GACMan - Modelling adsorption in water treatment

GACMan (Granular Activated Carbon Management) is a modelling tool developed by WRc to simulate the adsorption of specific contaminants during water treatment. Using data from its internal database or entered by the user, GACMan can simulate the removal of pesticides, arsenic and other contaminants at full scale in as many as 100 adsorbers.

GACMan can be used to:

GACMan Development

GACMan was originally developed to predict the removal of pesticides from water by GAC adsorbers. GACMan has recently been upgraded to simulate adsorption of a wider range of contaminants, including Arsenic, TOC, colour, taste and odour, etc.

GACMan incorporates a fundamental mathematical model of adsorption that predicts the concentration profile of an adsorbate as it passes through the adsorber bed. The model assumes external film and surface diffusion mass transfer mechanisms, while adsorption equilibrium is described by one of the Freundlich, Langmuir or Redlich-Peterson isotherms. Multicomponent adsorption is modelled by IAST (ideal adsorbed solution theory) or extended isotherms.

GACMan benefits from a strong team of developers and engineers, dedicated to supporting and upgrading the software.


GACman is used by several water supply companies and carbon manufacturers in the UK and Europe to optimise the design and operation of their GAC adsorbers.

Benefits include:


GACMan can be used to simulate the removal of a range of contaminants selected from its internal database on as many as 100 adsorbers. Alternatively, the user can calibrate GACMan for a specific application using laboratory, pilot plant or full-scale data.

Modes of Operation

Design mode
GACMan predicts the performance of a single adsorber and is used to determine the contact time necessary to obtain a desired bed life or regeneration frequency.

Simulation mode
GACMan is used to simulate the performance of a full-scale works to predict the quality of the blended works output as well as the performance of individual adsorbers. Regeneration of an adsorber is triggered when the contaminant concentration in the adsorber effluent exceeds a specified concentration.

GACMan’s internal database includes adsorption data for a range of contaminants:


Taste and odour causing compounds

Organic compounds

In addition, users can easily calibrate the model for adsorption of other parameters using their own experimental data.

GACMan has also been used to model the performance of other adsorbents, e.g. removal of arsenic by activated alumina or granular ferric hydroxide.

WRc Consultancy Service

WRc offers a consultancy service to model clients’ adsorption plants. Models are updated on a regular basis using clients’ data to provide a continuing prediction of performance, including adsorber and works effluent concentrations, remaining GAC bed life and optimum regeneration schedules.

Supported Operating Systems

GACMan Version 42.0 is currently available, running under IBM-PC compatible computers and Microsoft Windows and NT operating systems. A datasheet specifying the full hardware requirements is available from WRc Processes.