Referring to the illustration, suppose while in the oil separation processing mode, the oil content detector display screen shows 17.9 ppm and the oily-water separator is discharging back to the bilge water holding tank for re-circulation. What is most likely the cause? Refer to Illustration GS-0175

Correct Answer: Option A — The bilge water holding tank contents is excessively contaminated with oil.

An oil content detector reading exceeding 15 ppm triggers automatic recirculation to the bilge tank. If the separator is consistently recirculating, the influent bilge water is likely too heavily contaminated with oil for the separator to achieve the required discharge standard, necessitating further settling or treatment before processing.