상하수도 116회 3교시 문제 2. 수처리 단위조작에서 오존처리가 다른 처리법과 비교하여 우수한 점을 기술하고 오존처리 시 유의점을 설명하시오.

 

상하수도 122회 유사문제 답안예시를 아래 올려 드립니다.

문제 : 정수처리에서 오존처리 시 문제점

상하수도 122회 1교시 문제 5. 정수처리에서 오존처리 시 문제점

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[구글번역]

 

In water treatment unit operation, describe the strong points of ozone treatment compared to other treatment methods, and explain the points to be taken into account during ozone treatment.

 

A1. Overview of Ozone Treatment
- Recently, the need for advanced water purification treatment has emerged for aggravating pollution of water bodies, eutrophication, and treatment of pollutants that are not treated in general water treatment processes.
- Reinforcement of drinking water quality standards including pathogenic microorganisms, and increasing citizens’ demand for water quality improvement regarding taste and smell
- Therefore, to solve these problems, it is necessary to introduce an advanced water purification process, and in the case of the advanced water purification process in Korean treatment plants, ozone + BAC process is widely applied.

 

A2. Purpose of installation of ozone treatment
- Disinfection, sterilization: no residual effect
- Virus inactivation: dissolved residual ozone concentration of 0.4ppm, contact time 8 to 12 minutes
- Removal of taste and odor substances: Removal of odorous substances (2-MIB, Geosmin, etc.)
- Remove chromaticity
- Increased biodegradability of organic compounds
- Reduction of generation of disinfection residues (THMFP, THMs)
- Reduced chlorine demand
- Removal of Fe and Mn

 

A3: Problems in ozone treatment in water treatment
- There is no continuity of disinfection effect, and chlorine treatment is required to satisfy residual chlorine standards
- Requires ozone generator
- Produced on site
- Low economic feasibility due to high price
- Excessive power cost
- Initial investment cost, high ancillary equipment
- Concerns about damage in case of ozone leakage: need to treat ozone
- Secondary pollution (after-growth) by microorganisms in the supply and drainage network due to the increase of AOC and BDOC during ozone treatment

 

A4: Considerations when designing an ozone treatment process
1) Prevention of ozone leakage from the ozone contact point before and after
- Prevention of local complaints and health hazards of field workers
2) Selection of the proper location of the ozone contact tank
- To avoid damage from ozone leakage, avoid the office area and install additional ventilation facilities
3) Reasonable calculation of ozone production capacity
- Due to lack of technology and experience, the maximum ozone injection value was selected as 2-3ppm, the Japanese experience level.
- It is necessary to calculate the injection amount according to the characteristics of the influent to the actual water purification plant.
4) Rationalization of ozone contact tank design
- Retention tank design so that residual ozone can be sufficiently consumed at the end of the contact tank
5) Securing appropriate control technology for ozone process
- Design considering daily/seasonal changes and the impact on BAC, the follow-up process
- Establishment of a control system that can respond to changes in water quality and quantity in real time