Plug-flow(Continued) (d) Step feed Aeration tank E田ert Return activated suye Step feed is a modifioation of the conventional plug-flow process in which the settled wastewater is introduced at 3 to 4 feed points in the aeration kank bo equalize the F/M ratio, thus lowering peak oxygen demand Generally, three or more parallel channels are used. Flexibility of operation is one of the importont features of this process because the apportionment of the wastewater feed can be changed to suit operating passes as more infuent feed is added. The step-feed The step feed process can also be operated in the contact stabilization mode by feeding nly the last pass, and high wetweather fows can be bypassed lo the last 完全混合法 完全混合的概念 在分步曝气的基础上 步大大增加进水点,同肘相 应増加回流污泥开使其在曝气池中迅速混合,长条形池子 中也能做到完全混合状态。 进水 出水 回流污泥 图14-24完全混和法5 完全混合法 在分步曝气的基础上，进一步大大增加进水点，同时相 应增加回流污泥并使其在曝气池中迅速混合，长条形池子 中也能做到完全混合状态。 完全混合的概念