ADEQ Wastewater Collections 2 Practice Test 2026 - Free Wastewater Collections Certification Practice Questions and Study Guide

Electrodes measure conductivity by allowing ions in the liquid to move between their surfaces. If a film forms on the electrode, such as grease or fats, it acts as an insulating barrier that blocks or slows ion transfer. That coating increases the impedance at the sensor surface, making the conductivity reading drop or become unreliable. In wastewater, grease and fats from kitchen waste tend to coat sensors and foul them, which is why this coating is the correct cause of losing conductivity. The other options don’t describe a surface fouling effect that reduces conductivity.