JP3444382B2 - Sludge treatment method - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for treating sludge generated in turbid water treatment or purified water production. 2. Description of the Related Art First, a conventional sludge treatment method will be described with reference to FIGS. [0003] First, in a sand settling tank 1, large-sized earth and sand B contained in raw water A is naturally settled and discarded in a dumping ground. Next, the primary flocculant a is added, and the mixture is rapidly stirred sufficiently in the raw water pit 2 and the coarse-grained cylinder 3 to form a small floc. A large floc is formed by rapid stirring, the floc is settled after a sufficient residence time, and the supernatant water C is overflowed and retained in the water purifying tank 5 for reuse, or the pH is adjusted to flow into a river. On the other hand, the sediment that has settled out is removed from the bottom of the thickener 4 and stored in the sludge tank 6, and the concentrated sludge D is sent to the dehydrator or filter press 9 via the sludge storage tank 8 by the mud pump 7 to be dewatered and dewatered. It is discharged as cake E and disposed of at a dumping site. [0004] The above-mentioned dewatered cake E
Is the sedimentation of silt (small and finer than sand and larger than clay) and clay that have been washed out of natural ground by the addition of coagulants, and sewage that may contain harmful substances. Unlike sludge, it is safe. On the other hand, horticultural cultivation soil and soil dig out soil that is a natural material,
It is commercialized after moisture adjustment. Therefore, if the dehydrated cake E can be reused as such horticultural culture soil, it is significant as effective use of resources. However, this dewatered cake E has a drawback in that it has a low water holding power because it mainly uses a silt component and a clay component when used as a horticultural soil or a soil. [0005] An object of the present invention is to provide a sludge treatment method for recycling a dewatered cake generated in turbid water treatment or water purification treatment. According to the present invention, large-grained sediment (B) contained in raw water (A) is naturally settled and removed, and the primary water is removed in the raw water bit (2). The flocculant (a) is added and rapidly stirred to form small blocks, followed by the addition of a secondary flocculant (b) and introduction into the thickener (4),
In a sludge treatment method in which a large block is formed by slow stirring and sedimented sediment is sent to a filter press (9) via a mud pump (7) and dewatered to form a dewatered cake (E), a filter press ( The dewatered cake (E) obtained by dewatering and washing in 9) is replaced with a bark compost (c) having a volume of 10 to 30% and mixed with a forced kneading mixer (10). [0007] In the sludge treatment method configured as described above, a water improving power is imparted by mixing a soil improving material into a dewatered cake having a low water holding power, mainly a silt component and a clay component. It can be reused as horticulture cultivation soil or medium. An embodiment of the present invention will be described below with reference to the drawings. In these drawings, portions corresponding to those in FIGS. 3 and 4 are denoted by the same reference numerals, and redundant description will be omitted. In FIG. 1 and FIG.
Add the organic soil conditioner c such as bark compost or peat moss to the dehydrated cake E (FIG. 4) obtained by dehydration washing in
The modified dehydrated cake F is made by mixing with the forced kneading mixer 10. [Experimental example] Since dehydrated cake has a disadvantage of poor physical properties,
Bark compost was mixed as an organic soil improver in a range of 5 to 50% based on the whole volume, and the effective moisture and porosity were measured in order to evaluate the properties as a cultivated soil. The evaluation method of this measurement item is as follows: Effective moisture: the amount of soil moisture that can be absorbed by plants. This value is obtained when the range of the soil's water holding strength is from pF1.8 to pF3.0. It is said that 6% or more is preferable. Porosity: Ratio of water and air to the volume of soil The range of 40 to 60% is preferable for plants. Table 1 shows the experimental results of the physical property improvement in which the soil improving agent is mixed with the dewatered cake according to the present invention. [0014] As shown in Table 1, it is clear that the porosity and effective moisture, that is, the water holding power of the cultivated soil can be improved to a suitable value by replacing the dehydrated cake with an organic soil improver having a volume of 10 to 30%. According to the present invention, as described above, the soil improving material is mixed with the dewatered cake which has been conventionally discarded to obtain an improved dewatered cake, which is used as a horticultural culture soil or soil. Can be reused.

[Brief description of the drawings] FIG. 1 is a basic flow chart of water treatment of the present invention. FIG. 2 is a flow chart of the water treatment of the present invention. FIG. 3 is a basic flow chart of a conventional water treatment. FIG. 4 is a flow chart of a conventional water treatment. [Explanation of symbols] A: Raw water B: earth and sand C: supernatant water D: concentrated sludge E: Dehydrated cake F: Improved dehydrated cake a ... Primary flocculant b: Secondary flocculant c: Soil conditioner 1 ... settling tank 2 Raw water pit 3 ... Coarse-grained cylinder 4 ... thickener 5 ・ ・ ・ Water purification tank 6 ・ ・ ・ Sludge tank 7 ・ ・ ・ Sludging pump 8 ・ ・ ・ Sludge storage tank 9 ... Filter press 10 ... forced kneading mixer

Continuation of front page       (56) References JP-A-52-93539 (JP, A)                 JP-A-7-40 (JP, A)

Claims (1)

(57) [Claims 1] A large particle size soil (B) contained in raw water (A) is naturally settled and removed, and a primary flocculant (a) is removed in raw water bit (2). ) Is added and rapidly stirred to form small blocks, followed by the addition of a secondary flocculant (b) into the thickener (4), with slow stirring to form large blocks and the settling of sediment Is fed to a filter press (9) via a mud pump (7) and dewatered to form a dewatered cake (E) in a sludge treatment method. The dewatered cake (E) obtained by dewatering and washing with the filter press (9) is obtained. ) Is 10 to 30% by volume
Replaced with bark compost (c), and forced kneading mixer (10)
A sludge treatment method, wherein the sludge is mixed.