[A methodological study on treatment of hospital sewage]

With the view to finding a more effective and economic system for the disposal of hospital sewage, a series of experimental and on the spot investigations were conducted. The results are as follows. Disinfection must be taken as the key link in the treatment of hospital sewage. After primary treatment and chlorination, when the product value of concentration (mg/L) multiplied by time (min.) achieved to 240 (general hospital) and 540 (tuberculosis hospital), the content of suspended substances (SS) fell to 37 mg/L; the clearance rate of SS reached 82%. The BOD5 fell to 35 mg/L a drop to 42%. E. coli was less than 9 individual/L, the killing rate reached 99.999 99%. The intestinal pathogens and tubercle bacillus were completely wiped out. The sludge from the sewage can be treated with lime [Ca(OH)2] and when the pH value rose to 12, the requirement of disinfection was satisfied and both the sludge and sewage can be drained. The aeration of sewage through shooting flow, biological oxidation combined with sediment action by passing thru reclining tubes is an effective way for the secondary treatment of hospital sewage. In addition, we developed the double siphon equipment with water power-automatic controller, the WD-700 flowmeter, the anti-corrosive paint coating the contact pond; according to test parameters, we designed a simplified evaluation graph for the purpose of surveillance.