Stabilization of sewage sludge with CKD to be used as amended fertilizer in Saudi Arabia

Abstract EN

In order to utilize the domestic sewage sludge as fertilizer locally produced Cement Kiln Dust (CKD) was used to stabilize the sludge.

As presence of metals in the CKD and pathogens in the sewage sludge are the limitations for utilizing sludge as fertilizer, several blends (25% to 45%) CKD with sewage sludge were prepared and final blends were analyzed for pH, fecal coliform (FC), Heterotrophic Plate Cunts (HPC) and metal concentrations.

The results show that 32% of CKD may bring the pH of sludge above 12 which is enough to stabilize the sludge and reduce the microbiological counts up to the allowable limits provided by US-EPA and New Zealand Department of Health (FC < 102 MPN/g solids and HPC < 106 pfu/g solids respectively).

After treatment sludge achieved the Class-A bio-solid rank which can be use as fertilizer.

Furthermore, the concentration of heavy metals in the final blends compared with US-FR, European, and Canadian standards and found that the metal concentrations in the final blend are within the allowable limits if the percentage of CKD will not exceed 32% in the sewage sludge.

Therefore, study demonstrated that the CKD stabilized sludge can be used for land applications such as fertilizer safely.

This strategy of utilizing CKD will not only provide the economical means to save the environment and natural resources, it will also reduce the disposal cost of CKD and sewage sludge