FATS, OILS AND GREASES IN EFFLUENT STREAMS FROM SHOPPING CENTRES

Abstract

Fats, oils and greases (FOG) are an urban conundrum creating severe problems to municipal sewer infrastructures. FOG emanates from food service establishments or catering operations when cooking with plant or animal based oils or fats. However, its rise to becoming a globally recognised contaminant emanating from kitchen based wastewater is associated with the shift from rural to urbanized lifestyles, and the corresponding changing eating habits of city dwellers. The management, prevention and handling of FOG costs cause an exorbitant burden on municipalities, cities and countries. The scale and severity of FOG contamination has not been previously explored in South Africa. The cumulative effect of urbanisation, large scale shopping centre developments plus a fast-growing local fast food industry supports the view that a FOG problem should exist in shopping centres locally. The study explores this problem within the shopping centre industry by means of comprehensive questionnaires, site visits, telephone interviews, interviews with subject matter experts and online surveys at 38 shopping centres in the Gauteng province in South Africa. An index was developed to measure the number of food service establishments (FSEs) per shopping centre size. The results show that FOG is a real and imminent problem in shopping centres. Of the shopping centres surveyed, 88% confirmed experiencing FOG related problems. Based upon frequency of occurrence of sewer blockages, 12 of the 38 centres were categorised as experiencing severe problems. Five of the shopping centres surveyed installed external grease trap devices. The propensity of FOG deposition in sewer lines is dependent on the strength of the kitchen wastewater or FOG organics loading. The strength of FSE wastewater is affected by the operations and configuration of the catering business. The cuisine type or menu served has the highest impact on FOG loading.