Slide 1
A Short Introduction to Water
Recycling for Plant Nurseries
Salvatore Mangiafico
Rutgers Cooperative Extension
Environmental and Resource Management Agent
http://njaes.rutgers.edu/nursery/presentations.html
[email protected]
A short introduction to water recycling for plant nurseries.
.
http://njaes.rutgers.edu/nursery/presentations.html
.
http://salem.rutgers.edu/nre/contact.html
Slide 2
“Recycled” and “reused” water…
There are different terms used for different types of reused water, and,
unfortunately, the terms are not always used consistently. It is helpful
to understand the different terms when considering water source
options.
• Recycled water – An ambiguous term, but usually used in agriculture to
mean water that is collected, treated, and recycled on-site. The degree of
treatment and methods for treatment vary by site. Salts and plant pathogens
can be concerns in recycled water.
• Reclaimed water – Wastewater (sewage) that has been treated to a high
degree at a wastewater treatment facility, and usually meets certain water
quality standards. It may have high levels of salts or nutrients, and may have
the potential to contain human pathogens.
• Gray water – Water that has been used for some
domestic purpose other than flushing toilets, like for
laundry or washing. If untreated, it may contain bacteria
and other harmful organisms. In general, it should not be
used for irrigation without consulting local regulations.
There are different terms used for different types of reused water, and, unfortunately, the terms
are not always used consistently. It is helpful to understand the different terms when
considering water source options.
.
“Recycled water” is an ambiguous term, but it usually used in agriculture to mean water that is
collected, treated, and recycled on-site. The degree of treatment and methods for treatment
vary by site. Salts and plant pathogens can be concerns in recycled water.
.
“Reclaimed water” refers to wastewater (sewage) that has been treated to a high degree at a
wastewater treatment facility, and usually meets certain water quality standards. It may have
high levels of salts or nutrients, and may have the potential to contain human pathogens.
.
“Gray water” refers to water that has been used for some domestic purpose other than flushing
toilets, like for laundry or washing. If untreated, it may contain bacteria and other harmful
organisms. In general, it should not be used for irrigation without consulting local regulations.
.
Source: 2012. Use of Reclaimed Water in Floriculture Crops. K.A. Williams, D.J. Merhaut, and
S.S. Mangiafico. In Water and Nutrient Management for Floriculture Crops. University of
California ANR Press.
Slide 3
“Recycled” and “reused” water…
• Tailwater – Runoff created by excess irrigation or purposeful leaching from
containers. It has the potential to be collected and reused, though treatment
may be necessary. It is synonymous in this use with irrigation runoff.
• Stormwater – Runoff created by precipitation. Some treatment may be
necessary. It is synonymous in this use with stormwater runoff.
• Rainwater harvesting – The collection of rainwater from the roofs of
buildings or greenhouses.
“Tailwater” is runoff created by excess irrigation or purposeful leaching from containers. It has
the potential to be collected and reused, though treatment may be necessary. It is synonymous
in this use with irrigation runoff.
.
“Stormwater” is runoff created by precipitation. Some treatment may be necessary. It is
synonymous in this use with stormwater runoff.
.
“Rainwater harvesting” refers to the collection of rainwater from the roofs of buildings or
greenhouses. It’s recycled in the sense that if this water isn’t collected it might not be used
beneficially but instead contribute to stormwater .
Slide 4
Reclaimed water…
• Can be
used for agricultural crops
• Particularly in areas
where agricultural production is close to
residential development and wastewater treatment plants
• Used for golf courses, landscaping, roadsides, agriculture in
CA, WA, FL, etc.
• Advantages: drought-resistant, sometimes cheaper, water
conservation, water pollution prevention.
• Disadvantages: separate lines, potential
problematic contaminants (salt, B), human
pathogens, regulations.
Reclaimed water, which is sewage that has been treated at a wastewater treatment facility, can
be used for ornamental crops, particularly in areas where agricultural production is close to
residential development and wastewater treatment plants. Reclaimed water is relatively
commonly used for golf courses, landscaping, roadsides, and agriculture in CA, WA, FL, etc. The
advantages of using reclaimed water is that is it often a drought-resistant water source (because
wastewater continues to be generated in drought conditions); it is sometimes cheaper than
other sources of water, particularly than potable municipal water; and it furthers the goals of
water conservation and water pollution prevention on a watershed level. Disadvantages include
the need to maintain separate lines, one with potable water and one with purple pipe for the
reclaimed water; the potential for reclaimed water to have contaminants like salts or boron or
human pathogens; and the complication of dealing with additional regulations.
