Using Effluent WaterOn Your Golf Courseby DR. DAVID KOPEC, DR. CHARLES MANCINO, and DOUGLAS NELSONUniversity of Arizona, Tucson, Arizona

YOU MIGHT CALL IT a recycler'snightmare. Every day, 365 days ayear, hundreds of millions of gallons

of useable treated water is dumped need-lessly into the ground, rivers, and oceans ofthe world. Is this truly necessary, or is therean alternative method of disposal to allow therecapture of some of this water and put itthrough a natural filter? Actually, there is!Parks, golf courses, sports fields, and certainagricultural crops all can use effluent waterfor irrigation.

In addition to preventing needless dump-ing, a useable effluent water supply hasseveral other advantages. These include (1)guaranteed availability, even during periodsof drought, (2) a nutrient content that poten-tially can lessen dependence on manufac-tured fertilizers, (3) the freeing of limitedsupplies of potable water for other, moreessential uses, and (4) income, from the saleof effluent water to agricultural users, to payfor the construction of public sewage treat-ment plants.

Before running to the faucet and turningon an effluent water supply, however, thereare several points that should be considered.To begin with, a thorough understanding ofeffluent water and how it is produced isessential.

What is Effluent?

The source of most effluent water sup-plies comes from municipal sewage that isapproximately 99.9% water (effluent) and

Preliminary Primary Secondary Advanced

Effluent Effluent Effluent

Low-Rate Processesstabilization ponds

serated lagoons

Suspended Solids Removalchemical coagulation

filtration

Phosphorus Removalchemical precipitation

Nitrogen Removalnitrification • denitrification

selective ion exchangebreak point chlorination

gas strippingoverland flow

Dissolved Solids Removalreverse osmosiselectrodialysis

distillation

Organics and Metal Removalcarbon adsorption

INon-Biological

thickeningconditioningdewatering

filtercentrifugeincineration

High-Rate Processesactivated sludge

trickling filtersrotating biocontactors

,Disposal

IBiologicalthickeningdigestion

dewateringfiltercentrifugedrying beds

Sludge Processing

II

IIIIIIII~--------r------ __L --------------------------------~~------------ ---------

ScreeningComminutionGrit Removal

Figure 1 - Generalized Flow Sheet for Wastewater TreatmentSource: Asano, T., R. G. Smith, and G. Tschobanoglous, 1984

JULY/AUGUST 1993 9

bacterial count of less than 2.2 per milliliter,and can be used safely for most purposes.

Understanding what effluent water is andwhat it is not allows us to address concernsof the golfing public and to develop main-tenance practices to compensate for its useon the golf course.

::;23

Surface irrigation of orchards andvineyards

Fodder, fiber, and seed cropsPasture for milking animalsLandscape impoundmentsLandscape irrigation (golf courses,

cemeteries, etc.)Surface irrigation of food crops

(no contact between water andedible portion of crop)

Spray irrigation of food cropsLandscape irrigation (parks,

playgrounds, etc.)Source: California Department of Health Services, 1978

Oxidation and disinfection

Table 1Water Treatment and Quality Criteria for Irrigation in California

Coliform LimitsTreatment Level Per 100 Milliliters Type of Use

Primary

Oxidation, coagulation,clarification, filtration,and disinfection

continue the process with a final stageknown as tertiary treatment. Tertiary treat-ment involves the removal of non-biode-gradable organic pollutants and a significantpercentage of nutrients, such as nitrogenand phosphorus. Tertiary effluent can be de-scribed as having no foul odor and a coliform

.06% solids (sludge). To produce useableeffluent for golf course irrigation, treatmentplants process the raw sewage in severalsuccessive stages (Figure 1).

The first stage of the process is known asprimary treatment. This involves screeningthe raw sewage for large debris and placingit in settlement ponds. The solid particleseither sink or float and are removed. Primaryeffluent contains no more than 50% solids.Following primary treatment, the resulting

, effluent usually has a very foul odor andcontains numerous harmful pathogens.Effluent water at this stage is not yet suit-able for irrigation.

The next stage of the process is known assecondary treatment. This stage involvesremoving more than 90% of the originalsolids via microbial digestion by pumpingthe effluent through large cylindrical vatscontaining bacterial colonies. Followingsolid removal, the effluent usually is chlori-nated, so that the coliform bacterial countis less than 23 per 100 milliliters of water(Table 1). Because secondary treated efflu-ent has been chlorinated to reduce humanhealth risk and is virtually solid-free, itcommonly is used for irrigation of turf andseveral non-edible crops.

