Current status and views on the discharge of domestic wastewater to the environment in developing Asia

ABSTRACT A sufficient water supply is important for human health; however, it results in the generation of large amounts of domestic wastewater. This study aimed to determine the impact of domestic wastewater on the surrounding environment as well as residents' opinions on the issue. Domestic wastewater consists of blackwater (toilet wastewater) and greywater (miscellaneous domestic wastewater), each of which is discharged in different ways. Blackwater was treated using a septic tank, without the required desludging, despite policy goals, owing to a lack of awareness among residents as well as structural problems. However, the targeted septic tanks efficiently removed microbiological indicators. It is assumed that the larger capacity and tropical savanna climate, with consistently high temperatures, were beneficial for the treatment process. Greywater was discharged into public waters without any treatment and caused degradation of the waterside environment. More than 70% of respondents thought there was a problem with the canal that flows close to houses; however, there was variation in the awareness. It is necessary to reduce the greywater load from each household at the source as much as possible, and this goal requires residents to have an accurate understanding of greywater emissions.