Slide 5
Runoff Recycling… the rest of this presentation…
Why?
- #1 - environmental compliance and
perceptions…
(nurseries in particular as targets of
perceived “intensive agriculture” -water, nutrient, and pesticide use.
- Comparison of environmental water
quality standards with typical
fertigation (NO3- at 10 ppm for
drinking, lower for env.; TP at 0.1 or
0.05 ppm)
Salvatore Mangiafico
More could be said about the potential for using reclaimed in nursery production; however, the
rest of this presentation will focus on recycling runoff, which could include runoff from irrigation
and pot leaching or from stormwater.
.
Perhaps the largest motivator for adopting runoff recycling by the nursery industry is the need
to comply with environmental regulations or to combat negative perceptions some people may
hold for example the contention that plant nurseries may have higher uses of water, fertilizer,
and pesticides than other agricultural production. Considering this situation, it may be helpful
to consider that water quality standards for groundwater, lakes, and streams for nitrogen and
phosphorus are relatively low: 10 parts per million or lower nitrate-nitrogen for drinking water,
and often lower than that for streams or estuaries; and total phosphorus of 0.1 parts per million
or lower for lakes.
Slide 6
Runoff Recycling
Why?
– water costs (municipal) or need to
treat well water (e.g. B)
– water conservation / good neighbor
/ stormwater management
– no need to get additional water
allocation permits
Salvatore Mangiafico
Other reasons plant nurseries may adopt water recycling include reducing reliance on relatively
expensive municipal water or on low quality well water. Also, like using reclaimed water,
recycling runoff furthers the image of the nursery as a good neighbor that contributes to the
goals of water conservation and stormwater management. Finally, recycling water may give the
grower use of more water for irrigation without the need for seeking additional water allocation
permits.
Slide 7
Runoff Recycling
Becoming popular in nursery /
greenhouse…
- West Coast-- CA, OR….
- MD, VA, South-east
- More common in NJ
Salvatore Mangiafico
Recycling of runoff is becoming increasing common for nursery and greenhouse operations,
particularly on the west coast and southeast, and is increasingly common in New Jersey as well.
Slide 8
Runoff Recycling
Different types of operations…
- greenhouse sub-irrigation
- hydroponic reuse
- container areas
- entire operation
Salvatore Mangiafico
Recycled water can be used in different types of ornamental production operations and in
different parts of each operation. Greenhouse operations may reuse water from greenhouse
floor sub-irrigation or from hydroponic areas. Nurseries may collect and reuse from the entire
growing operation or just from, for example, container areas. Runoff could also be collected
from one area of the operation and reused in a different area, for example on plants would be
less susceptible to plant pathogens.
Slide 9
Runoff Recycling
Problems / concerns
- #1 – ability to easily clean sediment
from channels
- #2 – potential for recirculation of
pathogens
- #3 – potential for recirculation of
herbicide / herbicide persistence
- #4 – physical location of basin /
topography limitations
Salvatore Mangiafico
Probably the primary concern growers have with water collection and recycling systems ---after the costs ---- is the ability to easily clean sediment from the water-collection channels.
This can be solved by placing concrete sediment traps. These can be designed so that they can
be easily cleaned with a small skid loader or similar equipment. A large sediment trap can be
placed directly before the main water impoundment or basin.
.
As runoff water is collected and reused, there is a potential for plant pathogens (such as
Phytophthora and Pythium) to be distributed widely to crops through irrigation water. Because
of this, most growers employ treatment measures to sanitize recycled water. Common methods
include chlorine, ozone, and ultraviolet light to destroy pathogens, in addition to filtering.
.
A separate issue is the potential to distribute herbicides in collected water to crop plants. There
have been limited reports of herbicide damage from recycled water use, but the potential for
this problem has not been documented extensively.
.
Finally, a fourth concern growers commonly face relates to issues of the physical placement of
collection basins, for example if topography of the site does not lend itself to easily collect
runoff and channel it to a central collection basin.
