21 of 74  Construction of Giresun Wastewater Treatment Plant  Tender Dossier Volume 3 Employer’s Requirements  Section 3: Plant Description  Outlet channel of primary clarifiers tank or anaerobic bio-phosphorus tanks distribution chamber shall  be designed the following scenarios:  i) Wastewater should be transferred to biological treatment unit at normal operational  conditions  ii) If biological treatment units are out of operation, the whole amount of the incoming  wastewater shall be directly by-passed.  *For the calculation of the required minimum surface area of the primary clarifiers, the hourly  loading rate (not the daily loading rate i.e. m3/m2.day) based on the maximum hourly flow rate shall  be taken into consideration. Minimum number of primary sedimentation tank for Stage 2  : 3 tanks  Maximum surface loading at maximum flow  : 4 m$^{3}$/m$^{2}$.h  Maximum weir load at maximum flow  : 10 m$^{3}$/m.h  Type of bridge  : rotating half or linear operated  The distribution chamber shall be designed, constructed and equipped regarding the requirements set  in Table 2-1.  This distribution chamber shall receive the wastewater from the primary clarifiers and distribute it  evenly to the anaerobic bio-phosphorus tank or to the aeration tanks combined with anaerobic section.  The structure shall be made of reinforced concrete and shall be equipped with penstocks or appropriate  valves. There shall be the penstocks or valves with electric actuator in accordance with the  specifications given in Section 7.8.8 and 7.8.18. The operation status of the penstocks should be  monitored and controlled by the SCADA system. Chambers designed and constructed for the needs of  Stage 2 should be isolated by an appropriate material/construction assuring the isolation until  installation of penstocks proposed for Stage 2.  The location of the return sludge flow shall be selected and designed by the Contractor. 3.3.4.8 Distribution Chamber for Anaerobic Bio-phosphorus Tanks  3.3.4.9 Anaerobic Bio-phosphorus Tanks  3_Vol3_d4.3_Section 3_Plant Description_GIR_rev08  From the anaerobic bio-phosphorus tanks, the wastewater shall flow to a distribution chamber and  shall be distributed evenly to the activated sludge tanks. It shall be possible to operate the anaerobic  bio-phosphorus tank and activated sludge tanks separately and to take each tank out of operation for  inspection or maintenance. The anaerobic bio-phosphorus tanks shall be designed, constructed and equipped regarding the  requirements set in Table 2-1. The design flow (Q$_{DW,h}$) of the related stage requirements shall be met  for the unit. The microorganisms in the recycled sludge release captured phosphorus inside the body of the sludge  when they are exposed to anaerobic conditions. Anaerobic tanks shall be provided for biological phosphorus removal.