Energy Footprint Analysis of Orange County Sanitation District's Operations

The Orange County Sanitation District (OCSD) is one of the largest utilities wastewater in the United States, with a combined average flow treated exceeding 200MGD in dry days, and serving several million inhabitants of the Orange County, CA basin. OCSD owns and operates two treatment plants (Plant 1 in Fountain Valley, CA; Plant 2 in Huntington Beach, CA), inclusive of three biological processes: activated sludge (ASP) and trickling filters (TF) at Plant 1, high-purity oxygen (HPO) at Plant 2. Also, part of Plant 1 effluent (approximately 75 MGD) is currently sent to the neighboring OCWD plant for water reuse, and the remaining effluent (on average, exceeding 20MGD) is sent to Plant 2 for ocean discharge. Both plants are undergoing expansion. The OCSD Plants operate on-site co-generation at both facilities. Co-generation, on average, supplies 65-70% of the total energy drawn, the remaining being imported.This study presents the time-dependent energy footprint analysis of OCSD's operations. Our dynamic models output results as time-series with same frequency as available process data. This study is one of the components of our 2-year project to develop carbon and energy footprint models for these large treatment plants. The results presented help furthering our understanding of the role of all process components in energy footprint models. Also, our model benefits the wastewater treatment community at large by providing a valuable tool for modeling, simulation, and prediction of energy footprint in dynamic conditions.