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The achievable prediction quality of wastewater treatment facility simulation using STOAT will be demonstrated by this example of a large treatment facility with a two-step wastewater treatment, aerobic.
The following images compare results from a STOAT simulation with actual measurements of the parameters «COD» und «NH4-N» at the first biological treatment step between 1.1.2006 and 31.12.2006. STOAT results have been output for 2 hour intervals, the measurents are based on 24h composite samples.
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| Fig. 1: COD according to STOAT simulation compared with measurement values |
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| Fig. 2: NH4-N according to STOAT simulation compared with measurement values |
Obviously extent, resolution in time and quality of measurements at the treatment facility have significant influence onto the achievable quality of subsequent simulations. Therefore available data for the computation results depicted above shall be characterized briefly:
- In addition to influents and the effluent, quality of the wastewater is examined at five points along its path through the treatment facility. These examinations are mostly carried out as 24h composite samples.
- Among others the following quantities are determined at the company-owned laboratory: COD, suspended solids, NH4-N, NO2-N, NO3-N, N total, N organic, TKN, P total, o-PO4-P, pH, chlorides and sulfates. This completely covers the parameter set required for application of Activated Sludge Model #1.
- Flow is measured online at the same points. Data is recorded by the process control system, processed and archived every two hours.
- Values of oxygen transfer, recycled activated sludge (RAS) and wastage sludge (WAS) were also measured online and available with 2h intervals.
- Additionally, a number of special examinations were done (e.g. heavy metals, Nitritox), whose findings could also be used.
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