Browsing by Author "Gurd, Caroline"

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    Biological FOG degradation: development of a standardised bioadditive protocol.
    (Cranfield University, 2018-11) Gurd, Caroline; Villa, Raffaella; Jefferson, Bruce
    FSE, wastewater, Gerber, COD:N, bioaddition, bioremediation, Fat, oil and grease (FOG) rich effluents from commercial food service establishments (FSEs) have been identified as major contributors to sewer blockages. Under UK Legislation, all FSE kitchens should be fitted with an ‘effective mean of grease removal’. Currently, microbial bioadditives, one of the preferred FOG management options, do not have an industry-agreed testing methodology to prove their ‘effectiveness’. The primary goal of this research was to generate the scientific knowledge underpinning a testing protocol for FOG- degrading bioadditives. Environmental conditions prevalent in FSE wastewater streams were identified in a characterisation of effluents from three catering outlets on Cranfield University campus and used as a basis for design of synthetic culture media for testing bacterial degradation. To address interferences caused by high levels of surfactants in FSE wastewater, a novel FOG quantification method, based on the Gerber method used in the milk industry, was developed for the protocol. This method is efficient at recovering emulsified FOG, and also allows emulsified and free fractions to be quantified separately. Microbial utilisation of different wastewater components was evaluated in batch degradation trials using a model bacterium, Bacillus licheniformis NCIMB 9375, and different synthetic wastewater compositions. The source of readily available carbon showed great influence on FOG-degradation response. FOG uptake was also influenced strongly by the carbon to nitrogen ratio in the media composition, with removal rate constants decreasing by over an order of magnitude from 0.0285 to 0.0026 h-1 when initial COD:N increased from 33:1 to 147:1. A cost-benefit analysis of the currently available FOG management solutions suggest that bioadditives, as a standalone solution, are the best option in terms of total cost and space requirements, followed by bioadditives used with grease separators. Combining physical and biological treatments can enhance the individual performance of both technologies and allow energy recovery from physically separated FOG.
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    Characterisation of food service establishment wastewater and its implication for treatment
    (Elsevier, 2019-10-08) Gurd, Caroline; Jefferson, Bruce; Villa, Raffaella
    Essential for the selection of a reliable treatment system is the characterisation of the effluent to treat. Kitchen wastewater (KWW) from food service establishments (FSEs) is a strong organic and fat-rich effluent whose characterisation has not been sufficiently addressed. KWW composition is highly variable and linked to the FSE's size, the type of meals prepared and the amount of water used during the cleaning. COD, TSS and fat content (FOG) are the most common parameters found in literature. However, other physical and chemical parameters (e.g. temperature, pH, oil droplets characteristics and trace elements), correlated to commercial kitchen cleaning practices rather than the specific effluent, but equally influential on the treatment efficiencies of both physical and biological methods, have hardly been investigated. A comprehensive characterisation of wastewaters from three food service establishments was used to generate data to support the selection of appropriate FOG mitigation methods. Two novel analytical methods were used to quantify the proportion of emulsified FOG and associated droplet size from different kitchen washing effluents. The results showed that more than 90% of the FOG from the dishwasher effluent and around 35% of sink one was emulsified, with droplet sizes less than 100 μm, well below the removal capabilities of conventional grease interceptors, but easily removed using biological means. From the WW composition results, a formula for predictive modelling was derived to represent average organic matter composition for kitchen wastewater as C20H38O10N, applicable in remediation processes. These results offer a good starting point for the design, operation, and optimisation of wastewater treatment systems of oil-rich KWW.
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    ItemOpen Access
    Characterisation of food service establishment wastewater and its implication for treatment
    (Cranfield University, 2019-10-18 09:59) Villa, Raffaella; Jefferson, Bruce; Gurd, Caroline
    Essential for the selection of a reliable treatment system is the characterisation of the effluent to treat. Kitchen wastewater (KWW) from food service establishment (FSE) is a strong organic and fat-rich effluent whose characterisation has not been sufficiently addressed. A comprehensive characterisation of wastewaters from three food service establishments was undertaken to generate data to evaluate appropriate FOG management strategies.
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    ItemOpen Access
    Determination of fats, oils and greases in food service establishment wastewater using a modification of the Gerber Method
    (Wiley, 2018-11-13) Gurd, Caroline; Jefferson, Bruce; Villa, Raffaella; de Castro Rodriguez, C.
    Discharges from food service establishments (FSEs) are a major source of fat, oil and grease (FOG) which cause blockages in sewer networks. Previous research has identified that current methods are unsuitable for quantifying FOG in FSE wastewater owing to interference from surfactants in detergents, and protein from food residuals which emulsify FOG. A novel quantification method, based on the dairy industry Gerber method, has been developed which negates the impact of surfactants. Moreover, the method allows free and emulsified oil to be quantified separately providing greater insight into FOG management strategies. Trials in synthetic and real FSE wastewaters indicate the novel method is more reliable than standard liquid–liquid and solid phase extraction in FOG‐rich systems.