Holistic Aeration and Chemical Optimization Saves Big Money from 1 MGD to 600 MGD. Trevor Ghylin, PE PhD

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1 Holistic Aeration and Chemical Optimization Saves Big Money from 1 MGD to 600 MGD Trevor Ghylin, PE PhD

2 Outline Background Case Study: Sterno, Sweden (~1.8 MGD) 65% Aeration Energy Reduction Case Study: Wisconsin (0.6 MGD CAS) Automated DO control - Reduced operator labor/attention - Improved process stability - Energy savings Automated Biomass control Automated Chemical Feed control for P removal - 95% reduction in chemical usage Case Study: Indiana (~300 MGD CAS) ~90% Aeration Energy Reduction 2

6 MGD CAS) Automated DO control - Reduced operator labor/attention - Improved process stability -

3 Background: WWTP Energy Consumption 3

4 Sternö, Sweden Case Study 4

5 Introduction The complete aeration system was exchanged in one of two treatment lines in a full scale wastewater treatment plant Blower + Aeration grid + Control system The two lines were compared in terms of energy consumption and treatment performance for 36 weeks 5

Blower + Aeration grid + Control system The two lines were

6 Plant description: Sternö wastewater treatment plant Placed in Karlshamn, Sweden Effluent restrictions: Built in 1997 Designed for pe Currently pe BOD: Tot-P: TN: 10 mg/l (monthly) 0.5 mg/l (monthly) 12 mg/l (annual) Screening and grit chamber 6 Primary sedimentatio n Biological treatment Secondary sedimentation Filtration

7 Plant description Biological treatment layout Two parallell biological treatment lines Process layout: Anaerobic zone Anoxic zone Aerobic zones Pre-denitrification 7

8 Compared aeration systems Test line Reference line Aeration grids Sanitaire Silver Series Low pressure diffusers Fine bubble tube diffusers Blower Screw blower Lobe blower Control system Sanitaire process control system DO control without cascade 8

bubble tube diffusers Blower Screw blower Lobe blower Control

9 Performance comparison 36 week evaluation (Sept 2011 to June 2012) Monitored values: Online: DO, airflow, NH4, NO3, blower power consumption Lab: Weekly composite samples of BOD7 and NH4-N from influent and effluent Calculations: Mass of oxygen transferred and aeration efficiency calculated based on mass BOD 7 and NH 4 -N treated and blower consumption OTR f = X BOD 5,r + Y NH 4 N r β C β C DO f + Q DO f AE f = OTR f P 10

effluent Calculations: Mass of oxygen transferred and aeration efficiency calculated based on mass BOD 7

10 Results energy efficiency Performance of test line versus reference line: 66 % energy savings 35 % airflow savings Aeration efficiency 2.6 versus 0.9 kg O2/kWh 11

11 Results energy efficiency The higher energy efficiency were a result of: New aeration grid Improved control system Higher oxygen transfer efficiency Lower system pressure through reduced pressure losses More stable DO control with cascade More efficient use of aeration volume with the adjusted DO profile Reduced system pressure with MOV Blower Higher energy efficiency 12

reduced pressure losses More stable DO control with cascade More efficient use of aeration

12 Results treatment performance Performance of test line versus reference line: Similar BOD reduction in both lines 9 % higher ammonia reduction 13

13 Example of Improved DO Control Values from Sternö WWTP, Sweden 14

14 0.6 MGD CAS WI Case Study 15

15 Process Control Modifications DO/NH4 Control SRT/MLSS Control Ferric Chloride Control 16

16 Blower driven aeration control Dissolved oxygen control DO control NH4 control DO setpoint NH4 controller NH4 Setpoint PID controller DO NH4 17

17 10/7 10/10 10/13 10/16 10/19 10/22 10/25 10/28 10/31 11/3 11/6 11/9 11/12 11/15 11/18 11/21 11/24 11/27 11/30 12/3 12/6 DO (mg/l) DO profile during Reference and Test period 7 6 Reference 2.66±1.6 Test-Tuning 2.15±0.24 Test 2.00± Date 19

