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A slurry containing 0.35 kg of solid per kilogram of water is filtered using a rotary drum filter 100 cm diameter and 100 cm long. The density of solid is p= 2700 kg m³. The drum rotates at one revolution in 200 s and 18% of the filtering surface is in contact with the slurry at any instant. The filtrate is produced at a rate of 350 kg h¹¹, and the cake has a voidage, e=0.42. State the general equation of filtration and explain the terminology used. (i) [3 marks] (ii) Select the appropriate equation of filtration that needs to be used and comment your answer. [2 marks] (iii) Calculate the thickness of cake that is produced when filtering with a pressure difference (-AP)= 7x10¹ N m². [10 marks] (iv) The rotary drum breaks down and the operation has to be carried out temporarily in a plate and frame press with frames 30x30 cm. The press takes 3 minutes to dismantle, 3 minutes to reassemble, and in addition, 1 minute is required to remove the cake from each frame. Assuming that the cakes are incompressible and that the resistance of the filter medium may be neglected, if filtration is to be carried out at the same overall rate as in the rotary drum filter, with an operating pressure difference (-AP)= 1.1x105 N m², calculate the minimum number of frames that needs to be used and their thickness and comment your answer. [25 marks]