Water Journal : Water Journal September 2015
september 2015 water 49 Feature article AqMB solves design and membrane modelling issues for most dilute and concentrated water solutions. It is the only water treatment process modelling software to support over 40 inorganic analytes including halides, non-metals, alkaline earth metals, heavy metals, many transition metals and dissolved gases. Figure 2 shows an example water input table from within the platform. The software has in-built modelling algorithms for stream properties such as density, specific heat capacity, viscosity and thermal conductivity that are used within many of the relationships for the 36 separation and counter current unit processes. The software also uses a number of powerful numerical solvers and solubility modelling to perform the calculations required to determine component mass, energy balances and stream properties across each unit operation. Commercially, AqMB saves consultants and designers time during tendering and concept design. The software allows business development teams to test and compare the effectiveness of first-pass integrated process designs before passing on to process designers for refinement in vendor projection software. The software also allows easy exportation of design reports, flow sheets, mass balance information and equipment sizing details for budgetary pricing by vendors or fabricators, as well as quick configuration of proposal or design deliverable documentation. coMParIng MeMbranes usIng aqMb The AqMB software predicts the formation of insoluble compounds under process conditions while considering the influence of dissolved gases, metals and trace elements in solution. Membrane A and B values for over 60 RO and NF membranes are currently included, with more expected to be added as the platform’s capacity expands. The impact of chemical additions such as sodium bisulfite, acids and anti-scalants on species solubility and redox potential can be determined, alerting the user to inorganic scaling or membrane oxidation. AqMB highlights these impacts in the calculated suspended solids concentration, dissolved oxygen concentration and supersaturated species indicated in each stream. Primarily a concept design tool, AqMB users can also configure RO or NF operations for process modelling or forecasting water quality on existing operations by specifying all configuration parameters for each stage or train. Among the available design parameters, users can specify the array configuration, the membrane age (define a salt passage increase), fouling factor and feed pressure. Users can also configure each stage separately with inputs for feed or permeate pressure or override any B value with a per cent rejection for that ion. This last feature can be quite useful for modelling membrane performance in an operating scenario where historical data collected for the site shows a different permeate ion concentration than the value predicted by projection software for the same feed conditions. AqMB accurately calculates the osmotic pressure of a solution for both RO and NF applications. It uses the same simultaneous equations and parameters that are used in vendor projection software. The result is prediction of concentrate and permeate stream properties, ion concentrations and feed or concentrate Figure 3. the plant configuration set up on Aqmb for comparison of five different NF membrane types. Figure 4. stream properties including solubility are calculated by the Aqmb platform for comparing NF membrane types.
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