昆明市不同功能区排水管道沉积物性质

Sediment Characteristics of Sewer in Different Functional Areas of Kunming

为了解昆明市主城区排水管道沉积物的性质,调研和采集了居住区、综合服务区、文教区、商业区等不同功能区的排水管道沉积物,分析了沉积物的粒径、密度、有机质(VSS/TSS)和污染物含量等指标,结果表明各功能区沉积物理化性质存在明显差异,粒径大小关系为商业区>文教区>居住区>综合服务区,VSS/TSS的关系为居住区>文教区>商业区>综合服务区,与沉积物干密度呈负相关,与含水率呈正相关;对于COD而言,居住区>文教区>综合服务区>商业区,TN的关系为居住区>文教区>商业区>综合服务区,TP呈现居住区>综合服务区>文教区>商业区的关系,由支管至主干管,沉积物中COD、TN无明显规律,TP略有减小,且TP更易赋存在小颗粒沉积物上;对于重金属而言,商业区污染高于其他3区,沉积物中Cu、Zn、Pb和Cd这4种重金属含量分别是背景值的2.2、4.4、2.5和8.6倍,建议优先控制Cd和Zn.

The problem of sediment deposition in urban sewer network in different levels, will not only reduce the sewer flow ability, but also release pollutants and generate secondary pollution. The impact of secondary pollution is more serious in the study area, Kunming, because of the combined sewer overflow in rainy season. In order to obtain the characteristics of the sewer sediments in Kunming, the sewer sediments from residential area, service area, cultural district, and business district were investigated and collected. The particle size, density, organic matter （VSS/TSS） and pollutant content of the sediments were analyzed in this study. The results showed that there were different characteristics for the sediments from different areas. The size of the sediments exhibited business district 〉 cultural district 〉 residential area 〉 service area, and the D50 was concentrated in the 20 to 100 μm except the business district. As for VSS/TSS, the order was residential area 〉 cultural district 〉 business district 〉 service area. It was negatively correlated with the dry density with the correlation index of R2 = 0. 982 7 and positively correlated with the water content. The contents of sediments showed significant differences in different functional areas. The size of COD presented residential area 〉 cultural district 〉 service area 〉 business district, and the size of TN followed residential area 〉 cultural district 〉 business district 〉 service area. As for TP, it exhibited residential area 〉 service area 〉 cultural district 〉 business district. The COD, TN and TP were proportional to the population density of the area and TP was greatly influenced by sediment particle size. From the branch into the Sub-main sewer, COD and TN were irregular, and TP decreased slightly. TP mainly existed as particulate and was more likely to deposit onto the small particle. As for TN, there was no obvious rule about its distribution in different particle size sections. The pollution road was generally on the high side in Kunming. The content of heavy metals in business district was the highest among all functional areas, and the concentrations of Cu, Zn, Pb, Cd were 284. 6, 786.4, 201.2, 2.54 mg. kg -1 respectively. The average contents of Cu, Zn, Pb, Cd in urban area were 2. 2, 4.4, 2.5, 8.6 times than the background values. It is suggested to control Cd and Zn with priority.