Vermicomposting Of Deinking Sludge Of Waste Paper And Application Of The Residue To Soil Remediation

Millions of tons of deinking sludge of waste paper are produced in the papermakingindustry of China every year.This kind of sludge is complex and has a huge number, whichbelongs to national hazardous waste and causes great harm to the ecological environment. Thedeinking sludge should be disposed and resource-utilized in a scientific and reasonableway.Firstly,the basic properties,composition and pollutants of deinking sludge of waste paperwere studied.Then the deinking sludge was vermicomposted by the earthworms namedDapingⅡin order to reduce the contents of the major pollutants and increase the fertilizerefficiency of it.Finally,the deinking sludge that has been vermicomposted was made into anamendment for the soil polluted by heavy metals.This kind of amendment was used to repairthe soil polluted by Cd.The experimental results of analysis of basic properties,composition and pollutants ofdeinking sludge showed that, the content of C in deinking sludge of waste paper was245.91g/kg because of the existence of a lot of fibers.And the contents of TN、TP、TK were2.8g/kg、1.2g/kg、81.1g/kg respectively.The contents of Cu and As were269.02mg/kg and113.73mg/kg respectively which both exceeded national pollutant control standards inagricultural sludge(GB4284-84). The chemical forms of Cu and As were almost residual form.There were1,1-Biphenyl,2,2’,5,5’-tetramethyl and Di(2-ethylhexyl)phthalate in this kind ofsludge. The contents of them were0.22%and0.18%respectively.The experimental results of the vermicomposting showed that,the optimal technologicalconditions of vermicomposting:environmental temperature was20～30℃,sludge moisturewas60～80%,incubation time was30d,ratio of the weight of the earthworm and sludge was1:25,ratio of the weight of soybean straw,rice husk and sludge was1:1:100.Under the optimaltechnological conditions, the content of Cu in the sludge reduced from269.02mg/kg to153.67mg/kg,and the content of As reduced from113.73mg/kg60.52mg/kg.Both of them metnational pollutant control standards.After the vermicomposting,the contents of TN,availablenitrogen,TP,available phosphprus,TK,available kalium reached2.85g/kg、0.66g/kg、2.04g/kg、1.33g/kg、89.69g/kg、20.12g/kg respectively which were all above the national levelclassification standards of soil nutrients.Earthworm had absorption effect to Cu in the sludgeand the absorption coefficient was0.47.Earthworm also had concentration effect to As and theconcentration coefficient was1.41.The experimental results of soil remediation polluted by Cd showed that,the amendmentDA,DQA,DQXA could reduce the content of available Cd effectively and DQXA was the bestamendment.When the dosage of DQXA was2～4%,the content of available Cd in thesoil(5mg/kg,10mg/kg Cd) reduced by13.00～26.03%after30days.After the remediation, pHand fertility of the soil increased and the themal coefficient rose from1.76to1.78～1.82. Theorganic matter of soil tended to be stable and the humification degree increased.