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The demand of bubble dispersity in flotation is that the diameter of bubbles should be less than 100 um. But in clean water, the bubble dispersity usually cannot reach this demand.

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When treating oily wastewater by floatation, dosing clay particles will increase the flotation efficiency.

Suppose a certain kind of natural river is treated by coagulation and flocculation process in a reciprocating baffled flocculation tank. The water flow rate is 600 m3/h. Volume of the flocculation tank is 200 m3. There are 3 baffles in the flocculation tank. Assume that: the local headloss caused by all corners in the tank is 90% of the total headloss, and the local resistance coefficient of each corner is ζ=2.8. The average flow velocity in the corners is 0.2 m/s. Water temperature is 20 C. Water kinematic viscosity is ν=1.005×10-6 m2/s.Then, the average G is _________ __ s-1 (fill in an integer); The number of G is ___________ ______ (choose in/out of) the reasonable range.

Suppose the removal efficiency of TOC in water by a certain active carbon (AC) obeys Freundlich adsorption isotherm. The equation is qe=k Ce^(1/n), where k=0.006, n=1.1. The unit of qe is mg/mg-AC, and that of Ce is mg/L. Now, pump solution with 20 mg/L TOC into an adsorption column filled with such AC continuously.(1) When the adsorption column is completely saturated, the maximum adsorption capacity of AC is _________ __ mg/mg-AC. (2 decimal places shall be reserved for the result.)(2) After that, solution with TOC concentration increased to 40 mg/L is pump into the AC adsorption column, then, the column _________ __ (choose can/cannot) still adsorb the TOC in water.

Suppose a RH-RNa ion-exchange softening system is applied to treat raw water with salt contents shown below.Ca2+:120 mg/L Mg2+:42 mg/L Na+:69 mg/L K+:19.5 mg/LHCO3-:427 mg/L SO42-:120 mg/L Cl-:124.25 mg/LIf the effluent basicity demand is 0.5 mmol/L, the proportion of water flowing into RH exchanger should be ________ ___% of the total water flow.Please fill in an integer.

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