JPH0564782A - Treatment of water with activated carbon - Google Patents

Abstract

PURPOSE:To stably obtain high treatment efficiency while reducing treatment cost by extending the life of activated carbon by removing a biological membrane formed on the surface of activated carbon by washing activated carbon by mixing an organism inhibitor such as sodium hypochlorite with backwashing water at the time of the backwashing of an activated carbon water treatment device. CONSTITUTION:At the time of the backwashing of an activated carbon water treatment of an activated carbon water treatment device, an organism inhibitor injection pump fitted with a timer mechanism is operated to mix an organism inhibitor such as sodium hypochlorite with backwashing water to wash activated carbon. The proper concn. of residual chlorine in waste backwashing water is 0.1-2mg/l and the frequency of washing is pref. one per three days. As a result, high treatment efficiency can be stably obtained by removing the organism membrane formed on the surface of activated carbon and treatment cost can be reduced by extending the life of activated carbon.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for treating activated carbon of water, which is suitable for advanced treatment of tap water and sewage.

[0002]

2. Description of the Related Art As a conventional method for treating activated carbon with water, there is an activated carbon filtration method shown in FIG. In this method, water containing substances that are difficult to be decomposed by organisms such as COD and chromaticity is brought into contact with granular activated carbon in an upward flow or a downward flow, and these substances are removed by the adsorption action of the activated carbon. Usually, this method is performed under the conditions of a treatment speed of 50 to 150 m / day and a backflow frequency of 1 to 2 times / day.

The mechanism of this conventional method is, as shown on page 550 and below of the 28th Sewerage Research Presentation Lecture, published by the Japan Sewerage Association, as follows: activated carbon adsorption, activated carbon adsorption, and regeneration of adsorbed activated carbon pores by organisms. It consists of re-adsorption, decomposition by the biofilm formed on the surface of activated carbon, and removal by backwashing with water during backwashing (see Fig. 6), and the specific gravity of this treatment form changes with the progress of treatment.

In the early stage of the treatment, is preferential, and adsorption of activated carbon and regeneration of pores by organisms are repeated, resulting in good treatment efficiency. However, in the latter half of the treatment, biofilm is gradually formed on the surface of activated carbon. Therefore, the biofilm prevents the pollutants such as COD from diffusing into the pores, and the effect is reduced. If the effect of good treatment efficiency is diminished, there is a problem that the treatment efficiency as a whole of the activated carbon treatment is lowered, the activated carbon breaks through in a short period of time, and the treatment efficiency becomes unstable.

[0005]

DISCLOSURE OF THE INVENTION The present invention solves the above-mentioned problems of the prior art, can stably obtain high treatment efficiency, and extends the life of expensive activated carbon to reduce the treatment cost. It has been completed to provide a method for treating activated carbon of water capable of producing water.

[0006]

[Means for Solving the Problems] The above-mentioned problems are caused by backwashing biological inhibitors during backwashing in a method for treating active carbon in water in which components such as COD and chromaticity contained in raw water are removed by contacting with activated carbon. This can be solved by a method for treating activated carbon in water, which is characterized in that the activated carbon is washed by mixing it with water.

As described above, according to the present invention, the bioinhibitor is added to the backwashing water to carry out the backwashing, so that the organisms living inside the pores of the activated carbon are not inhibited from being formed on the surface of the activated carbon. The biofilm is regularly peeled off to prevent growth, and the pollutant components are sufficiently diffused into the pores of activated carbon to efficiently perform the treatment by "activated carbon adsorption → biological regeneration".

[0008]

The present invention will be described in more detail below with reference to the drawings. FIG. 1 shows a flow sheet of the present invention. The activated carbon treatment device 1 is filled with granular activated carbon to form an activated carbon layer 2. Although the raw water may be either an upward flow or a downward flow, in FIG. 1, the raw water is supplied from the upper part of the activated carbon treatment apparatus 1 by the downward flow, is withdrawn from the bottom and enters the treated water tank 3 via the valve V ₁ . At this time, the valve V ₂ ,
V ₃ and V ₄ are closed, blower B, backwash pump P ₁ and biodetergent injection pump P ₂ with timer mechanism are also stopped.

