Proceedings

This paper is about the acid-gas (AG) anaerobic digestion process. This is the first update presented by
the authors to the European Biosolids Conference since 2003 and is update of that paper. The AG
process is arguably the fastest growing digestion technology among larger US WWTPs. It also is growing
in popularity in the UK. Earlier papers have described the process and its evolution from a single
mesophilic plant that was constructed to eliminate a foaming problem and improve VSS destruction
through the first multi-phase plants and plants producing Class A biosolids. This paper brings in the new
trend of effectively using the AG process to treat organic wastes (co-digestion), using it to divert
Industrial Wastes, using to reduce plant maintenance, a new “free” approach to implementing it, its
rapid spread in the UK and an update the current status of most known projects.
In the 2003 presentation we listed only 10 known installations:
• DuPage County, IL
• Oslo, Norway (VEAS)
• Elmhurst, IL
• Inland Empire, CA (RP-1)
• Inland Empire, CA (RP-2)
• Macclesfield United Utilities, UK
• Thames Water, UK
• Ville d’Aix, France
• Rockaway, NYC DEP
Now in 2007, we know of 17 more:
• Denver, CO
• Dallas, TX
• Turlock, CA
• Lakeland, FL
• 91st Ave, Phoenix AZ
• 23rd Ave. Phoenix, AZ
• Truckee Meadows, Reno-Sparks NV
• Pinnelas Co Utilities, AZ
• Waco TX
• Delhi Township, MI ( D/C)
• Blackburn (United Utilities)
• Crewe (United Utilities)
• Bromborough (United Utilities)
• Goddards Green (Southern Water)
• Cambridge (Anglian Water)
• Avonmouth – Wessex Water
• Kings Lynn – Anglian Water
The presentation contains information about each of the new US project, including information about (co-digestion), using it to divert Industrial Wastes, using it to reduce plant maintenance and a new
“free” approach to implementing it,. The full paper includes information about all the new projects. Both
will also include updates of some of the original 10 projects.