# PARTICLE TECHNOLOGY

## Liquid filtration - Chapter 4

### Expert System for equipment selection

The selection of filtration and separation equipment can be quite challenging, this online expert system is designed to take information from the user and make recommendations for the most appropriate equipment to select. The link is within the particles.org.uk web site, having been moved and updated from the web site filtration-and-separation.com.

### Online filtration modelling and data

Online simulation of filtration processes, where you can enter your inputs and the simulation provides tabular data for constant pressure and constant rate filtrations. Information on the models (i.e. equations) behind the models is also presented in a set of slides.

In addition, there is a look-up table for the specific resistance of various known materials and the facility to calculate the theoretical specific resistance from a particle size distribution, via the Sauter mean diameter.

### Answers to problems at the end of Chapter 4:

Q1:
anthracite: outlet concentration is 24.4 ppm
sand: outlet concentration is 2.6 ppm
alumina: outlet concentration is 0.10 ppm
The inlet concentrations are the outlet concentrations from the previous layers, and the final treated effluent is 0.10 ppm.

Q2:
i) the correct answer is (c), the concentration by mass must be converted to concentration by volume, see equation (3.16) for this.
ii) the correct answer is (b), as the cake has a porosity of 50%; i.e. has equal volumes of solids and liquid.
iii) the correct answer is (a), starting with 5000 ml of slurry and the cake contains 200 ml of solids and 200 ml of liquid - leavers just 4600 ml.
iv) the correct answer is (a).
v) the correct answer is (c).
vi) the correct answer is (a).
vii) the correct answer is (d).
viii) the correct answer is (d), you need the integrated form of the general filtration equation under conditions of constant pressure - equation (4.19).

Q3:
i) the correct answer is (c), look at the equations in the box at the bottom of page 43. The total pressure rises due to increasing pressure required to maintain the flow through the cake, which is increasing in height. However, the pressure drop over the medium remains constant - for constant rate filtration. Now looking at the pressure rise equation, the constant pressure term is 6670 Pa.
ii) the correct answer is (d), this requires some algebra and use of dV/dt is equal to V/t. You will also need to equate the rising pressure term in the filtration equation with 168t, and assume alpha, etc. are the same as in the previous question.
iii) the correct answer is (d).
iv) the correct answer is (d).

Q4:
i) the correct answer is (c).
ii) the correct answer is (b).
iii) the correct answer is (a).
iv) the correct answer is (c)
v) the correct answer is (a).

Q5:
See this file for a view of the spreadsheet.

FAQ

### Illustrations of filtration equipment

For pictures and illustrations of equipment used for solid liquid separation please go to Josh's web site: Engineering Aspects in Solid-Liquid Separation.