多氯聯苯(PCBs)具有持久性、生物累積性及毒性的有機化合物,可長久儲存在環境介質。本研究應用加壓式臭氧處理技術(HOT ),測試二仁溪底泥PCBs之去除能力。底泥樣品採自二仁溪南萣橋上游;底泥有機質含量31.3%、pH值7.45,粒徑以砂粒含量最高(68%)。樣品PCBs濃度為2.1±0.28 mg/kg,樣本以Aroclor 1254為主及Aroclor 1242次之。以空氣為壓力填充氣體、底泥PCBs並無明顯降解。壓力填充氣體O3/air比例0.5%、150 psi、水:底泥比例1000:42(v:w)時,PCBs之去除率隨循環數增加而增加的趨勢,可達到61%去除效果。0.5%臭氧濃度對底泥PCBs有較高的去除率,而臭氧濃度0.25 與0.125%去除率無顯著差異,低於0.5%臭氧濃度、高於空氣為填充氣體之去除率。混和底泥重量22、42與98 g顯示40循環PCB去除率高於20循環,而在20循環時不同底泥重量PCBs去除無顯著不同,但40循環時以42 g重的底泥有最好的去除效果,22 g 與98 g重底泥,PCBs去除率無顯著不同。溶液起始pH值介於4及10對底泥PCB的去除無顯著差異
Polychlorinated biphenyls (PCBs) are persistent, bioaccumulated, and toxic organic compounds that can persist in environmental media for a long time. The study applied heightened ozonation treatment (HOT) for removal of PCBs from sediment obtained from an upstream location of the Nan-Ding Bridge in the Erh-Jen River. The sediment contained 31.3% of organic matter and 68% of sand mass at a pH of 7.4. PCBs in the samples were found at 2.1±0.28 mg/kg, consistent mostly with Aroclor 1254 and some with Aroclor 1242, as found by GC/ECD. The sediment slurry of 42 g in 1000 ml was treated with pressure cycles. No degradation was observed when air was used as the compressing gas. When a gas mixture of 0.5% O3 in air was used with compression pressure of 150 psi, PCB removal increased with increasing pressure cycles to a maximum of 61% removal. The removal rate was highest with 0.5% O3 and lower with 0.25 and 0.125% O3, higher with 40 cycles than with 20 cycles, higher at solid concentration of 42 g/1000 ml than at 22/1000 or 98/1000 g/ml. PCB elimination did not differ significantly when the initial solution pH was adjusted to 4 or 10.