Biofilm growth at high COD and particle concentration levels: application to the case of micro-irrigation emitters used for wastewater reuse

Wastewater reuse can properly supply irrigation demand by adopting suitable techniques and practices. Micro-irrigation optimizes water application and minimizes health hazards and crop contamination risks. Nevertheless, clogging is a common problem when using drip irrigation. In this study, we focus on emitters clogging due to biological and physical deposits. Experiments were carried out to investigate the interaction between biofilm growth and mineral particle deposits on 3 types of online emitters using a 200 mg/L COD synthetic effluent with and without mineral particles (size range: 0 to 80 µm). Emitter performance was monitored using flow rate measurement. Moreover the deposits of mineral particles and biofilms were analyzed optically, collected and dried at 105°C for 24 hours. Biofilm and mineral deposit induces flow rate decrease from the 30th day of the experiment. However, without mineral particles, emitter flow rate decrease was more significant. Thus, mineral particles seem to have an abrasive effect on biofilm depending on flow structure.