# Shifting from Conventional to Organic Filter Media in Wastewater Biofiltration Treatment: A Review
## 3 Filter Media Selection on the Efficiency of Biofililtration
### Conventional vs. Organic Filter Media Biofiltration Systems
The removal efficiencies of 90.8% of ammonia, 95.5% of iron, and 95.9% of manganese were achieved in their study. [PERSON] et al. [82] also reported on full-scale biofiltration for drinking water treatment using GAC and sand dual media in achieving a steady removal of NH\({}_{4}\)-N. In their finding, 57.0% of NH\({}_{4}\)-N is removed through complete nitrification while 21.5% of NH\({}_{4}\)-N is partially nitrification to NO\({}_{2}\)-N.  
With organic materials, [PERSON] et al. [62] utilized agricultural waste materials such as rice straws, date palm fibers, and wood chips of an orange tree as the biofilter media in the municipal wastewater treatment operated under a hydraulic rate of 4.8-12 m\({}^{3}\)/d. All of the materials show remarkable removal efficiency ranging from approximately 32.0% to 89.0% in terms of BOD\({}_{5}\), COD, TSS, TN, and TP. [PERSON] et al. [31] also noticed the good performance of _Agave_ fibers as a filter media operating under a consistent aeration rate of 0.62 m\({}^{3}\)/m\({}^{2}\)/h in treating municipal wastewater with removal efficiencies of 92.0%, 79.7%, 91.9%, 98.0%, and 99.9% for BOD, COD, TSS, helminth eggs, and fecal coliforms, respectively. Moreover, [PERSON] et al. [61], utilizing _Arundo donax_ as the filter media and an external carbon source in the anoxic/oxic biofilter, witnessed that the carbon releasing characteristics of the organic materials tend to exist as an external carbon source in the biofiltration system, thus promoting the denitrification process. The biofilter was operated under a temperature of 18-25 \({}^{\circ}\)C, an air water ratio of 4:1, and filtration rates of 1.35 m/d for the oxic column and 3.34 m/d for the anoxic column. From their study, the biofilter successfully removed 99.0% of NH\({}_{4}\)-N and 68.8% of TN from low C/N rural domestic sewage. Based on our review, biofiltration with organic media shows better performance in terms of the start-up period, denitrification efficiency, and organic matter removal compared to the conventional media biofilter. The start-up period or the biofilm formation on the conventional filter media takes around 20 days to 6 months while organic filter material requires a shorter period, i.e., ranging from 15 days to 3 months. The better start-up performance is believed to be attributed to the characteristics of organic media that provide sufficient surface for the attachment of a microbial community. Some of the organic materials comprise similar properties to GAC, such as large specific surface area, high porosity, and good adsorption ability due to the presence of functional groups, which promote the attachment of a biofilm [18]. Furthermore, the presence of cellulose, hemicellulose, and lignin in some of the organic materials offers a sustainably slow release of carbon sources and structure that supports the growth of denitrifiers and biofilm [95]. Moreover, the denitrification process is usually facilitated by the presence of a sufficient organic matter concentration in the treatment system; however, most of the treated water does not exhibit a sufficient C/N ratio and organic matter for the denitrification process. Therefore, an additional carbon source is needed to maintain the appropriate C/N ratio and organic substrate in the treatment system [59]. According to [PERSON] et al. [61], the carbon releasing ability of organic materials acts as a carbon source to promote the growth of denitrifiers, which then enhances the denitrification process and total nitrogen removal. This observation is supported by the study by [PERSON] et al. [94] which reported on the greater relative abundance of denitriftiers found in organic media compared to inorganic media. Other than that, the presence of chemical functional groups in organic materials facilitates chemical binding and improves the adsorption capacity of organic contaminants [57].