Remediation Of Deltamethrin Wastewater By Immobilized Aspergillus Niger

Deltamethrin is a typical example of pyrethroid insecticide commonly used in agriculture to protect crops from pest organisms.However,the residues of such pesticides and its degraded products have caused many environmental concerns and harmed the human health.At present,bioremediation technology is one of the effective ways to remediate the wastewater of pyrethroid pesticide.There are some limitations in the traditional bioremediation techniques of free microorganism,which restrictes the use of microorganism to remediate deltamethrin from wastewater.In this dissertation,it is actualized that a new technique using immobilized microorganism to remediate the wastewater of deltamethrin.Firstly,Aspergillus Niger using sodium alginate with biochar as the immobilized carrier was prepared.The preparation conditions of the immobilized Aspergillus Niger?IAN?were optimized by single-factor and orthogonal experiments.Next,the remediation mechanism of the IAN was analyzed by SEM.Finally,the toxicity of deltamethrin in wastewater was analyzed through the experiment of the seed germination and growth of barley.The main conclusions obtained from this study are as follows:The concentration of sodium alginate,CaCl₂,biochar and Aspergillus Niger is 20.0 g·L^-1,20.0 g·L^-1,2.0 g·L^-1 and 100.0 g·L^-1,respectively;the diameter of ball machine is 4 mm and the immobilized time is 2 h.The different methods of the storage of the IAN was cold storage with the deltamethrin concentration is 10.0 mg·L^-1.The relative removal rate of deltamethrin is 80%by the IAN preserved for 40 days.The relative removal rate of deltamethrin is 92%after the IAN was activated,the relative removal rate of deltamethrin is higher 12%than that nonactivated.The relative removal rate of deltamethrin is 82%after the IAN was recycled 7 times.The surface area carrier with biochar is higher than that of the carrier without biochar by SEM.IAN with biochar are:the initial concentration of deltamethrin is 100.0 mg·L^-1,the dosage of Aspergillus Niger is 20.0 g·L^-1,the ventilation is 150 mL,the rotate speed is 150r·min^-1,the initial pH is 7.38,the temperature is 30?and the time is 120 h.Under the optimal conditions,the highest removal rate gets to 95%.Sucrose or peptone with 0.50 g·L^-1 promotes the removal of deltamethrin,while,sodium acetate or ethanol inhibits the removal of deltamethrin.For the effect of Pb²⁺or AsO₄^3-,the removal of deltamethrin is reduced when the concentration range between 0.1².0 mg·L^-1.The toxicity of deltamethrin wastewater shows synergistic effect of residual contaminant and intermediate products through the hydroponic experiments of barley.