The Assessment of Water Treatment Plant Sludge Properties and the Feasibility of Its Re-use according to Environmental Standards: Shahid Beheshti Water Treatment Plant Case Study, Hamadan

Introduction & Water treatment leads to produce large volumes of sludges in water treatment plants which are considered as solid waste, and should be managed appropriately and logically to avoid bioenvironmental effects.
In this cross-sectional study, the required samples were taken from the sludge of Shahid Beheshti water treatment plant to assay physical and chemical characteristics during one year from summer, autumn and winter 93 until spring 94. Sampling and testing procedures were full fit according to standard methods.
The average concentration of total solids parameters (TSS), total suspended solids (TSS), and total dissolved solids (TDS) were 22346, 21350 and 1005 mg/L, respectively. Among the heavy metals, aluminum, iron, manganese and zinc have the highest concentrations with the values of 1400, 956, 588 and 100 mg per kg of dry solids, respectively. The measured concentrations for cadmium were also higher than the permissible limits for agricultural purposes and discharges into the environment. The average concentrations of nickel were more than the recommended standard for industrial, agricultural and parkland application purposes. The concentrations were also slurry higher than the dry sludge.
According to the past studies and results of this study, it could be concluded that contamination of heavy metals in sludge and slurry samples are more than dried sludge, .Therefore, if they are discharged into the environment, it is better to be disposed as dry sludges. Furthermore, because these types of waste sludges are routinely disposed in the environment, it is recommended to take the routine samples in order to measure the heavy metals and other relevant parameters contents of sludge before discharging it.