Slide 10
A schematic diagram of parts of the runoff recycling process. Starting in the upper right, runoff
from irrigation or stormwater is collected from production areas through ditches and pipes,
often primarily utilizing gravity. Before a large storage basin, sediment and debris are removed
by a sediment trap. A pond, basin, or impoundment is used to store water. Sometimes water is
further treated before storage, but commonly water is treated after being pumped out of the
main storage basin. Treatment typically consists of filtration to further remove sediment and
organic matter and then a disinfection treatment to destroy pathogens. Disinfection treatments
might include chlorine, ultraviolet light, or ozone. Once water is sanitized, it can prepared for
use as irrigation water by adjusting nutrient levels, pH, and by blending with fresh water to
lower salt levels.
.
Source: 2011. J. Johnson, S. Mangiafico, and C. Obropta. Protecting Natural Resources at Field
Nurseries: Sustainable Agricultural Management Practices for Soil, Water, Nutrient, and
Pesticide Conservation. Manual, 32 pages.
http://njaes.rutgers.edu/nursery/documents/Protecting Natural Resources at Field
Nurseries.pdf
Slide 11
Collection
• Size
- to contain irrigation runoff
- to contain initial stormwater
- consider greenhouse roofs, other
roofs, parking areas, roads runoff
- consider seasonal variability or both
rainfall and irrigation volumes
• Location
- topography – pre-planned site layout
vs. working with what you got.
- separation of sources – container areas
vs. field vs. roofs and parking areas
Salvatore Mangiafico
The size and location of the collection basin will depend upon site-specific conditions. The basin
is usually sized to collect and contain any irrigation runoff from production areas. Additionally,
the basin may include storage capacity to hold some initial flush of stormwater. Runoff from
areas such as greenhouse roofs and parking areas may be collected or intentionally excluded.
Typical rainfall amounts and season variability in the demand for irrigation water volume would
need to be taken into account in determining basin size.
.
If a new nursery site is planned, there is the potential to lay out the site to facilitate the
collection of runoff. In other cases, existing space and layout will determine the placement of
collection basins and the methods of runoff collection.
Slide 12
Collection
C
B
A
Salvatore Mangiafico
A fairly large, plastic-lined basin at a nursery in southern California. “A” indicates a gravel-lined
channel through which water flows to the basin. “B” indicates a settling basin to collect
sediment before water enters the main storage basin (“C”).
Slide 13
Collection
Salvatore Mangiafico
An unlined basin in southern California.
Slide 14
Collection
Salvatore Mangiafico
An impoundment at a nursery in southern New Jersey.
Slide 15
Collection
Salvatore Mangiafico
Another impoundment in southern New Jersey.
Slide 16
Collection
Salvatore Mangiafico
Another impoundment in southern New Jersey, with the effects of an aerator visible in the
water. The main pump to extract water from the impoundment is visible at the left.
Slide 17
Basin considerations
• engineering
- size, shape, capacity of basin
- hydrology, inlet-outlet design
- settling basins
- water conveyances – pipes, gravel, rip
rap, shells, grassed
- maintenance access
Salvatore Mangiafico
The design of collection basins usually requires the services of a qualified engineer.
Considerations include the size, shape, and capacity of the basin, as well as well-designed inlets
and outlets of the basin. Water conveyances may include pipes or open channels that could be
protected with gravel, rip rap, sea shells, or vegetation. Access for maintenance ---- particularly
the removal of accumulated sediment ---- should be considered.
Slide 18
Basin considerations
• basin lining
- prevents leaching of chemicals
- for high groundwater table
- for sandy soils
- just a good idea to prevent potential
environmental impacts
- plastic, clay, concrete, etc.
Salvatore Mangiafico
Collection basins are often lined to prevent the leaching of nitrogen, pesticides, and salts into
groundwater. They are especially indicated in cases where soils are sandy or the groundwater
table is high. Sealing of basin bottoms might be accomplished with the use of plastic, concrete,
clay, or compacted soil.
Slide 19
Basin considerations
• maintenance
- sediment removal (6–12 inches?)
