Efficiency Analysis of Coagulant and Energy Consumption of Surabaya Water Treatment Plant using Data Envelopment Analysis MethodAchmad Muzakky, Al Rizal Fiqri Dwi Ramdhani, R. Irwan Bagyo Santoso, Hilmi Putra Pradana and Ervin NurhayatiBIO Web Conf., 216 (2026) 06003DOI: https://doi.org/10.1051/bioconf/202621606003