The need for proper management of bilgewater to meet discharge regulations (e.g., 15 ppm oil) has revealed the necessity to expand the current understanding of bilgewater emulsions. This study proposed to evaluate emulsion stability under various environmental conditions and to identify governing parameters for emulsion formation. The stabilizing properties of eight-commercial cleaners and two-neat surfactants were evaluated. In situ characterization techniques were used for monitoring emulsion stability. Additionally, a needle-type pH microsensor and fluorescence spectroscopy were used for analyzing mass transfer at the oil-water interface. Water quality of extracted bilgewater showed to highly vary between vessels (e.g., conductivity: 1.74 -- 24 mS/cm, chemical oxygen demand [COD]: 1,279–42,800 mgO2/L, and total suspended solids [TSS]: 256–4,248 mg/L). Emulsion stability was significantly affected by surfactant type, temperature, and salinity. In particular, increase in salinity and temperature greatly reduced emulsion stability by enhancing emulsion coalescence. From the surfactants/detergents tested, emulsion stability was in the order of Type 1 > SDS > B&B > Power green > Solid surge> Calla= PRC > Triton X-100 > 6% AFFF= Blast-off from most to least stable. Suspended solids stabilized emulsions under certain environments, particularly at 0.5 x CMClog. Alkalinity of emulsifiers was found between 3.3 -- 413 mg/L CaCO3 and the presence of unknown additives in the NSBM#4 showed to increase emulsion alkalinity. pH microprofiles demonstrated the diffusion of additives at the interface, which was verified by the increase in bulk-water fluorescence, indicating the diffusion of organic compounds. In addition, the diffused additives enhanced the formation of stable emulsions. Overall, this study presents a systematic investigation of bilgewater emulsion characteristics using multi-faceted experimental approaches from conventional methods to a novel microsensor technique. The effect of environmental parameters on the formation and stability of bilgewater emulsions was evaluated. This work intended to assist in the selection of more suitable bilgewater treatment techniques and the detection of bilgewater conditions triggering emulsion stability.

Graduation Date





Lee, Woo Hyoung


Master of Science (M.S.)


College of Engineering and Computer Science


Civil, Environmental and Construction Engineering

Degree Program

Environmental Engineering; Environmental Engineering Sciences







Release Date

November 2020

Length of Campus-only Access


Access Status

Masters Thesis (Open Access)