Rainwater Harvesting and Water Reuse. Water Conservation: half-empty or half-full? Regional Webinar Series March 1, 2011

Transcription

1 Rainwater Harvesting and Water Reuse Water Conservation: half-empty or half-full? Regional Webinar Series March 1, 2011

2 Reclaimed Water Use Webinar: Water Conservation Using Reclaimed Water in the Urban Landscape Opportunities and Challenges George Hochmuth Soil and Water Science Department University of Florida

3 Huge water demand Thermoelectric (50%) Irrigation (30%) Public (10%)

4 Huge urban potable water demand for indoor and irrigation We generate waste water: can we re-use it?

5 Conservation opportunities with reclaimed water What is reclaimed water? Who is boss? Advantages and challenges How can you use this information References

6 Definitions Potable water-fresh water, typically groundwater for drinking Reclaimed water (reuse, recycled)-water that began as wastewater (sewer) and has been processed and treated to meet standards for reuse, not for direct application to food crops or drinking

7 Leaders in Reclaimed Water gal/person/day Florida 36.8 California 16.1 Virginia 1.5 Texas 1.3 Arizona 1.3 Colorado 1.0 Nevada 1.0 USA Australia UK

8 Why Reclaimed Water? Federal Clean Water Act Total Max. Daily Loads for utilities Numeric Nutrient Criteria could impact reuse Water conservation Fertilizer conservation

9 Bio-Denipho waste water treatment University of Florida Reclaimed Water Storage TN = 5 ppm TP = <1 ppm Chlorination Sludge Stabilization Clarifiers Tertiary Sand Filter, No chemical treatment Secondary Primary

10 Urban Uses Public Access Reuse Turf Grasses Residential Lawns Golf Courses Parks/Schools Highway Medians Secondary Treatment, Filtration, High Level Disinfection (pathogen monitoring) Reclaimed water has nutrients that must be accounted for during fertilization application. A low-concentration nutrient solution

11 Conserve potable water supply Residential Irrigation

12 Urban irrigation water conservation Acres of residential turf in Florida Typical irrigation use in Florida Savings in potable water About 3 million 30 ac-in (18K g/1000 sf) 360 gal/day/person

13 Sources of Constituents 1. Naturally occurring compounds in water: Inorganic: Ca, Mg, K, (e.g., the original potable water) 2. Added from residential, commercial, human activities Inorganic: (cleaning chemicals-b, P, Na, Cl) Organic: organic compounds are composed of C, H, O with N, P & S (human wastes, food wastes)

14 Plant Nutrients in Reclaimed Water Reclaimed water (ppm): 6N, 1P Hydroponic solution (ppm): 200N, 30P RW should be thought of as a dilute nutrient solution

15 Possibility of a Fertilizer Offset With RW Keep in mind you are working with a nutrient solution RW is a mixed fertilizer material You want the nutrients-you get the water; you want the water-you get the nutrients So, plant water needs come into play This is the challenge of using RW

16 Possibility of a Fertilizer Offset With RW Let s look at nitrogen Fawn tools Irrigation scheduler

17 Month Irrigation management is important for preventing leaching and runoff Amounts of N from RW containing 5 ppm N based on turf water needs during the year Mins run-time 2X per wk for 0.5 inches per hr (FAWN) Gallons/month/1000 sq ft; N supplied 1 acre-inch = 622 gal per 1000 sq ft January February March April May June July August September October November December Annual totals 24,461 / 1000 sq ft = 39 acre-inches (lbs per 1000 sq ft per 5 ppm N in the RW lb/1000 sq ft.

18 Amounts of nitrogen in reclaimed water at the utility - can do similar calcs for P N conc. In reclaimed water (ppm) 20 inches irrig. water 30 inches irrig. water 100 inches irrig. water Resulting lbs N per 1000 sq ft

19 Lbs N / 1000 sq ft Is there a N fertilizer offset? 1.2 Comparison of N from RW with fertilizer recommendations for St. Augustinegrass in central Florida, moderate maintenance level Fertilizer 5 ppm N J F M A M J J A S O N D Month application made

20 Other Issues with RW in the Landscape

21 Reclaimed water-advantages and disadvantages Conservation of potable water Resource vs. disposal Nutrients Safe for human contact Costly infrastructure Nutrient solution Nutrients Management important Phosphorus buildup Soluble salts

22 Using this information Helping clientele understand relative potable water use in homes and landscapes Reclaimed water as an alternative water source Understanding reclaimed water Helping homeowners use reclaimed water for its water and nutrient values

23 Some references O'Connor, G.A., H.A. Elliott, and R.K. Bastian Degraded water reuse: An overview. Journal of Environmental Quality 37:S

24 Some Calculations, Conversions 1 ppm = 1 mg per liter 1 liter = 0.26 gal 1 acre-inch = 27,100 gals or 102,400 liters 1 inch over 1000 sq ft is 620 gals 1 acre-inch RW with 5 ppm N, has 5 X = 512,200 mg N 512,200 mg N / 454,000 mg/lb = 1.13 lb N per acre 1 acre-inch has 1.13 / = lb N per 1000 sq ft.

25 Thank You! George Hochmuth Soil and Water Science Department University of Florida (352) X 318 hoch@ufl.edu