Phytoremediation Of Urban Sewage River Sediment Polluted By Typical Organic Pollutants

The organic pollution in urban sewage river sediment, which has potentialdamage to humans and environment, becomes more and more serious. The analysis ofchemical constituents of sediment by GC-MS showed that naphthalene andanthracene which belong to polycyclic aromatic hydrocarbons and DEHP whichbelongs to phthalate esters were the main pollutants. In order to study the effect of thephytoremediation on the organic pollution in urban sewage river sediment, Loliumperenne, Festuca ruudinacea Scherb and Maize were selected for phytoremediation,sewage river sediment and nutrient soil were mixed uniformly on pro rata of1:1,1:2and1:3. The number of naphthalene in sediment, anthracene in sediment, DEHP insediment, naphthalene in plant, and urease activity in sediment was monitored.According to the experimental research, the main conclusions are as follows:The sediment was extracted by Soxhlet extractor in90ml methylene chloride for12h, the solvent extracts of the sediment was purified by the optimized USEPA3630cmethod of silica gel column cleanup, and then the eluate was qualitatively andquantitatively analysed by GC-MS. Naphthalene and anthracene in sediment can beaccurately detected by this methed. The PAEs in sediment can be extrated byultrasonic extraction, the solvent extracts were purified by florisil column, and thenthe eluate was qualitatively and quantitatively analysed by GC-MS. This method canbe used to accurately detecte the PAEs in sediment.The naphthalene concentration in sediment reduced obviously after one month’sphytoremediation, while the anthracene concentration reduced stably in a period ofthree months. The experimental result showed that PAHs with less ring were removedmore easily, with the increase of the ring number, the removal rate reduced. Besides,the removal rate of PAHs in the planted sediment was faster than that in unplantedsediment at the earlier period of the experiment, while the removal rate in plantedsediment was the same with that in the unplanted sediment at the medium period ofthe experiment, and the removal rate of PAHs in the planted sediment was slower thanthat in the unplanted sediment at the later period of the experiment. The change of theremoval rate in different period indicated that the removal rate of PAHs in sedimentbecame slower with the reduction of the PAHs concentration. What’s more, someother conclusions were got as follows: The phytoremediation result of PAHs in sediment with Maize was better than that in the sediment with Lolium perenne andFestuca ruudinacea Scherb. The concentration of PAHs in planted sediment waslower than that in unplanted sediment after one month’s phytoremediation, whichshowed a remarkable phytoremediation result. However, the planted sediment had asame level of PAHs concentration with the unplanted sediment after three month’sphytoremediation, which showed a barely noticeable phytoremediation result. Thelowest concentration of naphthalene was observed in1:2sediment with Maize forthree months, while the lowest concentration of anthracene was observed in1:1sediment with Maize for a month. Naphthalene concentration in most of plants wasreduced. On the one hand, it is because of dilution effect from plants growth; On theother hand, naphthalene in plants was metabolised.The concentration of DEHP in the planted sediment was not significantlydifferent from that in the unplanted sediment, the removal of DEHP in sediment wasmaily effected by indigenous microbe.The activity of urease can reflect the pollution degree of sewage river sediment,because it has good negative correlation with organic pollutants concentration.