Designing Sustainable Wastewater Reuse Systems: Towards an Agroecology of Wastewater Irrigation - Governing the Nexus: Water, Soil and Waste Resources Considering Global Change - page 168

Annex 2 Wastewater Quality Guidelines for Agriculture

Primary wastewater quality parameters of importance from an agricultural viewpoint

Parameters Symbol Unit

Physical
Total dissolved solids TDS mg/l

dS/m a Electrical conductivity Ec w

Temperature T °C

NTU/JTU b

Colour/turbidity

Hardness mg equiv. CaCO3/l 3 /l

Sediments g/l

Chemical
Acidity/Basicity

pH

Type and concentration of anions and cations :
Calcium Ca ++ me/I c

Mg ++ Magnesium me/I

Na + Sodium me/I

CO 3 −− Carbonate me/I

Bicarbonate HCO 3 - me/I

Chloride CI - me/I

SO 4 −

Sulphate me/I

Sodium adsorption ratio SAR

mg/l d Boron B

Trace metals mg/l

Heavy metals mg/l

Nitrate-Nitrogen NO 3 -N mg/l

Phosphate Phosphorus PO 4 -P mg/l

Potassium K mg/l

a dS/m = deciSiemen/metre in SI Units (equivalent to 1 mmho/cm)
b NTU/JTU = Nephelometric Turbidity Units/Jackson Turbidity Units
c me/I = milliequivalent per litre
d mg/l == milligrams per litre = parts per million (ppm); also, mg/l - 640 × EC in dS/m
Source: Pescod ( 1992 )

WHO water quality standards for irrigation

Parameter Units Degree of restriction on use

None Slight to

moderate

Severe

Salinity EC a

dS/m <0.7 0.7-3.0 >3.0

TDS mg/l <450 450-2000 >2,000

TSS mg/l <50 50-100 >100

(continued)