Centrifugation method for reducing heavy metal content in sediment

Abstract

Heavy metal removal is a worldwide problem in the field of sludge treatment. Based on the principle of centrifugation, a new method for reducing heavy metal content in river sediment is proposed in this paper. The implementation process is: (1) adding water to the original sediment and thoroughly mixing to obtain a rinse sediment, which is centrifuged by the centrifuge and obtain the dry sediment; (2) adding water to the primary dry sludge and mixing thoroughly to obtain the secondary leaching sediment, which is centrifuged in a centrifuge to obtain the secondary dry sediment. And so on, until the criteria for design requirement is met. Through four relative centrifugal forces and two centrifugal separation experiments, primary and secondary dry sediment of a certain sediment under four different relative centrifugal forces were obtained. ICP-MS test results show that the dry sediment obtained in the experiment condition with the relative centrifugal force is 100g (where g is the gravitational acceleration) and the number of rinses is 1. The content of heavy metals Cd and Ni that exceeds the original standard content has decreased significantly and meets the technical requirements for green metal planting soil heavy metal content level IV standards, removal rates are 46.6% and 20.9%, respectively; the content of other heavy metals that did not exceed the standard also decreased significantly. The method in this paper has many advantages include of good removal efficiency, no secondary pollution, especially new pollutions couldn't be introduced or generated.