43 of 74  Construction of Giresun Wastewater Treatment Plant  Tender Dossier Volume 3 Employer’s Requirements  Section 3: Plant Description  pumps  Maximum daily operation time  :    16hours/day  Type of digested sludge feeding pump  : eccentric screw pump  Weekly operation time  : 7 days/week  Minimum dry solids content of dewatered sludge  :  22 % DS  Minimum number of polyelectrolyte preparation  system  : 1 duty unit  Minimum number polyelectrolyte dosing pumps  : 2 (1 duty + 1 stand-by) units  Capture rate of solids in dewatering   : min. 95%  Thermal sludge drying plant shall be designed, constructed and equipped to increase the dry solid  content, to further sterilize the sludge and to enhance storage capability before final disposal. Thermal  sludge drying plant shall be designed, constructed, supplied and installed in turn-key to meet the  required sludge output characteristics. Further requirements are given in Section 7.8.44. Foul air shall  be collected from the building and shall be sent to the odor control unit. The dry solid shall be  transferred from the sludge drying plant to the sludge cake storage area with conveyors (air shall not  be used for transferring of dry sludge).The dewatered sludge shall be dried to get minimum outlet  sludge dry solids content of 90%.  Please note that dewatered sludge prior to drying process shall be  taken as 22% DS as specified in Table 2.5. 3.3.4.31 Sludge Drying Units 3.3.4.32 Sludge Cake Storage  Supernatant from dewatering and thickening process(es) shall be delivered back to the system by  gravity as possible. However, in case gravitational flow is not possible, a supernatant pumping station  shall be provided.  Individual or common sludge cake storage area for dewatered and dried sludge shall be constructed.  Each cake storage area shall have at least 2 days storage capacity. The sludge storage area shall be  roofed top with metal sheds made from galvanized steel, aluminum or equivalent material. Floor shall  be reinforced concrete suitable for driving over with a front-end loader or similar machine and  surrounded by concrete walls. Adequate drainage system and lightening system shall be designed and  constructed. The service water supply system and sufficient connection port shall be supplied for the  cleaning of sludge cake storage areas.  3.3.4.33 Supernatant Pumping Station  All supernatant water shall be collected to the supernatant pumping station. The pumps for supernatant  shall be submersible pumps. The actual capacity of the pumps shall be calculated by taking the  maximum amount of supernatant water into account. The backwash water of mechanical thickener and  decanter shall also take into account in determination of maximum capacity. Ultrasonic level sensors  shall be used in pump tanks for pump operation. Supernatant water flow rate shall be measured in  accordance with “Measurement and Instrumentation” section of this document.  The mixture of supernatant with drainage water and sewerage generated in the WWTP buildings is not  permitted.  3_Vol3_d4.3_Section 3_Plant Description_GIR_rev08 