Primary Treatment

The Headworks

The Clarifiers

Clean Water Check

The Headworks

Wastewater from Arcata homes includes the water we use to wash our clothes, ourselves, our dishes, our food as well as the water we flush down the toilet.  After being flushed down the toilet; I, and other various materials, flow through a series of pipes below the City of Arcata. Using gravity and a few pumps as the means of transportation, I resurface at the "headworks" component of the marsh. The headworks is the component of the wastewater treatment process where much of the large and easily settleable solid material is removed. Two Archimedes Screw Pumps are used to lift me fifteen feet so I can pass through bar screens and grit separators(which remove large debris from the wastewater) before entering the clarifiers.

The Clarifiers

The are two primary clarifiers. One is 26 feet in diameter, the other is 60 feet in diameter. I sit in the clarifiers for approximately 4 hours, to let smaller solid materials, or sludge, settle to the bottom. I then flow into the oxidation ponds with the rest of the clarified water. All the sludge collected at the bottom of the clarifiers is pumped into digesters where it is converted to Bio-gas. Bio-gas is the gas produced by the breakdown of the sludge.  Much of the gas is methane which can be burned to produce electricity with the proper equipment.  Once I have moved on to the oxidation ponds, the sludge is pumped to the digesters and the primary treatment process is complete.

How Clean is the Water?

Here is an example of how primary treatment has cleaned me. On the left is a sample of "raw" water, that is wastewater that has not yet been treated. On the right is wastewater after primary treatment. There is only a slight difference in the appearance. The major difference is measured in the amount of solid material that has been removed. To get a grasp of the amount of solid material removed, please view the specification page.

The Digesters

Secondary Treatment

Marsh Specifications

These pages are under construction