• Many Cambodia families use wood for cooking; transforming cow waste through biodigestion means gas is available for cooking.

A team of Arup engineers has worked alongside Engineers without Borders and Live and Learn Environmental Education to develop a new single household based biodigester model for floating and flood affected communities in Cambodia. 

Engineers without Borders (EWB) has been working with floating and flood affected communities in Cambodia since 2000.  The communities currently have little access to appropriate sanitation technologies and rely heavily on wood for cooking.

The biodigesters system involves leveraging anaerobic digestion to turn human and animal waste into biogas for cooking and lighting, and fertilizer with which to grow crops. 

Arup worked with the EWB team remotely (see screenshot of modelling above) to explore biodigester flow patterns, comparing outlet pipe size, locations and height and providing guidance for future designs. The product is now in the process of being developed by ATEC biodigesters.

The process

The modelling of five biodigester options was carried out using OpenFOAM, an opensource mathematical solver often used in the application of computational fluid dynamics (CFD).  The models had varied inlet and outlet pipe size, location and heights.  Each of the models was modelled for three stages: sludge inflow, gas production, gas extraction.

The models provided information for EWB about how to develop future prototypes, providing relative guidance on inlet and outlet pipe locations, inlet and outlet pipe widths and outlet heights; the variables within the five models.

With a better understanding of the flows within the biodigesters, the design can be improved creating a better product for families in terms of treatment of waste and gas availability for cooking.

Since working on the project, the Arup team continues to provide remote support through computational fluid dynamic modelling.