Commercial Water Reclamation Presented by Brian Soderholm Water

Commercial Water Reclamation Presented by: Brian Soderholm Water Control Corporation

Water Reclamation is Not a New Concept! 1500 year-old, 21 million gallon Basilica Cistern in Istanbul, Turkey.

You May Have Major Questions! • How big of a rainwater cistern to use? • What to do with rainwater? • What are other sources of reclaimable water? • Where can I use graywater? • What are the benefits and payback? • What about sanitation? Is it safe? • How to collect the water? • How to store the water? • How to best disinfect the water? • How to best deliver the water to fixtures? • What system options are available in the market? • What about code compliance?

Sizing a Cistern: Educated Guessing • 1 ft² roof surface can generate approximately 0. 62 gallons of usable water per inch of rainfall. • Example: a 15, 000 ft² roof in MN could generate approximately 15, 000 X 4. 34 X 0. 62 = 40, 362 gallons in an average July. • A 40, 000 gallon cistern may not be practical in a wetter climate. • Only full after spring snow melt or major storm! • Fixtures/equipment may not require so much water • (in a dry climate, size near 100% and look for other sources) • Wetter Climate Rule of Thumb: divide total gallons by avg. peak monthly rainfall events – ex. For MN: 2 or 3 (i. e. 20, 000 or 13, ooo gallon cistern) and compare to gal. required. • Choose the smaller of the two when sizing cistern.

Other Potential Sources: • Cooling System Condensate: • 0. 1 gal/ton hour at 70% relative humidity • 0. 2 gal/ton hour at 80% relative humidity • 0. 3 gal/ton hour at 90% relative humidity • Challenge: low p. H, bacteria • Cooling Tower Blowdown • Challenge: high TDS, chemicals • Groundwater • Challenge: soil-based minerals • Softener/Filter Backwash • Challenge: suspended solids and high TDS (depending on type of filter)

Many Potential Uses: • Rainwater can be collected and re-used for: • Landscape irrigation • Cooling tower/Boiler make-up water • Tanker filling/ Backup fire systems • Nursery irrigation systems • Flushing toilets and urinals • Vehicle washes • Industrial process • Potable water applications not recommended – and probably not legal!

Graywater Reclamation: • Graywater = Water from showers, bathroom lavs, clothes washers, (possibly pool backwash). • Reclaimed for sub-surface irrigation and (possibly) fixture flushing • Toilet/urinal flushing requires disinfection and is only legal/possible without special approval in IPC (and IPC-based) states!

Graywater System Design Considerations: • Enough storage for 1 or 2 days’ demand (code dependent). • Tank water should turn at least every 3 - 7 days (code dependent). • Overflow to sanitary sewer • No blackwater! (toilet, kitchen sink, laundry with diaper service, etc. ) • Occupant # / Graywater discharge estimation tables in UPC and IBC

Water Reclamation: Many Potential Advantages: • Up to 12+ LEED™ points may be available: • “Stormwater Design: Quantity/Quality Control (2)” • “Water Efficient Landscaping (4)” • “Innovative Wastewater Technologies (2)” • “Water Use Reduction (4+)” • A virtual MUST for LEED™ Gold and Platinum certification! • Potential for drastically reduced sewer/water impact fees • Reduced water and sewer fees • Calculating “payback” requires number crunching! • Good systems: $2000 - $200, 000

Sanitation Potential Pitfalls: • Public health risks: • Bacteria, algae, pathogens, mold, insects, rodents, (and almost anything else imaginable) seem to find their way into cistern/storage tanks (ask your grandparents!). • Graywater is of particular concern. • Cooling towers and irrigation systems can diffuse these harmful agents into the air (think Leigionella bacteria!). • Toilets, urinals, and other fixtures supplied with reclaimed water can cause internal contact with these agents. = Potential for major liability!

Designing a System: The 4 Concerns: • Collection • Storage • Treatment • Delivery

Thoughts on Collection: • Consider roof drains with mesh screens if debris on roof will be minimal • Pre-filtration is always highly recommended! • Water from drain tiles may contain iron or other minerals (extra filtration required) • Water from parking lots not recommended: • May contain salt, oil, antifreeze, trash, goose feces, etc.

Thoughts on Storage: • Polyethylene, fiberglass, corrugated (lined), galvanized steel or concrete tanks (verify compatibility with disinfection method) • Buried or located indoors in northern climates • Overflow, vent, manhole access, and inlet/outlet tappings required • If above-ground, consider black or green color to prevent algae growth

Disinfection: Which Method to Use? : • Chlorination (oxidation): • Advantages: • Measurable • Residual disinfection • Calcium hypochlorite tablets • Sodium hypochlorite solution • Chlorine gas • Chlorine dioxide solution • Disadvantages: • Not terribly “green” (LEED®) • Chemical handling and storage • Not good for landscaping • Expensive/ongoing chemical purchase • Trihalomethanes (THM’s) and other harmful byproducts! • Only Cl. O 2 effective with algae

Disinfection: Which Method to Use? : • Ultraviolet (DNA destruction to prevent replication): • Advantages: • No chemicals • Relatively low cost and maintenance up to 80 GPM systems • Disadvantages: • No residual disinfection (circulation highly recommended!!!) • Ineffective if water is discolored or turbid (UV sensor highly recommended!!!) • Not as effective with viruses or cysts

Disinfection: Which Method to Use? : • Ozonation (oxidation using O 3): • Advantages: • No chemicals – generated on demand • 2000 times faster than chlorine • Back to O 2 in approx. 17 minutes • Residual disinfection • Powerful deodorizer • Works in dirty/discolored water • Measurable • May help with Green Roof discoloration • Disadvantages: • More $$ and maintenance if under 80 GPM • Cistern cannot be vented indoors w/o destructor

Thoughts on Delivery: • p. H may be an issue! (consider appropriate piping materials!). Ozone/ chlorine also corrosive. • Particulate filtration needed prior to delivery (cartridge, bag, basket, or membrane filter) • Most states have strict marking requirements (“Non-Potable Water”) • Incorporate a fresh-water bypass or make-up if tank goes dry, disinfection goes down, etc. • Ensure appropriate backflow prevention! (RPZ assembly or “break tank” with air gap).

So How Are People Doing It? • Individual component systems designed in-house (contractor builds) • Residential or light commercial “rainwater harvesting kits” • Large commercial turnkey systems

What About The Codes? ? ? • Code Issues: • A lack of clarity and consistency in state codes can lead to confusion, delays, and disapprovals. • Public health concerns • Confusion at state, engineer, customer and inspector level • Current code status: • IPC: Rules for graywater only – no rainwater • UPC: Rules for graywater and municipally treated wastewater. Rainwater code currently under development • Draft codes being developed by ARCSA, IAPMO • California Title 22 statutes and USEPA 2004 Guidelines for Water Reuse • Plan Review is the norm! The more robust a system, the less likely you are to experience hang-ups at state or inspector level!!!

Questions?