Performance of a Fixed-Bed Bioreactor Using Diatom Biofilms for Wastewater Bioremediation

This present study aims to demonstrate the efficiency of a simple biological wastewater treatment process using diatoms for removing mainly nitrogen and phosphorus from four types of effluents: synthetic wastewater (SW), a real urban effluent (RUE), industrial effluent (IE), and agricultural sewage (AS). The process consists of promoting the attachment of diatoms to several grain sizes to form biofilms, to define the best grain size for the performance and to study the evolution of diatom biofilms and some parameters, such as ammonium, nitrate, phosphorus, and chemical oxygen demand (COD). Diatoms used in this study are collected from the highest rate of biomass growth of diatoms grown in an experimental photobioreactor. Initially, four fixed-bed bioreactors in batch mode are experienced over artificial conditions and filled with coarse sand (B1), small gravel (B2), medium gravel (B3), and coarse gravel (B4). The bioreactor B2 is selected to study the evolution of nutrients for the four types of wastewater. The best removal rates are measured as 75.26% for ammonium, 72.43% for nitrate, and 61.65% for phosphorus for SW. Important rates of COD are also recorded for RUE (75.29%). These results demonstrate that nutrients in the wastewater can be successfully removed by diatom biofilms.