Question

Q8. Domestic sewage generated in Muscat is collected and being treated by Haya water company. During the treatment process all contaminants are removed from sewage water by adding some disinfectants and finally the sludge which it is coming out as a residue is directed to the agricultural farms. a. Why do you believe the sewage treatment plants are important even if it is going to disposed in land or water? Justify. (3 Marks) b. Is Disinfection necessary? Why? (2 Marks)

Answer 1

a. Yes it is necessary to treat wastewater in sewage treatment plants before disposing it to land or water because there is heavy amount of organic matter and microorganism present in the waste water which further can pollute the water or land. Organic matter and microorganisms if not removed from sewage and directly disposed to water or land then there will be reaction of organic matter and microorgansim in the water and dissolved oxygen will be used from water and as the dissolved oxygen level goes down there will be harm to aquatic life. Moreover microorganism will remain present in water and if this water is further used then it will harm the health of the people. Therefore it is necessary to carry out the treatment of sewage before disposal. During treatment almost 90% of organic matter is decomposed and microorganisms are removed from the treated sewage by application of disinfectants.

b. Disinfection is necessary. After decomposition of the organic matter microorganisms are still present in the sewage. If these microorganism will remain present in treated sewage and added to water then this water cannot be further used for daily usage of population as it will bs hazardous to health. Disinfection will remove the microorganisms from the sewage and it will be safer for disposal.