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Lean Six Sigma

Lean Six Sigma. Increasing Waste Activated Sludge. Cheryl Cronin, Waste Water Treatment Plant. Project Description. Only 50% of W.A.S is processed through the Centrifuge currently at an average Total Solids of 2.2%. Gallons wasted in 1999 – 176.15 MG Gallons Processed at Centrifuge – 88.1 MG

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Lean Six Sigma

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  1. Lean Six Sigma Increasing Waste Activated Sludge Cheryl Cronin, Waste Water Treatment Plant

  2. Project Description • Only 50% of W.A.S is processed through the Centrifuge currently at an average Total Solids of 2.2%. • Gallons wasted in 1999 – 176.15 MG • Gallons Processed at Centrifuge – 88.1 MG • Average TS (Thickened) – 2.2% • Average TS (W.A.S) – 0.7% Problem Statement: Increase gallons of W.A.S. processed by 40% and increase Total Solids to 4 to 5% Objective:

  3. Benefits • Savings of $28,000 per year (fuel and treatment) • $1.7 M for additional digester space • Plant able to treat 88,000,000 more gallons per year – Reduction in CSO’s

  4. Project Team Champion: Ted Rhinehart Financial: Ned Byrer Black Belt: Cheryl Cronin Mechanic: Brian Panzer Process Analyst: Gwen Bard Laboratory: John Kohne Operator: Mike Glymph Operator: Jeff Vachon Technical: Chris Gach

  5. Schedule • Measurement: 07/17/00 • Analyze: 08/25/00 • Improvement: 09/29/00 • Control: 11/03/00 • Completion 12/30/00

  6. Savings • Digester Space – Less Water, less energy for heating. • 33% reduction in use = $10,000.00 • Additional Digesters • “Class A” sludge must have a 38% reduction in Volatile Solids and 15 day Detention time. • Currently there is an average 45% reduction and 7 day detention. By EPA standards, another digester is needed to achieve a 15 day detention at a cost of $1.7M. • Reduction of Million Gallons Treated • $18,000 in savings • Increased Capacity of Primaries Tanks

  7. “Y” Y = Million gallons of W.A.S. processed through Centrifuge at 4% TS or higher per week

  8. 50,000 Foot Process Map

  9. C & E Matrix

  10. % Solids in September

  11. Revised Objective • After completing process mapping and the C & E matrix we were able to improve the process by moving the average thickness of the sludge to 5.2% and have kept the centrifuge running for 3months non-stop. • My new objective is to increase the gallons of WAS sludge processed by 40% and increase the thickness of the sludge to 6 to 8%.

  12. Capability

  13. Measurement Studies • Developed a more timely method to measure the influent W.A.S • Developed a method to measure the thickened sludge out of the centrifuge during production • Current methods are 24 hours behind actual operation

  14. Thickened Sludge Measurement System • Rented a viscometer and did an initial study that told us that we should be able to correlate CPs with % solids. • Did a Gage R % R to confirm

  15. Gage R & R Study on Effluent Measure System

  16. Effluent Gage Stats StdDev Study Var %Study Var %Tolerance Source (SD) (5.15*SD) (%SV) (SV/Toler) Total Gage R&R 1622.6 8356.3 13.90 8.36E+05 Repeatability 1037.6 5343.4 8.89 5.34E+05 Reproducibility 1247.5 6424.5 10.68 6.42E+05 C1 75.6 389.2 0.65 38923.91 C1*trials 1245.2 6412.7 10.66 6.41E+05 Part-To-Part 11563.4 59551.5 99.03 5.96E+06 Total Variation 11676.7 60134.9 100.00 6.01E+06 Number of Distinct Categories = 10

  17. Gage R & R Study on Influent Measure System

  18. Influent Gage Stats StdDev Study Var %Study Var Source (SD) (5.15*SD) (%SV) Total Gage R&R 0.040044 0.20623 19.76 Repeatability 0.035285 0.18172 17.42 Reproducibility 0.018934 0.09751 9.35 Operator 0.018934 0.09751 9.35 Part-To-Part 0.198604 1.02281 98.03 Total Variation 0.202601 1.04339 100.00 Number of Distinct Categories = 7

  19. Multi-Vari Testing • Collected Data on Operators, Shift, Wet Well Height, Lab centrifuge results, Feed rate, Pinion Speed, Load, Viscometer results. • Length of the Test 12 days • Purpose to eliminate more “Xs”

  20. Multi-Vari Study

  21. Conclusions to Multi-Vari • We can make either thick or thin sludge but have problems making sludge in the 6 to 7 % range. • We see that operators still have separate methods for making sludge. • We have developed a reliable method for determining the thickness of influent sludge. • Load is significant to making thick sludge

  22. Conclusions to Multi-Vari • Wet well height is not significant • Operators have a big impact on sludge produced

  23. Progress Update Centrifuge runs 44.9% of the available time INITIAL CAPABILITY POST-PROJECT CAPABILITY Centrifuge runs 82% of available time Total Improvement Our goal was to improve processing time by 40 %. To date processing time has improved 37.3%

  24. Centrifuge Runtime July-December 2000

  25. Progress Update Initial Capability 2.2% Average Total Solids Initial Goal Increase to 4-5% Average Total Solids Final Capability 5.01% Average Total Solids

  26. Thickening Results 3.4% 4.7% 5.1% 5.8% 5.6% 5.3% 5.0%

  27. Progress Update • Volatile Solids Reduction in 1999 was 44.9% and in the last 6 months of 2000 it has increased to 58.4% Goal is to be above 38% • Detention time in the Digesters in 1999 was 7.3 days and since this project was started the average detention time has increased to 10 days in December . Goal is to be 15days or better.

  28. Sludge Flow to Digester 1999-2000

  29. Progress Update • In 1999 $8,200 was spent on diesel fuel. • In 2000 $244. was spent on diesel fuel.

  30. Project Tracking Project Tracking Project Description Process Map C & E Matrix Preliminary FMEA MSA Measure Analyze Improve Control Initial Capability Study Multi-Vari DOE (or other improvement) ControlPlan Hand OffTraining Final Capability Study OwnerSign-Off Final ProjectReport

  31. Next Step • Set up at DOE (February) • Develop a control Plan (March)

  32. Hands-Off Training In December of 2006, all equipment and programming changes were completed. The operators no longer have to make any adjustments once the process has started. They only have to set the load needed and the PLC does the rest.

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