重金属在河湖底泥中的积聚已成为我国的一大环境问题,通过及时妥善的技术处理,可以避免重金属对环境的二次污染。基于生石灰降低底泥含水量,锯末灰初步固化,采用水泥和矿粉+水泥2种方式对生石灰-锯末灰固化后的污泥进一步固化的方法,对天津西青区某河流污染底泥开展试验。基于原子吸收分光法对试验样品进行重金属浸出浓度分析,比较水泥和矿粉+水泥固化2种方法的固化效果。研究表明,当生石灰掺入比为9%,养护2 d 时,污泥的含水率明显降低。锯末灰掺入比10% 、水泥掺入比20%、矿粉换掺水泥40%时,底泥中的 Ni2+ 、 Hg2+ 、 Pb2+ 、 Cd2+ 4种超标重金属浸出浓度分别降低71.61%、84.85%、58.49%、77.78%,均满足相关技术规范要求。为检验固化土的种植效果,选用牛筋草和牛繁缕2种植物进行室内60 d种植试验,发现2种植物的光合作用、根部发育、生长速度都很正常。结果表明生石灰掺入比9%、锯末灰掺入比10%、水泥掺入比20%、矿粉换掺水泥40%的固化方案得到的固化土可用于绿化种植。
Abstract
The accumulation of heavy metals in the sediment of rivers and lakes has become a major environmental problem in China. On the basis of reducing the water content of sediment by adding quicklime and preliminarily solidifying by sawdust ash, the polluted sludge from a river in Tianjin was further solidified by adding cement or mineral powder plus cement as a demonstration. The leaching concentrations of heavy metals in the test samples were examined using atomic absorption spectrometry, and the curing effects of cement and mineral powder plus cement were compared. Results unveiled that treated by a dosage of 9% quicklime for two days, the contaminated sludge saw an obviously reduction in moisture content. The leaching concentrations of Ni2+, Hg2+, Pb2+ and Cd2+ in the contaminated sediment declined by 71.61%, 84.85%, 58.49%, and 77.78% respectively when the content of saw dust was 10%, cement was 20%, and ore powder replacing 40% of the cement, which all met the requirements of relevant technical specifications. To test the planting effect of solidified soil,Eleusine indica and Malachium aquaticum were selected for indoor planting experiment for 60 days. The photosynthesis, root development and growth rate of the two plants were normal. It can be concluded that the contaminated sediment solidified by 9% quicklime, 10% sawdust ash, 20% cement and 40% mineral powder for replacing cement can be used for greening planting.
关键词
重金属 /
生石灰 /
锯末灰 /
水泥 /
矿粉 /
绿化种植
Key words
heavy metal /
quick lime /
sawdust /
cement /
mineral powder /
greening planting
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基金
国家自然科学基金项目(41877251);天津市科技支撑重点项目(19YFZCSF00820)
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