1. District Engineer/Manager
PLANT OPTIMIZATION AT NORTH TABLE MOUNTAIN WATER AND SANITATION DISTRICT
Presented By:
Rick Jeschke P.E.
District Engineer/Manager

2. NTMW&SD Background District formed in November 1958 Publicly owned
Run by an elected 5 member Board
3200 service connections
Serves a population > 10,000

3. NTMW&SD Water Plant Originally constructed in 1962 Major upgrades
1985 pump station
1986 new filters
1997 Actiflo ballasted floc system
1999 MIOX chlorination system
2001 new filters

4. NTMW&SD Water Plant Surface water plant Plant rated at 15 MGD
Yearly output 650 to 700 MG
Actiflo ballasted floc treatment
MIOX on-site chlorination system
8 multi media filters

5. Stage 1 D/DBP Requirements
Prompted by the EPA December 1998
TTHM MCL was set at mg/L
HAA5 MCL was set at mg/L
Chlorite MCL was set at 1.0 mg/L
Bromate MCL was set at mg/L
Systems with a population over 10,000 had to be in compliance by January 1, 2004

6. NTMW&SD DBP In 1997 NTMW&SD average DBP were
TTHM mg/L
HAA5’s mg/L
Chlorite and Bromate were below DL
The District felt that these values were to close to the MCL so plant upgrades were proposed

7. DBP Treatment Methods Oxidation Aeration Activated carbon
Ozone
Chlorine dioxide UV
Aeration
Activated carbon
Synthetic resins
Remove precursors
Old plant conventional sedimentation
District philosophy to add as few chem as possible

8. Actiflo Ballasted Floc Process
Coagulated with alum
Microsand and polymer are added next
Destabilized suspended solids bind to the microsand through polymer bridges
Maturation to form micro sand ballasted floc
Sludge/microsand sent to hydrocyclones to separate the microsand from the sludge

9. Actiflo Flow Schematic

13. NTMW&SD Actiflo Plant Construction started Sept. 1997 Online May 1998
Two 7.5 MGD trains
Each train 19 feet by 48 feet
Total max detention time 21 minutes
Total max settling time 10 minutes
Designed for 24 GPM/ft squared

14. Actiflo TTHM Reduction
Pre Actiflo TTHM levels mg/L
Post Actiflo TTHM levels mg/L
TTHM levels reduced by 35%

15. Actiflo HAA5 Reduction Pre Actiflo HAA5 levels 0.040 mg/L
Post Actiflo HAA5 levels mg/L
HAA5’s levels reduced by 31%

16. Actiflo Microscopic Particulate Analysis (MPA) Reduction
Pre Actiflo 3 to 4 log removal
Post Actiflo 4 to 5.5 log removal before filtration
Post Actiflo 6 to 6.7 log removal after filtration
Microscopic Particle Analysis

17. Clarified Turbidity
Poorly designed old sed basin

18. Filtered Turbidity
Added to much alum at first

19. Standard Plate Count (SPC)
Raw water SPC are 5/mL to 200/mL
Clarified SPC are 2/mL to 16/mL
Recycling sand not contributing to SPC

20. Sand Carryover
During initial startup some sand carry over was observed
After three days no sand carry over was observed
Sand carryover filtered out easily
MPA analysis showed no signs of inert matter so the sand was filtered out

21. Sand Consumption Hydrocyclones are not 100% efficient
Sand loss is approximately 4 pounds per million gallons produced
Equates to $0.40/MG
Sand purchased 12 tons at a time
Sand costs $0.10/pound delivered
Cost of shipping sand is the same for one bag or full load

22. Sand Abrasion Online since May 1998 Six years of operation
No wear on SS pipe
No wear on hydrocyclones
After six years lead pump liners were replaced
Higher flows more sand pumps

23. MIOX at NTMW&SD Before MIOX the District used chlorine gas
Safety was the main factor in the decision to go to on-site generation.
On-site generation eliminated the storage space for bleach
On-site generation meant that the chlorine would only be made when needed (with the system fully automated)

24. MIOX On-Site Chlorine Production
Electrolysis of salt water to generate chlorine practiced commercially for > 100 years
Chlorine produced at large chlor-alkali plants, packaged, and sold
Chlorine gas cylinders
Sodium hypochlorite drums
Calcium hypochlorite tablets
Within past 30 years, developed smaller equipment to generate sodium hypochlorite on-site by same process
On-site generation uses only salt, water, and electricity
Eliminates hazardous chemicals
Heart of technology is the electrolytic cell

