ABSTRACT
The present study aims to utilise the advantage of higher sludge solubilisation potential of sodium hydroxide (NaOH) and sludge management properties of lime to achieve sludge pretreatment and its subsequent management. The optimum dosage and time required for sludge pretreatment using NaOH was found to be 1.6 g l-1 and 3 hr, respectively. At the optimized condition, lime was added at varying concentration (0.3 to 1.6 g l-1) to study its effect on capillary suction time, soluble chemical oxygen demand (SCOD) release and total phosphorous (TP) removal. A lime dosage of 0.7g l-1 was found to be beneficial for soluble chemical oxygen demand (COD) release. When compared to control, the combination of alkalis (NaOH and lime) reduced the TP and capillary suction time (CST) in the supernatant of the sludge. The TP removal was from 100 to 40 mg l-1 and CST reduction was from 1360 to 350 sec, respectively. The combined alkali pretreatment not only prevent the subsequent TP increase in the effluent, but also decreased the time to filter the sludge, thus makes the digested sludge easier to manage.
ABSTRACT
PURPOSE: The purpose of this study was to compare the difference of change in oxygen saturation, vital signs and suction time taken for the suctioning during endotracheal suctioning performed with closed suction system and with opened suction system. METHODS: Data were collected from 31 adult patients with ventilator treatment who were admitted to a university hospital in Seoul and the collection period was from July 1 to November 15, 2005. Oxygen saturation, heart rate, respiration rate and mean arterial pressure were collected immediately prior to the suctioning intervention, during and 1 and 5 minutes after the suctioning from opened suction system and closed suction system. RESULTS: 1) The difference in oxygen saturation was statistically significant in recovery time for oxygen saturation to return to baseline values after suctioning was significantly rapid on closed suction system (p < .05). 2) The difference in heart rate, respiration rate and mean arterial pressure was statistically insignificant. 3) The suction time was shorter in closed suction system. CONCLUSION: Closed suction system is more efficient, as compared with the open suction system in the ventilator treatment.