- unclogging inlets and outlets after rains
- surrounding vegetation
- no clippings, debris into basin
- chemical-free zone around basin
- removal of algae and weeds
• mosquitoes
-
water flow
water cleanliness
biological control
chemical control
Salvatore Mangiafico
Maintenance considerations for collection basins include the need for sediment removal,
unclogging inlets and outlets after rains, maintaining surrounding vegetation, and removal of
algae and weeds. Preventing vegetation clippings and other debris from getting into basins is
helpful, as is maintaining a chemical-free zone directly around the basin to prevent herbicides
from getting into collected water.
.
The potential for mosquitoes to breed in collection basins is sometimes a concern. Mosquitoes
might be controlled by maintaining water flow and cleanliness, or employing biological or
chemical control.
Slide 20
Removal of sediment
• physical settling
- settling basin prior to main
impoundment
- channels with gravel, grass, etc.
- suspended clay can take up to days to
settle
- maintenance concerns… designing for
easy cleaning critical
- engineering for hydrology
Salvatore Mangiafico
The removal of sediment from collected water is critical to allow disinfection methods to be
successful as well as to prevent clogging of sprinklers and dirtying of plant leaves. Physical
removal of sediment from water is accomplished by slowing running water and allowing
sediment to drop out, for example in settling basins or grassed channels.
Slide 21
Removal of sediment
• flocculation
- Al alum, Fe, to flocculate clays, OM
- PAM – polyacrylamide – I’ve seen used
in CA
- can reduce settling time to minutes
• sand filters
Salvatore Mangiafico
The flocculation of fine sediments, in order to promote its removal from water, is sometimes
accomplished by adding aluminum or iron compounds or polyacrylamide (PAM). While fine
sediment particles may take hours or days to settle out of water, flocculation additives can
reduce their settling time to minutes. Sand filters can also be used to remove sediment and
organic matter from water.
Slide 22
Sanitation
• pathogens from surface water, production
area, not in groundwater
• grouping of plants by sensitivity to
pathogens and selective use of recycled water
• treatment and testing
Salvatore Mangiafico
Plant pathogens such as Pythium and Phytophthora may be found in surface water bodies or in
runoff from plant production areas. Because of this, there is a potential for these pathogens to
be found in collected and recycled water and thereby redistributed to crop plants through
irrigation water. Primary sanitation methods usually involve filtering coupled with a disinfection
method such as chlorine, ultraviolet light, or ozone. Other methods to minimize pathogen
problems include grouping plants by their sensitivity to likely pathogens and selectively using
recycled water, specifically by not applying recycled water to sensitive crops.
Slide 23
Treatment types
• Slow sand filtration
- I haven’t seen used much
- can give pathogen control
- fine sand physically removes
- schmutzdecke biofilm biologically removes
- must maintain water head, non-disturbance of sand surface
- cheap, simple, no chemicals
• Filtration
- I’ve seen reverse osmosis (RO) used in CA
for greenhouse areas
Slow sand filtration can be used to give pathogen control. Fine sand physically removes
sediment, organic matter, and some pathogens, while the schmutzdecke biofilm layer
biologically removes and destroys pathogens. Sand filtration is typically cheap, simple, and
requires no chemicals.
.
Reverse osmosis can be used to remove pathogens from water, as well as removing excess salts
or specific irons from water, such as excess iron. It might be appropriate for greenhouse
production.
Slide 24
Treatment types
• Chlorine
- probably most common in these
applications
- effective pathogen control
- chlorine dose x time
- too high can harm / mar plants, and some
plants more sensitive than others…
- one recommendation is 2 ppm free active
chlorine at sprinkler (may not be final
recommendation)
[beginning of line vs. end of line
considerations]
- water pH matters
- relatively cheap
- safety / regulatory concern for Cl2 gas
Salvatore Mangiafico
Chlorine is probably the most common water disinfection method used in nurseries, since it is
relatively cheap, familiar from drinking water treatment, and effective at destroying pathogens.
To be effective, the active chlorine dose must be maintained for a given period of time in the
water, and water pH and organic matter content affect chlorine effectiveness. Potential
problems with chlorine treatment include the potential to mar or harm sensitive plants if the
chlorine concentration in the water is too high, and concerns about safety or potential future
regulations with chlorine gas.
