Origins of Sewage
Wastewater is created within residences, institutions, hospitals, commercial and industrial establishments. It is comprised of sanitary waste (brown water) and other utility uses (grey water). Wastewater may also include some surface water due to infiltration and some residential drainage. Wastewater is primarily water with only 0.1% solids. The Durham Region does not have combined sewers, which consist of storm water runoff entering the wastewater collection system, rather the storm sewer collection system is separated from the wastewater collection system and discharges to natural waterways such as rivers and storm retention ponds.
1- Preliminary Treatment
Screening/straining:
Wastewater is initially strained to remove paper products and large objects that could harm pumps and other process equipment. Straining is typically accomplished using automated mechanically raked bar screen. The screenings are compacted and transported for disposal to landfill.
Grit removal:
Following the screening, the sewage then flows to a grit removal component. Grit removal is the process of removing sand, grit, and stones while keeping the majority of the organic matter suspended. This can be accomplished by carefully controlling the wastewater flow in a channel or a tank, or by introducing air to the wastewater within a tank or channel and/or also by dewatering equipment (e.g. centrifugal separator). The grit is then transported to landfill along with the screenings.
2- Primary Treatment
In this stage, the wastewater flows through large tanks commonly called ‘primary clarifiers’. These tanks are designed to remove larger particles by letting them settle to the bottom (sludge) while lighter and floatable materials such as grease and oils (scum) rise to the surface where it will be skimmed off. This process removes up to 60% of the suspended solids. Both the sludge and the scum are removed from the tanks and pumped to further sludge treatment processes (see Sludge Treatment).
3- Secondary Treatment
Bioreactor:
The secondary treatment stage of the process is where the components of the wastewater are substantially degraded. This is accomplished using microorganisms, oxygen and the remaining organic materials found in the wastewater. The microorganisms, bacteria and protozoans, consume some of the organic contaminants and bind much of the remaining organics into floc. A coagulant is added to assist in bonding the smaller flocs into larger settleable formations. This also aids in removing phosphorus. Excessive release of phosphorus could lead to an algal bloom which can be harmful to the receiving waters.
Secondary Clarifiers:
The final part of the secondary treatment stage is to settle out the biological floc to produce a clear and clean effluent. The floc (activated sludge) that settles to the bottom of the sedimentation tanks, often called ‘secondary clarifiers’, are rich in microorganisms and is returned to the bioreactor to repeat the biological degrading process. To prevent an overgrowth of microorganisms which will upset the process, some of the activated sludge is sent to the primary clarifiers to co-settle with the sludge and be further treated prior to disposal.
Tertiary Treatment
Filtration:
When the treated wastewater is discharged into small or sensitive receiving water course, it will often undergo a third level of treatment called tertiary treatment. This is also called ‘effluent polishing’. The Tertiary treatment used by the Region is sand filtration. This removes most of the remaining suspended solids.
4 - Disinfection
This stage is intended to substantially reduce the number of microorganisms in the effluent to be discharged back to the receiving waters. Two methods are used in the Region:
1-Chlorination/Dechlorination:
The effluent is dosed with chlorine and sent into a tank to allow the chlorine to come into contact with the microorganisms, killing them or inactivating them. At some plants chlorination is followed by dechlorination of the effluent prior to its discharge to the receiving waters.
2- Ultraviolet light (UV):
For this process to be efficient, the effluent must first undergo Tertiary Treatment to ensure the effluent is as clear as possible. Then the water is bombarded by radiation from a series of UV lights which damages the genetic material within the bacteria, rendering them unable to reproduce. It leaves no residual entering the receiving bodies. This process is very clean, however also very expensive.
5- Sludge Treatment
Sludge, scum and activated sludge collected from the clarifiers are either pumped to digester tanks, where it will either be further treated on site for eventual land application (biosolids), or stored in holding tanks until transportation to Duffin Creek Water Pollution Control Plant in Pickering for incineration or landfill disposal.
