Urban wastewater (Fez, Morocco): characterisation and coagulation-flocculation treatment

In this work, characterisation of urban wastewater from Fez City, Morocco, consisting mainly of a mixture of industrial and urban discharges, and its treatment using the coagulation-flocculation (C-F) process were conducted. Three coagulants were used: lime (Ca(OH)(2)), ferric chloride (FeCl3) and alum (Al-2(SO4)(3)). Ferric chloride achieved the highest reductions in turbidity, chemical oxygen demand (COD) and colour. Then, the Box-Behnken design was applied to optimise the amounts of the coagulant and flocculant and pH. The maximum response values were 78, 98 and 99% for COD, colour and turbidity, respectively, under the following optimal operating conditions: [FeCl3] = 720 mg/l, [flocculant] = 150 mg/l and pH = 7. The operational cost of C-F implemented in this study was estimated at US$0.52/m(3), proving that it could be a competitive and cost-effective process for the treatment of wastewater. These results will contribute to the existing literature and would be valuable for scaling up the C-F process.