BOD and COD Reduction Using Stratified Filter and Constructed Wetland

Abstract

Blackwater is known to be the major pollutant for the river ecosystem. As a solution, previous studies revealed that the filtration method and wetland system can be applied to remediate the blackwater. This study aimed to investigate the ability of stratified filter method combined with wetland system to reduce the level of BOD (Biological Oxygen Demand) and COD (Chemical Oxygen Demand). The stratified filter was composed using three materials, including gravel, charcoal and concrete sand. Meanwhile, the wetland system was constructed by utilizing Vetiver grass (Vetiveria zizanioides) and Cattail (Typha angustifolia). The treatment was obtained by applying different sand thickness and residence time in the wetland tube. The observation was emphasized on the measurement of BOD and COD level during the process. Generally, the result showed that stratified filter can reduce the levels of BOD and COD. However, the final results of residence time in the wetland tube have yet to meet the national standard of Class IV water. This does not necessarily mean that the method was ineffective, but the longer residence time is preferable for blackwater treatment.