Comparative evaluation of needle-felt coir fibre with conventional media in treatment wetlands

Abstract

The application of low-cost natural filter beds in treatment wetlands offers substantial environmental and economic benefits. This study investigates the use of needle-felt coir fibre (NCM) as a viable alternative to conventional filter bed materials viz. conventional gravel (CGM), waste concrete (COM), broken bricks (BBM), and coconut shells (CSM) in vertical up-flow treatment wetlands planted with Canna indica. The performance was assessed for organic content, nutrient and pathogen removal. Media characteristics such as porosity, size, shape, and elemental composition significantly influenced removal efficiencies. Media with higher porosity and elements like Al, Ca, K, and Fe facilitated better organic matter and nutrient removal and supported growth of Canna indica. The performance trend of the filter beds for organic matter and nutrient removal was NCM > BBM > COM > CGM > CSM. The removal percentages for NCM were 73.21 ± 9.3 %, 89.3 ± 0.6 %, 48.38 ± 22.9 %, and 50.21 ± 28.9 %, respectively for COD, BOD, TN and TP, respectively. The COD removal efficiency in NCM was nearly 39 % higher than CGM and 18 % higher as compared to BBM. The TN and TP removal efficiency in NCM was also higher than the CGM by 23 and 44 %, respectively. The pathogen removal in NCM was more effective, with a 2.7 log reduction for Vibrio and 2, 1.9, and 1.4 for Salmonella, E. coli, and Klebsiella. The metagenomic analysis revealed a diverse microbial community associated with NCM, which enhances pollutant removal. The microbial communities in the rhizosphere and media showed distinct abundance patterns.