Water Treatment
for Greenhouses and Nurseries
The Water Systems Approach Optional Storage
Water Source(s) Systems and Equipment
Pressurizing
Treatment
Blending
by Ratus Fischer 828-230-6934
rfischer@fischerecoworks.com
Distribution
Application Optional Storage
Optional Storage
University of Florida Workshop 2007
Re-circulation Pros and Cons
Before or after Treatment. Optional if incoming line pressure is sufficient Recirculation Collection Discharge
Suggested Pond Management
Saving Water
Initial Investment
Saving Fertilizer
Operating Costs
Zero Runoff
Need to Manage
Regulation - Proof Risk of Contamination
Integral Part of Flood and Gutter systems
Low Level
Treatment
High
Level
Treatment
Irrigation
Run-off
Contaminated
Storage
P
Roof Drain
Site Run-off
Silt Pond
Pond
Clean and contaminated water are separated.
Low Volume + highly effective treatment affordable.
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Common and New Water Treatment
Methods (Not including Liquid and Gaseous Oxidizers)
Residual effect
No Residual effect
Ozone
Sand Filters
Copper
Ionization
Slow Sand
Filtration
UV
Micro Filtration
Membrane Filtration
Pressure
Pump Skid
with VFD
(Variable
Frequency
Drive)
Heat
Pasteurization
Ultra Filtration
Nano Filtration
R/O
Reverse Osmosis
Screen
and
Disk
Filters
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Reverse
Osmosis
Media Filter
Nano Filtration
R/O
Nano
Removes “everything” Removes solids, CaCO3
.001 micron removal .01 micron removal
Incl. all pathogens
Removes bacteria, most
spores, some virus
Most plant nutrients pass
Operating Pressure
Operating pressure
300 PSI typ.
60 PSI + PSI
Best for EC reduction Best for Pre-treatment UV,
Ozone, Oxidizers, etc.
Rejection rate 25–50%
Nano Filtration 10 GPM
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Water Softeners/
Iron Removal
Replacing Calcium,
Magnesium
and Iron with
Sodium
Chlorine Dioxide
Copper Ionization
An electric charge is passed between
copper bars, releasing copper ions
into the water.
Automatic control of copper output
according to flow and EC is essential
Copper Ionization
Copper ions act throughout water system
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Copper Ionization Facts
1 ppm kills pathogens, 2 ppm stops algae.
10ppm ‘overdose’ shows no plant toxicity.
Effect on Pythium, Phytophthora and other
pathogens documented.
Lower cost than most treatments for
pathogens
Less affected by organic matter in the
water than other methods.
Copper Ionization 800 GPM
Ozone
Ozone Facts
Very potent oxidizer. Kills pathogens
and algae at low concentrations
Turns into O2, adding dissolved oxygen to water
An electrical arc is used to produce Ozone (O3) on
site from atmospheric or bottled Oxygen
System costs vary greatly depending on needs,
water quality, professionalism of supplier.
The Ozone is bubbled through water and dissolved.
Organic matter in water depletes ozone.
Good filtration and/or other pre-treatments
are essential.
Typical concentration for disinfection: 10 mg per hour
per m³, lower for Bio-film control.
Proper design will prevent ozone from
escaping and creating human health risk.
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Fertilizer Mixing
and Stock Tanks
Ultraviolet Light
Disrupts genetic material in cells
Low, medium or high pressure
mercury vapor lamps
Wide spectrum of biocidal Turbidity reduces efficiency;
Removal of solids is critical
activity
Lamps must be kept clean
Nothing added to water
Fe-chelates may be destroyed
Moderate capital and
operating cost at low flow
rates
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Heat
Pasteurization
195 °F for 2 minutes
Rote UV+Ozone 10gpm 3 log
Heat Treatment / Pasteurization
Reliable elimination of pathogens
Best for low volume – high sanitation
Can handle certain solids in water
Nothing is added to the water
Initial investment moderate if heat source available
Energy consumption high - best
in combination with cheap heat source
Needs low of pH (4.5) to prevent scaling
of heat exchanger
Can deplete dissolved oxygen in water
Slow Sand
Filtration
Medium is colonized by microorganisms
Physical and biological activity control
Phytophthora, Pythium, Fusarium and
others
Suitable for low flow applications
Typical 2 – 4 gph per sqft of filter area
Low energy use, no chemicals added
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Slow Sand Filtration Facts
•Aerobic process, needs oxygen in water.
•Water must circulate to keep filter “alive”
•Easy to build with common materials
•Medium: Carbonate-free sand .2mm
•Maintenance: scraping sand surface.
•Pre-filtration of dirty water reduces
clogging
•Often improved plant quality
(Suppression)
Selected
Biofilm and Algae Treatments
Ozone
.1 ppm ozone eliminates biofilm over time
.5ppm suggested for biofilm and algae control
Copper Ionization
1 – 2 ppm control biofilm and algae
Chlorine Dioxide
(such as Selectrocode)
.25 ppm control algae and biofilm
Water Pre-Treatment
Water Pre-Treatment: Nuts and Bolts 1
All water treatment methods require specific water quality to
be effective.
For Ozone, Copper, Oxidizers (Cl, Peroxide, etc):
Reduce solid and dissolved organic matter
Lack of appropriate Pre-Treatment is the single most common
cause for insufficient or failing treatment.
For UV:
Reduce solids and light absorbing dissolved matter
Most important:
Solid and dissolved organic matter absorbs oxidizers, clogs
filter membranes, shields UV rays, scales heat exchangers.
For Membrane Filters.
Reduce solids, org. matter, silicates
Pre-treatment can cost as much as the treatment itself, but
overall it will reduce investment and operating costs.
If anyone sells you water treatment systems without analyzing
your water, you are probably wasting money.
For Heat treatment:
Lower pH to 4.5
For Slow Sand filtration:
Remove inorganic and organic solids
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Water Pre-Treatment: Nuts and Bolts 2
Removing….
Debris, coarse plant matter, sand:
Screen filters, cascade filters, settling
tanks/ponds
Typ. $ 100 – 10.000
Inorganic and organic solids (algae, soil, debris):
Media filters (Clearstream©), fast sand filters
Typ. $ 3000 – 25,000
Dissolved organic matter (tannins, humic acids):
Ultra/nano filtration, aeration in ponds,
chemical
Aeration
BLOWER
Blending Unit
(Zwart)
•Finer bubbles transfer
more O2 into water
•Saturation depends on
temperature: warmer
water holds less O2
•Examples: 50ºFÆ11.3 mg/l
82ºFÆ 7.8 mg/l
DIFFUSER
WATER TANK
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