| The rapid increase in the scale of urban sewage treatment has led to a sharp increase in sludge production in sewage plants,difficulty in disposal,and serious secondary pollution.In order to practice the idea of ecological civilization and seek efficient and fast sludge harmless treatment and resource utilization technology,it is necessary to realize "equal emphasis on mud and water" in the operation of sewage treatment plants.In this study,low-temperature plasma technology was used to directly treat sewage sludge.The effect of heavy metals,and the heavy metal stabilizer peat combined with low-temperature plasma to achieve rapid stabilization and harmlessness of sludge;The Tagetes erecta L,Argyranthemum frutescens L.and Salvia splendens Ker-Gawler planted to investigate their effects on biological growth and biological toxicity,in order to evaluate the resource utilization potential of the treated sludge.The main findings are as follows:(1)When the voltage of the applied sludge reaches 300 V and the initial current reaches 40 A,plasma can be generated,which can degrade the organic matter in the sludge.After the reaction,the effective phosphorus and alkali-hydrolyzed nitrogen of the sludge increase;the properties of the sludge change.It is related to the action voltage,action time and initial p H value of sludge.The treatment effect is obvious under the conditions of voltage 400 V,treatment time 40 min,and initial p H value 7.0.At this time,sludge organic matter is reduced by 11.70%,and sludge SCOD is increased by 515.6 mg/L.,the fecal coliform value of sludge was 0.43,indicating that plasma treatment has the effect of breaking sludge cells and sterilizing.(2)After low-temperature plasma treatment,the weak acid extractable content of heavy metals such as Zn,Pb,Cd and Cr in the sludge increased significantly,and the percentage of oxidizable state content significantly decreased,while the content of reducible and residual heavy metals remained basically unchanged.,thereby increasing the ecological risk of these heavy metals,especially in the utilization of sludge resources,it is necessary to stabilize these heavy metals;after plasma treatment,the weak acid extractable content of heavy metals Cu and Ni in the sludge is reduced,and the content of oxidizable state is reduced.The content of reducible state and residue state remained basically unchanged.(3)The addition of peat to the sludge significantly reduced the weak acid extractable state percentage of heavy metals Cu,Ni,Pb and Cr,and when combined with low temperature plasma,the stabilization efficiency of heavy metal Ni in the sludge increased by 13.37%,But the stabilization effect of heavy metal Zn is poor.(4)The low-temperature plasma treated sludge is stabilized with peat for land use,which can obviously promote the germination of the seeds of the Tagetes erecta L,and the germination rate of the Tagetes erecta L is increased by 10% compared with compost sludge;The average plant height of the Tagetes erecta L treated with low-temperature plasma treated sludge increased by 6.59% compared with composted sludge,and the fresh weight each plant increased by 12.98%..(5)Investigate the effect of sludge treated with low temperature plasma(sludge sample: soil = 1:9)on the growth of the Argyranthemum frutescens L.and the Salvia splendens Ker-Gawler,the results show that different treatments have different effects on garden plants the Argyranthemum frutescens L There was no significant difference between the two groups;after low-temperature plasma treatment,the peat-stabilized sludge sample(S4)had no significant difference in promoting the growth of the Salvia splendens Ker-Gawler compared with composted sludge,but after 30 d of application,the average plant height of the Salvia splendens Ker-Gawler It was38.71% higher than that of the sludge treated by low temperature plasma without peat stabilization. |
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