What defines an experimental sewage treatment system?

An experimental sewage treatment system is characterized as one that is not classified as either a standard or alternate system. Such systems are evaluated on a case-by-case basis, which allows for adaptability and assessment of their effectiveness in specific contexts. This classification is crucial in fostering innovation in sewage treatment technologies that may not yet have established regulatory approvals or widespread acknowledgment within standard practices.

Options that suggest a universal standard system or a system restricted to temporary use do not capture the essence of what differentiates an experimental system. Likewise, a definition confining a system solely to industrial applications does not encompass the broader array of potential uses that an experimental system might address. Therefore, the correct characterization emphasizes its unique position in being evaluated on an individual basis, signifying its experimental nature and potential for future development within the field of sewage treatment.