In the last O&M Matters article, we started a series discussing the concept of the treatment train as a way to view and evaluate an onsite wastewater treatment process and to provide insights for professionals who want to perform operations and maintenance service as a line of business. Having discussed the first component of the treatment train (the source) in the last article, we now move downstream to the pretreatment tank. Most onsite wastewater treatment systems, whether standard gravity or advanced systems, employ some type of pretreatment tank. It may be a trash tank, a septic tank or a pump
