COMPARISON OF MBBR AND Suspended growth BNR Performance at the HRWTF Erika L. Bailey, PE NC AWWA WEA Annual Conference November 16, 2015

01 02 03 04 05 Introduction, Drivers, and Challenges Segregated Treatment Concept 03 MBBR / Suspended Growth Comparison 04 Conclusions 05 Project Status

Introduction, PROJECT DRIVERS, AND CHALLENGES 01 Introduction, PROJECT DRIVERS, AND CHALLENGES

HRWTF is a publicly owned industrial treatment works Located 20 miles southeast of Richmond, VA 50 mgd capacity, currently treating 28 mgd Small domestic base flow 23,000 residents LARGE industrial contribution 85% of flow High Purity Oxygen (HPO) activated sludge with denitrification No nitrification currently

HRWTF Existing liquid treatment Process “HAP” Foul Condensate VAWCO Gravelly Run RockTenn Industrial Headworks Reaeration Hercules Denit. Basin Industrial Primary Clarifiers HPO Aeration Tanks Evonik Final Clarifiers RAS Honeywell HOCl Domestic Domestic Headworks 2012 Improvements (Phase 1) Domestic Primary Clarifiers & Chlorine Contact Tanks

Total Nutrient Discharge Load by Year (Mlb/yr) Project Drivers Nitrogen (TN) Reduction Chesapeake Bay Nutrient TMDL HRWTF currently purchases TN credits Future market for credit purchases unknown Ammonia (NH3-N) Reduction Current NH3-N limit: 18.9 mg/L 30% - 90% reduction anticipated Monthly Avg: 2.0 – 14.2 mg/L Daily max: 3.1 – 21.6 mg/L Total Nutrient Discharge Load by Year (Mlb/yr) TP TN HRWTF Waste Load Allocation 0.075 1.83 2005 ND 1.9 2006 1.55 2007 1.7 2008 0.048 1.57 2009 0.013 1.88 2010 0.028 2.02 2011 0.020 1.77

Nitrogen Removal is Challenge at hRWTF Exceeds upper temperature limit for stable nitrification High influent temperatures exceed 37 ºC Cooling creates air permitting challenges High concentration of VOCs Impacts process performance stability Variable influent wastewater characteristics Slower nitrification rates expected (larger aeration tanks) Wastewater contains nitrification inhibitors

Addressing BNR Challenges: Segregated Treatment Concept 02 Addressing BNR Challenges: Segregated Treatment Concept

Project development approach Effectively build upon previous studies “Segregated Treatment” alternatives to address key challenges Leverage knowledge from previous testing Effectively address nitrification inhibition 2007 Comprehensive Alternatives Evaluation identified Segregated Treatment as preferred alternative

Unique “Segregated Treatment” Approach Addresses Temperature Challenge Separate high nitrogen and high temperature streams Achieves biological nutrient removal on portion of flow Eliminates need for cooling industrial influent BUT Honeywell wastewater contains nitrification inhibitors Final Effluent Domestic Honeywell Biological Nutrient Removal Secondary Treatment Combined Influent Total Influent Ashland RockTenn VAWCO Evonik Primary Segregated Stream Is there any issue naming all these industrial? Check with Hopewell, if you haven’t yet.

MBBR: Moving Bed Biofilm Reactor Segregated Treatment Approach Must Also Address Nitrification Inhibition Limit Honeywell flow to Segregated Treatment Use MBBR system for biological treatment High rate process Concentrated biomass; media provides high surface area to volume environment Biofilm structure Media contained within separate cells Self-regulating system (do not manage SRT) MBBR: Moving Bed Biofilm Reactor Bullets look off. What’s supposed to be happening here? Anoxic Cell BOD Removal Cell Nitrification Cells

Pilot Testing Conducted to Confirm Design Basis Side-by-side comparison of suspended growth and MBBR processes Both processes fed with the same influent flow stream Domestic primary effluent Gradually increased levels of Honeywell flow

Comparison of MBBR / suspended Growth Performance 03 Comparison of MBBR / suspended Growth Performance

Pilot Testing Configuration

Pilot Testing Conditions Scenario Description Influent % Honeywell 1 40% HW @ Design Avg 19% 2 70% HW @ Design Avg 29% 3 100% HW @ Design Avg 37% What is the ‘1’ superscript for? What does HW stand for? What is design average? What is the domestic portion? I don’t quite understand this.

Scenario 1 – 40% Honeywell TN removal in MBBR dropped when internal recycle was temporarily stopped. TN removal quickly increased to the same levels as the Suspended Growth system once the recycle stream resumed. This was done initially to purge any inhibitory compound remaining in the system following the nitrification inhibition event on February 28th but was left off for an additional three weeks to test a theory concerning MEKO. Difficult to read grey-shaded tables.

Scenario 1 – 40% Honeywell Ammonia reduction Solids removal Both systems achieved <1.0 mg/L NH3 for 85% of the time. Solids removal MBBR DAF unit provided greater and more consistent solids removal. Polymer was not needed. Both systems achieved an effluent ammonia concentration less than 1.0 mg/L for 85% of the time. Unexplained ammonia breakthrough in the MBBR is the reason for the sharp peak as the MBBR curve moves from the 90% to the 100% probability point on the x-axis. MBBR DAF unit provided greater and more consistent solids removal when compared to the Suspended Growth clarifier. No polymer addition to the DAF was required to achieve this level of TSS removal.

