# Brown Coconut Husks as Media Within an Anaerobic Filter for Improving On-Site Wastewater Treatment
## 4 Discussion
This suggests that the coconut husks may not need frequent replacement; however, further work would be needed to determine the frequency of maintenance needed. The findings of this work suggest that the use of brown coconut husks within an anaerobic filter shows potential as an appropriate solution for improving wastewater treatment from septic tanks in countries where coconut husks are abundant. The key limitation of this study is the use of synthetic wastewater. While the use of synthetic wastewater is needed to provide consistency and evaluate treatment over time, future work should move to evaluating this process at a larger scale using household wastewater. This would serve several purposes. The use of wastewater from a household would allow the true variations in daily wastewater use to be evaluated. While this study attempted to mimic daily wastewater production, actual daily and weekly variations need to be evaluated. The presence of pathogens within wastewater would also allow any form of pathogen removal to be determined. The start-up of the reactor could also be evaluated. The anaerobic filter would be receiving wastewater from the septic tank, which contains an anaerobic environment. The constant inoculation of microorganisms from the septic tank \begin{table}
\begin{tabular}{c c c c c c} \hline
**Coconut Shell or** & **Wastewater Type** & **Average Feed** & **Hydraulic** & **Percentage** & \\
**Husk Type** & **Concentration** & **Retention Time** & **COD** & **Source** \\  & & **(mgCOD/L)** & **(hours)** & **Removal** & \\ \hline Coconut shells & Raw sewage & 1105 & 9 & 73\% & [17] \\ Coconut shells & Raw sewage & 982 & 9 & 65\% & [26] \\ Coconut shells & Raw sewage & 837 & 16 & 63\% & [18] \\ Dried green & Raw sewage treated & 403 & 16.8 & 51\% & [16] \\ coconut husks & by septic tank & 403 & 16.8 & 51\% & [16] \\ Fresh green coconut husks & Synthetic wastewater & 125 & 16.8 & 21\% & [20] \\ Brown coconut husks & Synthetic wastewater & 125 & 16.8 & 49\% & [20] \\ Brown coconut husks & Synthetic wastewater & 250 & 12 & 68\% & This study \\ \hline \end{tabular}
\end{table} 
Table 2: Summary of studies examining the use of coconut husks or shells in anaerobic filters treating household wastewater. may mean that the anaerobic filter would not require inoculation; however, this needs to be tested as inoculation with material such as cow manure may speed up the start-up phase. Longer-term operation of the reactor is required to establish the frequency of maintenance for the system. This would be dependent on the breakdown of the coconut husks themselves, which may compress and block the filter over time. The formation of biofilms may also build up to the point of causing a blockage. If this occurs, then the filter may need flushing to allow for longer operation. This work should be conducted using household wastewater to provide the most useful information on these key parameters. Finally, the eventual disposal of the coconut husks needs to be evaluated, but this does depend on the final physical characteristics of the coconut husk pieces and cultural considerations. Once this information has been determined, a robust framework should be used to evaluate this technology against alternative solutions, accounting for economic affordability, treatment performance, and environmental sustainability in addition to local stakeholder input to consider social and cultural needs [28].