Relationship between manual air valve positioning, water quality and energy usage in activated sludge processes

Samuel Reifsnyder; Manel Garrido-Baserba; Francesca Cecconi; Larry Wong; Phil Ackman; Nikos Melitas; Diego Rosso

doi:10.1016/j.watres.2020.115537

Relationship between manual air valve positioning, water quality and energy usage in activated sludge processes

Water Res. 2020 Apr 15:173:115537. doi: 10.1016/j.watres.2020.115537. Epub 2020 Jan 27.

Authors

Samuel Reifsnyder¹, Manel Garrido-Baserba², Francesca Cecconi³, Larry Wong⁴, Phil Ackman⁴, Nikos Melitas⁴, Diego Rosso⁵

Affiliations

¹ Department of Civil and Environmental Engineering, University of California, Irvine, CA, 92697-2175, USA; Water-Energy Nexus Center, University of California, Irvine, CA, 92697-2175, USA. Electronic address: sreifsny@uci.edu.
² Department of Civil and Environmental Engineering, University of California, Irvine, CA, 92697-2175, USA; Water-Energy Nexus Center, University of California, Irvine, CA, 92697-2175, USA. Electronic address: mgbaserba@gmail.com.
³ Department of Civil and Environmental Engineering, University of California, Irvine, CA, 92697-2175, USA; Water-Energy Nexus Center, University of California, Irvine, CA, 92697-2175, USA. Electronic address: fcecconi@uci.edu.
⁴ Sanitation Districts of Los Angeles County, 1955 Workman Mill Rd, Whittier, CA, 90601, USA.
⁵ Department of Civil and Environmental Engineering, University of California, Irvine, CA, 92697-2175, USA; Water-Energy Nexus Center, University of California, Irvine, CA, 92697-2175, USA.

PMID: 32014702
DOI: 10.1016/j.watres.2020.115537

Abstract

Diffused aeration is the most implemented method for oxygen transfer in municipal activated sludge systems and governs the economics of the entire treatment process. Empirical observations are typically used to regulate airflow distribution through the adjustment of manual valves. However, due to the associated degrees of freedom, the identification of a combination of manual valves that optimizes all performance criteria is a complex task. For the first time a multi-criteria optimization algorithm was used to minimize effluent constituents and energy use by parametrizing manual valves positions. Data from a full-scale facility in conjunction with specific model assumptions were used to develop a base-case facility consisting of a detailed air supply model, a bio-kinetic model and a clarification model. Compared to the base-case condition, trade-offs analysis showed potential energy savings of up to 13.6% and improvement of effluent quality for NH₄⁺ (up to 68.5%) and NO_x (up to 81.6%). Based on two different tariff structures of a local power utility, maximum costs savings of 12800 USD mo^-1 to 19000 USD mo^-1 were estimated compared to baseline condition.

Keywords: Aeration; Air valve; Multi-objective; Pareto; Wastewater.

MeSH terms

Bioreactors
Oxygen
Sewage*
Waste Disposal, Fluid
Water Purification*
Water Quality

Substances

Sewage
Oxygen