Slide 1

Rockdale Water Resources UASB Pretreatment Facility

Overview and Key Process SummarySeptember 2015

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

UASB What is it?

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 5sCurrent target = 25%

UASB Reactor (Upflow Anaerobic Sludge Blanket)Acid/Methane Formers granularized around Ca core0.35 m3/day methane production per 1 Kg COD removedTarget COD removal = 90%Target effluent VFA < 2Target N/P residualsTarget Reactor pH/Alkalinity 6.8/mid 40s

UASB Process Basics

Facility Timeline SummaryOriginal 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

Project Basics

FlaresScreeningEQ Tank700,000 gallonsPAC Tank145,000 gallonsUASB Reactor540,000 gallons

UASB Biomass A Different Animal

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

SCOD Treatment

PAC DOA

UASB Reactor

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

Questions?