18 What is SRT? Solids Retention Time = average duration of time an organism spends in the system SRT = Basin Mass Mass wasted per day = Basin volume(m 3 ) MLSS (mg/l) WAS Q(m 3 /day) WAS TSS(mg/l) = kg kg/day = days MLSS Volume TSS Q 20

19 SIMS Control Flexibility Four available modes of control Time Set your preferred wasting MLSS SRT Smart SRT time Set your preferred run time of pump for each wasting event Control to an operator selected MLSS Control to an operator selected SRT Control to an optimized SRT calculated based on real-time process parameters 21

wasting event Control to an operator selected MLSS Control to an operator

20 SIMS Benefits Inadequate treatment Optimized treatment Wasted energy Ammonia removal efficiency [kg NH 3 /kwh] Power 22

21 SIMS Control accuracy Operation example: Stable control within on average 0.5 days from set point Stable, step-wise adjustment to set point changes Data from Hammarby ICEAS pilot plant, Feb to May

22 SRT Control Results 24

23 MLSS Control Results 25

24 How Does P Control Work? PO4 Setpoint PO4 controller TP eff = PO4 eff + TP eff SS PO4 Controller Chemical (Ferric/alum) P Removal Effluent Solids Phosphorus (~ mg/l) PO4 Analyzer Anaerobic Zone Aerobic Zone 26

25 Ferric Chloride Usage (gpd) Total Phosphorus (mg/l) Case Study Ferric Chloride Usage Average Ferric Chloride Usage Influent Total Phosphorus Effluent Total Phosphorus Real-time control system installed for phosphorus control % reduction in chemical feed

26 Case Study: Cost Savings Ferric Chloride Cost ($/gal) $ 3.3 Caustic Cost ($/gal) $ 5.3 Capital Cost of OSCAR system $ 21,000 January 2015 Ferric Chloride Usage )gpd) 35 March 2015 Ferric Chloride Usage (gpd) 1.4 January 2015 Caustic Usage )gpd) 17.5 March 2015 Caustic Usage (gpd) 0 Annual Savings $ 74,501 Annual Return on Investment 355% Payback Period (Years)

27 300 MGD CAS Indiana Case Study 30

28 Project Wet Weather Upgrade Install new DO control (most open valve) with NH4 control Replace coarse bubble diffusers with fine bubble membrane diffused aeration system Replace PD blowers with single stage centrifugal Add anoxic selector zones for denitrification 31

29 How Does NH 4 Control Work? DO control NH4 control DO setpoint NH4 controller NH4 Setpoint Airflow Aeration controller Airflow Aeration controller Airflow Aeration controller DO DO DO NH4

30 NH4 Control Benefits Stabilized process 34

31 NH4 Control Benefits Energy savings 35

32 Anticipated % Aeration Energy Savings 36

33 Aeration Energy Savings (% Reduction) 37

34 Savings ($/year) 38

35 Conclusions Aeration is the largest energy consumer at WWTPs Holistic systems approach (efficient diffused aeration and blowers with optimized controls) can lead to 65-90% reduction in aeration energy requirements Online instrumentation exists for nearly any relevant parameter (DO, TSS, NH4/NO3, ORP, ph, PO4, etc) and can be used for control purposes Real-time chemical feed control can result in savings up to 95% Good investments with very high ROI (30-400% annual). Payback period from 3 months to 3 years. 39

36 Questions? 40

Phosphorus Removal. Wastewater Treatment

Phosphorus Removal. Wastewater Treatment Phosphorus Removal In Wastewater Treatment by Derek Shires (512) 940-2393 Derek.Shires@ett-inc.com Why do we care? Eutrophication of surface water - Especially reservoirs Maximum agronomic uptake - Limiting