What is the primary composition of sewage?

The primary composition of sewage consists of organic and biodegradable or decomposable waste. This includes materials such as human waste, food scraps, and other organic substances that naturally break down over time through biological processes. Such waste is rich in nutrients and can be effectively managed and treated by sewage systems, making it suitable for further processing and potential reuse in applications like fertilizers after adequate treatment.

Understanding the composition of sewage is crucial for the design and operation of on-site sewage facilities, as the presence of biodegradable materials allows for biological treatment methods that utilize microorganisms to decompose organic matter. This biological activity is fundamental to the treatment process, reducing the overall volume and harmfulness of sewage before it is released or reused.

Other options describe materials that do not typically make up the primary composition of sewage. For instance, non-biodegradable materials can contribute to waste but are not a primary component of sewage that facilities are designed to treat. Likewise, while industrial waste products may appear in specific contexts, they do not form the general basis of domestic sewage composition. Semi-solid waste, although a component of sewage, does not encompass the broader range of organic and biodegradable materials that characterize the bulk of sewage content.