1. Paving a Path to Potable Reuse Flexible Treatment for To Be Determined Regulations
Michael Watts, PhD, PE
Water Technology Leader Garver

2. Reuse Drivers – Shrinking Water Supplies
September, 2011

3. Reuse Drivers – Legislative
House Bill 3055 – Water for 2060 Act
No more fresh water consumption in 2060 than in 2010

4. Reuse Drivers - Financial
Water Conservation = Diminishing Water Revenue
Non-Potable Reuse Can Recover Some of this Lost Revenue
Potable Reuse Maintains Current Water Price Structure, while avoiding costly conservation measures

5. Oklahoma Reuse Regulations
Category
Treatment
Reuses
1A, 1C
Reserved (for potable reuse)
IPR, DPR 2
Secondary Treatment (nutrient removal, coagulation, filtration & disinfection)
Drip irrigation on orchards & vineyards; spray or drip on sod farms, public landscapes, golf courses, and toilets, fire protection, vehicle washing, and range cattle watering. 3
Secondary Treatment plus disinfection
Subsurface irrigation of orchards or vineyards; restricted access landscapes; livestock pasture, concrete mixing, dust control, restricted golf course 4
Primary Lagoon Treatment and Lagoon Storage plus disinfection
Soil compaction, similar construction activities, and restricted access golf course. 5
Primary Lagoon Treatment and Lagoon Storage
Restricted access pasture irrigation for range cattle, fiber, seed, forage, silviculture.
Under Development

6. Category 1A Reuse
Indirect Potable Reuse (IPR) through Reservoir, Lake, or Stream Augmentation
WRRF
WTP

7. Addressing Category 1A (IPR) Reuse Regulation Hurdles
Receiving Water Conditions (Sensitive Water Supply)
Defined Regulation for Municipal Reuse Projects
Pathogen Removal Criteria
Effluent Concentrations of Conservative Substances

8. Category 1A (IPR) Reuse in OK
Regulations are Currently Being Defined
Meet defined Water Quality Standards and Beneficial Uses
Category 2 Reuse Disinfection (no residual at discharge point)
No long-term concentration of conservative substances above Water Quality Standards
Development of New Category for Sensitive Water Supplies (SWSr)
Must maintain chlorophyll-a standard in SWS (< 10 mg/L)
Only municipal reuse projects will be permitted in SWSr watersheds

9. The Engineering Challenge for Category 1A (IPR) Reuse
From Conventional Activated Sludge to Water Resource Recovery Facility (WRRF)
PRIMARY
CLARIFICATION
SECONDARY
FROM HEADWORKS
RAS/WAS PUMPING
Mean Effluent
cBOD < 10 mg/L
Aeration
TSS < 15 mg/L
TDS < 500 mg/L
Ammonia-N < 0.5 mg/L
Nitrate-N < 20 mg/L
Phosphorus < 10 mg/L

10. Scope of Additional Treatment for Category 1A (IPR) Reuse
YES / Likely
Ensure protection of
SWS from Title 785- Ch. 45 Organics
Mean Effluent
More Organics Oxidation?
cBOD < 10 mg/L
TSS < 15 mg/L
TDS < 500 mg/L
Ammonia-N < 0.5 mg/L
Nitrate-N < 20 mg/L
Phosphorus < 10 mg/L

11. Scope of Additional Treatment for Category 1A Reuse
Mean Effluent
YES / Likely
Many OK SWS are already impaired
for turbidity
cBOD < 10 mg/L
Coagulation and/or Filtration?
TSS < 15 mg/L
TDS < 500 mg/L
Ammonia-N < 0.5 mg/L
Nitrate-N < 20 mg/L
Phosphorus < 10 mg/L

12. Scope of Additional Treatment for Category 1A Reuse
Mean Effluent
cBOD < 10 mg/L
TSS < 15 mg/L
Dissolved Minerals Removal?
As a conservative pollutant which can impair public water supplies, this determination will likely be case-by-case
Maybe
TDS < 500 mg/L
Ammonia-N < 0.5 mg/L
Nitrate-N < 20 mg/L
Phosphorus < 10 mg/L

13. Scope of Additional Treatment for Category 1A Reuse
Mean Effluent
cBOD < 10 mg/L
TSS < 15 mg/L
TDS < 500 mg/L
Enhanced Nitrification/ Denitrification?
Ammonia-N < 0.5 mg/L
Maybe
As a semi-conservative pollutant (NO3-) which
can impair public water supplies, this determination will likely be case-by-case
Nitrate-N < 20 mg/L
Phosphorus < 10 mg/L

14. Scope of Additional Treatment for Category 1A Reuse
Mean Effluent
cBOD < 10 mg/L
TSS < 15 mg/L
TDS < 500 mg/L
Ammonia-N < 0.5 mg/L
YES / Likely
Nitrate-N < 20 mg/L
Phosphorus Removal?
OK SWS are often phosphorus-limited for chlorophyll-a production
Phosphorus < 10 mg/L

15. Biological Phosphorous Removal (BNR) Design
Zone
Possible HRT1 (hr)
% of Total Volume
Anaerobic 2
16%
Anoxic
2.5
20%
Aerobic 8
64%
Total
12.5
(1) Based on average day flow of MGD.
Goal of Treatment: Reduce Total Phosphorus from 10 to < 1 mg/L as P

16. Phosphorus Accumulating Organisms in Action
Biological Nutrient Removal

17. Chemical Phosphorous Removal
Goal of Treatment: Reduce Total P from ~1 to < 0.5 mg/L as P
Chemical Feed & Storage A
Secondary Clarifiers
Conventional Disinfection
Chemical Feed & Storage B
Alum
Samples to Phosphate Analyzer
Tertiary Filters
Aeration Basins
Category 1A Disinfection

18. Effluent Water Quality
Filtration
BNR
CNR
cBOD < 5 mg/L
TSS < 5 mg/L
TDS < 500 mg/L
Ammonia-N < 0.5 mg/L
Nitrate-N < 10 mg/L
Phosphorus < 0.5 mg/L

19. Category 1A Disinfection?
If Category 2 Rules are Promulgated for Category 1A:
3-log Giardia inactivation
5-log Salmonella inactivation
5-log Adenovirus inactivation
Can be accomplished with sequential
UV (UV Doses ≥ 40 mJ/cm2)
Free Chlorine Residual
CT for 4 to 5-log virus inactivation

20. Water Cycle for Cat. 1C (DPR)
Direct Potable Reuse
WRRF
WTP

21. Addressing Category 1C (DPR) Reuse Regulation Hurdles
Pathogen Removal
Concentration of Conservative Substances
Contaminants of Emerging Concern?

22. Category 1C (DPR) Disinfection?
WateReuse Foundation (2012) – Study of Innovative Treatments for Reclaimed Water
Evaluated Disinfection/Oxidation Technologies
Bacteria
Virus
Protozoa
CECs UV O3
UV AOP
O3 AOP
Free Chlorine
Chloramines
Peracetic Acid (PAA)
Excellent
Very Good
Good
Fair
Poor

23. Questions?
Michael Watts, PhD, PE