Experimental Study on the Application of the Permeation Injection Technique to Groundwater Bioremediation

現地生物整治法為現今常被應用於地下水受含氯有機物污染之整治方式。此法常利用重力流方式使基質自然沈降並擴散，但此種方式不易確認基質是否能有效地滲透且均勻地散佈於欲整治範圍。 因此，本研究應用大地工程中常用於土壤改良之滲透灌漿技術進行基質注入技術之研究試驗，藉由自行設計的高速渦輪攪拌機及氣壓式灌漿設備，以低壓滲透灌漿的方式，將三種市售基質(EOS、HRC及EcoClean)灌注於7種不同級配分佈之土柱試體中(A土(D50=0.51mm)、B土(D50=0.45mm)、C土(D50=0.30mm)、D土(D50=0.27mm)、E土(D50=0.25mm)、F土(D50=0.01mm)及G土(D50=0.05mm))，以滲透性與持續性來評估不同土層條件下之各種基質適用性。 滲透性試驗結果發現，於A土試驗中三種基質皆能達到目標灌注高度；於B土、C土及D土試體中，僅EcoClean能達到目標灌注高度，而HRC與EOS未能達目標高度；E土試體中，HRC、EOS及EcoClean三種基質僅可分別滲透至48cm、42cm及43cm，而於F土及G土試體中，三種基質皆無法滲透。 持續性試驗結果發現，A土、B土、C土及D土試體中，HRC之殘留率較佳，EOS次之，而EcoClean較其他二者為差；而於E土試體中，三種基質之殘留率皆超過94%，其中又以EOS之殘留率較為佳，其次為HRC，而EcoClean較差。 綜合而言，本研究發現除了基質之特性外，滲透性或是持續性皆與土壤之D10有關，其相關係數可分別高達0.96即0.78；因此，土壤之D10 可用作可灌性評估之依據。未來對於與A土、B土、C土及D土粒徑分佈相似之土壤，建議使用HRC基質進行灌注。而對於與E土、F土及G土粒徑分佈相似之土壤，由於三種基質之滲透性皆較低，故未來建議能朝向提高稀釋比例、增加灌注壓力等方向努力，以改善滲透不佳之情形。The method of in-situ bioremediation has been widely used to treat the groundwater polluted by chlorinated organic compounds. This method by gravity flow is commonly used, so that the substrates or nutrients will settle and diffuse freely. However, it is difficult to confirm whether the substrates are distributed effectively and evenly in the areas to be treated. Therefore, in this research, a method of permeation grouting which has been often used in geotechnical engineering to improve the soil was applied to inject substrate. With the self-designed high speed vortex colloidal mixer and air compressor system, 3 kinds of commercial substrate (EOS, HRC and EcoClean) is permeably injected into 7 kinds of different soil column-shaped specimens (Soil A(D50=0.51mm)、Soil B(D50=0.45mm)、Soil C(D50=0.30mm)、Soil D(D50=0.27mm)、Soil E(D50=0.25mm)、Soil F(D50=0.01mm) and Soil G(D50=0.05mm)),and the indexes of the permeability and persistence will be used to evaluate the applicability of these 3 kinds substrate. The permeability results are as follows. For the specimens of Soil A, the targeted heights of permeation grouting was reached for the 3 kinds of substrates. As for the specimens of Soil B, Soil C and Soil D, only EcoClean could reach the targeted heights; however, HRC and EOS could not reach the targeted heights. For the specimens of Soil E, HRC, EOS and EcoClean can only be grouted to 48(cm), 42(cm) and 43(cm), respectively. For the specimens of Soil F and Soil G, those 3 kinds substrate are completely unable to be grouted. The results of persistence showed that the retention rates of the substrates, in decreasing order, were HRC, EOS and EcoClean. As for the specimen of Soil E, the persistence of 3 kinds substrate are more than 94%, and the persistence in decreasing order, were EOS, EOS and EcoClean. Generally speaking, it is found that the permeability and persistence is affected by not only the properties of substrate, but also the D10 of the soil. The R2 of D10 between the permeability and the persistence are 0.96 and 0.78, respectively. Therefore, the D10 of soil may be used to assess the goutability. For the soils with particle size distribution similar to that of Soils A, B, C and D, HRC is suggested to be used. As for the Soils with particle size distribution similar to that of Soils E, F and G, because of low permeability, it is suggested to increase dilution ratio and injection pressure to improve the permeation in the future