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Water Treatmentfor Greenhouses and Nurseries

Systems and Equipment

University of Florida Workshop 2007 by Ratus Fischer 828-230-6934 rfischer@fischerecoworks.com

 

Before or after Treatment. Optional if incoming line pressure is sufficient 

Water Source(s)  Pressurizing Treatment Distribution

Collection 

Application 

Discharge

Blending

Recirculation 

        The Water Systems Approach 

Optional Storage

Optional Storage

Optional Storage

Re-circulation Pros and Cons

Saving Water

Saving Fertilizer

Zero Runoff

Integral Part of Flood and Gutter systems

Initial Investment

Operating Costs

Need to ManageRisk of ContaminationRegulation - Proof

Silt Pond

Low LevelTreatment

PondP

IrrigationRun-off

Roof DrainSite Run-off

Suggested Pond Management

Clean and contaminated water are separated.Low Volume + highly effective treatment affordable.

ContaminatedStorage

High Level Treat-ment

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Pressure Pump Skid with VFD (Variable Frequency Drive)

R/OReverse Osmosis

Common and New Water Treatment Methods (Not including Liquid and Gaseous Oxidizers)

CopperIonization

Slow Sand Filtration

Heat Pasteurization

Nano Filtration

Ultra Filtration

Micro FiltrationOzone

UV

Mem

brane Filtration

Residual effect No Residual effect

Sand Filters

Screen and Disk Filters

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Media FilterReverse Osmosis

Nano FiltrationR/O NanoRemoves “everything” Removes solids, CaCO3.001 micron removal .01 micron removalIncl. all pathogens Removes bacteria, most

spores, some virus

Most plant nutrients pass

Operating Pressure Operating pressure 300 PSI typ. 60 PSI + PSIBest 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

Copper Ionization

An electric charge is passed betweencopper bars, releasing copper ions into the water.

Automatic control of copper output according to flow and EC is essential

Copper ions act throughout water system

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Copper Ionization 800 GPM

Copper Ionization Facts1 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.

Ozone

An electrical arc is used to produce Ozone (O3) on site from atmospheric or bottled Oxygen

The Ozone is bubbled through water and dissolved.

Typical concentration for disinfection: 10 mg per hour per m³, lower for Bio-film control.

Ozone FactsVery potent oxidizer. Kills pathogens and algae at low concentrations

Turns into O2, adding dissolved oxygen to water

System costs vary greatly depending on needs, water quality, professionalism of supplier.Organic matter in water depletes ozone. Good filtration and/or other pre-treatments are essential.

Proper design will prevent ozone from escaping and creating human health risk.

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Fertilizer Mixing and Stock Tanks

Disrupts genetic material in cells

Low, medium or high pressuremercury vapor lamps

Wide spectrum of biocidalactivity

Nothing added to water

Moderate capital and operating cost at low flow rates

Turbidity reduces efficiency;Removal of solids is critical Lamps must be kept clean

Fe-chelates may be destroyed

Ultraviolet Light

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Rote UV+Ozone 10gpm 3 log

Heat Pasteurization

195 °F for 2 minutes

Heat Treatment / Pasteurization

Reliable elimination of pathogensBest for low volume – high sanitation Can handle certain solids in waterNothing is added to the waterInitial investment moderate if heat source available

Energy consumption high - bestin combination with cheap heat source Needs low of pH (4.5) to prevent scalingof heat exchanger Can deplete dissolved oxygen in water

Slow Sand FiltrationMedium is colonized by microorganisms

Physical and biological activity control Phytophthora, Pythium, Fusarium andothers

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 Ionization1 – 2 ppm control biofilm and algae

Chlorine Dioxide (such as Selectrocode)

.25 ppm control algae and biofilm

Water Pre-TreatmentAll water treatment methods require specific water quality to be effective.

Lack of appropriate Pre-Treatment is the single most common cause for insufficient or failing treatment.

Most important: Solid and dissolved organic matter absorbs oxidizers, clogs filter membranes, shields UV rays, scales heat exchangers.

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.

Water Pre-Treatment: Nuts and Bolts 1For Ozone, Copper, Oxidizers (Cl, Peroxide, etc):Reduce solid and dissolved organic matter

For UV: Reduce solids and light absorbing dissolved matter

For Membrane Filters.Reduce solids, org. matter, silicates

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 filtersTyp. $ 3000 – 25,000

Dissolved organic matter (tannins, humic acids): Ultra/nano filtration, aeration in ponds, chemical

Blending Unit(Zwart)

Aeration•Finer bubbles transfer more O2 into water

•Saturation depends on temperature: warmer water holds less O2•Examples: 50ºF 11.3 mg/l

82ºF 7.8 mg/l

WATER TANK

BLOWER

DIFFUSER