Scenario 2 – 70% Honeywell MBBR Suspended Growth More stable removal of ammonia and TN Suspended Growth Drop in nitrification performance due to an unexplained loss of biomass The MBBR provides more stable performance in terms of ammonia, TN, and COD removal at this testing condition. Suspended Growth system experienced a drop in nitrification performance that did not occur with the MBBR due to an unexplained loss of biomass which appeared to be a result of biomass deflocculation.

Scenario 2 – 70% Honeywell Sudden increase in effluent TSS from the Suspended Growth system Decrease in SRT and MLSS SRT may have reached as low as 9 days (7 day aerobic SRT). Nitrifier washout not expected (at 18 °C) But continuous nitrification inhibition experienced in the Suspended Growth system would make it more sensitive to the low SRT impacts. Sudden increase in effluent TSS from the Suspended Growth system had a significant effect on the MLSS concentration and SRT. Based on the observed drop in MLSS, it is estimated that the SRT may have reached as low as 9 days (7 day aerobic SRT). Nitrifier washout would not usually be expected at the operating temperature at this time (18 degrees Celsius); however, the continuous nitrification inhibition experienced in the Suspended Growth system would make it more sensitive to the low SRT impacts.

Scenario 2 – 70% Honeywell Ammonia Removal Solids removal: Suspended Growth system achieved <1.0 mg/L NH3 about 70% of the time. MBBR achieved <1.0 mg/L NH3 for almost 100% of the time. Solids removal: MBBR DAF unit provided greater and more consistent solids removal. Polymer was not needed. The MBBR achieved an effluent ammonia concentration less than 1.0 mg/L for nearly 100% of the time. The Suspended Growth system achieved an effluent ammonia concentration less than 1.0 mg/L for approximately 70% of the time. The MBBR DAF unit consistently is able to provide greater and more consistent solids removal when compared to the Suspended Growth clarifier. No polymer addition to the DAF was required to achieve this level of TSS removal.

Scenario 3 – 100% Honeywell MBBR provides more stable performance in terms of ammonia and TN removal.

Scenario 3 – 100% Honeywell Ammonia Removal Solids removal: Both systems achieved <1.0 mg/L NH3 about almost 100% of the time. MBBR achieved effluent ammonia < 0.1 mg/L 75% of the time Suspended Growth achieved effluent ammonia < 0.1 mg/L 55% of the time Solids removal: MBBR DAF unit provided greater and more consistent solids removal. Polymer was not needed.

Suspended Growth Performance Overview Kinetic Parameter PER Estimate (at 40% HW) % Honeywell based on Pilot Testing Units Scenario 1, 40% Scenario 2, 70% Scenario 3, 100% Specific Nitrification Rate Normalized to 20 Deg C (from reactor profiles) 2.1 2.22 2.47 2.84 mg NOx-N/g MLVSS*hr (from batch testing) 3.43 4.13 4.12 μmax at 20 Deg C 0.7 0.78 0.57 0.49 day-1 Denitrification Rate (normalized to 14.7 Deg C) 0.21 0.1112 0.18 0.19 lb NOx-N/lb MLVSS*day Observed Yield 0.53 0.59 0.41 (#/day VSS produced)/ (#/day influent cBOD) 0.23 0.25 0.16 (#/day influent COD) Nitrogen Uptake Rate 0.11 0.09 # TKN/# VSS 0.08 # TKN/# TSS Phosphorus Uptake Rate 0.02 0.01 # TP/# VSS 0.015 # TP/# TSS Won’t be able to read the table. Suggest 2 slides?

MBBR Performance Overview Rate PER Estimate (at 40% HW) % Honeywell based on Pilot Testing Units Scenario 1, 40% Scenario 2, 70% Scenario 3, 100% Denitrification 0.56 0.25 0.30 g NOx-N/m2-day BOD-Removal 4.51 - g BOD/m2-day COD-Removal 9.231 7.01 7.33 2.7 g COD/m2-day Nitrification (in BOD-removal zone) 0.63 0.27 0.49 g NH4-N/m2-day Nitrification (in nitrification zone) (from reactor profiles) 0.48 0.04 (from batch testing) 0.84 0.69 0.35 Observed Yield 0.61 0.54 0.73 (#/day VSS produced)/ (#/day influent cBOD) 0.23 0.20 0.24 (#/day influent COD) Nitrogen Uptake Rate 0.11 0.10 # TKN/# VSS 0.08 0.09 # TKN/# TSS Phosphorus Uptake Rate 0.02 0.03 # TP/# VSS 0.015 # TP/# TSS Won’t be able to read the table. Suggest 2 slides?

04 Conclusions

Pilot Testing Confirms Selection of MBBR System Typically outperformed Suspended Growth system More stable During loading condition transitions At higher fractions of Honeywell in the combined influent Better solids separation/control

Planned Segregated Treatment Process Upgrades Grit Removal Screen Domestic PCs Industrial PCs CCT Denit Basin Post Aeration Gravelly Run WAS RAS to Solids Handling Secondary Clarifiers Aeration Tanks (HPO) Domestic Wastewater Industrial Wastewater MBBR Honeywell DAFT NaOH SBS

05 Project Status