1. Rockdale Water
Resources – UASB
Pretreatment Facility
Overview and Key Process Summary
September 2015

2. • Facility Origins and Updates through 2013
• UASB Process Basics
• Operational Changes and Updates 2014 to present
• 2015 Performance Summary
• Questions and Facility Tour
Agenda/Overview

3. UASB – What is it?

4. • Influent is high strength (COD >10,000 mg/l) with variable
pH and NH3 levels
• PreAcidification (PAC) = conditioning of influent (COD=>
VFAs)
– pH in the low 5’s
– Current target = 25%
• UASB Reactor (Upflow Anaerobic Sludge Blanket)
– Acid/Methane Formers granularized around Ca core
– 0.35 m3/day methane production per 1 Kg COD removed
– Target COD removal = 90%
– Target effluent VFA < 2
– Target N/P residuals
– Target Reactor pH/Alkalinity 6.8/mid 40s
UASB Process Basics

5. Facility Timeline Summary
• Original Project (1994) – PreAcidification Tank (PAC),
Reactor and ancillary chemical feed building
• 2001 – Flow Equalization Tank and Rotoscreen
• 2001 – UASB Reactor Feed Header Modification
• 2004 – PAC tank rehabilitation (upper 2 rings)
• 2015 – Recycle Stream Separation/Piping Mods/Dual
Chem Feed Systems

6. Project BasicsFlares
Screening
EQ Tank
700,000
gallons
PAC Tank
145,000
gallons
UASB Reactor
540,000 gallons

8. UASB Biomass – A Different Animal

9. • Isolated Reactor and PAC recycle returns
• Added independent dual N/P feeds to PAC/Reactor
• DOA control drives PAC process changes
• Reactor N/P residuals drive UASB process changes
Operational Changes 2014 - Present

10. SCOD Treatment

11. PAC DOA

12. UASB Reactor

13. • Improve BioGas regulator controls
• Trial MagOx (less hazardous alkalinity control)
• Restore/rebuild original PID control loop concepts
• Replace existing PAC tank
• Update/improve odor control
• Install pigging bypass piping (to EQ vs Quigg)
Operational Changes Moving Forward

14. Questions?