A Basic Study on the Seawater Purification Function of the Biofilm Process Method and Its Strengthening

通过室内试验研究了滤石式生物膜工艺对真实的海水中有机物、植物营养盐和悬浮物的去除特性。通过一系列系统的试验研究，发现滤石式生物膜工艺对COD、SS等的去除过程可用一级反应方程表示，方程中的去除率系数主要取决于滤石的平均流速U和滤石的比表面积A。利用U和A两个物理量经验地建立了COD、SS去除率系数和耗氧率系数，并将其应用于碎石填料中，利用有限元方法对碎石填料围隔的有限海域海水潮汐净化过程进行了预测，结果表明，碎石填料对海水的净化效果与潮汐作用有关。结果表明，抛石护岸对COD和SS的最终去除率与护岸的布置和围海面积的大小关系不大，而主要取决于护岸的长度。随着路堤长度的增加，SS的最终去除率显著增加，当路堤长度大于25 m时，SS的最终去除率几乎不变。COD随长度的增加而逐渐增加。最后提出路堤的最佳长度为10 ~ 12.5m。

Laboratory experiments were performed to observe the characteristics of removal of organic matter, plant nutrients and suspended solids from real seawater through the rockfilter-type biofilm process. Based on the results of a series of systematic experiments, it was found that the removal process of COD, SS and so on through the rockfilter-type biofilm process could be expressed by the first-order reaction equiation and the coefficient of removal rate in the equation depended mainly on the mean velocity U of seepage flows through the rockfilter and the specific surface area A of the rockfilter. The coeffecients of removal rate for COD and SS and the coefficient if oxygen consumption rate were formulated empirically by the two physical quantities U and A.Applying these formulated purification characteristics of the rockfilter-type biofilm process to rubble embankments, the process of seawater purification due to tidal actions in a restricted coastal area enclosed by rubble embankments were predicted by means of the FEM.As a result, it was seen that the ultimate removal ratios through rubble embankments for COD and SS do not depend so much on the layout of embankments and the size of an enclosed coastal area, but mainly depend on the length of embankment. The ultimate removal ratio for SS increases considerably with the increase of the length of embankment up to about 15m and becomes almost constant when the length is larger than about 25m. As for COD, it increases gradually with the increases of the length. It may be finally proposed that the optimum length of embankment is about 10m to 12.5m.