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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

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“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.

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“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 .

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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.

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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.

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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.

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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.

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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