Physico-chemical Characteristics of Municipal Sludge Produced at Three Major Cities of the Eastern Province of Saudi Arabia

Due to uncontrolled dump of dried municipal sludge and its use by farmers as soil conditioner and/or fertilizer, an extensive research was conducted in order to determine the physical and chemical characteristics of municipal sludges produced at three major cities, namely, Qateef, Dammam and Khobar in the Eastern Province of Saudi Arabia between April 2000 and February 2001. Sludge samples were collected, from sand drying beds, twice a season for one year and were analyzed for certain potential parameters such as total solids, oil and grease, nitrogen compounds and heavy metals. The results indicated that total solids concentration in dried sludge samples collected from the three cities was found to reach 87%, which was higher than that reported in literature and that volatile solids were within those reported internationally. Dried sludge samples collected from Dammam were found to contain an oil and grease concentration of 8.66%t which is the highest when compared to other cities that was attributed to the industrial activities in that city. With respect to sludge fertilizer value, sludge samples collected from the three cities were found to be deficient in nitrogen, where TKN concentration was between 0.66 and 1.25%. With respect to heavy metals, sludge samples collected from the three cities were found to contain concentrations that are within ranges reported in literature. Arsenic, cadmium, chromium, lead and mercury concentrations were 10, 40, 67, 3.3 and 0.3 mg/1, respectively.