礫間接觸氧化法源至於淺流河川之自淨原理,透過礫石間附著之生物膜有效處理水中有機污染物,參考日本過去成功之操作經驗,礫間接觸氧化法之平均BOD去除率約為20~70%,而礫間接觸曝氣氧化法之平均BOD去除率約為50~80%,礫石大小約為20~150mm,孔隙率為30~40%。另外透過模擬生物膜基質利用與擴散之機制,以國內外案例探討分析,結果顯示,當比表面積越大時,BOD去除率相對較大,且去除效果會隨進流濃度增加而減少。比較國內兩處礫間淨化處理設施,由於操作期間較短、礫石粒徑大(150~300 mm)、進流水濃度過高,而造成礫間接觸氧化設施之處理效果不彰。
The pebble-based biofilm oxidation technique, resulting from the concept of self-purification process of natural shallow river systems, employed the biofilm degradation process to treat the organic pollutants in the domestic sewage. According the practical experience in Japan, the pebble-based biofilm oxidation technique with and without purge system resulted in the BOD removal efficiency of domestic sewage at the range of 50%~80% and 20%~70%, respectively. Besides, the pebble size and porosity of the treatment system ranged around 20~150 mm and 30~40%, respectively. With the mathematical simulation of biofilm theory, data collected from foreign and domestic sites showed that better treatment efficiency might be expected with higher specific area and lower in influent concentration. From the monitoring data collected from two domestic sites, it was shown that the treatment efficiency of these two sites did not provide satisfactory performance on BOD removal, and the reasons for such a result may be due to bigger pebble sizes, instability of the biofilm system, and higher influent BOD concentration.