# Shifting from Conventional to Organic Filter Media in Wastewater Biofiltration Treatment: A Review
## 5 Research Prospects  
Based on this review, many intensive studies are needed to overcome the limitations or drawbacks of biofilters. Unlike conventional filter material that could reach up to 50% of the operational cost, utilizing organic materials or plant-based wastes as the alternative filter media should be focused on in the future due to their advantages such as cost-effectiveness and environmental friendliness. The characterization of organic material in terms of physicochemical and morphological properties and their respective potential as biofilter media is notably important to provide structural stability in the cleaning process. The physicochemical and morphological characterization of established organic media can be a significant reference for researchers when selecting suitable alternative organic filter media. Another limitation of the biofilter is the time-consuming acclimatization of a biofilm on the new filter medium, which results in a longer start-up period; thus, further studies should be focused on identifying a suitable method to reduce the start-up period and enhance the biofilm formation on the filter media.  
Further investigation in the future on the optimum operating conditions for simultaneous nitrification and denitrification (SND) in a single biofilter reactor will also be relevant as the operating conditions for the SND process are difficult to obtain and maintain throughout the treatment process. Identification of these suitable environmental conditions that promote the coexistence of nitrifiers and denitrifiers is important to ensure the microbial stratification and feasibility of the SND process. Moreover, there is a lack of studies that apply an organic material as a carbon source in the SND biofiltration system. Therefore, studies should focus more on investigating alternative types of organic materials that are suitable as biodegradable media, which have carbon releasing ability, that ensure the sufficient supply of donor electrons for the denitrifying organisms in the biofiltration system.  
Studies also need to be conducted on the cold-water temperature effects on the removal performance of biofilters. Currently, there is a lack of novel methods to overcome the limitation in terms of the decrease in bacteria growth rate due to the cold-water temperatures. Moreover, the assessment of the kinetic analysis of organic media biofilter removal performance is an aspect that is least considered. Extensive analysis is needed on the development and modeling of the kinetics analysis for the treatment process in an organic media biofilter, which serves to clarify the removal mechanism of the organic media biofiltration treatment system. Further characterization of the microbial community present in an organic media biofilm concerning their role in pollutant removal is needed as the microbial species is highly related to the biofilter removal performance. Up to date studies regarding the microbial community present on the organic media and their relationship with the operational conditions of the biofilters are still rare.