#BNRFORDUMMIES ERIC WAHLBERG, BROWN AND CALDWELL JASON TINCU, CITY OF DAYTON SWOWEA-PLANT OPERATIONS SEMINAR NOVEMBER 20, 2014 MANOR HOUSE-MASON, OHIO

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1 #BNRFORDUMMIES (with an Activated Sludge Primer) ERIC WAHLBERG, BROWN AND CALDWELL JASON TINCU, CITY OF DAYTON SWOWEA-PLANT OPERATIONS SEMINAR NOVEMBER 20, 2014 MANOR HOUSE-MASON, OHIO

2 BEGINNING WITH THE END IN MIND Reinforce the relevance of nutrients within our integrated water system and how future regulations will affect the way we do business and how you operate your facilities Provide insight and reasoning behind the bold statement: Engineers and operators alike need to change the way they think about activated sludge process control. Introduce BNR concepts, configurations, and operational strategies to consider

3 THE NEXT GENERATION S TASK Managing Nutrient Pollution Excessive amounts of point and non-point source Nitrogen and Phosphorus threaten our integrated water system Posing threats to Our environment, our economy, our health and safety Must manage Holistically with affordable and effective strategies aimed at point and non-point source loads Phosphorus directly in the bullseye, but Nitrogen should be on the radar Near Field now, but Far Field to come

4 Setting the right goals: Narrative vs. numeric, customized vs. one-sizefits-all, point-exclusive vs combined Working together towards solutions: Combining sound science and shared accountability while convincing regulators Turning to technology: Embrace both conventional and emerging approaches for nutrient removal and recovery The right moves: Stakeholders must work towards common good: healthy waters and livable communities SOLVING THE NUTRIENT PUZZLE BC-TODAY (2014)

5 STATUS OF NUTRIENT MANAGEMENT WITHIN THE STATE OF OHIO Ohio s Nutrient Reduction Strategy Joint effort by Ohio EPA, Department of Ag and ODNR Submitted to Feds in 2013 assessment of current efforts to reduce the negative impacts on Ohio s water resources Nutrient Technical Advisory Group (TAG) Diverse make-up of stakeholders Meetings since the Spring of 13 with a 15 target date Aimed at developing State surface water quality standards for nutrients

6 IT S NOT A QUESTION OF IF, BUT RATHER WHEN will our regional POTWs be required to treat to some reduced levels of Phosphorus and Nitrogen, especially in light of the recent Toledo water quality issue! Ohio EPA preaching shared responsibility for Nutrient Management with recent rumblings of statewide POTW Optimization Studies for nutrient reduction. Considering the issues and challenges at hand, it would behoove all POTWs to begin thinking about upgrades or process conversions to BNR.

7 BEFORE WE CAN DELVE INTO THE WORLD OF BNR, WE MUST ENSURE THAT THE FOUNDATION Activated Sludge Primer IS SOLID!

8 Hard to get there without the BASICS What I m going to cover 1. Process control aeration basin (mostly WAS) 2. A little nitrification and nitrogen removal 3. A little biological phosphorus removal 4. Process control secondary clarifier (mostly RAS)

9 The Books Tell Us How to Control the Activated Sludge Process 1. Control by constant MLSS concentration or mass 2. Control by constant MLVSS concentration or mass 3. Control by constant F:M 4. Control by constant MCRT I SRT I Sludge age I don t know how to tell you this without telling you

10 This is the Only One that Matters 1. Control by constant MLSS concentration or mass 2. Control by constant MLVSS concentration or mass 3. Control by constant F:M 4. Control by constant MCRT I SRT I Sludge age All the others are controlled by MCRT!

11 Why Is That? The Nine Signs of Stagnation? 1. We've never done it that way. 2. We ve always done it that way. 3. We're not ready for that, yet. 4. We're doing all right without it. 5. We tried it once, and it didn't work out. 6. It costs too much. 7. That's not our responsibility. 8. It just won't work. 9. Our facility is too small (big, hot, cold, different) for that.

12 This is the Equation Engineers Use to Design Activated Sludge Systems SRT Q BOD MLSS = (ISS INF + Y g INF sbod EFF ) 1 + b SRT V a The MLSS is a response variable so can t be used for control

13 Response Variables Not Control Variables 1. Control by constant MLSS concentration or mass 2. Control by constant MLVSS concentration or mass 3. Control by constant F:M 4. Control by constant MCRT I SRT I Sludge age Same holds true for MLSS mass, MLVSS concentration, MLVSS mass, and F:M

14 The Future Depends On It! X X X 1. Control by constant MLSS concentration or mass 2. Control by constant MLVSS concentration or mass 3. Control by constant F:M 4. Control by constant MCRT I SRT I Sludge age

15 And It Doesn t Work

16 Figure Out How to Make It Work At Your Plant MCRT = V a MLSS + V blanket TSS blanket Q WAS TSS WAS + Q EFF TSS EFF SRT = V a MLSS Q WAS TSS WAS + Q EFF TSS EFF You won t regret it!