25. How the Cell Works Brine -- NaCl dissolved in H2O
Positive ions are drawn to the cathode; negative ions are drawn to the anode
Apply power
Possible electrolytic reactions
Anode:
2 Cl- ==> Cl2 + 2e-
HOCl + H2O ==> ClO2 + 3H+ + 3e-
2H2O ==> O2 + 4H+ + 4e-
O2 + H2O ==> O3 + 2H+ + 2e-
Cathode:
2H2O + 2e- ==> H2  + 2OH-
Hydrolysis in Bulk:
Cl2 + H2O ==> HOCl + Cl- + H+

26. MIOX On-Site Chlorine Generation System

27. Brine pump
Cell

28. Control Panel

30. DC POWER SUPPLY

32. On-Site Chlorine Generation Advantages
Safety
No hazardous chemicals used, generated stored, or transported
Chlorine concentration approx %
No potential for chlorine leak
No possibility of forming chlorine gas cloud by mixing with water
No combustible combinations

33. On-Site Generation Advantages (continued)
Regulatory Ease
No RMP
No HAZMAT training
No SCBA equipment
No “two man rule” for changing out cylinders
No chlorine scrubber, as required by Uniform Fire Code
No DOT trucking requirements
No corrosion due to chlorine off-gassing
Risk Management Plan
Self Contained Breathing Apparatus

34. On-Site Generation Advantages (continued)
Cost Savings
Operating costs depend on cost of salt and power
Cost of power offset by not purchasing chlorine
Lower than bleach or calcium hypochlorite
Lower than ozone, UV, or ClO2
Lower liability

35. On-Site Generation Advantages (continued)
Freshness and Consistency of Solution
Generated on-site as need
Shelf-life is a non-issue
No need to change dilution or mixing ratios
No degradation to chlorite or chlorate on shelf

36. MIOX at NTMW&SD Three 50 pound per day cells
One 100 pound per day cell
Bulk salt storage
Storage capacity of up to 600 gallons of MIOX solution

37. 3-50 PPD PPD

39. MIOX TTHM Reduction
With the Actiflo system reducing the TTHM by 35%, no further improvement was expected using MIOX
Pre-MIOX TTHM levels mg/L
Post-MIOX TTHM levels mg/L
TTHM levels reduced by 44%

40. MIOX HAA5’s Reduction
With the Actiflo system reducing the HAA5’s by 35%, no further improvement was expected using MIOX
Pre-MIOX HAA5 levels mg/L
Post-MIOX HAA5 levels mg/L
HAA5’s levels reduced by 43%

41. NTMW&SD Chlorine Dosage
District policy is to maintain a minimum 0.4 mg/L residual in the distribution system
Pre-MIOX residual leaving the plant was 1.1 mg/L
Post-MIOX residual leaving the plant mg/L
Chlorine dosage reduced by 27%

42. NTMW&SD Lime Dosage MIOX is near pH neutral Chlorine gas has a low pH
Post-MIOX the lime dosage reduced by 50%

43. MIOX System Maintenance
Amps and volts checked daily
Pressure at cell checked daily
Combined chlorine concentration checked daily
Individual MIOX cell concentration checked monthly
Hardness checked weekly

44. MIOX System Maintenance (continued)
Orifices are checked for blockages weekly
Flows through the cells are checked twice per month
Cartridges Filters are changed out twice per year

45. Control Panel

47. MIOX Cell Acid Cleaning
MIOX cells are acid cleaned twice per year
Cleaned with a 50/50 HCl solution
Allowed to sit for 15 minutes
Rinsed with softened water
Entire process takes approximately 1 hour
Can use other cells while cleaning one
Easier to clean out of the cabinet

48. Miscellaneous MIOX Information
Important to buy highest quality salt
Salt received in 25 ton bulk shipments
25 tons of salt costs $1,600 including delivery
MIOX provided a list of recommended spare parts
Cells don’t have to be cleaned as often if high quality salt is used

49. Total TTHM Reduction Pre-Actiflo and pre-MIOX TTHM levels 0.063 mg/L
Post-Actiflo and post-MIOX TTHM levels mg/L
TTHM levels reduced by 63% in total

50. Total HAA5 Reduction Pre-Actiflo and pre-MIOX HAA5 levels 0.040 mg/L
Post-Actiflo and post-MIOX HAA5 levels mg/L
HAA5 levels reduced by 60% in total

51. THANK YOU!!
ANY QUESTIONS?