A Study on the Characteristics of Sewage Generated by Commercial Buildings in Private Sewage Treatment Areas

This study determines the actual amount and quality of sewage generated from various types of buildings with diverse sewage inflow patterns. The findings highlight the necessity of revising the notice to account for deviations from the existing sewage calculation method. Samples were retrieved from flow equalization tanks of sewage treatment plants. The inflow biochemical oxygen demand (BOD) concentration of general restaurants ranged from 153.8 to 2,700.0 mg/L, i.e., 46.6 to 818.2% of the standard value of 330 mg/L issued by the Ministry of Environment. For cafeterias, BOD concentration ranged from 85.5 to 690.0 mg/L, and for the rice cake manufacturing factory, it ranged from 360.0 to 855.0 mg/L—exceeding the issued standard value of 100 mg/L in both cases. The daily sewage amount generated per unit floor area in five restaurants ranged from 12.9 to 97.0 L/m2. These values were below the existing standard of 60 L/m2 except for that of restaurant A (i.e., 97.0 L/m2). The daily sewage generation for cafeterias ranged from 62.6 to 104.2 L/m2. In most cases, these values exceeded the existing standard of 35 L/m2 by a factor of > 2. For the rice cake manufacturing factory, the daily sewage generation was 19.8 L/m2, i.e., higher than the existing standard of 15 L/m2. Since the characteristics of sewage generation vary significantly depending on the building use type, it is necessary to further subdivide and manage the amounts of sewage generation under the existing law.