Experimental Investigation for Monitoring Corrosion Using Plastic Optical Fiber Sensors.

The timely and cost-effective identification of the onset of corrosion and its progress would be critical for effectively maintaining structural integrity. Consequently, a series of fundamental experiments were conducted to capture the corrosion process on a steel plate using a new type of plastic optical fiber (POF) sensor. Electrolytic corrosion experiments were performed on a 5 mm thick steel plate immersed in an aqueous solution. The POF sensor installed on the upper side of the plate and directed downward detected the upward progression of the corrosion zone that formed on the underside of the plate. The results showed that the POF sensors could detect the onset of the upward-progressing corrosion front as it passed the 1 and 2 mm marks related to the thickness of the corroded zone. The POF sensors were designed to optically identify corrosion; therefore, the data obtained by these sensors could be processed using a newly developed graphic application software for smartphones and also identified by the naked eye. This method offered an easy and cost-effective solution for verifying the corrosion state of structural components.

Kinetic study on nitrogen removal performance in marine anammox bacterial culture.

Kinetics of anaerobic ammonium oxidation (anammox) reaction in marine anammox bacterial culture was first investigated. The nitrogen removal performance of the reactor was compared with prediction of Monod model, modified Stover-Kincannon model, first-order and the Grau second-order substrate removal models. Based on calculations, Monod model, modified Stover-Kincannon model and the Grau second-order model proved to be more appropriate to describe the nitrogen removal kinetics of the reactor than first-order model with high determination coefficients of 0.993, 0.993 and 0.991, respectively. According to the modified Stover-Kincannon model, the maximal substrate removal rate (rm) and saturation rate constant (KB) were suggested as 7.37 and 6.41 g N/L/d, respectively. In addition, in light of the Monod model, the saturation concentration (Ks) and the maximal specific substrate removal rate constant (Rm) were determined to be 0.107 g/L and 0.952 g N/g MLVSS/d, respectively. Moreover, model evaluation was carried out by assessing the linear correlation between measured and predicted values. Both kinetics study and model evaluation showed that Monod model, modified Stover-Kincannon model and the Grau second-order substrate removal models could be used to describe the kinetic behavior or design of the marine anammox reactor.

Temperature effect on nitrogen removal performance and bacterial community in culture of marine anammox bacteria derived from sea-based waste disposal site.

Anaerobic ammonium oxidation (anammox) bacteria have been detected in variety of marine environment in recent years, however, there have been only a few studies on their characteristics in the culture. The aim of this study is to reveal the effect of temperature on nitrogen removal ability and bacterial community in a culture of marine anammox bacteria (MAAOB). The MAAOB were cultured from the sediment of a sea-based waste disposal site at the North Port of Osaka Bay in Japan. The maximum nitrogen removal rate (NRR) was observed at 25°C in the MAAOB culture, and it decreased both at below 20°C and over 33°C. The activation energy of the MAAOB culture was calculated to be 54.6 kJ mol(-1) in the 5°C to 30°C range. No significant change in bacterial community according with temperature (5-37°C) was confirmed in the results of polymerase chain reaction and denaturing gradient gel electrophoresis (PCR-DGGE). Meanwhile, a number of bacteria related to the oxidation-reduction reaction of sulfur were confirmed and it is speculated that they involved in the activity of MAAOB and nitrogen removal ability in the culture.