Wastewater Operator Certification Quiz: 1. If the effect of temperature on the rate of sludge digestion is considered. it may be safely assumed that a. A digester operating at 90° F can safely handle more sludge than one operated at 60° F. b. Temperatures of 85° to 95° F will destroy the bacteria present in a digester. c. Digestion will be most satisfactory if the temperature of the digester is maintained at the same temperature as the incoming raw sludge. 2. The reason for concentrating (thickening) sludges before digestion is to a. Increase detention time. b. Reduce pumping. c. Reduce heat requirements. d. All of the above. e. None of the above. 3. The action that occurs in a properly functioning anaerobic sludge digester may best be described as a. A biological and chemical process that breaks down complex organic substances in the absence of atmospheric oxygen into a simpler and more stable state. b. An aerobic process of decomposition of organic solids. c. A purely chemical process of separating the liqUid from the solids. 4. Sludge digestion tank capacity requirements vary with the type of sludge to be handled. With heated tanks. the recommended cubic feet to be allowed per capita are a. 1 to 3 b. 2 to 4 c. 4 to8 d. 6 to12 5. The proper pH range for digested sludge is a. 5.8 to 6.2 b. 7.8 to 8.2 c. 6.8 to 7.2 d. None of the above. Answers: 1. a 2. d 3. a 4. a 5. c
Posted on: Mon, 04 Aug 2014 12:53:07 +0000
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