``GPS-X is a great tool. It was successfully applied in a project in which the return activated sludge flow was adjusted as we extended from pre-denitrification to build a separate post de-nitrification step. We found that the return activated sludge flow could be reduced by more than 50% since we didn't need to return the nitrates. Energy savings due to reduced pumping costs were US$ 21,500 a year, thicker sludge with easier dewatering, as well as better settling properties were the result.''

``The sensitivity analysis and steady-state solver are the features we like the most. The GPS-X technical support is great!''

``We have been using GPS-X mainly to assist with capital scheme development. I have recently completed a works design using GPS-X. Had the works been designed using conventional rule-of-thumb design techniques it would not have achieved consent. GPS-X exposed the weakness in the design philosophy being adopted and helped better identify what was actually required. In fact a new activated sludge process which had been planned to be built was postponed because GPS-X showed that it was not necessary. In cash terms this meant we were able to save around £5 million. However, I believe the benefits are more than just the bottom line - what value do you put on getting it right, i.e. Confidence?''