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## 4.21.2.1  Pre-conditions for the verification of the process performance 

The fulfillment of process performance covers only conditions that the Contractor is able to control and regulate, whereas the following general and particular reservations are in force: 

 The average load of substances on the wastewater treatment plant will not exceed the pre- conditions stated in Section 2.3. 

 The maximum hydraulic load on the wastewater treatment plant will not exceed the pre- conditions stated in Section 2.2. 

 No harmful substances (heavy metals, toxins, etc.) are conveyed to the inlet in concentrations that in accordance with ISO 9509 can effect an inhibition of more than 25% of the nitrification process. 

 Tests shall be conducted by the End Recipient. A representative from the Engineer shall supervise the performance testing and the verification. A representative from the Contractor may also be attended to tests. 

 The wastewater treatment plant has completed its period of tests after completion. A representative from the Engineer will supervise the performance testing and the verification. 

 The wastewater treatment plant has been operated in accordance with Contractor's operation- and maintenance manual. 

 The treatment process is operated under normal conditions (where influent characteristics do not exceed the design parameters). 

 No occurrence of sludge with poor settling characteristics, which can result in non- compliance with the control requirements for suspended solids. Sludge with poor settling characteristics is defined either as occurrence of sludge particles of a size (<10 µm), which makes separation with standard sedimentation impossible or as occurrence of extraordinary large amounts of filamentous bacteria. Poor settling characteristics as a result of raw wastewater quality will not be the responsibility of the Contractor. 

 Failure in the delivery of electricity, water, chemicals etc., failure in analyses and sampling, failure in sludge disposal, extreme weather, etc. has not occurred. 

 Nutrients are available in sufficient quantities, i.e. in incoming wastewater: 

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 If one or more pre-conditions for the verification of the process performance stated above shall not be occurred in some days of OPEX monitoring period in DNP, the data of consumables (electricity and chemicals) of those days shall be omitted from OPEX 