Even though secondary effluent can beused for irrigation, many treatment plants

10 USGA GREEN SECTION RECORD

Table 2Constituents of Concern in Wastewater Treatment and Irrigation with Effiuent Water

Measured Parameters Reason for ConcernConstituentSuspended solids

Biodegradable organics

Pathogens

Nutrients

Stable(refractory organics)

Hydrogen ion activity

Heavy metals

Dissolved inorganics

Residual chlorine

Suspended solids, includingvolatile and fixed solids

Biochemical oxygen demand,chemical oxygen demand

Indicator organisms, totaland fecal coliform bacteria

NitrogenPhosphorusPotassium

Specific compounds(e.g., phenols, pesticides,chlorinated hydrocarbons)

pH

Specific elements(e.g., Cd, Zn, Ni, Hg)

Total dissolved solids,electrical conductivity,specific elements (e.g.,Na, Ca, Mg, CI, B)

Free and combined

Suspended solids can lead to the development of sludge depositsand anaerobic conditions when untreated wastewater is dischargedin the aquatic environment. Excessive amounts of suspended solidscause plugging in irrigation systems.

Composed principally of proteins, carbohydrates, and fats. Ifdischarged to the environment, their biological decomposition canlead to the depletion of dissolved oxygen in receiving waters and tothe development of septic conditions.Communicable diseases can be transmitted by the pathogens inwastewater: bacteria, viruses, parasites.

Nitrogen, phosphorus, and potassium are essential nutrients forplant growth, and their presence normally enhances the value of thewater for irrigation. When discharged to the aquatic environment,nitrogen and phosphorus can lead to the growth of undesirableaquatic life. When discharged in excessive amounts on land,nitrogen can also lead to the pollution of groundwater.

These organics tend to resist conventional methods of wastewatertreatment. Some organic compounds are toxic in the environment,and their presence may limit the suitability of the wastewater forirrigation.

The pH of wastewater affects metal solubility as well as alkalinityof soils. Normal range in municipal wastewater is pH = 6.5-8.5, butindustrial waste can alter pH significantly.

Some heavy metals accumulate in the environment and are toxic toplants and animals. Their presence may limit the suitability of thewastewater for irrigation.

Excessive salinity may damage some crops. Specific ions such aschloride, sodium, boron are toxic to some crops. Sodium may posesoil permeability problems.

Excessive amount of free available chlorine (0.05 mg/l) may causeleaf-tip bum and damage some sensitive crops. However, mostchlorine in reclaimed wastewater is in a combined form, which doesnot cause crop damage. Some concerns are expressed as to the toxiceffects of chlorinated organics in regard to groundwatercontamination.

Source: Asano, T., R. G. Smith, and G. Tschobanoglous, 1984

Human Considerations

The most common question raised bythe golfmg public concerns that of humanhealth (Table 2). Although effluent water isderived from municipal sewage, peopleshould generally feel safe if exposed toeffluent because it has been chlorinated. Infact, many public health officials concedethat some tertiary effluent supplies could beused for swimming, although at this pointin time adequate supplies of potable waterare still available.

Despite the low human health risk in-volved with using effluent water, legislationnonetheless has been written to reduce ex-posure to an absolute minimum. This legis-lation consists primarily of restricting the

use of the irrigation system to non-daylighthours, when golfers are absent from thecourse, and posting the course with signs,such as "Warning: Course Irrigated WithReclaimed Wate!:" In some cases, to complywith this legislation requires the installationof an automatic irrigation system that candeliver the volume of effluent water neces-sary to irrigate the course within a nightlyeight-hour irrigation cycle.

In the environmental '90s, some concernalso is being raised by the general public asto possible adverse side effects on wildlife.Again, due to chlorination, irrigation witheffluent water poses little risk to wildlife.Furthermore, the use of effluent water ongolf courses prevents its dumping in pristine

public waterways, where the nutrient con-tent would promote damaging algae growth.

Chemical Interactions

The first step in developing maintenancepractices to accommodate effluent waterusage is to have a sample analyzed to deter-mine the following parameters:

• Salt concentration.• Sodium hazard.• Bicarbonate concentration.• Toxic ion concentration.• pH.Salt Concentration - Effluent water

generally contains a significant amount ofseveral salts that are combinations of sodium

JULY/AUGUST 1993 11

(Na), chlorine (CI), magnesium (Mg), cal-cium (Ca), sulfate (S04), and bicarbonates(HC03). After irrigation with effluent, thesesalts accumulate in the soil and attract purewater molecules, preventing some of thewater from being absorbed by the turfgrassplants. As a result, less "free" water is avail-able for turfgrass uptake and symptoms ofdrought stress begin to occur.

Sodium Hazard - Sodium hazard indi-cates the relative amount of sodium (Na) inrelation to calcium (Ca) and magnesium(Mg). A high amount of sodium in effluentwater is undesirable from a water and soilstandpoint. In addition to being a componentof salt stress, sodium (Na) accumulationeventually will result in displacement ofcalcium (Ca) and magnesium (Mg) on theexchange sites of soil particles. This in turninhibits the ability of the soil to aggregate andform peds necessary to maintain good soilstructure.

Bicarbonate Concentration - Bicarbon-ate (HC03) concentration is important be-cause of its ability to form precipitates ofcalcium carbonate (CaC03) and magnesiumcarbonate (MgC03). These precipitates"steal" calcium and magnesium from thesoil particle exchange sites, and in turn canbe replaced by sodium. Oflesser importanceis that excess bicarbonate can lead to anincrease in soil pH.

