• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.12 no.3
• /
• pp.175-179
• /
• 1979

One of the major problems in tile activated sludge system has been difficulty in separating the microbial solids from the treated effluent and in returning them to the aeration tank. Another problem has been the digestion of the excess activated sludge. In constrast, it has not been difficult to separate the microbial solids from the treated effluent from the biological fixed-film systems(RBC process, Trickling Filter, FAST process). These systems have also featured less sludge production. Recently, it was proposed to experiment with the RESMAS process in order to eliminate the settling tank and sludge concentration facilities and to reduce the quantity of excess sludge for final disposal. The effluent quality could be predicted by .the concept of the maximum accumulation capacity. However, the hydraulic characteristics of the screen media in the RESMAS reactor were not dynamic. The object of the present study is to evalute the sludge accumulation rate and effluent quality prediction in the REMSMAS process designed in the dynamic hydraulic structure. This process can eliminate the final sedimentation tank and sludge concentration tank needed in the RBC, CMAS, Trickling Filter and FAST processes. Also, the effluent quality is desirable to compare with other processes. It appeared that the value of the sludge holding capacity was higher than those of the RESMAS and FAST processes, and the periods of the critical operating time were proportional to the substrate hydraulic loadings.

• Journal of the Korean Society of Radiology
• /
• v.9 no.1
• /
• pp.9-16
• /
• 2015

The purpose of this study is finding optimum contrast medium quantity during abdominal CT using dual energy technique. The study subjects are 30 patients who had received general single energy abdominal CT and received double energy technique follow-up abdominal CT. dual energy technique abdominal CT images were obtained after setting contrast medium quantities at 30%, 40%, 50%, 60% and 70% of contrast medium quantity at the time of single energy technique. Then the contrast enhancement (Hounsfield Unit; HU) was estimated by setting-up the regions of interest at aorta, inferior vena cava, hepatic portal vein and hepatic parenchymal. The obtained values were compared to the values of the same parts measured during single energy technique abdominal CT. The results of the study were as following. The 60% set up group had HU in aorta : $210.80{\pm}13.609$, IVC : $190.40{\pm}25.215$, hepatic portal vein : $198.40{\pm}21.232$ and hepatic parenchymal : $119.20{\pm}7.98$, The single energy abdomianl CT images had HU in aorta : $205.40{\pm}16.426$, IVC : $188.20{\pm}21.476$, hepatic portal vein : $195.40{\pm}22.744$ and hepatic parenchymal : $121.00{\pm}6.595$. Therefore, it is possible to obtain contrast enhancement by dual energy technique abdominal CT similar to the same by single energy technique abdominal CT by setting-up the quantity of contrast medium at 60% of contrast medium at the time of single energy technique abdominal CT. Based on the result of this study, it is possible to decrease existing quantity of contrast medium by _% and the injection velocity can be also decreased. Accordingly, it is believed that the result of study would be quite useful for patients who have renal function disorder, weak vein or side effect of contrast medium in the past.