation was achieved through a combination of mechanisms including biological uptake and precipitation as a by-product of photosynthesis and nutrient metabolism. As such, immobilised microalgae have been proven to be an effective alternative solution for PO43− and NH4+ remediation of wastewater effluents at HRTs of 6–12 h.
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    Uncovering the impact of metals on the formation and physicochemical properties of fat, oil and grease deposits in the sewer system
    (Elsevier BV, 2024-09-01) Yusuf, Hamza Hassan; Roddick, Felicity; Jegatheesan, Veeriah; Jefferson, Bruce; Gao, Li; Pramanik, Biplob Kumar
    The deposition of fats, oil, and grease (FOG) in sewers reduces conveyance capacity and leads to sanitary sewer overflows. The major contributing factor lies in the indiscriminate disposal of used cooking oil (UCO) via kitchen sinks. While prior investigations have mostly highlighted the significance of Ca2+ from concrete biocorrosion, the influence of common metal ions (e.g., Mg2+, Na+, K+) found in kitchen wastewater on FOG deposition has received limited attention in the existing literature. This study aimed to elucidate the roles of Ca, Mg, Na and K in FOG deposition in sewers and examine the influence of metal ions, fat/oil sources, and free fatty acids (FFAs) on the physicochemical and rheological properties of FOG deposits. To examine FOG deposit formation, synthetic wastewater containing 0.1 g/L of each metal ion was mixed with 40 mL of fat/oil and agitated for 8 h. Following FOG deposition, three distinct phases were observed: unreacted oil, FOG deposit and wastewater. The composition of these phases was influenced by the composition of metal ions and FFA in the wastewater. Mg produced the highest amount of FOG of 242.5 ± 10.6 mL compared to Ca (72.5 ± 3.5 mL) when each FFAs content in UCO was increased by 10 mg/mL. Molar concentration, valency and the solubility of metal ion sources were identified to influence the formation of FOG deposits via saponification and aggregation reaction. Furthermore, Fourier-Transform Infrared spectroscopy indicated that the FOG deposits in this study were similar to those collected from the field. This study showed that the use of Mg(OH)2 as a biocorrosion control measure would increase FOG deposition and highlights the need for a comprehensive understanding of its roles in real sewage systems.