JPH0732920B2 - Enzymatic modification and concentration method of organic sludge - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention is an enzyme-based organic substance capable of reforming sludge containing a large amount of organic matter such as municipal sewage sludge without chemical injection and easily concentrating it. The present invention relates to a method for reforming and concentrating sludge.

(Prior Art) In order to coagulate organic sludge containing a large amount of organic matter, it is common to add slaked lime, ferric chloride, polymer coagulant, etc. to the sludge as an auxiliary agent and mix them to coagulate. Is. However, the addition of slaked lime, ferric chloride, etc. increases the volume of the dehydrated cake, and has the disadvantage that scale adheres to the inside of the piping of the equipment, etc. There was a drawback that it was difficult to reduce the rate.

Therefore, there is a demand for a method of performing sludge treatment by chemical injection without using these auxiliaries, and for example, in JP-A-61-278400, sludge is reformed by electrolysis treatment. It shows how to do it. However, this method has a drawback that the cost is high because a lot of power is required.

(Problems to be Solved by the Invention) The present invention solves such a conventional problem by using an enzyme capable of rapidly modifying and concentrating organic sludge without chemical injection and at low cost. It was completed for the purpose of reforming and concentrating organic sludge.

(Means for Solving the Problem) The first invention made to achieve the above object is to bring sludge into contact with a lytic enzyme such as lysozyme by contacting the organic sludge with stirring at a temperature of 10 to 50 ° C. The second invention is characterized in that organic sludge is brought into contact with lysing oxygen such as lysozyme and agitated to agglomerate the sludge to precipitate and concentrate it. It is what

In the first invention, a lytic enzyme is contacted with an organic sludge (TS value of about 1 to 5%) such as biologically treated sludge, and the cell wall of the microbial cells in the organic sludge is dissolved by its catalytic action. To improve sludge. Lysozyme is a typical lytic enzyme, but other lytic enzymes such as zymolyase can also be used. The lytic enzyme may be added to sludge in a free state and reacted by stirring, or may be immobilized on a carrier and brought into contact with sludge. In the former case, the addition amount of the lytic enzyme is 30 U / or more, and the stirring may be weak stirring so that the sludge and oxygen can be sufficiently brought into contact with each other. In the latter case, the lytic enzyme may be immobilized on a ceramics carrier such as a sepiolite carrier, which may be packed in a column and sludge may be passed through the column in an upflow or downflow system to cause a catalytic reaction. In this case, the residence time of 1 hour is sufficient. It should be noted that the reaction temperature is 10 to 50 ° C at which the activity of the lytic enzyme becomes large, and more preferably 30 to 40 ° C. It is not practical because it is expensive and causes a bad odor.

In the second invention as well, a lytic enzyme such as lysozyme is brought into contact with the organic sludge in the same manner. In this case, the addition amount of the lytic enzyme may be 1 U / or more, which is small compared to the first invention. . In the present invention, the lytic enzyme does not completely dissolve the cell wall of the microbial cell, but plays a role as a binder for assembling the microbial cells in a free state with each other, and also rapidly agglomerates the non-dehydrating sludge. be able to. If the aggregated sludge is gravity-concentrated, a high-concentration sludge can be obtained.

Hereinafter, each invention will be described in more detail with reference to Examples.

(Example) Example 1-Sludge reforming method Put organic sludge into a 1 m x 1 m x 1.5 m reforming tank, add lysozyme to various concentrations in a free state, and perform 1 at 35 ° C.
Stir for hours. The stirring was for the purpose of contacting sludge and lysozyme, and was weak stirring at 100 rpm or less. The sludge thus modified was dehydrated with a belt press dehydrator. The dehydration conditions are a filter cloth speed of 0.75 m / min and a filter cloth tension pressure of 2 kg / cm ² . The filtration rate by the belt press is 50 kg / m for excess sludge.
・ Hr, 120 kg / m ・ Hr for mixed sludge.

Fig. 1 is a graph showing the relationship between the water content of dehydrated sludge and the amount of enzyme obtained in this way. Especially in the case of mixed sludge, when the amount of enzyme is 30 U / or more, the water content reaches 70%. It can be seen that the water content decreases to 83% in the case of excess sludge. Fig. 2 is a graph showing the relationship between the CST value, which is an index of the filterability of sludge before dehydration, and the amount of enzyme, 30 U / g
When the above enzymes are added, the sludge will be modified and the CST value will be 20-5.
It can be seen that it drops to 0 seconds.

On the other hand, if the water content of dehydration treatment by a belt press using a conventional polymer coagulant is 78% for mixed sludge and 86% for excess sludge, it is proportional to dry sludge as shown in the following table. The amount of attached water per (DS) is 21 for mixed sludge.
%, And in the case of excess sludge, it has decreased by 34%.

In addition, the same measurement was carried out using a column having a diameter of 0.5 m and a height of 1 m, in which the carrier in which lysozyme was immobilized was packed while varying the number of carriers packed in the column.
Shown in the figure. Thus, the same sludge reforming effect was confirmed when the free enzyme was used and when the immobilized enzyme was used. As described above, according to the present invention, the organic sludge can be reformed without chemical injection.

Example 2-Sludge flocculation method 0.1 U for diluted non-dewatering organic sludge with a concentration of 0.52%
Add various amount of / of lysozyme, 200 rpm for about 1 minute
Was rapidly stirred, followed by gravity concentration for 1 hour.
As a result, lysozyme acted as a binder to agglomerate the sludge, and the concentration of the concentrated sludge was measured by the method specified in JIS. The results shown in FIG. 5 were obtained. As is clear from FIG. 5, the concentration of the concentrated sludge increased to 3% or more by the addition of 1 U / or more lytic enzyme, and the following dehydration could be easily performed.

When the sludge was concentrated for 24 hours by the usual gravity concentration method, the concentration of the concentrated sludge was 1.5%. From this result, it is clear that the concentration is approximately doubled in a short time as compared with the usual weight concentration method.

(Effect of the invention) As described above, the present invention is capable of reforming or agglomerating sludge by contacting a lytic enzyme such as lysozyme with organic sludge,
Since sludge treatment is possible without chemical injection, unlike the conventional method of adding slaked lime or ferric chloride, the volume of the dehydrated cake does not increase, and it can be concentrated to a high concentration in a short time. No scale adheres to the inside of the pipe. Further, according to the present invention, the water content of the dehydrated cake can be reduced, and the sludge treatment cost can be reduced as compared with the sludge electrolysis method. Therefore, the present invention, as a method for modifying and concentrating an organic sludge with an enzyme that eliminates the conventional problems, is extremely important in contributing to industrial development.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a graph showing the relationship between the amount of free enzyme and the water content of dehydrated cake in the first invention, and FIG. 2 is the amount of free enzyme and CS.
Graph showing the relationship with T value, Fig. 3 is a graph showing the relationship between the amount of immobilized enzyme and water content, and Fig. 4 is the amount of immobilized enzyme and CS
FIG. 5 is a graph showing the relationship with the T value, and FIG. 5 is a graph showing the relationship between the enzyme amount and the gravity-concentrated sludge concentration in the second invention.

Claims (2)

[Claims] 1. A method for modifying an organic sludge with an enzyme, which comprises decomposing and modifying the sludge by bringing a lysing enzyme such as lysozyme into contact with the organic sludge and stirring the mixture under a temperature condition of 10 to 50 ° C. Quality method. 2. A method for concentrating sludge with an enzyme, which comprises contacting a lysing enzyme such as lysozyme with organic sludge and stirring to agglomerate the sludge to precipitate and concentrate the sludge.