Slide 25
Treatment types
• Chlorine
Forms:
- Cl2 – gas
- NaHClO, Ca-HClO – bleach
- ClO2 – Chlorine dioxide
- generated with system
- more expensive, but gaining adoption
Salvatore Mangiafico
Common forms of chlorine used for water disinfection include chlorine gas and hypochlorite,
which is the same form used in common bleach. Chlorine dioxide is more expensive to use, but
its use is increasing since it typically doesn’t have the safety or potential for regulatory concerns
as chlorine gas. In nursery applications, chlorine dioxide is generally generated onsite with
special equipment.
Slide 26
Salvatore Mangiafico
Tanks of chlorine gas, and chlorine gas injector in a water line.
Slide 27
“Chlorine”…
• Chlorine (Cl) is a chemical element…
• Chloride (Cl-) is a common form of
chlorine, it is found in common
table salt, sodium chloride, and also
in salt fertilizers, such as potassium
chloride...
• Chlorine – The term chlorine is used
in water sanitation to refer to those
forms of chlorine that are effective
in killing microbes, specifically,
chlorine gas (Cl2), hypochlorous acid
(HOCl), and hypochlorite (OCl-).
These are similar in form and action
to chlorine bleach and swimming
pool chlorine….
Salvatore Mangiafico
The term “chlorine” can refer to several different chemical substances.
.
First, chlorine (Cl) is a chemical element, while chloride (Cl-) is a common form of chlorine. It is
found in common table salt, sodium chloride, and also in salt fertilizers, such as potassium
chloride.
.
The term “chlorine” is used in water sanitation to refer to those forms of chlorine that are
effective in killing microbes, specifically, chlorine gas (Cl2), hypochlorous acid (HOCl), and
hypochlorite (OCl-). These are similar in form and action to chlorine bleach and swimming pool
chlorine.
.
Source: 2012. Use of Reclaimed Water in Floriculture Crops. K.A. Williams, D.J. Merhaut, and
S.S. Mangiafico. In Water and Nutrient Management for Floriculture Crops. University of
California ANR Press.
Slide 28
“Chlorine”…
▪ Active chlorine – The forms of
chlorine active in killing microbes,
but expressed as a normalized
value, so that one gram of chlorine
gas (Cl2) is equal to 100%, but one
gram of hypochlorite (OCl-) is less,
because it is less effective.
▪ Residual chlorine – The amount of
chlorine left in water after it has
reacted with any organic matter in
the water. Therefore, the amount of
chlorine left to continue killing
pathogens in the water.
Salvatore Mangiafico
Active chlorine is the forms of chlorine active in killing microbes, but expressed as a normalized
value, so that one gram of chlorine gas (Cl2) is equal to 100%, but one gram of hypochlorite (OCl) is less, because it is less effective. Residual chlorine is the amount of chlorine left in water
after it has reacted with any organic matter in the water. Therefore, the amount of chlorine left
to continue killing pathogens in the water.
.
Source: 2012. Use of Reclaimed Water in Floriculture Crops. K.A. Williams, D.J. Merhaut, and
S.S. Mangiafico. In Water and Nutrient Management for Floriculture Crops. University of
California ANR Press.
Slide 29
Treatment types
• Ultra-violet light (UV)
- really needs pre-filtering to remove
particulates – sand, paper, charcoal, flocculants
- no chemicals
- can be relatively inexpensive
- small system, simple
- may degrade chelates
- may degrade pesticides
- does not affect water pH
- does not affect plants
Salvatore Mangiafico
While most dissinfection measures require pre-treatment to remove sediment and organic
matter to be effective, ultraviolet light treatment in particular requires the removal of sediment
and organic matter that can block the light passing through the water. Filtering methods might
include sand filters, paper or charcoal filters, and flocculants. Ultraviolet treatment can be
relatively inexpensive, requires no chemicals, does not affect water pH, and doesn't harm
plants. Systems are relatively small and simple.
Slide 30
Salvatore Mangiafico
An ultraviolet treatment system installed in a water line. The blue canister is a filter, installed
before the ultraviolet treatment canister, which is silver.
