.. index:: pair: watertap.unit_models.thickener;thickener
The main assumptions of the implemented model are as follows:
- Single liquid phase only
- Steady state only
- Has no volume
Sludge thickening is a process commonly used in wastewater treatment plants to increase the sludge concentration of a stream as well as reduce its volume by removing free water. In doing so, the thickener reduces the load of downstream processes, such as digestion and dewatering. This implementation of the thickener unit is based on the IDAES separator unit.
The degrees of freedom in a thickener unit model are the inlet feed state variables:
- temperature
- pressure
- component mass compositions
The thickener unit model does not use ControlVolumes, and instead writes a set of material, energy and momentum balances to split the inlet stream into two outlet streams. Thickener models have a single inlet Port (named inlet) and two outlet Ports (named overflow and underflow).
Description | Symbol | Indices |
---|---|---|
Time | t | [0] |
Phases | p | ['Liq'] |
Particulate Components | j | ['X_I', 'X_S', 'X_P', 'X_BH', 'X_BA', 'X_ND'] |
Non-particulate Components | j | ['H2O', 'S_I', 'S_S', 'S_O', 'S_NO', 'S_NH', 'S_ND', 'S_ALK'] |
NOTE: These components are defined in the ASM1 Property Package documentation.
Description | Symbol | Variable Name | Index | Value | Units |
---|---|---|---|---|---|
Percentage of suspended solids in the underflow | p_{thick} | p_thick | None | 0.07 | \text{dimensionless} |
Percentage of suspended solids removed | TSS_{rem} | TSS_rem | None | 0.98 | \text{dimensionless} |
Description | Equation |
---|---|
Suspended solid concentration | C_{TSS} = 0.75 (C_{X_{I}} + C_{X_{IP}} + C_{X_{BH}} + C_{X_{BA}} + C_{X_{S}}) |
Thickening factor | f_{thick} = p_{thick} (\frac{10}{C_{TSS}}) |
Remove factor | f_{q_{du}} = \frac{TSS_{rem}}{100 * f_{thick}} |
Overflow particulate fraction | split_{particulate} = 1 - TSS_{rem} |
Overflow soluble fraction | split_{soluble} = 1 - f_{q_{du}} |
.. currentmodule:: watertap.unit_models.thickener
.. autoclass:: Thickener :members: :noindex:
J. Alex, L. Benedetti, J.B. Copp, K.V. Gernaey, U. Jeppsson, I. Nopens, M.N. Pons, C. Rosen, J.P. Steyer & P. A. Vanrolleghem Benchmark Simulation Model no. 2 (BSM2)