Which of the following is excluded from the definition of grease in sewage systems?

Petroleum products are excluded from the definition of grease in sewage systems because they are not organic in nature and do not originate from food sources. Grease is typically understood to refer to substances that come from the processing of food, such as animal fats and vegetable oils, which are commonly found in kitchen waste. Cooking oils from restaurants also fall under this category as they are used in food preparation.

In contrast, petroleum products are derived from non-renewable resources and do not share the same characteristics or impacts on sewage systems as organic greases. Their presence can lead to different issues in wastewater treatment facilities, such as contamination and difficulties in the treatment process, which is why they are specifically excluded from the definition of grease in this context. Understanding these distinctions helps in proper management and handling of waste within sewage systems.