Comparative Study of the Characteristics of Three Types of Sludge From Wastewater Treatment Plants

whatever the adoptod treatment system, the wastewater treatment is accompanied by production of large amounts of sludge which must be disposed. Several pathways exist lor the disposal of sewage sludge, but the choice must depend on the cost of installation, the result as an added value of the product and the possible impact of the chain retained on the environment To justify the choice of sludge recycling in agriculture, we will have to estimate the fertilizer value of sludge through the analysis of physico-chemica1 and microbiological parameters complying with regulations. Considering these parameters will detennine the worth of sludge,the environmental impact and precautions for use. For this purpose, we have to compare the sludge characteristics from three wastewater treatment plants (WIV) in the wilaya of Mascara, (west of Algeria), Mascara, Tizi and Ghriss. The results show that our overall sludge is rich in nutrients (N, P, K) but contains a hight concentrations in Nickel (Ni) of lIbout 8.6 mg I kg prohably due to industrial waste. To enhance ille fertilizing power of the sludge in an agricultural field we recommend an additional treatment