3. A sewage treatment plant is constructed to treat domestic wastewater from a newly developed residential area. The treatment plant is designed to receive an average daily flow of 4500 m/d. (i) (ii) (iii) Determine the population equivalent (PE) of the residential area. Calculate the peak flow rate of sewage entering the treatment plant. If the area consists of the flowing premises (in Table below), determine the number of residential units (X). (note: please use the PE values as listed in Table 1.0) Premise Unit/Area Residential X units House Others Semi-detached houses, terrace houses and flats Non-residential school for 1200 Primary School 1 unit students Mosque 1 unit Capacity for 1000 people Commercial 1 unit 10,000 m shopping mall has centre 200 shop lots Petrol station 1 unit 10 service bay Private Hospital 1 unit 150 beds and 80 staffs (7 marks) Table 1.0 Population Equivalent Design Value for Premises Type of Premise Residential Commercial Educational Institutions -Day Schools Residential Schools Hospitals Hotels Mosque Petrol station Population Equivalent (PE) 5 per house 3 per 100m area 0.2 per student 1 per student (residential) 4 per bed 4 per room 0.5 per people 18 per service bay