How it works

The pretreatment chamber is the first phase of the unit. In the 500 gallon per day system, the pretreatment chamber is built on the tank itself. It holds a minimum of 325 gallons of raw wastewater from the house. In the 750 and 1000 gallon per day system you will need an additional tank for pretreatment. The pretreatment chamber is not built on the larger systems for different reasons. First, the molds would cost more than two (2) separate molds individually. Second, installation would be a hassle due to the size of the hole and the tank required for installation. The main reason the larger systems do not have a pretreatment chamber built on them is the Combo molds. The Combo mold is capable of producing the 500-gallon per day system and the 750-gallon per day system.

The 750-gallon per day system requires a pretreatment chamber to hold no less than 488 gallons of wastewater from the house or building. When installing the system, make sure you have sufficient fall (no less than 1/8 of an inch per 10 feet) from the pretreatment chamber to the aeration chamber. The 1000-gallon per day system requires a pretreatment chamber to hold no less than 650 gallons of wastewater from the house or building.

On both the larger systems, you can use a larger pretreatment tank. Just keep in mind too much pretreatment can “starve” the system of enough organic material to maintain normal and proper operation.

THE 4-INCH BAFFLE

Inside the pretreatment chamber, you will need to mount and glue a 4-inch tee baffle. This tee baffle has two major functions.

1. It will keep floating solids like grease and other foaming materials from entering the aeration chamber.

2. It will keep gases separate during the treatment process.

The tee baffle should be firmly installed and glued. After the tee is installed, a 14 to 16 inch section of pipe will be required to fit under the tee facing the bottom of the pretreatment chamber. This will aid in the retention of solids in the pretreatment chamber.

You can use SCH. 40 piping and fittings if your state requires it. If not, it is not recommended for cost purposes. SDR 35 has been shown to work as well.

During the manufacturing process of the tank itself, be sure the man way is closed (about 4 to 6 inches) to the inlet and tee baffle. The man way is used for services and installation purposes only.

Note: We have a patent pending on a coupling that is intended for this application. Using regular couplings, the seal between baffles may be weakened by forcing too much pressure on the coupling during manufacturing. We have a new coupling model that incorporates a flashing completely around the outside wall of the coupling. During the manufacturing process, it is placed where the regular couplings would go. Once the concrete cures, the flashing is locked into place making a permanent seal completely around the outside of the coupling. If you would like samples of this coupling, contact the sales department at H. E. McGrew, Inc.

THE AERATION CHAMBER

The aeration chamber is the first phase of the treatment process. It is also the most important part because this is where the majority of the treatment is done. Without the aeration chamber, the unit will not function properly. The aeration chamber should hold no less than 551 gallons of wastewater.

Inside the aeration chamber, air will be forced through a diffuser bar on the bottom inside of the tank. Air will force its way to the water surface creating a rolling motion in the water body in the aeration chamber. This means the oxygen will have a greater transfer and higher dissolved oxygen levels. Higher oxygen levels in the water means the water environment will great for bacteria survival. Aerobic bacteria cannot live in places absent of oxygen. More information is given in Chapter 2.

THE DIFFUSER BAR

The diffuser bars sit at the bottom of the aeration chamber flat against the baffle (wall) dividing the pretreatment chamber and the aeration chamber. Its main purpose is to break up air into smaller air bubbles in the water in the aeration chamber. The smaller, more numerous air bubbles, the better the oxygen transfers to the wastewater.

The diffuser bar for the wastewater treatment plant is made of a stone type material. This stone material is outstanding for air diffusion. The size of stone needed is predetermined by size unit that is to be installed. A 500- gallon per day system will need two stones, six- inches long. When making the diffuser bar, remember to use good glue on the pipe connections.

THE CLARIFIER

The clarifier is the second and final phase in the Cajun Aire Wastewater Treatment process. The clarifier should hold no less than 186 gallons of treated water. The treated water will enter this quite zone through the bottom of the baffle separating the aeration chamber and the clarifier through a four- inch gap. The suspended solids and the settable solids will settle downward to the bottom of the clarifier and return to the aeration chamber. At the bottom of the clarifier, there will be a 45- degree slope. This slope helps return the solid material to the aeration chamber.

The outlet of the system will be found at the top of the clarifier on the inside end wall. The outlet will control the water level and air gap for the entire system.

DO NOT ATTEMPT TO CHANGE OR ALTER IN ANY WAY THE OUTLET LEVEL OF THE SYSTEM FOR ANY REASON WITHOUT PRIOR WRITTEN APPROVAL FROM THE HOME OFFICE OF H. E. MCGREW,LLC.