What's the cost-effective pattern for rural wastewater treatment?

Inadequate sanitation infrastructure is a global problem that is particularly impacting rural areas. And decentralized wastewater management system is considered as the feasible solution for rural sewage treatment (RuST). However, determining the cost-effective (CE) pattern for decentralized RuST is methodologically challenging because of scarce decision-support tools. In this research, a RuST optimization model (RuST-OM) was developed to gain an insight into the CE pattern of RuST based on the greedy algorithm. This model involves tradeoffs in the economy-of-scale and technology of wastewater treatment system versus the cost and energy consumption of the sewage collection system. The investment associated with the CE pattern for RuST is closely linked to the environmental demand, RuST coverage, topographic complexity, and degree of household dispersion. The cost of the CE pattern falls between the onsite-B and community-based pattern, and this range represents the optimized interval for RuST planning. Nature-based technology is a sustainable alternative for RuST in areas characterized by low or moderate environmental demand. To ensure applicability of the RuST-OM in other countries/regions, built-in datasets (e.g., technology and pipeline design parameters) are designed based on rural area features that can be modified as necessary. This research highlights the utility of the CE pattern for RuST planning, and can serve as a reference for RuST planning around the world.