为探究城市生活污水处理厂脱水污泥作为土壤改良剂对风蚀沙土的改良效果,确定合适的污泥沙土掺混比例,试验以污水厂离心脱水污泥与沙漠表层土壤按污泥掺混量为10%,15%,20%,30%,50%充分掺混,以水分入渗能力、土壤饱和含水率和土壤保水能力为指标,研究了不同掺混比例“泥—沙”复合土壤中水分入渗规律和土壤保水性能,用以确定最佳污泥掺混比例和最佳保水层。结果 表明:污泥与沙土的掺混比例对水分入渗湿润锋影响较大。掺混比为10%的“泥—沙”复合土壤入渗时间最短,速率最大,30%,50%的入渗时间长,速率较慢; 不同污泥与沙土掺混比例,土壤水分累积入渗量的大小依次为:10%(54.15 cm)>15%(47.12 cm)>20%(40.80 cm)>沙土(34.97 cm)>30%(23.10 cm)>50%(12.68 cm),累积入渗量与时间关系符合Kostiakov土壤水分入渗模型; 在污泥与沙土不同掺混比对各土层含水率及水分再分布试验中,污泥与沙土掺混比为20%的复合土壤为最佳选择,保水性最好的土层是40—60 cm。
To explore the effect of dewatered sludge from urban domestic sewage plants as soil amendments on wind erosion of sandy soil, determine an appropriate mixing proportion of sludge and sandy soil, the test was carried out by mixing centrifugal dewatered sludge with desert surface soil in proportions of 10%, 15%, 20%, 30%, and 50%. Water infiltration capacity, soil moisture content and soil water retention capacity were selected as indicators, the law of water infiltration and soil water retention in different ‘sludge-sand' composite soils with different mixing ratios were studied to determine the optimum sludge blending ratio and the best water retaining layer. The results showed that the mixing ratio of sludge and sand had a great influence on the moisture infiltration wetting front; the ‘sludge-sand' composite soil with a mixing ratio of 10% had the shortest infiltration time and the highest rate, while the composite soil with 30% and 50% mixing ratio had longer infiltration time and shorter rate; soil moisture cumulative infiltration under the different ratios of sludge and sand mixing decreased in the order: 10%(54.15 cm)>15%(47.12 cm)>20%(40.80 cm)>sand(34.97 cm)>30%(23.10 cm)>50%(12.68 cm). The relationship between cumulative infiltration and time followed Kostiakov soil water infiltration model. In the test of soil moisture content and redistribution of water in soil with different ratios of sludge and sand, the mixed sandy soil with 20% sludge is the best choice, and soil layer with the best water holding is 40—60 cm layer.
