Abstract:
Fats, oils and greases (FOG) are by-products of cooking and food preparation
originating from households, food service establishments (FSEs) and industrial
food facilities. Under UK legislation, industries are the only sources of FOG
monitored by water authorities under trade effluent consents. In addition, whilst
all FSE kitchens must be fitted with an “effective mean of grease removal”,
experience within the water sector has demonstrated that very few premises were
managing their effluents to minimise FOG emissions. Critically, large volumes of
FOG are entering drainage systems resulting in impacts both in the sewers
(formation of fatbergs) and downstream at the treatment works (reduced
treatment efficiency), and in turn contributing to high operational costs for water
utilities. With changing food habits and projected population growth, FOG-related
problems will only become an increasingly worrying operational and financial
burden for the water industry. Yet, FOG can be a valuable resource for energy
recovery with the potential to offset operational costs and improve the overall
sustainability of wastewater treatment.
This thesis establishes an evidence base by assessing the potential of alternative
FOG management options in order to provide guidance to water utilities for
improving current practices. A comprehensive study identified the contribution of
current kitchen practices to FOG emissions from domestic and commercial
sources, suggesting the need for educational campaigns to raise awareness on
the problem. Production rates and quality of FOG from different sources were
benchmarked clarifying variations amongst these wastes. The potential of FOG
for energy recovery, via biogas generation from anaerobic digestion, was
assessed through laboratory-scale studies. The occurrence of FOG at the
treatment works was investigated, and the performance of enhanced treatment
for its removal was further studied. Finally, data produced during this project was
used to develop a business case for the implementation of more sustainable
approaches.
