Q4: What would happen if you left the Sedimentator upright overnight? Most of the suspended plant remains, silt and clay would settle overnight. The sand and plant layers would be compacted because the pieces are close together. The gravel has too many large spaces to be compacted.

Sediment moves from one place to another through the process of erosion. Erosion is the removal and transportation of rock or soil. Erosion can move sediment through water, ice, or wind. Water can wash sediment, such as gravel or pebbles, down from a creek, into a river, and eventually to that river’s delta.

Why? (Answer: Because there are larger spaces between the gravel particles.) water, in which would you drill a well? (Answer: Gravel. Water moves easier through gravel than sand or clay.)

A sedimentation tank allows suspended particles to settle out of water or wastewater as it flows slowly through the tank, thereby providing some degree of purification. A layer of accumulated solids, called sludge, forms at the bottom of the tank and is periodically removed.

The Secondary Sedimentation Tanks are circular tanks equipped with rotating mechanical sludge and scum collectors. The effluent from the Aeration Structure enters each tank through the bottom, rises up through the center column, and then is distributed into the sedimentation zone.

The purpose of secondary clarifiers is to separate the incoming biomass from the biological reactors into clarified effluent and thickened sludge. For processes such as trickling filters and rotating biological contactors, the solids are typically settled and wasted, similar to primary sedimentation.

Secondary treatment removes the soluble organic matter that escapes primary treatment. It also removes more of the suspended solids. Removal is usually accomplished by biological processes in which microbes consume the organic impurities as food, converting them into carbon dioxide, water, and energy…

There are two basic stages in the treat- ment of wastes, primary and secondary, which are outlined here. In the primary stage, solids are allowed to settle and removed from wastewater. The secondary stage uses biological processes to further purify wastewater. Sometimes, these stages are combined into one operation.

The main difference is the way each respective treatment is processed. Primary treatment works on sedimentation, where solids separate from the water through several different tanks. In contrast, secondary treatment uses aeration, biofiltration and the interaction of waste throughout its process.

Typically, solids in the primary clarifier are inorganic whereas in a secondary clarifier, sludge is nearly 100 percent organic and thus can compact readily, making sludge far denser in a secondary unit than that of a primary system.

The moving collection units push all the sludge to one end of the clarifier, and dumps it into a low area, called a sump. The sump is deep enough so that as the sludge settles in it, it pushes out some of the water.