Muhammad H - Civil Engineering Department, King Fahd University of Petroleum & Minerals, Box ۱۱۵۰, Dhahran, Saudi Arabia
Alaadin A. Bukhari - Civil Engineering Department, King Fahd University of Petroleum & Minerals, Dhahran, Saudi Arabia
Nabil S. Abuzaid - Research Institute, King Fahd University of Petroleum & Minerals, Dhahran, Saudi Arabia

Disinfection of municipal sludge was investigated using UV radiation, lime stabilization, and storage and rewetting using sludge produced at Al-Khobar wastewater treatment plant, Eastern Province, Saudi Arabia. The investigation showed that UV radiation was not an effective method of inactivation of pathogenic bacteria in municipal sludge. The results on UV radiation were attributed to the blockage of UV radiation by solid particles. After 60 minutes of exposure to the UV radiation, only 0.4 logs of total coliform were removed. Lime stabilization was found to be an effective tool of inactivation of total coliform in municipal sludge. After 15 days of contact with lime, the density of total coliform was reduced by 2.23, 2.24, and 3.04 logs, when the sludge was treated at pH of 10, 11, and 12, respectively. Rewetting of sludge, after 30 days of storage in plastic bags, revealed that pathogens continued to decrease in density in spite of water addition. Total coliform were found to migrate to the underneath soil during the rewetting period.

Disinfection, Lime, Pathogens, Rewetting, Sludge, Stabilization, Storage, Total coliform, UV radiation