DieselShip's Online Content Library

Q6. A. Describe a vacuum sewage system;

B. With reference to the system described in (A) - i. State ONE advantage of the system;

ii. State why a holding tank may be required to be fitted to the system;

iii. State the problems resulting from the retention of untreated sewage in a holding tank.

Q4. A. With reference to shipboard sewage systems, Describe the principle of operation of EACH of the following types - I. Flow through system; II. Collection / Holding / transfer system; III. Zero discharge system. B. I. Explain why sewage systems involving aerobic action are to be preferred to those with anaerobic action. Aerobic Action: II. Explain the meaning and significance of the term Biological oxygen demand.

Q6. i) Sketch and describe a biological sewage treatment system. (6)

ii) How does the biological Sewage Treatment Plant work? Explain. (6)

iii) What Is understood by the term BOD? What factors affect BOD. (4)

Q5. (a) A biological sewage system develops a fault, which necessitates opening the unit for repair. Explain the following:

i) The risk associated with opening the unit. (5)

ii) The precautions taken to reduce the risk. (5)

(b) Explain the significance of biological oxygen demand (B.O.D). (6)