Post on 14-Dec-2015
Urban Landscape Irrigation with Recycled Urban Landscape Irrigation with Recycled Wastewater: Wastewater:
Water Quality and Salinity IssuesWater Quality and Salinity Issues
Yaling Qian
Colorado State University
Water ReuseWater Reuse
In dry and highly populated In dry and highly populated metropolitan areas, where water is a metropolitan areas, where water is a limited natural resource, water reuse limited natural resource, water reuse is a viable means of coping with is a viable means of coping with potable water shortages. potable water shortages.
Without doubt, water reuse for Without doubt, water reuse for landscape irrigation will increase in landscape irrigation will increase in the future.the future.
Benefits of Recycle Water Benefits of Recycle Water IrrigationIrrigation
Water conservation;Water conservation; Always available;Always available; Water reclamation;Water reclamation; Nutrient recycling.Nutrient recycling.
Water Source for Golf Courses in Water Source for Golf Courses in Colorado - Colorado - In 2000In 2000
Potable Water 11%
Well Water 18%
Reclaimed Wastewater
10%
Surface Water 61%
Using recycled wastewater for landscape irrigation in Colorado Using recycled wastewater for landscape irrigation in Colorado started in the 1960’s to irrigate golf courses.started in the 1960’s to irrigate golf courses.
Water Source for Golf Course in Water Source for Golf Course in Colorado: Colorado: In 2002In 2002
Potable Water 12%
Well Water 16%
Recycled Wastewater
20%
Surface Water 52%
Water reuse practice has increased dramatically recently.Water reuse practice has increased dramatically recently.
Successful Recycled Wastewater Reuse CasesSuccessful Recycled Wastewater Reuse Cases
Olympic Club Castle Pine International
ChallengesChallenges
Sodicity and salinity problems;Sodicity and salinity problems;
Residential use of water typically adds about 200-400 Residential use of water typically adds about 200-400
mg/L of dissolved salts. Those salts have relatively high mg/L of dissolved salts. Those salts have relatively high
Na content that remain after wastewater treatment. Na content that remain after wastewater treatment. Nutrient issues;Nutrient issues; Groundwater quality.Groundwater quality.
ParameterParameter UnitUnit Value Value
Salt loadSalt load
Total dissolved salts (TDS)Total dissolved salts (TDS) ppm or mg/Lppm or mg/L 540540 0.448 lb/100 gal0.448 lb/100 gal
Electrical conductivity (EC)Electrical conductivity (EC) dS/m or mmho/cmdS/m or mmho/cm 0.840.84
SodiumSodium ppm or mg/Lppm or mg/L 9999
CalciumCalcium ppm or mg/Lppm or mg/L 6161
MagnesiumMagnesium ppm or mg/Lppm or mg/L 1515
Sodium adsorption ratioSodium adsorption ratio 3.13.1
Adjusted SARAdjusted SAR 5.05.0
BicarbonateBicarbonate ppm or mg/Lppm or mg/L 112112
ChlorideChloride ppm or mg/Lppm or mg/L 9595
BoronBoron
NitrogenNitrogen
ppm or mg/Lppm or mg/L
ppm or mg/Lppm or mg/L
0.230.23
10.310.3
PhosphorusPhosphorus ppm or mg/Lppm or mg/L 0.80.8
Water QualityWater Quality
Effects of salinity on landscape plantsEffects of salinity on landscape plants
Physiological drought:Physiological drought:
PPlants cannot take up enough water due lants cannot take up enough water due to salts.to salts.
Turf Injury Turf Injury
Salinity caution levels in irrigation water: Salinity caution levels in irrigation water:
EC > 0.75 mmho/cm EC > 0.75 mmho/cm
or or
TDS > 500 ppm.TDS > 500 ppm.
Turf Injury Turf Injury Salinity problems are functions of:Salinity problems are functions of: soil type, soil type, management, management, shallow water table will reduce shallow water table will reduce
leaching and introduce salts to the leaching and introduce salts to the root zone,root zone,
salinity of irrigation water.salinity of irrigation water.
Susceptible sites for salt accumulation: Shallow water table,High clay content,Poorly drained sites,Compacted sites.
To reduce salt accumulation in To reduce salt accumulation in the soilthe soil
Improve irrigation uniformity;
Improve drainage;
Leach and flush periodically.
ParameterParameter RWWRWW
Total dissolved salts (ppm)Total dissolved salts (ppm) 514514
Conductivity (dS/m)Conductivity (dS/m) 0.840.84
Sodium (ppm)Sodium (ppm) 9999
Calcium (ppm)Calcium (ppm) 6161
Magnesium (ppm)Magnesium (ppm) 1515
Sodium adsorption ratio (SAR)Sodium adsorption ratio (SAR) 3.13.1
Water QualityWater Quality
Sodium absorption ratio Sodium absorption ratio (SAR)(SAR)
[Na][Na]
SAR = [Ca]+[Mg]/2SAR = [Ca]+[Mg]/2
Sodium permeability hazard: Sodium permeability hazard:
High SAR (> 12) can induce soil structure High SAR (> 12) can induce soil structure deterioration, including soil sealing, deterioration, including soil sealing, crusting, and reduced water penetration.crusting, and reduced water penetration.
