# 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
[PERSON] and [PERSON] [71] examined the use of sand as filter media in the biological denitrification of drinking water and obtained an average of 94.0% NO\({}_{3}\)-N removal efficiency while [PERSON] et al. [74] removed 96.2% of iron, 97.7% of manganese, and 98.2% of arsenic in the treatment of groundwater. A few studies have compared the performance of using sand and anthracite filter media to other alternative media such as GAC and zeolite in the past few years [55; 70]. [PERSON] et al. [70] investigated the application of zeolite and sand as filter media in a lab-scale biological aerated filter in the treatment of textile wastewater. It was observed that zeolite media shows better performance in terms of COD, SS, and TKN removal. The superior performance of zeolite is due to the NH\({}_{4}\)-N ion exchange ability, which favors the growth of autotrophic nitrifiers, thus promoting the TKN removal. [PERSON] et al. [55] demonstrated the treatment of raw stormwater by using GAC and \begin{table}
\begin{tabular}{c c c c} \hline \hline  & & **Organic Media** & \\ \hline
**Organic Material** & **Operating Condition** & **Removal Efficiency** & **Additional Remark** & **Reference** \\ \hline Rice straw & & BOD\({}_{5}\): 81.5\% & & \\  & & COD: 79.7\% & & \\ Rice straw & & TSS: 82.4\% & & \\  & & TN: 50.2\% & & \\  & & TP: 41.9\% & & \\ \hline Wood chips of orange tree & Hydraulic rate: 4.8–12 m\({}^{3}\)/d & BOD\({}_{5}\): 66.7\% & & \\  & & COD: 64.6\% & & Start-up period: 2 weeks \\  & & TSS: 68.3\% & & Treatment of raw sewage \\  & & TN: 45.0\% & & \\  & & TP: 32.5\% & & \\ \hline Date palm fiber & & BOD\({}_{5}\): 88.3\% & & \\  & & COD: 88.3\% & & \\  & & TSS: 86.6\% & & \\  & & TN: 55.0\% & & \\ \hline Mesquite wood chips & Hydraulic Loading Rate: & BOD\({}_{5}\): 92.0\% & & Start-up period: 60 days \\  & 1.07 m\({}^{3}\)/m\({}^{2}\)/d & COD: 78.0\% & & Treatment of municipal \\  & & Aeration rate: & & \\  & 0.62 m\({}^{3}\) air/m\({}^{2}\)/h & Fecal Coliform: 4 units & & wastewater \\ \hline Fibrous Carrier and biological ball & Hydraulic Retention Time: 24 h & TN: 37.0–44.0\% & & Treatment of heavily polluted \\  & & COD: 70.4–80.2\% & & river water \\ \hline _Ficus_ & Hydraulic loading: & & \\ _benjamin_ wood chips & Hydraulic loading: & & \\  & 0.18–0.37 m\({}^{3}\)/m\({}^{2}\)d. & & & \\  & & NH\({}_{3}\)-N: 81.0\% & & \\ \hline Wood Chips & Hydraulic rates: & COD: 80.0\% & & \\  & 0.5–1.5 m\({}^{3}\)/m\({}^{2}\)/d & Volatile solids: & & \\ \hline Peanut shells & & 40.0–63.0\% & & \\ \hline \multicolumn{4}{c}{Air-water ratio: 4:1} \\  & Nitrate Recycling Ratio: & & & \\ \multicolumn{4}{c}{150\%} \\ _Arundo donax_ & Temperature: 18–25 \({}^{\circ}\)C & TN: 68.8\% & & \\ \multicolumn{4}{c}{Filtration rates:} & & \\ \multicolumn{4}{c}{1.35 m/d, 3.34 m/d} & & \\ \hline \hline \end{tabular}
\end{table} 
Table 1: _Cont._anthracite as the filter media under pH 7.5 and a filtration velocity of 0.12-0.25 m/h. The GAC filters show remarkable removal performance in terms of turbidity, DOC, TN, TP, and color with a higher removal efficiency in terms of organic matter and heavy metal compared to anthracite. The superior performance of GAC compared to other alternative media is largely due to the higher specific surface area, adsorption capacity, porosity, and surface roughness that support a denser microbial population compared to sand and anthracite [20,53]. Other than GAC, sand, and anthracite, materials such as expanded clay, polystyrene, polypropylene, and polyurethane also show good treatment performance as biofiltration media. Additionally, some researchers also investigated the use of multi-media by combining different materials as supporting media for a biofilter. [PERSON] et al. [75] conducted a pilot-scale experiment by using a combination of manganese, sand, and anthracite as the filter media operating under a temperature of 8 \({}^{\circ}\)C and pH 7 for the removal of iron, manganese, and ammonia from groundwater.