Medium-rate anaerobic

Download the ADI-Hybrid brochure.

Medium-rate anaerobic treatment systems cover a wide range of applications and wastewater types and are some of the most versatile types of anaerobic treatment technology.  Typically loaded at rates of about 4 to 10 kg COD/m³·d, these systems provide effective, low-maintenance treatment in a compact footprint.

ADI offers two types of medium-rate anaerobic technologies:

1. ADI-Hybrid
2. Modified BVF^® Process

ADI-Hybrid
The ADI-Hybrid process is a medium-rate anaerobic system that combines the elements of two other anaerobic treatment technologies, the UASB (Upflow Anaerobic Sludge Blanket) process and the UFF (Upflow Fixed Film or Upflow Filter) process, and retains the process advantages of each technology.

The lower part of the reactor volume is the UASB portion where an anaerobic sludge bed develops. Much of the organic stabilization (treatment) may occur in this sludge bed. The upper part of the reactor is the UFF section. In this section, a cross-flow type media provides extensive surface area for the fixed-film bios to develop and grow. The media intercepts sludge bed solids and raw influent solids, promotes flocculation, and returns the solids to the sludge bed. Biomass sloughed from the media is directed to the sludge bed below in a similar fashion.

Some of the advantages of ADI-Hybrid technology include:

• Does not require granular sludge bed
• Eliminates need for expensive and often difficult-to-acquire seed
• Is stable and resilient to shocks because of large biomass inventory
• Higher loadings and more consistent performance as a result
• Solids digestion and lower sludge production
• Can handle toxic substances and difficult-to-degrade wastewaters
• Fixed-film biomass less susceptible to toxic shock
• Improved solids retention makes it superior for wastewaters with low sludge yield

The ADI-Hybrid process has been used in more than twenty-five installations worldwide and is often utilized to treat difficult wastewaters, including:

• Chemicals production
• Polyester
• Terephthalic acid / PTA
• Ethylene Glycol

but can be applied to nearly any soluble wastewater.

Modified BVF^® Process
The Modified BVF^® process is a form of anaerobic contact or completely stirred tank reactor (CSTR) process. The anaerobic contact process is one of the oldest forms of anaerobic technology and the one that is most familiar to engineers and operators due to its widespread use in municipal wastewater treatment systems for the digestion of waste sludge.  It is a highly effective treatment technology for highly concentrated wastes and wastewaters with high solids (TSS) and fats, oils and grease.

The process involves maintaining a completely mixed reactor volume to enhance or ensure “contact” between the substrate and the anaerobic bios. This is typically accomplished through the use of submersible mechanical mixers, but can also utilize a variety of mechanical or gas-type mixing schemes.  

The other key component of the Modified BVF^® process is the gas/liquid/solid separation mechanism which permits collection of biogas and treated effluent while retaining the anaerobic bios within the reactor. Due to the vigorous agitation within the reactor, conventional internal separation mechanisms are not suitable, and external clarifiers, centrifuges and other systems are typically utilized. ADI’s two different versions of the anaerobic contact process utilize two different methods of gas/liquid/solid separation and biomass retention—centrifuges and a truly unique method involving submerged membranes.

Anaerobic contact treatment systems are utilized to treat many different types of wastewaters, including:

• Food processing
• Fuel ethanol plant thin and whole stillage
• Distillery
• Yeast production
• Sugar processing
• Other highly concentrated wastewaters