Presented at the 2013 Utah Green Conference sponsored by the Utah Nursery and Landscape Association, 28 January 2013. The entire slide set was recorded with audio and you can view it at: http://youtu.be/GCd6P85dBmg

1. Greenhouse Water
Recycling and Reusing Water
Steven E. Newman, Ph.D., A.A.F.
Greenhouse Crops Extension Specialist and
Professor of Floriculture
Colorado State University Extension

2. Water Quality
Water is the one factor that will more than
likely ultimately control the population
growth of Colorado
Water is also one of the major factors of a
greenhouse that influence crop
productivity
Water quality is just as important as water
quantity

3. Water Quality
 Greenhouses get
their water from three
sources:
– Agricultural wells

4. Water Quality
 Greenhouses get
their water from three
sources:
– Agricultural wells
– Surface irrigation
canals or reservoirs

5. Water Quality
 Greenhouses get
their water from three
sources:
– Agricultural wells
– Surface irrigation
canals or reservoirs
– Municipal providers
• well or surface

6. How do we measure water quality?
 Alkalinity
 Salinity
 pH
 Sodium Absorption
Ratio
 Specific Ions
 Suspended Solids

7. Alkalinity
 The ability to neutralize acid
(meq·L-1) or ppm (upper limits)
– 2 meq·L-1 = 100 ppm alkalinity
as total carbonates
– 122 ppm bicarbonates (HCO3 )
1 meq·L-1 = 122 ppm
– Hardness (Ca + Mg) 150 ppm
as CaCO3
 Restrictions to use:
– <2 None
– 2-8.5 Slight to
moderate
– > 8.5 Severe

8. Salinity
 Total dissolved solids
 Measured by electrical
conductivity
– determined by passing a
current through the solution
and determining its
electrical conductance
– units are millimhos/cm, or
– decisiemens/meter (dS/m)

9. Irrigation Water Sanitation
Pythium Plant pathogens
have been found in
irrigation water
Fusarium Nematodes
Phytophthora Tobacco mosaic virus
Erwinia

10. Irrigation Water and Fungicides
Fungicides are often considered to be the grower’s
first line of defense.
• Intended to be applied to the substrate
• May be applied through the irrigation system
• Blending with irrigation is a violation of the label

11. Irrigation Water Disinfection
UV-C Sterilization
Heat Treatment
Chlorination
Ozone Treatment
Hydrogen Peroxide

12. Ultraviolet (UV) Radiation
UV-radiation is electro-
Visible light 200
magnetic energy between
and 400 nm
200 and 400 nm

13. UV Radiation
UV Radiation
UV-A UV-B
315-400 nm 290-315 nm
Smog, fades Effects plants
fabrics and animals
UV-C
220-290
Movie courtesy of the NASA/Goddard Space Flight Absorbed by
Center Scientific Visualization Studio ozone layer

14. UV-C Sterilization
UV-C dose assuming
Plant Diseases 25% clarity
Priva@ Vialux system
Bacteria, nematodes
Pythium, Phytophthora 80
and Fusarium
Pepino mosaic virus 150
Other viruses 250
0 50 100 150 200 250
2
UV-C dose (mJ/cm )
H 310 Greenhouse Management

15. UV-C for Greenhouse Irrigation
H 310 Greenhouse
Management

16. Vialux Disinfection System
H 310 Greenhouse
Management

17. Vialux Disinfection System
Multimedia Acid injection
filter
H 310 Greenhouse
Management

18. Vialux Disinfection System
UV-C Lamp
chamber
H 310 Greenhouse
Management

19. Issues With UV-C Disinfection
Issues:
• Turbidity
• Scale
• No residual
disinfection
H 310 Greenhouse
Management

20. Heat Pasteurization of Water
Heat Pasteurization
203 F for 30 seconds
H 310 Greenhouse
Management

21. Heat Pasteurization of Water
Hot water pasteurization for greenhouse irrigation water
H 310 Greenhouse
Management

22. Cost of Heat Pasteurization
Natural Gas Consumption
270-530 ft3 fuel / 100 gallons water
or 3-5 therms / 100 gallons water
H 310 Greenhouse
Management

23. Oxidation Reduction
Oxidation is defined as an
increase in the positive
oxidation number with a
corresponding loss of electrons
Reduction is a decrease in
the positive number of
ions with a corresponding
gain in electrons
H 310 Greenhouse
Management

24. Industrial Oxidizing Compounds
Common industrial oxidizers and their potential relative to chlorine
Oxidation potential Oxidation relative
Oxidant (mV) to chlorine
Fluorine 3,050 2.25
Ozone 2,070 1.52
Hydrogen peroxide 1,780 1.31
Potassium permanganate 1,680 1.25
Chlorine dioxide 1,570 1.15
Chlorine 1,360 1.00
Bromine 1,070 0.70
H 310 Greenhouse
Management

25. Hypochlorous Acid and pH
Water solutions of sodium hypochlorite and its impact on
oxidation reduction potential and pH
Oxidation potential
NaOCl (%) (mV) pH
Water 210 6.8
0.3 715 8.9
0.5 690 9.6
1.0 655 10.1
1.5 630 10.6
2.0 599 11.2
3.0 570 11.7
H 310 Greenhouse
Management

