Bozüyük Waste Water Treatment Plant has been designed by General Directorate of State Hydraulic Works to treat urban wastewater of Bozuyuk Town in Bilecik Province.
The plant will be constructed in two phases and treat approximately 40.000 m3/day wastewater.
Urban waste water of Bozuyuk Town is collected by a sewerage network and transferred to the plant via 4.8 km collector line
The plant has been designed using advanced biological treatment unit processes with the objective of wastewater reuse for irrigation. Hence the plant includes rapid sand filtration and UV disinfection unit processes.
In addition tominimizednet energy consumption, energy generation technologies are included in plant. A solar power generation system isincorporated into the design to supply the electrical power requirements of the plant and will operate as a supplementary system to the power grid system.
Waste water is transferred to the plant inlet structure via the main collector line. Then wastewater enters the pre-treatment units for screening, grit and grease removal.
At the beginning, wastewater passes through mechanically cleaning coarse screens wherein coarse materials are captured. After that, the wastewater flows through mechanically cleaning fine screens to remove fine materials which are not captured by coarse screens. The solid materials captured by both coarse and fine screens are dewatered and transferred by helical screw conveyors to adjacent waste containers which will then be periodically taken away from the plant site for sanitary disposal off-site.
Following the screening processes, wastewater flows to the aerated grit& grease removal unit processes for the removal offloating materials such as fats, oils and grease and settable inorganic materials such as sand and gravel. Airflow is generated by a blower and is introduced into the Aerated Grit Chamber viatubediffuserslocatednearthebottom of the chamber, thereby creating a circular or toroidal flow pattern in the wastewater. The continuous rising flow deflects off an energy-recovery baffle at the liquid surface. This flow pattern causes the grit to settle to the bottom of the chamber while keeping lighter organic material in suspension to be processed further downstream. Oncethegritsettled, an air-lift pump is used to remove the grit slurry and send it on for dewatering in a sand separator. The lighter organic materials such as fats, oils and greases float to the surface and are scraped from wastewater surface by mechanical scrapers mounted to a moveable bridge and are then transferred to an oil sump from where it will then be periodically taken away from the plantsite for sanitary disposal off-site.
After the completion of pre-treatment, wastewater flowsthrough a flow-measuring chamber prior to entering the main biological treatment unit processes.
Main biological process design in Bozüyük plant is an activated sludge process that can achieve nitrification, denitrification and biological phosphorus removal as well as BOD removal. The 3-stage process includes an anaerobic zone of about 1 hour retention followed by an anoxic zone of similar size and finally an aerobic zone of 4 to 6 hours retention In the process the 3rd aerobic zone is used for BOD removal and nitrification.
Recycle from the end of the aeration zone back to the anoxic zone results in the nitrate being mixed with the wastewater in the anoxic zone and nitrate is denitrified to nitrogen gas. Recycle of the RAS from the aeration zone back to the start of the anaerobic zone facilitates Biological Phosphorus Removal.
Specifically, main biological treatment unit processes in Bozüyük plant consists of 3 anaerobic tanks, 4 aeration tanks and for operational flexibility with the help of sluice gates, pumps and interconnecting channels can be operated as A 2 O, Bardenpho or staged feeding processes.
Forbiologicalphosphorusremoval biologicalprocessdesign in the plant has wastewater and return activated sludge first flowing in to an anaerobic tank, then onward to an aerobic tank. This first anaerobic tank is referred to as the Biophosphorus tank.
The Bozüyük plant design has 3 Biophosphorusanaerobic tanks that can operate in series or in parallel. Wastewater passes through the pre-treatment units and is mixed with return activated sludge in these tanks. Submerged mixers are located in each tank to prevent the sedimentation of solids and air is specifically not added so that Phosphorus-Accumulating Organisms can thrive. In an anaerobic environment, Phosphorus-Accumulating Organisms have the ability to sequester readily biodegradable biochemical oxygen demand Most other activated sludge bacteria do not. phosphorusremoval is dependent on maintaining a sufficient population of Phosphorus-Accumulating Organisms and the overall phosphorus removal occurs as the Phosphorus-Accumulating Organisms are wasted from the system.
Wastewater passes from the biophosphorus anaerobic tanks to the aeration tanks through a distribution chamber. Blowers and fine-bubble membrane diffusers provide oxygen to the aeration tanks and each tank is equipped with submerged mixers to prevent the sedimentation of solids.
Wastewater flows from the aeration tanks to final sedimentation tanks through a distribution chamber and sedimentation of the biomass occurs by gravity. Treated wastewater flows over the top of the sedimentation tanks via a v-notch weir mechanism. In the case this effluent is used for irrigation it is transferred for further treatment torapid sand filters and thereafter disinfected with ultraviolet unit processes. If the effluent is not used for irrigation it is discharged to adjacent Karasu Creek after flowing through a flow-measuring chamber.
The settled sludge in the final sedimentation tanks is transferred to a return and excess sludge pumping station. A portion of the sludge is returned to the biophosphorus tanks inlet as described above and the excess sludge is taken from the system and is transferred to sludge balancing tanks and then to sludge dewatering and stabilization unit processes. The sludge balancing tanks are equipped with membrane diffusers to maintain oxygenated conditions and mixers to prevent the sedimentation of solids.
The sludge dewatering and stabilization unit processes consist on decanter centrifuges for sludge dewatering and lime dosing units to stabilize the sludge and reduce odors. Decanted water from the decanter centrifuges is returned to the inlet of biophosphorus tanks. The stabilized sludge is periodically taken away from the plant site for disposal.
Main unit processes in the plant are supported with an Administrative Building which includes a laboratory and system control room. Computer hardware and software is provided to monitor and automatically control the plant unit processes, and the on-site laboratory allows operators to monitor the treatment efficiency of the plant by analyzing the wastewater and sludge samples throughout the treatment process.
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