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

通过室内实验，观察了岩滤式生物膜工艺对真实海水中有机物、植物营养物质和悬浮物的去除特性。通过一系列系统实验发现，岩滤式生物膜对COD、SS等的去除过程可以用一级反应方程表示，方程中去除率系数主要取决于岩滤的平均渗流速度U和岩滤的比表面积a。将得到的滤石式生物膜工艺的净化特性应用于碎石堤防，利用有限元方法预测碎石堤防封闭沿海受限区域潮汐作用下的海水净化过程。结果表明，碎石堤防对COD和SS的最终去除率与堤防布置和封闭海岸面积的关系不大，而主要与堤防长度有关。随着路堤长度的增加，SS的最终去除率在15m左右显著增加，当路堤长度大于25m左右时基本保持不变。COD随长度的增加而逐渐增加。最后提出堤防的最佳长度为10m ~ 12.5m左右。

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.