Automatic medicine adding control method and device for chemically-assisted dephosphorization in sewage treatment

Abstract

The invention discloses an automatic medicine adding control method and a device for chemically-assisted dephosphorization in sewage treatment. A total-phosphorus on-line monitor and an iron-ion on-line monitor are used for respectively sampling and monitoring the middle position of the aerobic zone of a biological reaction tank of a sewage treatment plant and the water outlet of a secondary sedimentation tank; the total phosphorus concentration of a water sample on the middle position of the aerobic zone of the biological reaction tank and the iron-ion concentration in a water sample on the water outlet of a secondary sedimentation tank are collected; meanwhile, the water inlet flow of the biological reaction tank is monitored by a flowmeter; according to the total phosphorus concentration of the water sample on the middle position of the aerobic zone of the biological reaction tank and the water inlet flow of the biological reaction tank, the medicine adding amount is determined; and meanwhile, the medicine adding amount is rectified by the total phosphorus concentration calculated by the iron-ion concentration in the water sample on the water outlet of the secondary sedimentation tank. The medicine adding amount determined by the invention is more economic and reasonable, the effluent total phosphorus of a sewage treatment plant is feasibly guaranteed to reach the standard,the effluent stability is improved, the effluent water quality stability is guaranteed, and the resistance to impact load of the chemical synchronous dephosphorization technology is enhanced.

Description

technical field [0001] The invention relates to an automatic dosing control method and device for chemically assisted phosphorus removal in a sewage treatment plant in an urban sewage treatment plant, and belongs to the technical field of sewage treatment. Background technique [0002] In recent years, the trend of water eutrophication has been increasing, which seriously threatens people's production and life. The study found that for inland water bodies, phosphorus is the main limiting factor of water eutrophication, and phosphorus discharge from urban sewage treatment plants is one of the main reasons for water eutrophication. Therefore, all countries have formulated strict phosphorus discharge standards for urban sewage treatment plants. [0003] The existing sewage phosphorus removal processes at home and abroad are mainly biological phosphorus removal and chemical phosphorus removal. Compared with the chemical treatment method, the biological treatment method has the...

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Problems solved by technology

Although this method is more economical and efficient than the first two methods of chemical dosing, it has serious defects in the current application of urban sewage treatment plants: 1) Since the development and application process of this automatic control method does not have bio-enhanced removal Phosphorus capacity, the dosage of the agent is only calculated and determined according to the chemical reaction relationship between the agent and the total phosphorus. In addition, in order to give full play to the flocculation ability of the chemical agent, the agent dosing point is arranged at the front of the biological reaction tank

2) Usually, during the treatment and disposal of excess sludge in urban sewage treatment plants, the returned supernatant carries a large amount of phosphate, which has an impact on the quality of influent water. If the impact of this part of phosphate is not considered, it is difficult to ensure that the effluent Stable and up-to-standard discharge of total phosphorus

[0008] Therefore, for urban sewage treatment plants, how to achieve the best chemical dosing through the automatic control system to achieve the best synergistic effect of chemical phosphorus removal and biological phosphorus removal is still a technical problem.

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