26,814 Gallon Anaerobic Degradation and 5,600 gallon Anaerobic Digestion Mixing Systems for Waste Treatment:

In designing a mixer for an anaerobic mixing system, the application is generally defined by the percent by weight solids.  Anaerobic digesters typically operate with weight percent solid concentrations of between 10 to 15% with extremes of up to 25% with some types of solids.  Please reference Sludge Mixing for these higher solids rates.  Anaerobic mixing, at the other extreme, is generally relatively low solids rates.  The following mixer design generally applies applications of this type.      

There are two Anaerobic Digestion is a process where microorganisms break down biodegradable material in the absence of oxygen to process waste and release energy (methane along with carbon dioxide).  The anaerobic processes can be managed in a "digester" (an airtight tank) or a covered lagoon (a pond used to store animal waste) for waste treatment. The primary benefits of anaerobic digestion are nutrient recycling, waste treatment, and odor control. Except in very large systems, the biogas production is  generally captured and then recycled for use in for other unit operations within a treatment plant.

Attached is a typical 26,800 gallon anaerobic digestion mix tank optimized for your consideration.  Anaerobic digestion tanks are constructed either using concrete basins, ponds, or various other tank configurations.  The basis of the design makes the following assumptions:

1. Maximum Specific Gravity = 1.09
2. Viscosity Range = 500 centipoise max.
3. A standard 28,814 Anoxic storage tank, 16' long x 16' wide x 16' tall with 14' Side Water Depth (SWD) supplied by others.  
4. A vertical-on-tank-centerline mounting arrangement is used 
5. No in-tank anti-swirl baffles are required. 
6. 316D/316 Stainless Steel mixer wetted parts.
7. 230/460 Volt Power source.
8. Mixer support bridge supplied by others.  

The advantages are significant:

1. Lower horsepower 3/4. 
2. Engineering Mixer Specification
3. Pedestal mounted with coupling above mounting surface, easy maintenance design.
4. Hydrofoil in combination with lower mixer speed, creates lower fluid shear, which maximizes polymer chemical efficiency.    

Complete design for 24,800 gallon Anaerobic Storage mixing application. Includes engineering specifications, tank drawing, mixer mounting orientation for waste water treatment systems.

09.21.23