Objective In order to study the effect of different earthworm density on the availability of heavy metals in sludge,a new idea was provided for sludge earthworm composting.Methods 2kg sludge was composted with var-ying densities(0,10,20,40)of Eisenia fetida earthworms and rice husks(0g,25g,50g)as additive,and the changes in the availability of heavy metals in domestic sludge under different earthworm feeding densities were in-vestigated.Results With the increase of earthworm density,sludge pH(pH),OM(organic matter),TN(total ni-trogen)and TP(total phosphorus)decreased,while EC(electrical conductivity)increased.With the increase of rice husk addition,sludge pH,OM,TN and TP continued to decrease under the synergic effect with earthworms.Under a certain amount of rice husk,the total amount of Cu,Zn,Pb and Cd in the sludge decreased with the in-crease of earthworm placement density.When 50g rice husk was composted with 40 earthworms,the total amount of Cu and Cd decreased by 34.04％and 35.85％respectively.Under a certain amount of rice husk,with the in-crease of earthworm placement density,the available Cu and Zn in the sludge tended to increase,the available Cd was decreased,and the available Pb was significantly decreased(P＜0.05).Among them,when 50g rice husk was composted with 40 earthworms,the effectiveness of Pb in the sludge was the most significant,decreasing by 42.43％.Through correlation and regression analysis,it was found that the increase of earthworm placement den-sity affected the availability of Cu by changing EC,and the change of TN and TP affected the availability of Pb,Zn and Cd.Conclusion When 50g rice husk and 40 earthworms were combined to treat sludge,the effect of reduc-ing heavy metal activity in sludge was the best.
earthworm compostearthworm densityrice huskheavy metal
NETL
NSTL
维普
万方数据
