Identifier

etd-12192003-173942

Degree

Master of Science in Civil Engineering (MSCE)

Department

Civil and Environmental Engineering

Document Type

Thesis

Abstract

Lauryl Alkylbenzene Sulfonate (LAS) is the major anionic surfactant used worldwide in detergent and household cleaning product formulations. Its biodegradation and removal has been extensively studied in wastewater treatment facilities and laboratory-scale tests at low concentrations (<10 mg/L) typical of those encountered in municipal wastewater treatment plants. Less effort, however, has been expended investigating degradation of higher concentrations of LAS representative of those expected in wastewater generated at LAS manufacturing operations. The research described in this thesis was conducted to study biological processes for treating wastewaters containing high concentrations (e.g., 400 mg/L) of LAS. Initial experiments were carried out using a respirometry technique, and subsequently, three different laboratory-scale bioreactor systems. The three systems studied were a Sequencing Batch Reactor (SBR), a Sequencing Batch Biofilm Reactor (SBBR), and an Intermittent Cycle Extension Aeration System (ICEAS). The SBR and ICEAS were operated on a five-day cycle basis with a hydraulic retention time of four days. The SBBR was operated mainly in a two-day cycle having a hydraulic retention time of ten days as well, and polyurethane foam cubes were used as a support medium for attached biomass growth. The three systems were compared on their ability to remove LAS measured in terms of total organic carbon (TOC) and methylene blue active substances (MBAS). The reactors were also compared on the basis of foam production. The ICEAS showed the best performance in terms of controllable foam production while exhibiting a capacity for effectively dealing with transient periods of elevated loading. When a short Fill period was used, the SBR and SBBR had the disadvantage of producing excessive foaming, and an intermittent aeration strategy was required avoid overflow.

Date

2004

Document Availability at the Time of Submission

Release the entire work immediately for access worldwide.

Committee Chair

William M. Moe

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