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Q3 (25 marks) a. What is the significance of ammonia in treated wastewater effluents discharged into surface water bodies? Name the forms of ammonia that are usually determined and reported in the effluent analysis. Which of these forms will be important and why, if the receiver has (a) high DO but an endangered species sensitive to toxicity (b) low DO but no concerns with toxicity (c) both low DO as well as toxicity concerns. Also comment on the impact of the pH values on the ammonia toxicity and how it can be controlled. (12 marks) a. With a process flow diagram, name and briefly describe the key treatment stages in municipal wastewater treatment comprising a conventional activated sludge system and anaerobic sludge digestion. (13 marks) a. Q4 (25 marks) Describe the phenomenon of Inter-particle bridging, sweep coagulation and ionic layer compression in coagulation-flocculation theory. (12 marks) b. List the key requirements of an adequate water distribution system. Discuss the advantages and disadvantages of grid iron and dead-end system. (13 marks) Q5 (25 marks) a. The invert elevation of a 300-mm sewer drops by 0.25 m over a 100 m distance. Determine the discharge and flow velocity in the sewer when full and at a flow depth of 200 mm. Assumen = 0.013. Refer the pipe flow curves provided on the next page. (25 marks)