Accelerated Start-Up and Microbial Community Using Novel Plant-Based Waste Biofilter Media for Treatment of Real Domestic Wastewater via Simultaneous Nitrification and Denitrification

In this study, plant-based Cocos nucifera fiber media were prepared and implemented in a simultaneous nitrification and denitrification (SND) biofilter. The experimental results revealed that the fiber media contained ideal biofilter media properties, such as high porosity (82.33%) and large specific surface area (3.23 m2/g). Additionally, the high lignin composition (44.6%) provides resistance to biodegradation, thereby increasing the media’s lifespan, which is estimated to be an overall lifespan longer than 5 years. The fiber media facilitate the start-up process, enabling the biofilter to start up within 30 days and perform remarkably in terms of chemical oxygen demand (COD), soluble chemical oxygen demand (sCOD), total suspended solids (TSS), ammonia (NH3–N), nitrate (NO3–N), and nitrite (NO2–N) removal. The ammonia, high nitrite, and nitrate removal were confirmed by the presence of nitrite-oxidizing bacteria (NOB) (Nitrospira), heterotrophic nitrifying and aerobic denitrifying (HNAD) bacteria (Acinetobacter), and denitrifiers (Dechloromonas) within the coconut fiber media biofilm. It was also discovered that there was no system failure during the nonfeeding period, and the system performance quickly recovered after the second feeding day.