17 The MCRT (SRT) Controls the Growth Rate G R = (1/MCRT) + γ + b Because γ and b are small G R (1/MCRT)

18 The Growth Rate Controls Sludge Quality, Which We Can Measure

19 Absurd! Floc Characterization Worksheet Company: Location: Sample Site: FML 5 Sample Date: 6/13/2014 indicating possible low F/M conditions Sludge age appears to be younger to medium age Filament Effect on Floc Structure Images: X X Image 1: None Very little Bridging Internal Bulking Filament Abundance X None Few Some Common Abundant Excessive Morphology of Floc X X Firm Weak Size of Floc Structures (µm) X X X <100 µm µm µm µm >500 µm Floc Structure X Round Compact Diffuse Irregular Open Lacy Floc Color Image 2: X <10% Clear Gold/Brown Red/Purple Black (young) (healthy) (unusual) (anaerobic) Pin or Straggler Floc Absent Very little Some Moderate Additional Comments: X Floc color is a dark brown color with less than 10% black (septic) areas. Floc structure is irregular and diffuse with little filament effect but some bridging. A large amount of crawling ciliates and stalked ciliates are present along with few amoebas. There are few filaments present including filaments with attached growth indicating possible low F/M conditions. There is a moderate amount of straggler floc throughout sample. Sludge age appears to be a younger to medium age. Image 1: Floc structure and color Image 2: Amoeba Image 3: Bouquet of stalked ciliates Image 4: Stalked ciliates and filament with attached growth X Image 3: Image 4:

20 Nitrogen Comes in Many Forms TIN: total inorganic nitrogen Nitrogen Gas (N 2 ) Nitrite (NO 2 ) Nitrate (NO 3 ) Ammonia/Ammonium (NH 3 /NH 4+ ) Organic Nitrogen Kjeldahl studied protein content of grains: less protein meant more beer. TKN: total Kjeldahl nitrogen

21 Nitrogen Comes in Many Forms TN: total nitrogen Nitrogen Gas (N 2 ) Nitrite (NO 2 ) Nitrate (NO 3 ) Ammonia/Ammonium (NH 3 /NH 4+ ) Organic Nitrogen

22 Nitrogen Cycle Valence NO 3 - NO - 2 N 2 NH 3, Organic N Assimilation Organic N N 2 NO 2 - Ammonification Assimilation Biological Fixation NO 3 - NH 3 By Heterotrophs Associated with Growth and Decay Denitrification Reduction Nitrification Autotrophs Lightning Fixation By Heterotrophs Associated with Organics Removal Reduction Nitrification

23 First Step to Understanding Nitrification NH 4 + H + + NH 3 Ammonium Ammonia

24 Nitrifiers Only Use Ammonia Nitrite Nitrate NH 4 + H + + NH 3 NO 2 NO 3 AOB NOB

25 Nitrifier Growth Rate Changes with Temperature

26 Happens All the Time: MLSS Control Leads to Summer-time Nitrification

27 Denitrification Removes N When Nitrate is Used as Terminal Electron Acceptor NO 3 (N0 2 ) N 2 e - NO 3 - N 2

28 Biological Phosphorus Removal Totally Different than Nitrogen Removal Influent During Treatment Following Treatment TP Soluble - P (Ortho-P) Particulate P Biological Transformation Soluble - P Particulate P EBPR or Chem P Removal Soluble - P Particulate P Effluent TP WAS

29 Anaerobic-Aerobic Cycling Key PHB storage P release Anaerobic Aerobic PHB oxidation Excess P uptake Cell synthesis RAS P-Rich WAS

30 We Trick the Microbes VFAs P Release CO2 + H2O O2 P Uptake Energy PHB PHB Energy Stored P PAO Cell Growth Stored P PAO Anaerobic Zone Aerobic Zone

31 IMPORTANCE OF GOOD SOLIDS CAPTURE Determined by EBPR or Chem-P removal efficiency Soluble-P Determined by solids capture efficiency (clarifier & filter) Particulate P Effluent TP Achieving low effluent TP ( 0.5 mg/l TP) consistently will require tight solids control

32 Impact of Effluent TSS Effluent TP = Soluble P + Particulate P 10% P 8% P 6% P 4% P 2% P

33 Keeping Track of all the Different Microbes 1. Heterotrophs that use oxygen 2. Heterotrophs that use nitrate 3. Ammonia oxidizing bacteria 4. Nitrite oxidizing bacteria 5. Phosphorus accumulating organisms 6. Lions and tigers and bears... Anammox How are you going to control all of them?

