Optimization of an Aeration System at an Industrial Wastewater Treatment Plant

Transcription

1 Optimization of an Aeration System at an Industrial Wastewater Treatment Plant Philip L. Schwartz, P.E Keystone Engineering Group, Inc., Exton, PA and Lawrence R. Sandeen, P.E Rohm and Haas Company, Bristol, PA

2 Outline Reduce O&M costs and optimize Focus on aeration system Apply reliability engineering and common sense Examine air requirements, blowers, instruments and controls, etc Implement improvements Results Application to other WWTPs

3 Description of Treatment Plant Average flow: 1.44 MGD (1,000 GPM) Average influent BOD: 195 mg/l Average influent ammonia: 40 mg/l 4 aeration tanks, 2 zones each 3 centrifugal blowers, 300HP, 5,500 scfm each

4 Splitter Box, Equalization Tanks and Scrubber

5 Aeration Tank/Clarifier Unit

6 Clarifier Inside Aeration Tanks

7 Effluent Sand Filters

8 300 HP Centrifugal Aeration Blower

9 20 Diameter Fine Bubble Diffuser With EPDM Cover

10 Mass Flow Meter

11 Main Instrument Panel and DCS Consoles in Control Room

12 DCS Screen of One D.O. And Air Control Loop

13 Computer Display of Aeration Tank Instrumentation and Controls

14 Hourly Average Aeration System Performance Data Collected Between Feb and June 2001 Degrees F or mg/l Average Dissolved Oxygen (mg/l) Aver Temp (C) Air to Aeration Tanks (SCFM) Oxygen Transfer Requirement (Lbs/Day) 9,000 4,500 SCFM or Pounds/Day - Feb-01 Mar-01 Apr-01 May-01 -

15 Histogram of Hourly Average Oxygen Transfer Data Collected Between Feb and June ,000 1,250 1,500 1,750 2,000 2,250 2,500 2,750 3,000 3,250 3,500 Hours Hours ,000 1,250 1,500 1,750 2,000 2,250 2,500 2,750 3,000 3,250 3,500 Pounds of Oxygen/Day Pounds of Oxygen/Day

16 Calculated Air Requirements for Various WWTP Operating Conditions Temperature (C) Target DO (mg/l) OTR (#s/day) SCFM (Caculated) 30 Max 4 Max 1900 Average Max 4 Max 3200 Max Min 4 Max 1900 Average Min 4 Max 3200 Max Max 2 Optimal 1900 Average Max 2 Optimal 3200 Max Min 2 Optimal 1900 Average Min 2 Optimal 3200 Max Max 1 Min 1900 Average 751 T 30(C) Max DO (mg/l) 1 Min OTR 3200 (#s/day) Max SCFM Min 1 Min 1900 Average Min 2 1 Min Max Max 0.5 Min Average Max 0.5 Min 3200 Max Min 0.5 Min 1900 Average Min 0.5 Min 3200 Max 1817

17 Mechanical Efficiency of 300 HP Blower and Histogram of Air Demand Blower Air Flow (SCFM) Air to Aeration Tanks (SCFM) Mechanical Efficiency Hours at Airflow Rate Blower Mechanical Efficiency

18 300 HP Centrifugal Blower Curves, Actual and Two Design Conditions (68F and 100F) SCFM/KW KW Actual Blower Performance Design (100F) Alternate (68F) 1,500 3,500 5,500 7,500 9,500 Air Flow (SCFM)

19 Display of Sludge Holding Tank Showing Aeration Blower Current Control

20 Operational Scenarios Possible With One 100 HP Blower, Two 40 HP Blowers, and One 300 HP Blower (Air Flow/KW) SCFM/KW HP Centrifugal Blower (Design Data) 0 300HP Centrifugal Blower (Actual Data) 100 HP Cent. & 40 HP PD Blower (Design Data) 100 HP Cent. & Two 40 HP PD Blowers (Design Data) SCFM

21 Dissolved DOs Aeration Tanks Oxygen for Paper.atplot (Mg/l) Versus Time Demonstrating 06/05/2001 9:37: AM Inhibitory Substance Elevating Dissolved Oxygen Levels (Screen Print From Data Acquisition System) Name Server Description Value Status Plot Min.Plot Max.AggregateEng. UnitsMap

22 Results of Project Reduced Operating and Maintenance Costs Control Room Alarms reduced by 90% Improved staff response to Alarms Improved Operator Attitudes More stable and responsive operation Real time window into the biological process

23 Conclusions Better On-Line Data Acquisition allows for discovery of Optimization Opportunities Traditionally Engineered Aeration Systems may be Inefficient, only actual Operating Data reveals actual System Performance Dissimilar sized equipment (blowers, pumps, etc.) may allow more efficient operation Improve your knowledge and data concerning your process and you will reduce total cost

24 What should you do? Consider plant design efficiency at normal operating conditions. Establish accurate DO, Airflow and Blower current measurement programs. Evaluate data to relate system/blower performance at normal turndown to process needs.

25 Contact Information Phil Schwartz Keystone Engineering Group, Inc. (610) Larry Sandeen Rohm and Haas Company (215)