For fine textured soil and heavy traffic For fine textured soil and heavy traffic areas, irrigation water SAR as low as 6-9 areas, irrigation water SAR as low as 6-9 can cause problems.can cause problems.
Sodium Management Sodium Management
I. Chemical amendments of water and soil
Water TreatmentsWater Treatments
Calcium nitrate;Calcium nitrate;
Gypsum (calcium sulfate);Gypsum (calcium sulfate);
Calcium chloride;Calcium chloride;
Soil TreatmentsSoil Treatments
Lime + sulfuric acid injection;Lime + sulfuric acid injection;
GypsumGypsum
Calcium nitrateCalcium nitrate
Calcium chlorideCalcium chloride
ParameterParameter RWWRWW
Total dissolved salts (ppm)Total dissolved salts (ppm) 614614
Conductivity (dS/m)Conductivity (dS/m) 0.840.84
Sodium (ppm)Sodium (ppm) 9999
Calcium (ppm)Calcium (ppm) 6161
Magnesium (ppm)Magnesium (ppm) 1515
Sodium adsorption ratioSodium adsorption ratio 3.13.1
Adjusted SARAdjusted SAR 5.05.0
Bicarbonate (ppm)Bicarbonate (ppm) 112112
Water QualityWater Quality
Adjusted SAR: Adjusted by considering bicarbonate, carbonate, and the water’s total salinity, in addition to water’s calcium, magnesium, and sodium content.
Bicarbonate and Adjusted SARBicarbonate and Adjusted SAR
• Bicarbonate can combine with Ca++ and Mg++ to precipitate them out and increase the water SAR;
• Bicarbonate can also raise water pH to undesirable levels;
• If recycled wastewater has high bicarbonate (> 120 mg/L), it is recommended that SAR be adjusted to consider bicarbonate content in the water - SARadj.
To reduce bicarbonate in To reduce bicarbonate in irrigation water irrigation water
Acidification of irrigation water (to 6.5 –7.0 Acidification of irrigation water (to 6.5 –7.0 pH) is effective in converting bicarbonate to pH) is effective in converting bicarbonate to COCO22 and H and H22O. O.
ParameterParameter RWWRWW
Total dissolved salts (ppm)Total dissolved salts (ppm) 614614
Conductivity (dS/m)Conductivity (dS/m) 0.840.84
Sodium (ppm)Sodium (ppm) 9999
Calcium (ppm)Calcium (ppm) 6161
Magnesium (ppm)Magnesium (ppm) 1515
Sodium adsorption ratioSodium adsorption ratio 3.13.1
Adjusted SARAdjusted SAR 5.05.0
Bicarbonate (ppm)Bicarbonate (ppm) 112112
Chloride (ppm)Chloride (ppm) 9595
Sodium (ppm)Sodium (ppm) 9999
Boron (ppm)Boron (ppm) 0.230.23
Water QualityWater Quality
Specific ion toxicities/problemsSpecific ion toxicities/problems
Trees are more sensitive to salts Trees are more sensitive to salts especially sodium and chloride are especially sodium and chloride are sprayed directly onto plant leaves sprayed directly onto plant leaves through irrigation water. through irrigation water.
If irrigation water is applied to roots If irrigation water is applied to roots rather than leaves, plant tolerance level rather than leaves, plant tolerance level to Cl and Na will increase.to Cl and Na will increase.
B is usually absorbed by roots.B is usually absorbed by roots.
Use low angle nozzle to reduce leaf ion Use low angle nozzle to reduce leaf ion toxicity on trees and shrubs.toxicity on trees and shrubs.
Mineral Concentration Mineral Concentration in Ponderosa Pine Needlesin Ponderosa Pine Needles
ParametersParameters Surface Water Surface Water
IrrigationIrrigation
Recycled WaterRecycled Water
IrrigationIrrigation
Firing (0-100%)Firing (0-100%) 3.17****3.17**** 33.5833.58
BB 35.69***35.69*** 50.2750.27
KK 22982298 21282128
NaNa 237****237**** 27502750
K/NaK/Na 9.7****9.7**** 0.80.8
ClCl 13831383 32483248
*, ***, **** Significant at P0.05, 0.001, and 0.0001 respectively.
Pine needle burn and NaPine needle burn and Na++ in the needles in the needles
y = 0.0096x + 4.6998
R2 = 0.7661
0
10
20
30
40
50
60
0 1000 2000 3000 4000 5000 6000
Sodium Concentration in needles (ppm)
Le
af
firi
ng
(0
-10
0%
sc
ale
)
ParameterParameter RWWRWW
Total dissolved salts (ppm)Total dissolved salts (ppm) 614614
Conductivity (dS/m)Conductivity (dS/m) 0.840.84
Sodium (ppm)Sodium (ppm) 9999
Calcium (ppm)Calcium (ppm) 6161
Magnesium (ppm)Magnesium (ppm) 1515
Sodium adsorption ratioSodium adsorption ratio 3.13.1
Adjusted SARAdjusted SAR 5.05.0
Bicarbonate (ppm)Bicarbonate (ppm) 112112
Chloride (ppm)Chloride (ppm) 9595
Boron (ppm)Boron (ppm)
Nitrogen (ppm)Nitrogen (ppm)
0.230.23
10.310.3
Phosphorus (ppm)Phosphorus (ppm) 0.80.8
Water QualityWater Quality
Nutrients in Irrigation PondNutrients in Irrigation Pond
Test recycled wastewater on regular basis, and calculate N and P input via irrigation. These amounts of N and P should be deducted from the fertilization program.