When the treatment progresses and the activated carbon layer 2 is clogged with SS in the raw water and the activated carbon treatment device 1 reaches the specified filtration height, the flow of raw water is stopped and the valve V ₁ is closed to reverse. Go into the wash. Backwashing is the same as the conventional method, with valve V ₃ open, air washing by operation of blower B → further valve V ₂ opening, mixed backwashing with addition of backwashing pump P ₁ open → valve V ₃ closed, water reversal by blower B stopped It is performed in the order of washing.

This backwashing is usually carried out about twice a day, but once every 2 to 7 days, preferably once every 3 days, V _{4 is} opened during mixed backwashing and water backwashing. The bio-inhibitor injection pump P ₂ with a timer mechanism is operated to mix the bio-inhibitor in the backwash water, and the biofilm that has started to form on the surface of the activated carbon by contacting with the activated carbon is peeled and removed. If this number is more than once every two days, not only will the biofilm be peeled off as shown in Fig. 2, but the organisms that live inside the activated carbon will also be killed. However, the processing efficiency drops rapidly. If it is less than once every 7 days, the biofilm will grow too much before the bioinhibitor is added and the biofilm cannot be completely peeled off, resulting in an effect close to that of the conventional method.

As the biological inhibitor used here, CuSO
₄ , HCHO, O ₃ , chlorine-based oxidizer, etc., but considering secondary pollution, O ₃ and chlorine-based oxidizer are good, and economical efficiency
Considering the controllability of the injection rate, chlorine-based oxidizing agents such as NaClO are preferable. The injection rate was 0 as residual chlorine in the backwash drainage.
1 to 2 mg / L, preferably 0.1 to 0.5 mg / L. If the residual chlorine in the backwash water is less than 0.1 mg / L, as shown in Fig. 3, the biofilm is not sufficiently exfoliated, and the effect of bioregeneration is weakened. As shown in the figure, not only is the activated carbon oxidized by the oxidizing power of chlorine to be wasted, but also the organisms in the activated carbon pores are killed, so the effect of bioregeneration is diminished. After backwashing, open the valve V ₁ as before and supply raw water,
Restart processing.

Table 1 shows the results of treating the secondary treated water of the sewage at a treatment scale of 130 m ³ / day for the present invention and the conventional method. The number of treatment days is 60% or more and the present invention is 30%.
It can be seen that the conventional method has a life span of 6 times or more in 44 days.

[0013]

[Table 1]

[0014]

INDUSTRIAL APPLICABILITY As described above, the present invention prolongs the life of activated carbon by 6 times or more as compared with the conventional method by mixing the bioinhibitor into the water for backwashing during backwashing to wash the activated carbon. In addition, since it is possible to obtain treated water stably with less deterioration of treatment efficiency, it is extremely important to contribute to industrial development as a method for treating activated carbon of water that solves the conventional problems. It is a thing.

[Brief description of drawings]

FIG. 1 is a flow sheet illustrating an example of the present invention.

[Fig. 2] The number of times backwashing is performed by adding NaClO to the backwash water.
It is a graph which shows the relationship with the change of a COD removal rate.

FIG. 3 is a graph showing the relationship between the residual chlorine concentration in backwash wastewater and the change in COD removal rate.

FIG. 4 is a graph showing a relationship between a cumulative injection amount of NaClO and a reduction amount of activated carbon.

FIG. 5 is a flow sheet illustrating a conventional method.

FIG. 6 is a sectional view illustrating a processing mechanism of a conventional method.

[Explanation of symbols]

1 Activated carbon treatment device 2 Activated carbon layer 3 Treated water tank 4 Biological inhibitor storage tank P ₁ Backwash pump P ₂ Biological inhibitor injection pump with timer mechanism B Blower V ₁ valve V ₂ valve V ₃ valve V ₄ valve

Claims (3)

[Claims] 1. A method for treating activated carbon in water, which comprises removing components such as COD and chromaticity contained in raw water by contacting them with activated carbon, to wash the activated carbon by mixing a biological inhibitor into the backwash water during backwashing. A method for treating activated carbon of water, which is characterized by carrying out. 2. The method for treating activated carbon in water according to claim 1, wherein the biodetergent is a chlorine-based oxide such as sodium hypochlorite. 3. Residual chlorine 0.1 to 2 mg in backwash drainage
The method for treating activated carbon in water according to claim 2, wherein the injection amount of the bioinhibitor is adjusted so that / L of available chlorine remains.