JPH0440248A - Solid-liquid separating method - Google Patents

Abstract

PURPOSE:To facilitate solid-liquid separation of a liquid containing suspended matters hard to precipitate easy by mixing a magnetic powder and a coagulant to a liquid to form coagulating matters which are the suspended matters and the magnetic powder combined each other and drawing and concentrating the coagulating matters in a specified position owing to the magnetic force and then separating them from the liquid. CONSTITUTION:A magnetic powder and a coagulant are mixed with a liquid to produce coagulating matters which are suspended matters and the magnetic powder combined each other and the coagulating matters are drawn and concentrated in a specified position owing to the magnetic force and then they are separated from the liquid. As the magnetic powder to be used, iron powder, iron sand, ferrite, etc. with 0.01-100mum grain size are suitable. The addition amount of the magnetic powder is preferably 0.1-10wt.% of the suspended solid matter. The magnetic force is generated by a permanent magnet or an electromagnet. In this way, organic suspended matters which are hard to precipitate by normal gravity precipitation precipitate extremely quickly.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to an improvement in a method for separating suspended matter in a liquid using a flocculant.

[Conventional technology]

When solid-liquid separation is performed on a liquid containing suspended fine solids that have poor settling properties, a flocculant is used to convert the fine solids into coarse aggregates that make them easier to settle. in a stationary state or under the action of centrifugal force, etc.
Often separated by precipitation.

However, even if a flocculant is used, if the flocculates formed are soft or have a small difference in specific gravity from the liquid, the sedimentation rate will not be very high, and it will be difficult to dehydrate the flocculates that have been sedimented and separated.

[Problem to be solved by the invention]

Therefore, the present invention provides a means for quickly separating fine solids that are difficult to settle and separate from a liquid by simply using a flocculant, and facilitates solid-liquid separation of liquids containing difficult-to-settle suspensions. This is what I am trying to do.

[Means to solve the problem]

The present invention, which has succeeded in achieving the above object, involves mixing magnetic powder and a flocculant with the liquid to separate the suspension and magnetic powder when performing solid-liquid separation of a liquid containing fine suspensions. The method is characterized in that agglomerates are formed by coalescing, the aggregates are attracted to a specific position by magnetic force, concentrated, and then separated from the liquid.

As the magnetic powder used in this solid-liquid separation method, iron powder, iron sand, ferrite, etc. having a particle size of about 0.0 l to 100 u are suitable.

The amount of magnetic powder added varies depending on the type of suspended matter to be separated, but is suitably about 0.1 to 10% by weight per suspended solid matter.

Magnetic force is generated by a permanent magnet or an electromagnet.

Suspension aggregates containing magnetic material are heavier than aggregates formed without the addition of magnetic material, so sedimentation due to gravity alone also tends to be accelerated. Therefore, in static separation, it is advantageous that magnetic force also acts to accelerate sedimentation due to gravity. That is, a magnet is placed directly under the bottom plate of a settling tank made of non-ferrous metal or plastic, and a magnetic force is applied to the magnetic material in the aggregates, thereby attracting the aggregates downward and accelerating the sedimentation due to gravity. However, depending on the nature of the aggregates, it may be more advantageous to attract them by magnetic force in a direction other than the direction of the bottom plate, and the direction of attraction is not limited even in static separation. When performing separation that does not involve standing still, such as centrifugation, a magnet is placed forward in the direction of centrifugal force to attract magnetic substance-containing aggregates.

In either case, the aggregates are concentrated near the magnet film placement part more quickly and to a higher degree than in the case where no magnetic material is added. The aggregates concentrated into a slurry or cake are separated from the upper groove portion by any method.

By containing the magnetic powder, the concentrated aggregate can be easily handled in subsequent processing such as filtration and drying even in the case of a soft organic suspension.

[Dormitory example]

The method of the present invention was applied to solid-liquid separation treatment of digested sludge containing organic suspended matter with extremely poor settling properties. The sample digested sludge was collected from a municipal sewage treatment plant, and the suspended solids content was O,
It is S%.

Take 10,100 O of digested sludge in a tall beaker with a capacity of 11, add 10% solution of polymer flocculant/IK floc (product of Ichikawa Keori Co., Ltd.) 5011 and 0.5 g of iron powder at the same time, and stir with a magnetic stirrer for 5 minutes. Stirred.

Next, place a permanent magnet (45x30x10m+) at the bottom of the beaker.
*; 3,500 Gauss) was fixed, and then allowed to stand without stirring, and the volume of the precipitate at the bottom of the beaker and the turbidity of the supernatant were measured over time. Note that turbidity was measured at a wavelength of 620 +n using a spectrophotometer.

For comparison, a test was conducted in the same manner as above except that no iron powder was added and no magnet was used (Comparative Example 1), and a test was conducted in the same manner as above except that neither iron powder nor polymer flocculant was added (Comparative Example 2).
was carried out.

The measurement results are shown in Table 1.

Table 1 [Effects of the Invention] As described above, according to the present invention, even organic suspended matter that does not easily settle by normal gravity sedimentation can be sedimented very quickly. Furthermore, according to the present invention, it is possible to collect aggregates at a high density at any location, which not only enables more efficient solid-liquid separation than before, but also allows for sedimentation separation, which was previously impossible. It also becomes possible to separate suspended substances that do not easily settle.

Claims (1)

[Claims] When performing solid-liquid separation of a liquid containing fine suspensions, magnetic powder and a flocculant are mixed with the liquid to form aggregates in which the suspensions and magnetic powders are combined, and the aggregates are A solid-liquid separation method characterized by attracting concentration to a specific position by magnetic force and then separating it from a liquid.