Increased nutrient content will increase algae Increased nutrient content will increase algae population in irrigation ponds, which will result in population in irrigation ponds, which will result in secondary problems, such as decreased clarity and secondary problems, such as decreased clarity and aesthetic appearance. Some algal metabolites are aesthetic appearance. Some algal metabolites are toxic. toxic.
Irrigation pond maintenance level will increase, Irrigation pond maintenance level will increase, needing additional aeration and chemical needing additional aeration and chemical modification. modification.
To make water reuse a success:To make water reuse a success:
Support water reuse;Support water reuse; Recognize that reused water and fresh water Recognize that reused water and fresh water
are not of equal value and quality;are not of equal value and quality; Yes, we can manage aesthetic appealing Yes, we can manage aesthetic appealing
landscapes, but hidden costs exist.landscapes, but hidden costs exist.
What should be done to manage landscapes What should be done to manage landscapes receiving recycled wastewater?receiving recycled wastewater?
IrrigationIrrigation Regularly monitor water quality.
More vigorous aeration in irrigation pond;
Improve irrigation uniformity;
Irrigate based on ET with additional periodic leaching and flushing;
Improve drainage;
Conversion to low angle nozzles to reduce leaf damage of trees.
What should be done to manage landscapes What should be done to manage landscapes
receiving recycled wastewater?receiving recycled wastewater? Compaction controlCompaction control
More intensive cultivation programs (deep aeration and water injection) to maintain oxygen diffusion and water movement;
More vigorous traffic control.
What should be done to manage landscapes What should be done to manage landscapes
receiving recycled wastewater?receiving recycled wastewater? Fertilization and AmendmentsFertilization and Amendments
Reduce N and P fertilization;
Fertilize to alleviate nutrient imbalance;
Additional chemical amendments to displace Na;
Add to soil
Add to water
Leaching to remove excess Na after soil amendment treatment;
What should be done to manage landscapes What should be done to manage landscapes
receiving recycled wastewater?receiving recycled wastewater? Plant SelectionPlant Selection
Replace with more salt tolerant species and cultivars.
Deciduous Woody Plants Deciduous Woody Plants Salinity ToleranceSalinity Tolerance
Pear Pear Cottonwood Cottonwood Siberian Elm Siberian Elm Green Ash Green Ash
Red Maple Red Maple Amur MapleAmur MapleLittleleaf LindenLittleleaf Linden
High
Low
Cool Season TurfgrassesCool Season Turfgrasses
AlkaligrassAlkaligrass
Creeping bentgrassCreeping bentgrassTall fescueTall fescueFine fescuesFine fescues
Perennial ryegrassPerennial ryegrass
Kentucky bluegrass Kentucky bluegrass
High
Low
Management Options for Mitigating Sodium Management Options for Mitigating Sodium Stress in Effluent Irrigated Turfgrass SystemsStress in Effluent Irrigated Turfgrass Systems
Research Project at CSU
Sponsored by the City of Westminster, Denver Water,Plum Creek Water Authority, and Castle Pine Golf Club
Treatments: Treatments:
1 2 3 4 5 6 7
Treatment GypsumCalcium chloride Humate
Mycorrhizae (VAM)
Humate
+ Gypsum
VAM +
Gypsum Control
Application Rate
50 lb/ 1000 ft2
1qt/ 1000 ft2
15 lb/ 1000 ft2 1.4 lb/1000 ft2 1 + 3 1 + 4
No amendment
Preliminary FindingsPreliminary Findings
Soil texture is playing a dominant role; Soil texture is playing a dominant role; Mycorrhizae treatment did not help to reduce Mycorrhizae treatment did not help to reduce
sodium problems and improve turf quality, but sodium problems and improve turf quality, but enhanced soil redox status;enhanced soil redox status;
Gypsum (CaSOGypsum (CaSO44) treatment enhanced leaching of ) treatment enhanced leaching of
Na, but did not improve turfgrass quality; Na, but did not improve turfgrass quality; Calcium chloride treatment helped to reduce Na Calcium chloride treatment helped to reduce Na
accumulation and increased turf quality in both accumulation and increased turf quality in both greenhouse and field studies. greenhouse and field studies.
Development and Selection of Development and Selection of Salt Tolerant PlantsSalt Tolerant Plants
Sponsored by US Golf Association
Selecting Conifers Trees For Landscapes Selecting Conifers Trees For Landscapes
With Recycled Wastewater IrrigationWith Recycled Wastewater Irrigation
Sponsored by Denver Water