In wastewater, which type of solids are subject to decomposition?

Organic solids are subject to decomposition in wastewater because they consist of carbon-based compounds that can be broken down by microorganisms. These solids include materials like food waste, plant matter, and animal by-products, which are rich in nutrients that microbes utilize as a food source. During the decomposition process, these microorganisms metabolize organic matter, resulting in the production of gases, such as carbon dioxide and methane, as well as simpler organic substances.

This biological decomposition is a crucial part of the wastewater treatment process because it helps reduce the volume and toxicity of the waste. Effective management of organic solids can lead to better treatment outcomes, such as improved effluent quality and reduced sludge production.

In contrast, inorganic solids do not undergo decomposition as they are composed of minerals and metals that do not break down through biological processes. Settable solids may settle out of wastewater but do not inherently decompose. Heavy solids typically refer to denser materials that may precipitate out of the wastewater but are not relevant to the biological decomposition process.