Abstract: Given rural domestic wastewater with small quantity and scattered distribution, an environment-friendly decision framework based on the hybridization of clustering and bi-objective mixed-integer programming (BOMIP) is proposed to plan wastewater treatment networks systematically and efficiently. The clustering corresponds to the wastewater collection stage, while the BOMIP matches the wastewater treatment stage. An improved NSGA-II algorithm is found to solve the model to make decisions related to plants locations and pipes laying. A numerical example verifies the case with the basic data of a typical village in the Yangtze River Delta region. The computational results demonstrate that the solution quality of the improved algorithm is close to that of the conventional constraint method but with less time. The proposed framework and algorithm could help decision-makers to build cost-effective and environment-friendly rural wastewater treatment networks.

Key words: rural wastewater, pipe network optimization, environment disutility, bi-objective mixed-integer programming, decision support, non dominated sorting genetic algorithm-II (NSGA-II)