1. Water Reuse in Saudi Arabia: Approaches to Increase Use and Acceptance
Thomas M. Missimer and Gary Amy
Water Desalination and Reuse Center 
King Abdullah University of Science and Technology
Kingdom of Saudi Arabia

2. Water Reuse in Saudi Arabia
Water reuse in Saudi Arabia is currently only about 10% of the total treated water use.
Most treated wastewater effluent in Saudi Arabia is currently discharged into the sea with no beneficial use and environmental consequences.

3. Categories of Reuse Definition Of Reclamation: Treatment for Reuse
Planned/Intentional vs. Unplanned/Unintentional Reuse
(e.g., Effluent-Dominated Rivers or Lakes)
Potable vs. Non-Potable Reuse
Non-Potable Reuses:
Agricultural Irrigation
 Crops Intended for Human Consumption
(raw versus cooked)
 Animal Crops
Urban (Landscape/Golf Course) Irrigation
Industrial Cooling and Process Water
Groundwater Recharge or Injection
Potable Reuse
Indirect Potable Reuse (IPR), via an Environmental Buffer
Direct Potable Reuse (DPR), Pipe-to-Pipe, via an Engineered Buffer?

4. Categories of Reuse - cont
Primary Uses of Recycled Water (reclaimed wastewater)
Agricultural Reuse  Constrained by location of use, seasonality, need for dual (purple pipe) distribution system, need for possible winter storage
Industrial Reuse  Constrained by location of use, varying quality requirements, need for dual distribution system and storage
Landscape Irrigation  Constrained by dispersed nature of demand
Groundwater Recharge  Intent may vary (e.g., controlling salt water intrusion in coastal aquifers) but represents a salient feature of indirect potable reuse
Unplanned, Unintentional Potable Reuse Widely Practiced Globally  Need to Move to Planned, Intentional Potable Reuse

5. Water Quality (not Water History) as Driver for Safe Water Reuse (Asano, 2006)
Singapore:
NeWater

6. Acceptance of Water Reuse

7. Potable Reuse Constraints and Opportunities
Water Quality Issues: (Secondary) WW Effluent
Elevated Levels of Organic Matter (DOC)
Effluent-Derived Organic Micropollutants (PhACs, EDCs, WW DBPs)
Emerging Pathogens (e.g., new strains of E. Coli)
Attributes of WW Effluent as a DW Source
Proximity of Source
RO in WW reclamation/reuse: Lower unit cost for WWRO than SWRO
Range of Treatment Options
Advanced Processes (membranes, oxidation, UV disinfection, adsorption)
Natural Systems (aquifer recharge and recovery (ARR))
Direct (DPR) vs. Indirect Potable Reuse (IPR)
Environmental Buffer (e.g., Aquifer Recharge and Recovery, ARR) in IPR

8. Indirect Potable Reuse
Reservoir
Wastewater WW
Reclamation
Plant
e.g., Occaquan Reservoir, Virginia USA DW
Treatment
Plant
Consumer

9. Indirect Potable ReuseWW
Reclamation
Plant
Wastewater
Surface spreading
or injection
e.g., California and
Arizona Sites USA DW
Treatment
Plant
Consumer
Soil
Passage
(ARR)

10. Direct Potable Reuse Wastewater Consumer WW Reclamation Plant
Pipe-to-Pipe
e.g., Windhoek, Namibia
(O3, UF, etc.) DW
Treatment
Plant
Consumer

11. e.g., Big Springs, Texas (planned)
Direct Potable Reuse
Wastewater WW
Reclamation
Plant
Pipe-to-Pipe
e.g., Big Springs, Texas (planned) DW
Treatment
Plant
Consumer

12. e.g., Cloudcroft, New Mexico
Direct Potable Reuse
Wastewater
Post-Storage
Treatment WW
Reclamation
Plant
Engineered
(Storage)
Buffer
Pipe-to-Pipe
e.g., Cloudcroft, New Mexico
(planned) DW
Treatment
Plant
Consumer

13. Advanced Treatment Processes for Potable Reuse
Advanced Disinfection (UV Irradiation)
Difficult to Inactivate Microbes/Pathogens
Constraint: Some UV-Resistant Viruses
Oxidation (Ozonation, Advanced Oxidation)
Organic Micropollutant (OMPs)
Constraint: Metabolites (by-products)
Adsorption (Activated Carbon, Iron Oxides)
Organic Micropollutant (OMPS) and Inorganic Micropollutants (trace metals)
Constraint: Polar OMPs
Membrane Separation (ultra- and nano-filtration)
(Physical) Removal of Microbes and OMPs
Constraint: Removal of Small Microbes or OMPs
Aquifer Recharge and Recovery (ARR)  An Advanced Process!

