a b s t r a c tCoal Fly Ash and Coal Bottom Ash are a solid waste generated from coal combustion. Recently, the management of these wastes has become an important subject for environmental researchers. Due to their physical and chemical characteristics, coal ashes were used in different fields like building material, agriculture and wastewater treatment. In the present investigation, a radiological assessment of Waste Water Treatment Plant (WWTP) based on the use of coal ashes as filters was performed. The WWTP under investigation uses four stages of treatment: Coal Fly Ash filtration, Coal Bottom Ash filtration and sand filtration. Radiation risk of coal ashes was evaluated by 2 techniques: Dosimetry alpha based on the use of LR115 detector and gamma ray spectrometer. The surface exhalation rate in coal ash samples were found to be below the world average 57600 mBq•m À2 h À1 and most of the coal ash samples show the value of Raeq less than the allowed upper limit of 370 Bq kg À1 . Moreover, the radon concentration of water samples during the treatment were evaluated for each stage in order to identify if there was any impact of coal ashes on the treated water. Radon activity of treated water remains in the standards with a average value of 196 ± 13 (Bq/m 3 ) less far than the permissible limit (11100 Bq/m 3 ). The obtained results indicate that the radiological characteristics of the treated water was not influenced by radiological characteristics of coal ashes. It be concluded that coal ashes from TAQA Morocco are a safe materials and did not present a significant radiological risk which make them a suitable material for wastewater treatment.

The production of electrical energy in thermal power plants generates huge quantities of solid waste (fly ash and bottom ash). The valorization of these by-products becomes imperative for safeguarding the environment. The fly ash is used in the manufacture of cement; but locally, it is not the case of the bottom ash that is buried in landfills. In this paper, we present the results of wastewater treatment of a cardboard plant by an optimized prototype cascade station (scale: 1/1000). The succession of filter beds consists of crude bottom ash, crushed bottom ash, and coastal sands in appropriate proportions. The filtrate at the outlet of each floor is analyzed. Respecting the current regulations, the desired parameters are the suspended solids (TSS), COD, BOD 5 , pH, and trace elements (As, Fe, Zn). The results of the tests allowed us to reach a COD abatement is 85%. When leaving the 3rd floor, it was 94.5% and finally, at the exit of the fourth, it is 95%, an important reduction of BOD5. At the exit of the 2nd floor, the abatement is 75.6%, at the exit of the 3rd, it is 78.6%. Finally, an overall rate of 79% was obtained, a significant TSS reduction up 95.6% at the output of the 2nd floor. By leaving the 3rd floor, it is 96.12%. Overall, the developed system achieves a TSS abatement rate TSS of 96.34%.and the elimination of trace elements such as zinc, iron, and arsenic (84%, 48%, and 57% respectively).

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