CW-MFC REACTOR OPTIMIZATION: ANALYSIS OF THE RELATIONSHIP BETWEEN PLANT COMPOSITION AND RHIZOBACTERIA PHYLUM PROFILE ON EFFLUENT TREATMENT EFFICIENCY AND BIOELECTRICITY PRODUCTION

Abstract

This study investigated the optimization of Constructed Wetland–Microbial Fuel Cell (CW-MFC) systems by analyzing the relationship between plant composition, rhizobacterial phylum profiles, effluent treatment efficiency, and bioelectricity production. The research, conducted over six days with a three-day hydraulic retention time, used a horizontal subsurface flow (HSSF) CW-MFC reactor with a total volume of 12.5 liters. Wastewater samples were sourced from domestic wastewater. Key parameters like BOD, COD, and pH were measured according to Indonesian National Standards (SNI), and bacterial diversity was analyzed using Next Generation Sequencing (NGS). The results demonstrated that the reactor utilizing Echinodorus palaefolius, Lactobacillus plantarum (2 x 10⁸ CFU), and a graphite electrode (T2B1E1) showed the most effective BOD and COD removal, achieving 36.36% and 33.57% reduction respectively. This setup also exhibited the highest pH reduction at 13.22%, indicating significant microbial and electrochemical activity. Bioelectricity production was consistently higher during the daytime, with T2B1E1 and a combination plant reactor (T3B1E1) reaching peak power densities of 61.96 mW/m² and 61.16 mW/m² on day six. Analysis of bacterial phyla revealed that the combination of Echinodorus palaefolius and Equisetum hyemale fostered a more balanced microbial community, including Firmicutes, Proteobacteria, Actinobacteria, and Cyanobacteria, suggesting reduced competitive pressure and enhanced system functionality. These findings underscore the critical role of plant selection and microbial interactions in optimizing CW-MFC performance for sustainable wastewater treatment and bioenergy generation.