34 X Seems Obvious to Me 1. Control by constant MLSS concentration or mass 2. Control by constant MLVSS concentration or mass 3. Control by constant X X F:M 4. Control by constant MCRT I SRT I Sludge age

35 RAS TSS Concentration Very Predictable Either or TSS RAS = ( Q Q RAS + 1) MLSS TSS RAS = ( 1 r + 1) MLSS

36 Results Can be Staggering Process optimization work started Daily SSEC Eff. TSS (mg/l) Jan-05 May-05 Oct-05 Mar-06 Aug-06 Jan-07 Jun-07 Nov-07 Apr-08 Sep-08 Feb-09

37 RAS Flow Control is Simple Maintain the lowest RAS flow possible without expanding the sludge blanket.

38 BNR TIPS AND TRICKS Many learned the hard way

39 DENITRIFICATION VS PHOSPHORUS REMOVAL Where Phosphorus is removed exclusively via the solid stream, Nitrogen can only be removed as a gas to the atmosphere. Denitrification is anaerobic biological reduction of nitrate-nitrogen causing the removal of Nitrogen as a gas from the system.

40 BNR IS OUR GENERATION S ACTIVATED SLUDGE Be ready for it in your NPDES permit horizon Be prepared to see it within industry educational curriculum and certification content Accept the challenge to advance your knowledge and launch our industry into the next eon As most things, Slo-Hio is a bit behind the left and right coasts as well as environmentally sensitive regions

41 Profile your system on a regular basis Biological reactors are dynamic creatures that need to be monitored. Profile your system regularly. It will define your treatment systems habits and increase operator education and awareness.

42 # 9 --

43 Identify and quantify all sources of P & N inside and outside the gates Perform collection system surveys, side stream profiles, and analyze RAW water supplies to better understand sources and loadings

44 Consider air distribution within the initial section of the Aerobic Zones Ortho-P uptake is promoted rapidly with adequate air supply inside the first 1/3 of the Aerobic Zone (up to 75%).

45 Phophorus Uptake (% Total Uptake) 100% 80% 60% 40% 20% Aeration Zone #1 Aeration Zone #2 10-Sep Sep Sep-07 0% 0.0% 20.0% 40.0% 60.0% 80.0% 100.0% Aeration Volume (% of Total Aeration Vol.) Figure: Aeration Zone Ortho-P Profile (Ford Road WWTP, City of Xenia, OH)

46 Consider the HRTs of both Anaerobic and Aerobic Zones Insufficient HRTs within an Anaerobic zone will hamper Bio P treatment through a time deficiency for VFA uptake/ortho-p release. Excessive HRTs within an Aerobic Zone will affect Bio P treatment through the promotion of Cell Lysis/Digestion and its subsequent Ortho-P release.

47 Protect the integrity of the Anaerobic Zone Insufficient time and excessive oxygen and nitrates will hamper the zone s effectiveness. Eliminate and/or minimize sources of DO and NO3 in the system. i.e. pre-aeration, screw pumps, free fall over weirs or gates, internal recycles, RAS flow, aggressive turbulence and mixing, backflows

48 #BNRFORDUMMIES (with an Activated Sludge Primer) ERIC WAHLBERG, BROWN AND CALDWELL JASON TINCU, CITY OF DAYTON

49 BIOLOGICAL PHOSPHORUS REMOVAL Removal exceeding metabolic requirements Luxury P removal Excess P removal Enhanced Biological P removal (EBPR) Bio-P

50 WHO DOES THIS WORK? = PAOs Phosphorus Accumulating Organisms Aerobic heterotrophs normally remove BOD When properly conditioned, some (about 10%) can also store high levels of P (4-10% weight basis) Conditioning Achieved by Anaerobic Selector feed/starve cycle Feed is Anaerobic battery charging Starve is Aerobic battery discharging

51 BIO-P MECHANISM Anaerobic (no oxygen) condition Readily biodegradable substrate (Food) Aerobic condition uptake of P by PAOs Most of the P-rich bugs (PAOs) recycled as seed Selection of PAOs P transferred from the wastewater to the PAOs Some P-Rich bugs wasted from system Net P Removal

52 FACTORS IMPACTING BIO-P REMOVAL Influent characteristics Integrity of the anaerobic zone Solids control Aerobic zone design Secondary release Competition between PAOs & GAOs

53 INFLUENT CHARACTERISTICS ARE CENTRAL TO P REMOVAL PAOs need rapidly biodegradable substrate Volatile Fatty Acids (VFAs) - Acetic, propionic, etc. Sources of VFAs: Sewer system during warm climate Anaerobic zone of the bioreactor Primary sludge fermentation Purchased acetic & propionic acids