What is STOAT anyway and what do I have to do with it?

STOAT, an abbreviation of Sewage Treatment Operation Analysis over Time, is a software package for dynamic sewage plant simulation, developed in the early '90s by WRc, Swindon/GB.

I came into contact with it when, in the mid-2000s shortly after the founding of EnviaTec GmbH, we received an order from a well-known pharmaceutical company in Rhineland-Palatinate to compile a wastewater register. After the client had gained some experience with our wastewater register, they approached us asking whether they could also commission us to simulate the company's sewage treatment plant. The background to this request was that our wastewater register already contained all the input information on the quantity and composition of the wastewater substreams arriving at the treatment plant that are needed for a simulation.

This flattered us and since you can supposedly do everything in a pinch, we agreed to set up a sewage treatment plant simulation. It quickly became clear, however, that with our "on-board resources" we were by no means up to the task. Thus the only option was to use a commercially available software package.

There was a large number of offers of software for sewage treatment plant simulation. As our wastewater register was essentially based on Microsoft software (MS Access, Excel, Word, linked using Visual Basic), we chose, after weighing all the pros and cons of the available solutions, the STOAT package from WRc. This offered an almost seamless compatibility with our wastewater register based on Microsoft's Office solutions.

We managed to produce a simulation within the agreed deadline. However, the simulation quality left much to be desired. The main deficiency from today's perspective was the faulty fractionation of organic matter and the nitrogen compartments.