Reduction of BOD and COD of by using stratified filter and constructed wetland for blackwater treatment

Abstract

Blackwater is a type of domestic wastewater that must be processed before discharge into the river. This study uses gravel, sand, and charcoal as filtration materials which arranged from coarse to fine, and also wetland system using Vetiver grass (Vetiveria zizanioides) and Cattail (Typha angustifolia). The treatment process is obtained by applying different treatments related to the sand thickness and blackwater residence time in the wetland. The focus of observation is emphasized on the measurement of BOD (Biological oxygen demand) and COD (Chemical oxygen demand). Both parameters measured and compared with the standard of water for agricultural purposes (Grade IV) regulated by Indonesian Government. The results showed that stratified filters can reduce the levels of BOD and COD effectively. The final results obtained after blackwater flowed through the wetland tube shows that BOD and COD levels have yet to meet the standard of grade IV water, although the overall result indicated the significant reduction of both parameters. This can be related to the input of organic matter from wetland itself, and it also can be considered an indication that blackwater treatment requires longer residence time.