Agri-Ash
Agri-Ash is a by-product of the sewerage treatment process, which is used as a soil conditioner for agricultural purposes. The use of Agri-Ash offers the benefit of recycling sewerage waste.
Agri-Ash has a high calcium content because lime (CaCO3) is used in the treatment of sewage at the Lower Molonglo Water Quality Control Centre (LMWQCC). It is an ideal alternative to agricultural lime for correcting soil acidity.
How is Agri-Ash produced?
At LMWQCC, sewage sludge is treated with lime and ferrous chloride. These chemicals react with soluble phosphorus in the sewage to form insoluble compounds. The compounds, and other solids, are collected and removed as lime-rich sludge.
Water is removed from the sludge by centrifuges. The sludge is then fed into an incinerator where it is processed at a minimum temperature of 680°C. The high temperature processing also sterilises the Agri-Ash.
Chemical composition of Agri-Ash
Agri-Ash is approximately 60 per cent calcium-based compounds, including calcium
carbonate, calcium oxide and tricalcium phosphate. These calcium compounds neutralise
soil acidity. The phosphorus content of Agri-Ash is around six per cent.
The Agri-Ash also contains traces of heavy metals such as zinc, copper, nickel,
lead, cobalt and cadmium. Nearly all the metals are locked up in insoluble forms
and will not harm pastures or livestock.
Agri-Ash meets the composition standards for Soil Improving Agents under Order No. 2001/02 of the Fertilisers Act 1985.
Component |
Value |
Standard |
Phosphorus |
6.6 % |
> 2 % total phosphorus |
Cadmium |
9.1 |
< 300 milligrams of cadmium per kilogram of phosphorus |
Lead |
28.0 |
< 100 milligrams of lead per kilogram of the fertiliser |
Mercury |
<0.10 |
< 5 milligrams of mercury per kilogram of the fertiliser |
|
Please contact us if you have
any queries or require additional information about Agri-Ash.