Domestic Sewage Emission Dynamics and Pollutant Loading Capacity of the Daqing River Valley:A Case Study on the Village Scale

The domestic sewage from the intersection of city and countryside is becoming a significant pollution source to the Dianchi Lake.Surveys of the quality characteristics and the discharge dynamics of domestic sewage provides scientific basis for the development of pollution control strategies and the implementation of efficient environmental engineering.In this study,on-site surveys were continuously conducted in typical suburban villages of the Daqing River basin to reveal sewage water quality and its discharge pattern.The pollutant loading capacity of the experimental area was further estimated.Our results showed that:domestic sewage water of the study area was characterized by high concentrations of TN,TP and CODCr,and low ratio of BOD5/CODCr,indicating poor biodegradability of the sewage from these villages;higher pollutant contents in the sewage was monitored at 8:00 am and 18:00 pm as well;the sewage discharge was peaked at 10:00 am and 20:00 pm;except that CODCr of the sewage in work days was obviously higher than in the weekends,other water quality indicators showed no signif-icant differences between work days and weekends.The total pollutant load of the study area was higher in rainy season as compared with dry seasons.Particularly,soluble inorganic salts were discharged mainly in rainy season.Per capita pollution discharge was also higher in rainy season.Conclusively,per unit area pollution load of domestic sewage in the survey villages was in high risk;and the major daily pollution con-trol time periods should be in early mornings and evenings that reflect activities of human behavior.On the seasonal scales,rainy seasons should be greatly accounted for pollution control.