14. IPR Concept Pre-Treatment Environmental Buffer Post-Treatment
 Conventional WW Treatment
 Advanced WW Treatment
 Groundwater Aquifer
 Surface Reservoir
 Conventional DW Treatment
 Advanced DW Treatment

15. ? The Water Industry Standard for to Indirect Potable Reuse
e.g., California (OCWD)
Microfiltration (or MBR)
Disinfection
Secondary treatment
Tertiary filtration
MAR (Direct Injection or Infiltration) ?
AOP
Reverse Osmosis

16. Environmental “Buffers”
Inherent Component of Indirect Reuse
Aquifer or Reservoir as Environmental “Buffer”
Short-Circuiting?
Retention Time (e.g., 6 months  Die-Off of Viruses
% Reclaimed Water  Recycled Water Contribution (RWC)
Storage vs. Treatment?
Synergistic Hybridizations
ARR  Membranes (NF or RO)
Lowered membrane fouling (ARR pretreatment)
Secondary barrier for organic micropollutants
Oxidation  ARR
Biodegradation of oxidation metabolites

17. Aquifer Recharge and Recovery (ARR) for Wastewater Reclamation
Wastewater treatment plant effluent
Post-treatment
Pre-treatment
Aquifer
Recharge Recovery
Primary
Secondary
Tertiary/Advanced
None
Oxidation (O3 , AOP)
Membrane Filtration (MF)
UF (viruses)
NF (trace organics)
Post disinfection (Chlorination or UV)
(Depends on intended
use of reclaimed water)
Process conditions
Residence time
Travel distance
Redox, HLR

18. ARR: Infiltration to Recovery (Cikurel, 2004)

19. Aquifer Recharge and Recovery (ARR): Variations on a Theme
ARR = Aquifer Recharge and Recovery
(injection well or infiltration basin  recovery well)
- ASR = Aquifer Storage and Recovery
- ASTR = Aquifer Storage Transfer and Recovery
ARR (infiltration basin)
Options for Management of Travel Distance, Travel (Residence) Time, Redox 
Suitable (Geo)Hydrology and Storage ?
Dissolution of Natural Contaminants (e.g., As) ?

20. Water Quality Benefits of ARR: Removals of…
Turbidity
Dissolved Organic Carbon (DOC)
Bacteria, Protozoa, and Viruses
Organic Micropollutants (OMPs)
Pesticides
Pharmaceutically Active Compounds (PhACs)
Endocrine Disrupting Compounds (EDCs)
Personal Care Products (PCPs)
Nitrogen (ammonia and nitrate)
Multi-Objective (-Contaminant) Process:
 Potentially, A Total Treatment System
Biologically-Driven  Sustainable

21. DPR Industry Standards/Benchmarks (Tchobanoglous et al (2011)
Windhoek, Namibia
Advanced Processes: O3, GAC, UF (no RO!)
Direct blending of reclaimed water with potable water

22. DPR Industry Standards/Benchmarks (Tchobanoglous et al, 2011) - cont
OCWD Groundwater Replenishment System (GWRS)
An IPR Facility, But Conceptually Approaches That Envisioned for DPR
Advanced Process: MF, RO, AOP
Groundwater Injection for Minimum of Six Months (of Storage)

23. Summary of Opportunities for DPR and IPR (Tchobanoglous et al, 2011)

24. Regional Considerations: DPR vs. IPR
Because of Cultural and Religious Constraints, DPR is Unlikely for GCC/MENA Region
Fatwa  Potable Reuse Permitted If Water Is Returned to the Water Cycle, i.e., IPR

25. Conclusions-IPR
Indirect potable reuse (IPR) can be accomplished with public acceptance, but requires buffering from potable water during treatment and storage.
Public acceptability can be achieved using IPR if all aspects of the process can be demonstrated to provide health security and aquifer integrity.
Buffers are a key to gaining IPR acceptability

26. Thank you… 26