Toxic Ion Concentration - High concen-trations of specific ions, such as chlorine andboron, can cause damage as they accumulatein plant tissue. Fortunately, turfgrasses arerelatively tolerant of several toxic ions.These ions tend to accumulate in the leaftip and are removed during mowing. Manyornamental trees and shrubs are not asfortunate, however, and can experience dis-figuring leaf bums. The type and amount oftoxic ions found in effluent is a function ofwhere the raw sewage emanates from.Generally speaking, most municipal efflu-ent does not contain high toxic ion concen-trations, whereas industrial and miningeffluent does.

pH - The pH (negative logarithm of thehydrogen ion concentration) of effluentwater serves as an indication that there maybe some type of ion imbalance in the water.In general, it is held that the pH of the wateritself is not a problem, as most soils have agreat resistance to pH alteration.

What Next?

With an understanding of the chemicalcharacteristics of effluent water, developingmaintenance practices that compensate forany negative attributes is a relatively simplematter. To begin with, the highest manage-ment priority is determining the water's totalsalt concentration. As mentioned previously,dissolved salts can quickly accumulate inthe soil and inhibit "free" moisture/nutrientuptake.

To avoid such an occurrence, periodicheavy irrigation cycles must be programmedto saturate the soil and leach the salts belowthe root zone. To accommodate salt leach-ing, the importance of good subsurfacedrainage cannot be overstated. This point isespecially important in regard to puttinggreens, where excessively wet conditionswould make the soil more susceptible toexcessive compaction from concentratedfoot traffic.

Another high priority is the sodiumhazard, or the relative amount of sodium incomparison to calcium and magnesium. Ifthe sodium hazard is high, the sodium ionswill accumulate on the soil exchange sitesand cause degradation of the soil structure.As a counterbalance, additional calciumshould be added to the soil. In a majority ofcases, this can be done by applying calciumsulfate (gypsum) in either a granular or liquidformulation.

In cases where the soil has a high pH andexcess free calcium carbonate, however,sulfur should be applied. As the sulfurbreaks down, it dissolves the natural calciumdeposits and increases the availability ofminor nutrients by lowering the pH.

As a potential benefit, many effluentwater supplies contain substantial amountsof nitrogen, phosphorus, and potassium(Table 3). However, due to daily and seasonalnutrient fluctuations, it is not possible tocalculate the exact amount of these nutri-ents that will be deposited on the turfso that it can be subtracted from the annualfertilization program. Therefore, monitoringof both turf performance and soil test datashould be done to make the necessaryadjustments.

Although nutrient content is a potentialbenefit, toxic ions are another matter. Ifpresent, some toxic ions can lead to thedeterioration of the turf and the surround-ing landscape. Since the removal of toxicions from an effluent supply would not beeconomically feasible in most cases, andthey cannot be effectively leached throughthe soil, blending of the effluent with otherwater sources is likely to be the only realsolution. For example, the concentration ofboron could be reduced to a nontoxic levelby blending an effluent water supply with awell water supply.

Though not directly toxic to plants, highbicarbonate levels in effluent water cancontribute to sodium buildup in the soil byreacting with calcium and magnesium. Toprevent this reaction, acid injection (theaddition of acid to the effluent water) some-times is used to lower the pH and nullify thebicarbonate ion. To determine the potentialbenefits of acid injection, water samples canbe submitted for special testing.

Conclusion

As an alternative to potable water use,effluent water can in fact be a logical, safe,and economical choice for golf course andsports turf irrigation. Furthermore, it offersan environmentally responsible choice to thewholesale dumping of treated water intoexisting waterways. Turning on the faucetsimply requires understanding both whateffluent water is and what it is not!

REFERENCES

*Commercial value based on average fertilizer prices for the summer of 1980:N = 18~l1b.,P = 47~l1b.,K = 16~l1b.Source: Asano, 1:, 1981

Asano, T. (Proj. Dir.). 1981. Evaluation of agri-cultural irrigation projects using reclaimedwater. Agreement 8-179-215-2. Office of WaterRecycling. California State Water ResourcesControl Board. Sacramento, CA.

Asano, T., R. G. Smith and G. Tschobanoglous.1984. in Pettygrove, G. S., and T. Asano (eds.).1984. Irrigation with Reclaimed MunicipalWastewater - A Guidance Manual. Report No.84-1 California State Water Resources ControlBoard. Sacramento, CA.

California Department of Health Services. 1978.Wastewater reclamation criteria. CaliforniaAdministrative Code.

Commercial*Value $/ac.-ft.

$11.272.826.10

$20.19

Pounds/ac.-ft.

62.66.0

38.1

Concentrationmg/l23.0

2.213.9

Table 3Potential Fertilizer Value of Irvine Ranch

Water District Reclaimed Water (Per Acre-Foot)

Nutrients

Nitrogen (N)Phosphorus (P)Potassium (K)

Total Potential Fertilizer Value

U USGA GREEN SECTION RECORD