牧草和污泥微生物对污泥PAHs修复的贡献分析研究

摘要

本研究以紫花苜蓿和无芒雀麦两种牧草为研究对象,通过盆栽试验,开展了牧草和污泥微生物对污泥多环芳烃(PAHs)修复的贡献分析研究.结果表明,污泥盆栽5个月后,与灭菌污泥相比较,不种植牧草处理的污泥微生物对污泥PAHs的去除率达20.52％,且对不同环数的去除率表现为6环≈4环≈3环＞5环一2环.牧草一污泥微生物联合作用对16种PAHs总量的去除率可达83.74％(苜蓿)和78.73％(雀麦),比污泥微生物单一作用平均提高了2.96倍,且对6环PAHs的去除效果表现最突出.扣除污泥微生物对PAHs的去除率后,苜蓿和无芒雀麦对污泥PAHs的去除率分别为63.22％、58.21％,比牧草一污泥微生物联合作用平均降低了33.90％,对不同环数的去除率表现为5环PAHs效果最明显.进一步分析牧草和污泥微生物对PAHs修复的贡献可知,牧草因直接吸收去除PAHs的贡献率平均为1.35％,污泥微生物单一作用的贡献率为24.67％,其他可能因牧草一污泥微生物的交互作用、牧草的蒸腾作用及根系分泌物的作用等共同去除的贡献率为79.46％.同时,污泥碱性磷酸酶活性大小顺序呈现出了未灭菌污泥+苜蓿处理(J+M)≈未灭菌污泥+雀麦处理(J+W)＞未灭菌污泥处理(J)＞灭菌污泥处理(CK)(P＜0.05)的结论,与PAHs降解规律表现一致.综上,在牧草和污泥微生物联合修复污泥PAHs的过程中,除了污泥微生物和牧草的单一作用外,牧草一污泥微生物的交互作用、蒸腾等共同作用对去除的贡献占据了较大优势.%A pot experiment was conducted to investigate the contribution of alfalfa (Medicago sativa),smooth brome (Bromus inermis),and sludge microbes to the remediation of polycyclic aromatic hydrocarbons (PAHs).After 5 months,the total removal rate of polycyclic aromatic hydrocarbons (PAHs) by sludge microbes was 20.52％ in the absence of forage grass,and the removal rate of PAHs with different rings was as follows:six rings≈four rings≈three rings＞five rings≈two rings.The total removal rate of PAHs by grass-sludge microbes was 83.74％ (alfalfa) and 78.73％ (smoothbrome).Therefore,the addition of a grass significantly increased the average PAH removal rate by almost three times compared with that of sludge microbes alone.The highest degradation rate was for the six-ring PAHs.In the absence of sludge microbes,the degradation rate of PAHs by alfalfa and smoothbrome was 63.22％ and 58.21％,respectively (on average,33.90％ less than that of the grass-sludge microbes combination).The grasses showed the highest PAH removal rate for five-ring PAHs.Further analyses of the contribution rates of grass and sludge microbes to PAH degradation showed that 1.35％ of PAHs was removed by direct absorption,24.67％ by microbes,and 79.46％ through grass-sludge microbial interactions,transpiration,and the effects of root secretions.The treatments were ranked from highest sludge alkaline phosphatase activity to lowest as follows:non-sterilized sludge+alfalfa treatment (J + M) ≈ non-sterilized sludge + smooth brome treatment (J + W) ＞ non-sterilized sludge treatment (J)＞sterilized sludge treatment (CK) (P＜0.05),consistent with the order of the treatments based on PAHs degradation.In conclusion,the use of grass and sludge microbes was more effective for removing PAHs from contaminated sludge than either grass or sludge microbes alone.The combined action of grass and microbes removed PAHs as a result of their interactions and transpiration.