Method and apparatus for determination of coagulant injection rate in water treatment process

Abstract

Provided are a method and an apparatus that enable rapid and automatic determination of the coagulant injection rate in a process of water treatment through coagulation and sedimentation. Using a coagulation analyzer comprising sample tanks 1 A to 1 D each for keeping a predetermined amount of raw water, a water supply pump 7 , water supply / discharge valves 4, 6 for raw water and washing water, mixers 3 A to 3 D, a coagulant injection unit 21 , and a detector 30 for determining the particle size and the particle number of flocs, the time within which the coagulant 20 injected into the sample tanks is dispersed by mixing and the particles begin to agglomerate (agglomeration start time) is determined, and based on the thus-determined agglomeration start time, the coagulant injection rate is determined, or the amount of the coagulant to be injected is controlled.

Description

technical field [0001] The present invention relates to determining the coagulant injection rate (ratio of the coagulant injection amount to the treated water volume) in coagulation treatment for surface water such as river water, lake water, etc., industrial water, sewage, sludge, factory wastewater, etc. method and device. Background technique [0002] A water purification plant that adopts a rapid filtration method is usually composed of a mixing tank, a floc formation tank, a sedimentation tank, and a filter tank. In the mixing tank, a coagulant is injected and stirred rapidly. Generated aggregates (flocs) grow, the settling tank is used to settle the grown flocs and remove them, and the filter tank is used to remove particles or flocs that have not been completely settled (refer to Patent Document 2 Figure 7 ). [0003] The main point of the rapid filtration method is to control the injection rate of the coagulant to an appropriate value according to the quality of th...

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Problems solved by technology

[0020] (1) The method of the beaker test has the problem that skilled operators are required, and different operators are likely to obtain different results

In addition, there is also the following problem: Since it takes about 30 minutes to determine the coagulation status and the appropriate injection rate of the coagulant, it is difficult to perform frequent beaker tests, and the feedback to the implementation facility on the injection rate of the coagulant is delayed.

[0021] If an automatic beaker tester that realizes the automation of the beaker test operation is used, the operation of the operator can be greatly reduced, but it still takes about 30 minutes to obtain the measurement result, and the problem of a large time lag cannot be solved.

[0022] The method of the injection rate formula of (2) Since the injection rate formula is different depending on the raw water, it is necessary to manage the injection rate formula of each water purification plant, and there is no guarantee that the injection rate formula can be used permanently

That is, there is a problem that the relationship between each water quality and the optimum coagulant injection rate may be destroyed due to the construction of a dam on the upstream side of the water intake, construction of coastal works, and the influence of heavy rain. Time is not universal

That is, there is such a problem that it is necessary to obtain data obtained from the condensation sensor over the entire four seasons, and it takes time until the actual operation

[0024] The problems that exist in water purification plants have been explained above, but it goes without saying that the same problems exist in the condensation of industrial water, sewage, and factory wastewater.

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