Both processes thicken the sludge creating a lighter liquid supernatant. This
ต้นกำเนิดของน้ำเสียสร้างระบบบำบัดน้ำเสียภายในเรสซิเดนซ์ สถาบัน โรงพยาบาล สถานประกอบการธุรกิจ และอุตสาหกรรม ประกอบด้วยของเสียสุขาภิบาล (น้ำสีน้ำตาล) และโปรแกรมอรรถประโยชน์อื่น ๆ ใช้ (น้ำสีเทา) น้ำเสียอาจรวมถึงน้ำผิวเนื่องจากการแทรกซึมและระบายน้ำที่อยู่อาศัยบาง น้ำเสียเป็นน้ำหลัก มีเพียง 0.1% ของแข็ง เดอรัมภูมิภาคได้รวมท่อระบายน้ำ ซึ่งประกอบด้วยน้ำที่พายุเข้าระบบรวบรวมน้ำเสีย ค่อนข้าง ระบบคอลเลกชันของท่อระบายน้ำพายุแยกออกจากระบบรวบรวมน้ำเสียและปล่อยให้การบ้านธรรมชาติแม่น้ำและพายุคงบ่อการรักษาเบื้องต้น 1คัดกรอง/รัด:เริ่มมีย้ำเสียเอาผลิตภัณฑ์กระดาษและวัตถุขนาดใหญ่ที่อาจเป็นอันตรายต่อปั๊มและเครื่องมือเครื่องใช้อื่น ๆ รัดโดยทั่วไปได้ใช้กลไก raked แถบหน้าจออัตโนมัติ ฉากมีกระชับ และส่งขายทิ้งเพื่อนำเอา grit:ต่อไปนี้คัดกรอง น้ำเสียแล้วไหลเอา grit องค์ประกอบ เอา grit เป็นกระบวนการเอาทราย grit และหินในขณะที่การรักษาส่วนใหญ่ระงับอินทรีย์ นี้สามารถทำได้ โดยระมัดระวังการควบคุมขั้นตอนการบำบัดในสถานีหรือถัง หรือ โดยการแนะนำอากาศเสียภายในถังหรือช่องทาง หรือ โดยการแยกน้ำอุปกรณ์ (เช่นแรงเหวี่ยงแยก) Grit จะส่งไปนำพร้อมกับฉากที่แล้ว2- Primary TreatmentIn this stage, the wastewater flows through large tanks commonly called ‘primary clarifiers’. These tanks are designed to remove larger particles by letting them settle to the bottom (sludge) while lighter and floatable materials such as grease and oils (scum) rise to the surface where it will be skimmed off. This process removes up to 60% of the suspended solids. Both the sludge and the scum are removed from the tanks and pumped to further sludge treatment processes (see Sludge Treatment).3- Secondary TreatmentBioreactor:The secondary treatment stage of the process is where the components of the wastewater are substantially degraded. This is accomplished using microorganisms, oxygen and the remaining organic materials found in the wastewater. The microorganisms, bacteria and protozoans, consume some of the organic contaminants and bind much of the remaining organics into floc. A coagulant is added to assist in bonding the smaller flocs into larger settleable formations. This also aids in removing phosphorus. Excessive release of phosphorus could lead to an algal bloom which can be harmful to the receiving waters.Secondary Clarifiers:The final part of the secondary treatment stage is to settle out the biological floc to produce a clear and clean effluent. The floc (activated sludge) that settles to the bottom of the sedimentation tanks, often called ‘secondary clarifiers’, are rich in microorganisms and is returned to the bioreactor to repeat the biological degrading process. To prevent an overgrowth of microorganisms which will upset the process, some of the activated sludge is sent to the primary clarifiers to co-settle with the sludge and be further treated prior to disposal.Tertiary TreatmentFiltration:When the treated wastewater is discharged into small or sensitive receiving water course, it will often undergo a third level of treatment called tertiary treatment. This is also called ‘effluent polishing’. The Tertiary treatment used by the Region is sand filtration. This removes most of the remaining suspended solids.4 - DisinfectionThis stage is intended to substantially reduce the number of microorganisms in the effluent to be discharged back to the receiving waters. Two methods are used in the Region:1-Chlorination/Dechlorination:The effluent is dosed with chlorine and sent into a tank to allow the chlorine to come into contact with the microorganisms, killing them or inactivating them. At some plants chlorination is followed by dechlorination of the effluent prior to its discharge to the receiving waters.2- Ultraviolet light (UV):For this process to be efficient, the effluent must first undergo Tertiary Treatment to ensure the effluent is as clear as possible. Then the water is bombarded by radiation from a series of UV lights which damages the genetic material within the bacteria, rendering them unable to reproduce. It leaves no residual entering the receiving bodies. This process is very clean, however also very expensive.5- Sludge TreatmentSludge, scum and activated sludge collected from the clarifiers are either pumped to digester tanks, where it will either be further treated on site for eventual land application (biosolids), or stored in holding tanks until transportation to Duffin Creek Water Pollution Control Plant in Pickering for incineration or landfill disposal.Both processes thicken the sludge creating a lighter liquid supernatant. This
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