Cumulative toxicity ratio “CTR” as a measure of sludge potential for land application

Abstract EN

Jordan is a semi-desert country with very limited resources.

All prevailing factors and conditions in Jordan make waste stabilization ponds the first choice for wastewater treatment.

The sludge handling and treatment in anaerobic ponds is the most economic arid effective method.

Sludge of anaerobic ponds has beneficial effects when used as fertilizer.

The NPK value in the sludge was found to be US $ 0.01 per capita per year.

Application of sludge to soil requires good management to eliminate the potential adverse effects on the soil and heavy metal uptake by crops.

This can be achieved by defining the Cumulative Toxicity Ratio (GTR) of heavy metals in a specific sludge to determine the most limiting element and subsequently the limit of the amount of sludge which can be applied to soil.

For Jordan it has been found that CTR's for Zn, Se, Ni, are as follows; 67.5, 18.5, 10.7 and 8,5 respectively, whichmeans that Mb is the limiting element since it has the highest CTR value, while on the other hand the CTR value for Cr shows that it was the lowest limiting element (CTR =? 1).

The life time of sludge application for corn was found to be about 2 years in irrigated lands and 6 years for dry fanning lands.