26. Oxidation Reduction and pH
OCl-
pH
HOCl
H 310 Greenhouse
Management

27. Oxidation Reduction and pH
Acid injection
Regal geranium
stock plants
------------------
Hypochlorous
acid injected into
irrigation water
H 310 Greenhouse
Management

28. Oxidation Reduction and Cl
Colorado
Greenhouse
Example
---------------------
With acid injection
ORP=825 mV
Free Cl=1.4
Total Cl=2.25
H 310 Greenhouse
Management

29. ORP and Pathogen Survival
Pathogen survival from laboratory simulations and
hydrocooler studies according to Suslow (2003)
Survival at ORP (mV)
Pathogen < 485 550<X<620 >665
E. coli O157:H7 > 300 s < 60 s < 10 s
Salmonella spp. > 300 s > 300 s < 20 s
L. monocytogenes > 300 s > 300 s < 20 s
Thermotolerant coliform > 48 hr > 48 hr < 30 s
H 310 Greenhouse
Management

30. ORP Measurement and
Chlorine
Panel Mount with Installed Handheld
ORP Electrode ORP Meter
$135-$150
Free
Chlorine
H 310 Greenhouse
Management

31. Chlorine Sources
Sources Chlorine reaction in water
Chlorine gas Cl2 + H2O 4 HCl + HOCl
Sodium hypochlorite NaOCl + H2O 4 NaOH + HOCl
Calcium hypochlorite Ca(OCl)2 + 2 H2O 4 Ca(OH)2 + 2 HOCl
Chlorine dioxide HOCl+HCl+2NaClO2 4 2ClO2+2NaCl+H2O
H 310 Greenhouse
Management

32. Chlorine Gas
Chlorine Gas
--------------------------
Cheapest source
Inject at 25-200 ppm
Most active pH 6-7.5
Dangerous to handle
H 310 Greenhouse
Management

33. Sodium Hypochlorite
Chemical
Injectors
H 310 Greenhouse
Management

34. Hypochlorous Acid (OxcideTM)
Metering
Pumps
H 310 Greenhouse
Management

35. Calcium Hypochlorite
High volume system
Tablet
reservoir
HOCl
concentrate
H 310 Greenhouse
Management

36. Calcium Hypochlorite
Medium volume
system Water
Storage
Tablet
feeder
H 310 Greenhouse
Management

37. Chlorine Dioxide
Gas pure
membrane
Sodium
chlorite
from storage
25x more active
+ than chlorate
No
Cell Water
trihalomethanes
Water
Pump Weak caustic
Control - soda
system
H 310 Greenhouse
Management

38. Ozonation of Irrigation Water
Ozone occurs naturally
-------------------------------
Lightening
Automobile exhaust
Arc welders
Copy machines Single bond of
ozone is unstable
and will oxidize
organic materials
H 310 Greenhouse
Management

39. Ozone Generator
Electrode chambers
Air inlet
O3 outlet
Air pump
H 310 Greenhouse
Management

40. Ozone Generator
H 310 Greenhouse
Management

41. Hydrogen Peroxide
Common industrial oxidizers and their potential relative to chlorine
Oxidation potential Oxidation relative
Oxidant (mV) to chlorine
Fluorine 3,050 2.25
Ozone 2,070 1.52
Hydrogen peroxide 1,780 1.31
Potassium permanganate 1,680 1.25
Chlorine dioxide 1,570 1.15
Chlorine 1,360 1.00
Bromine 1,070 0.70
H 310 Greenhouse
Management

42. Hydrogen Peroxide
3% as a disinfectant
10% for hair treatment
35% for greenhouse
and industrial
H 310 Greenhouse
Management

43. Hydrogen Peroxide
 ZeroTol (hydrogen dioxide)
– Contaminated water
• 1:500 dilution
• 540 ppm H2O2
– Clean water
• 1:10,000 dilution
• 27 ppm H2O2
H 310 Greenhouse
Management

44. Water in the West
With water, the law of the
West is simple:
The first one to use it
gets it.
This doctrine, known as "prior
appropriation," originated
during the California Gold
Rush days, with miners who
needed water for their placer
operations on public lands.
To this day, prior appropriation
governs water in nine Western Frederick Remington’s 1903 painting “Fight for the Water Hole”
states.

45. Western Water Rights
"Farms and friendships
have been lost over water
rights, and the tension it
creates is more real than
in any Hollywood
Western."
Elizabeth Arnold
National Public Radio
28 Aug 2003
Discussing Water Rights, A Western Pastime
Duckboy Cards – Paul Stanton

46. Developing Water in the West
In 1878, explorer and scientist John
Wesley Powell published a report, which
laid out a concrete strategy for settling the
West without fighting over scarce water.
He wanted to stall the waves of
homesteaders moving across the plains
and mountains. He proposed planned
settlements based in part on the
cooperative model practiced in Utah by
Mormon settlers.
“If Congress had listened to Powell 125
years ago, the American West today might
be an entirely different place.”
Howard Berkes
National Public Radio
26 Aug 2003