Which of the following is not a type of equipment used in mechanical dewatering?

The hydrologic siphon is not a type of equipment used in mechanical dewatering because it primarily functions as a method to transfer liquid from one location to another by creating a pressure differential, utilizing atmospheric pressure and gravity. Its main purpose is to move water, not to remove water from solids, which is the core function of mechanical dewatering processes.

In contrast, a filter press is specifically designed to separate liquids from solids under pressure, making it a key piece of equipment in dewatering applications. Similarly, a belt press uses a continuous belt to squeeze water from sludge, and a centrifuge operates by spinning sludge at high speeds to use centrifugal force to separate liquids from solids. Each of these alternatives is specifically engineered to enhance the dewatering process, highlighting that the hydrologic siphon does not fit within this categorization. This distinction emphasizes the purpose and design of mechanical dewatering technologies compared to simpler fluid transfer methods.