Performance of pozzolan in trickling filter for secondary treatment of urban wastewater in Tlemcen, Algeria

The research aims to study the purification performance of a local and natural material as an input or as a biological filter for treating urban domestic wastewater. For this purpose, pozzolan was used as the biofiltration support that was provided from Beni Saf located in the North-West of Algeria. Tests were carried out with a specially modified pilot unit (TE900) for wastewater treatment over a period of four months. To assess the efficiency of the treatment, two main parameters have been focused on - the height of the sprinkler filter (40 cm and 80 cm) and the flow rate (10, 16, and 25 dm3∙h-1). Physicochemical and bacteriological analyses were carried out on raw wastewater and treated water. The obtained results show that the Beni Saf pozzolan-filled trickling filter eliminates a large fraction of the studied pollutants. The purification yields obtained are fairly encouraging; 98% for turbidity, 88% for suspended solids (SS), 94% for chemical oxygen demand (COD), and 98% for biological oxygen demand (BOD5 ). As for bacterial indicators, the formation of biofilms has significantly reduced bacterial activity with a percentage of over 80%. It can be concluded that the reduction of pollutant parameters clearly indicates the effectiveness of the treatment by this ecological process. Therefore, the use of local and natural materials for wastewater treatment can be a promising alternative based on sustainable environmental technologies and development.