Civil Engineering

KIMATHI UNIVERSITY COLLEGE OF TECHNOLOGY UNIVERSITY EXAMINATIONS 2012/2013 THIRD YEAR FIRST SEMESTER EXAMINATIONS FOR THE DEGREE OF BACHELOR OF SCIENCE IN CIVIL ENGINEERING ECE 2305: PUBLIC HEALTH ENGINEERING 1 DATE: AUGUST 2012 TIME: 2 HOURS

INSTRUCTIONS TO CANDIDATES: • The paper has FIVE questions • Question ONE is COMPULSORY • Attempt any other TWO questions. • The marks for each part of question are as shown. QUESTION ONE a) The in-line system for coagulation ,flocculation and sedimentation has the following sized units; flash mixing chamber with a volume of 5.7 m3,a flocculator 4.6 m wide,21m long and 2.5 m liquid depth and a settling tank 23 m square,3.6 m liquid depth and 90 m of effluent weir. Calculate the major parameters used in design of these units based on a water flow of 11400m3/day. (8 marks) b) The population of a locality as obtained from census report is as follows

Census Year Population 1900 8,000 1910 12,000 1920 17,000 1930 22,500 1940 29,000 1950 37,500 1960 47,000 1970 57,000 1980 66,500

Estimate the population of the locality in year 2000 using incremental increase, arithmetical progression and geometrical progression methods. (6 marks) c) Starting from the first principles derive the formula for terminal velocity of a settling spherical particle (6 marks)

QUESTION TWO (a) Compare the rapid and slow sand filters under the following sections i) Rate of filtration ii) Loss of head iii) Efficiency iv) Effective size of sand (4 marks) (b) Define sterilization and discuss at least three common sterilization methods used in water treatment giving advantages and disadvantages of each (7 marks) (c) Explain by use of neat sketches how a rapid sand filter is cleaned (9 marks) QUESTION THREE a) The following are some of the drinking water characteristics. Discuss in detail each giving causes and its significance in deciding portability of water. i. Turbidity ii. Hardness (11marks) (b) State four reasons for treating water (c) Highlight six...