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

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.

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?

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

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

Acceptance of Water Reuse

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

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

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

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

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

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

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!

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

? 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

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

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

ARR: Infiltration to Recovery (Cikurel, 2004)

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) ?

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

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

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)

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

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

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

Thank you… 26