A demonstration of enhanced biological phosphorus (P) removal (EBPR) in one battery at the Stickney WRP was performed using existing plant infrastructure. The site-specific EBPR process was developed by creating anoxic (A), anaerobic (An), and aerobic (O) zones, referred as AAnO, in the return activated sludge (RAS), influent mixing channels, and aeration tanks, which would favor the growth of and luxury P uptake by phosphate-accumulating organisms (PAOs). The demonstration study included five phases (I-V) and focused on operational changes that could be made without investing in additional infrastructure. The test battery has been well outperforming control (non-EBPR) batteries with respect to P removal throughout the study, and effluent total P (TP) from the converted battery has generally improved through each of the first four phases. The whole Stickney plant was converted to AAnO process in Phase V. The average TP of plant outfall was below 1 milligram per liter (mg/L) as monthly average after 5 months of full conversion.

Recently, more and more wastewater treatment plants (WWTPs) are upgrading their conventional solids treatment systems which produce Class B biosolids to produce Class A biosolids. This trend has triggered rapid growth of not only new sludge treatment technologies but also conventional treatment modification technologies. The main focus of this paper is on anaerobic digestion process modification techniques to produce Class A biosolids or enhanced digestion to achieve multiple solids processing objectives. The paper is based on information collected from various WWTPs throughout the US on practices and trends to enhance sludge digestion, worldwide literature review, and from technology vendors. A systematic analysis (case studies) of 4 WWTPs to evaluate and shortlist alternatives to enhance the existing solids thickening-anaerobic digestion-dewatering complex into either Class A or enhanced solids processing system as well as estimation of the operational carbon footprint (OCF) of each of the alternatives are presented in this work.

No abstract