THE SMOOTHING EFFECT OF PITS FOR WASTE WATER

Several mixing models are proposed in order to analyse the mixing process of pits for waste water and to offer some data for evaluating the smoothing effect of them. In general, real pits are found to be very effective for smoothing the pollution level of waste water. In the case that the variation of flow rate with time is small, perfect-mixing tank model reasonably explains COD variation of effluent from a pit. On the other hand, in the case that the variation is large, various modified models expressing the deviation from perfect-mixing for low flow rate are much better than simple perfect-mixing tank model.