Study On Utilization And Purification Of Roof Rain Water In Residential Communities

Nowadays, the utilization of rainwater harvesting researches have been focused in the southern and western regions, but the study of the Northeast China rainwater using was limited. In response to the situation, Changchun City was selected as typical northeast city to be the subject, and study on roof rainwater quality monitoring, residential rainwater harvesting and utilization system mode and cleaning devices. Through the research, it was found that the level of roof runoff pollution load was high in spring,and pollution load in summer was low, which was connected with precipitation. There was a similar changing rule of CODcr, SS, TP, ammonia nitrogen pollution loads of the rainfall by the variation of rainfall duration: the higher pollution load in the early rains, with the variation of rainfall duration, pollution load gradually reduced, stabilized and maintained at a lower level. The pollution load of asphalt roof was slightly higher than which from tile roof runoff, and CODcr concentration was obvious. The result of the monitoring indicates that there was a first flush effect of roof rainwater runoff. The concentration of the roof runoff pollutants would be steady within 20-40 minutes in a continuous effective rainfall. So, roof rainwater utilization should be focused in summer and attention to early flow abandoning control. Pollution load was high in spring rainfall, before collecting the water,it should be cleaned manually on the roof to reduce the cost of treatment.During the roof runoff monitoring, CODcr and SS concentrations are seriously overweight, which need some kinds of treatments before reuse. TP concentration was in the allowable range. Ammonia was much lower than the standards. The study of community rainwater utilization mode was started from roof rainwater and community rainwater utilization, focusing on roof rainwater collection system design and conducted a laboratory device to test. It was found that pre-filter unit has some removal to rain on the SS, but the removal of CODcr was not effective. In a certain time, loop filter unit has a high removal rate to CODcr and SS .