Low-cost Packing Materials in an Aerated Biofilter for Lagoon Effluent Treatment

Abstract

As part of a comprehensive evaluation of post-treatment techniques for the removal of chemical and microbiological pollutants from lagoon effluents, an aerated biofilter was designed. The main objective of this study was to evaluate the performance of pozzolan and Luffa cylindrica as low-cost packing materials for the advanced treatment of Stidia natural lagoon effluent. The aerated biofilter operates in down-flow with HLRs of 11.37 to 28.43 m3 m−2 d−1 and an air/liquid flow ratio of 3 : 1. The different experiments performed on the pilot showed that the percentages of sCOD removal vary with the HLRs and the wastewater concentration at the biofilter inlet. In this study, sCOD removal efficiencies above 78.9 % were achieved depending on HLR, and a maximum removal efficiency of TSS of 71.5 % was obtained for 28.43 m3 m−2 d−1. At low HLR (11.37 m3 m−2 d−1), the treated effluent had the following average concentrations: sCOD of 29.5 mg l−1, BOD5 of 21.7 mg l−1 and TSS of 26.4 mg l−1. These experimental results were used with an empirical model to determine the media constant n and treatability factor K. The faecal coliforms and Escherichia coli detected in the treated effluent were less than 105 CFU/100 ml, which meet the national guidelines for wastewater reuse in irrigation.

Keywords

• natural lagoon
• wastewater reuse
• aerated biofilter
• luffa cylindrica
• pozzolan