Paul Truong, Tvn And Dnr&m, And Barbara Hart Environmental Consultant, Brisbane, Australia

VETIVER SYSTEM FOR WASTEWATER TREATMENT Paul Truong, TVN and DNR&M, and BARBARA HART Environmental Consultant, Brisbane, Australia The The following following extraordinary extraordinary characteristics characteristics make make vetiver vetiver grass grass an an exceptional exceptional candidate candidate for for wastewater wastewater treatment treatment ** Higher ** Highly Higher evapo-transpiration evapo-transpiration rate rate than than most most wetland wetland plants plants Highly tolerant tolerant to to soil soil acidity, acidity, alkalinity, alkalinity, salinity salinity and and sodicity sodicity ** Very ** Highly Very high high and and fast fast absorption absorption rate rate of of nutrients, nutrients, particularly particularly Highly tolerant tolerant to to heavy heavy metal metal toxicity toxicity Ammonia, ** Highly Ammonia, total total Nitrogen Nitrogen and and Phosphorus Phosphorus Highly tolerant tolerant to to water water logging logging and and inundation inundation ** Vetiver ** Highly Vetiver grass grass is is normally normally sterile sterile and and non non invasive invasive Highly tolerant tolerant to to concentrated concentrated leachates leachates

Leachate pond infested with Blue Green algae

Decontamination trial using floating platform

Removal rates of pollutants from polluted water Left: Sewage effluent infested with BlueGreen algae due to high Nitrate (100mg/L) and high Phosphate (10mg/L) Right: Same effluent after 4 days treatment with vetiver, reducing N level to 6mg/L (94%) and P to 1mg/L (90%) General view of vetiver four months after planting. Effluent was released upslope from the vetiver rows

River 1*

River **

Tap water

Concentration (mg/L)

13.8

10.5

0.1

Removal %

71.0

58.1

Concentration (mg/L)

0.94

1.03

Removal %

99.3

93.7

Pollutants Total N Total P

*After 3 weeks

* * After 2 weeks

ND

ND Not detectable

Vetiver planted to treat effluent discharge from this toilet

Two month old roots of a floating platform

Extensive one year old root system

Nine months later, note the excellent growth of vetiver on the RHS and poor growth on the LHS, indicating most if not all the discharged effluent was absorbed by the first few rows of vetiver.

Toilet

Vetiver

Effluent

Ten months after planting, vetiver grew vigorously and dried up the discharged effluent completely

A sustainable wastewater treatment system 18 months after planting

MODEL for EFFLUENT DISPOSAL by LAND IRRIGATION Vetiver is currently being calibrated for application in the MEDLI model.

Effectiveness of vetiver in reducing N level in domestic blackwater 5 rows 2 rows Entry : Total N level at 95.2mg/L

From initial results, the MEDLI model indicated that vetiver is approximately twice as efficient as some tropical pasture grasses in treating effluent. For example the effluent volume that an area

Entry : Total N level at 95.2mg/L

of 65ha can be sustainably irrigated with effluent from an abattoir:

• For Kikuyu grass: 0.73ML/day • For Vetiver grass: 1.45ML/day The difference can be attributed mostly to the tall canopy and extensive root system of Effluent from this intensive nursery is highly loaded with nutrients, particularly Nitrogen and Phosphorus

This small area of vetiver planting was successfully used to treat all the effluent runoff from this nursery

vetiver grass as compared with the prostrate canopy and shallow roots of Kikuyu.

Monitoring wells

Exit : Total N level at 16mg/L or a reduction of 83%

Monitoring wells

Exit : Total N level at 1.2mg/L or a reduction of 99%