Performance Comparison of Waste Stabilization Ponds and Centralized Mechanical Wastewater Treatment Plants in Urban Domestic Wastewater Treatment

Abstract

Indonesian cities treat their piped domestic wastewater through two very different families of centralized technology. Plants built in the early 1990s under bilateral and multilateral loans generally use waste stabilization ponds (WSP), while almost everything commissioned after 2010 uses compact mechanical reactors such as anaerobic baffled reactors with aerobic biofilters, or moving bed biofilm reactors. This study compares the two families using operational data from six urban plants: Bojongsoang in Bandung Regency, Sewon in Bantul, Pucangsawit, Mojosongo and Semanggi in Surakarta, and Losari in Makassar. The study is a descriptive comparative analysis of secondary data taken from peer-reviewed evaluations and monitoring reports published between 2019 and 2026. Removal efficiency was calculated for BOD, COD and TSS, effluent quality was checked against Permen LHK No. 68 of 2016 and its successor Permen LH No. 11 of 2025, and land intensity was expressed as square metres of plant area per cubic metre per day of design capacity. The pond system at Bojongsoang removed 70.33 to 84.95 percent of influent BOD across four consecutive years and 72.47 to 87.23 percent of TSS, with the spread between the best and worst year staying under fifteen percentage points. The mechanical plants produced a much wider range, from 20.45 percent BOD removal at Semanggi to 97.86 percent at an MBBR facility in Jakarta. Land intensity ran about 4.3 square metres per cubic metre per day at Sewon against roughly 1.6 at Losari. Neither family is better in the abstract. Pond systems are steadier and cheaper to run but consume land that most Indonesian cities no longer have, while mechanical plants reach higher peaks and fall further when aeration or maintenance lapses. Both are undermined by the same problem, which is that sewer connection rates are too low to load the plants anywhere near their design flow.