Slide 31
Treatment types
• Ozone (O3)
- long contact time ( ~ 20 minutes)
- useful if water can be stored
- can use ORP meter to check levels
- need relatively clean water (pre-filter)
- may degrade chelates
- may degrade pesticides
- some safety concerns
Treatment with ozone requires a long contact time, on the order of 20 minutes, making its use
practical if water can be stored. An ORP meter can be used to check the ozone level in water.
Use of ozone treatment requires relatively clean water, and so pre-filtering is usually required.
Slide 32
Treatment types
• Copper (Cu)
- isn’t favored for a few reasons : cost, concerns with heavy metal, copper
toxicity, effectiveness
• Heat
- I’ve seen it used
- If you need to heat greenhouses anyway, could be cost-effective
- also potential to use solar, etc., to lower costs
- no chemicals, no not much safety concerns
- costs and need to cool main disadvantages
- ~ 130 F @ 1.5 hrs.
Copper is sometimes used for a water disinfection method, though its use is not widely favored
due to its relatively high costs, concerns with copper as a heavy metal and potential to harm
crops, and limited effectiveness.
.
Heat can be used as a disinfection method, and might be practical in cases where heaters must
be run to keep greenhouses warm or where solar heating can keep costs low. Advantages
include the absence of chemicals and safety concerns. Energy costs and the need to cool water
before use in irrigation are its main disadvantages.
Slide 33
Some sources and resources…
2008. Merhaut, D. J. Water Recycling in Nurseries. In Newman, J. (ed). Greenhouse and
Nursery Management Practices to Protect Water Quality. University of California
Division of Agriculture and Natural Resources Press.
2011. J. Johnson, S. Mangiafico, and C. Obropta. Protecting Natural Resources at Field
Nurseries: Sustainable Agricultural Management Practices for Soil, Water, Nutrient, and
Pesticide Conservation. Manual, 32 pages.
http://njaes.rutgers.edu/nursery/documents/Protecting Natural Resources at Field
[email protected]
2008. Lu et al., Erosion Control and Runoff Management. In Newman, J. (ed.)
Greenhouse and Nursery Management Practices to Protect Water Quality. University of
California Division of Agriculture and Natural Resources Press.
2012. Use of Reclaimed Water in Floriculture Crops. K.A. Williams, D.J. Merhaut, and
S.S. Mangiafico. In Water and Nutrient Management for Floriculture Crops. University
of California ANR Press.
2003. C. X. Hong, P. A. Richardson, P. Kong, and E. A. Bush. Efficacy
of Chlorine on Multiple Species of Phytophthora in Recycled
Nursery Irrigation Water. Plant Disease / Vol. 87 No. 10.
Some sources and references:
2008. Merhaut, D. J. Water Recycling in Nurseries. In Newman, J. (ed). Greenhouse and Nursery
Management Practices to Protect Water Quality. University of California Division of Agriculture
and Natural Resources Press.
2011. J. Johnson, S. Mangiafico, and C. Obropta. Protecting Natural Resources at Field Nurseries:
Sustainable Agricultural Management Practices for Soil, Water, Nutrient, and Pesticide
Conservation. Manual, 32 pages. http://njaes.rutgers.edu/nursery/documents/Protecting
Natural Resources at Field Nurseries.pdf
2008. Lu et al., Erosion Control and Runoff Management. In Newman, J. (ed.) Greenhouse and
Nursery Management Practices to Protect Water Quality. University of California Division of
Agriculture and Natural Resources Press.
2012. Use of Reclaimed Water in Floriculture Crops. K.A. Williams, D.J. Merhaut, and S.S.
Mangiafico. In Water and Nutrient Management for Floriculture Crops. University of California
ANR Press.
2003. C. X. Hong, P. A. Richardson, P. Kong, and E. A. Bush. Efficacy of Chlorine on Multiple
Species of Phytophthora in Recycled Nursery Irrigation Water. Plant Disease / Vol. 87 No. 10.
Slide 34
Salvatore Mangiafico
County Environmental and Resource Management Agent
Cooperative Extension of Salem County
51 Cheney Rd, Ste. 1
Woodstown, NJ 08098
856-769-0090
[email protected]
http://salem.rutgers.edu/nre
http://salem.rutgers.edu/nre/
.
http://njaes.rutgers.edu/nursery/
.
http://salem.rutgers.edu/nre/contact.html