JPH11192402A - Inorganic flocculant - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an inorganic flucculant enabling to simply neutralize water for dehydration treatment of sludge and waste water treatment to form sufficient flocks and also control a precipitation degree, and perform stable coagulation and solid separation from liquid, especially in the dehydration treatment of submarine sludge. SOLUTION: This inorganic flocculant consists of an inorganic flocculation component and aggregate, and cement is used as the aggregate, and the inorganic flocculation component is incorporated by 2-10 pts.wt. for 10 pts.wt. aggregate and is powdery. Thus, water quality is adjusted from around the inorganic flocculation component and the flocks are formed without degrading coagulation power, and a stabilized coagulation power can be exhibited and also solid can be promptly separated from liquid.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a coagulant for treating seawater, river water, lake water, sewage, human waste, and wastewater from various business establishments, and a coagulant for dewatering sludge produced therefrom. In particular, the present invention relates to an inorganic coagulant capable of performing solid-liquid separation with stable cohesion even in dewatering of marine sludge.

[0002]

BACKGROUND OF THE INVENTION Conventionally, as part of environmental protection, sludge deposited on the bottom of the sea, rivers, lakes and marshes has been recovered. In general, sludge is collected using a dredging method using a shovel-type or sand-pump-type dredging device, and sludge is efficiently collected from the water bottom using a dredger or the like. This is concentrated with a thickener and dewatered by natural dehydration, vacuum dehydration, pressure dehydration, centrifugal dehydration, etc. At this time, the separated water contains fine and hard-to-precipitate mud particles and impurities. Since a suspended substance (so-called SS component) is contained, a coagulant is added to remove the suspended substance, and the suspended substance is coagulated and settled to be solid-liquid separated.

[0003] By the way, the sludge includes those in which various impurities discharged from each home or business are settled and deposited.
In addition, sewage contains suspended solids such as fine mud particles and impurities that are unlikely to settle. These often rot and make the water quality acidic. Furthermore, various substances exist in an ionic state in sewage, and particularly in seawater, a large amount of ions such as sodium, chlorine and calcium and other minerals are contained as components in seawater.

[0004] Therefore, in the dewatering treatment of sludge, especially marine sludge, even if an attempt is made to remove suspended solids from the separated water, the flocculence of the flocculant is impeded by these water qualities and ions, and floc is not easily formed. It is difficult to settle, and it is difficult to settle, and it is difficult to settle.
Furthermore, seawater has a stronger buoyancy than fresh water, and thus tends to hinder floc sedimentation.

Therefore, conventionally, in the sludge dewatering treatment and the sewage treatment, for example, a pretreatment such as lime is previously performed to neutralize the water to make it easy to coagulate. However, solid-liquid separation cannot be carried out by positively controlling the degree of sedimentation, and a cumbersome and large-scale apparatus is required. For this reason, the flocculant can neutralize water more easily, form a sufficient floc, control the degree of sedimentation, and can perform stable coagulation and solid-liquid separation, especially in the dewatering of marine sludge. Is strongly desired.

[0006]

[Technical matters to be solved] In view of such a situation, the present applicant has selected an agglomerated component and aggregate, studied the composition and form thereof, found an optimal composition, and found an optimum composition for sludge containing a large amount of seawater. It is another object of the present invention to provide an inorganic flocculant which exhibits a stable flocculation force and can perform solid-liquid separation.

[0007]

That is, the inorganic coagulant according to the first invention of the present application comprises an inorganic coagulation component and an aggregate, cement is used as the aggregate, and the inorganic coagulation component is 10 wt. And 2 to 10 parts by weight per part, and is in the form of a powder. And, by using such specific features of the invention as a means, even for dewatering and drainage of marine sludge, water quality is adjusted from around the inorganic coagulation component to form flocs without reducing cohesion. In addition, stable cohesion can be exhibited, and solid-liquid separation can be quickly performed.

[0008] In the inorganic coagulant according to a second aspect of the present invention, the inorganic coagulant is one or both of aluminum oxide and sodium carbonate. Silica as a material auxiliary component,
It is characterized by having one or all of a sulfate band and an anhydrous gypsum. By using such specific features of the invention as a means, the cohesive force can be increased and flocs can be easily formed, and sedimentation can be easily performed, so that solid-liquid separation can be achieved with more stable cohesive force.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION The inorganic coagulant of the present invention will be specifically described below. The inorganic flocculant of the present invention can use, for example, an inorganic flocculant such as aluminum oxide or sodium carbonate as the inorganic flocculant. Since this inorganic coagulation component is inorganic and chemically stable,
Suspended substances can be agglomerated without changing physical properties even by components in seawater.

The inorganic coagulant of the present invention has cement as an aggregate in addition to the inorganic coagulant. By doing so, cement as an aggregate contains lime and the like in its components, so that water can be neutralized in the same manner as in the conventional pretreatment step required for sludge dewatering and sewage treatment. Although it is possible, neutralization starts from the water near the cement existing around the inorganic coagulant, so that the inorganic coagulation component can always exhibit a stable cohesion. Furthermore, since the cement as the aggregate is a powder having a so-called inorganic adhesive function, if it contains moisture, it will stick to the inorganic coagulation component and floc.
And, since the cement containing water is heavier than water, even if it is seawater in particular, it is settled down without being affected by the specific gravity, and gradually accumulates on the surface of the sludge. For this reason, even if the floc that has been separated into solids and liquids is slightly wavy, the deposited cement has a function of suppressing the sludge and the flocks from rising. The cement remains in the sludge, but is non-toxic and can be used safely.

Further, the aggregate may have any one or all of silica, a sulfate band, and anhydrous gypsum as an aggregate auxiliary component. These can enhance the function of the cement such as the water absorption, adhesiveness, and sedimentation of the cement, and can also neutralize the charge of the suspended substances in water to increase the cohesion of the inorganic coagulation component. Incidentally, the aggregate auxiliary component mentioned here does not indicate silica, gypsum or the like contained in the cement component, but is further compounded separately from the cement component. The anhydrous gypsum may use calcium sulfate instead of natural gypsum.

In forming the powder comprising the inorganic aggregate component and the aggregate, the powder can be formed, for example, by using a known cement manufacturing process. In the production of this cement, for example, when using a cement production device by a dry method, when crushed slaked lime or silica stone is sieved and then fired in a rotary kiln, an inorganic aggregate component and an aggregate auxiliary component are added. In this case, the produced cement powder can have an inorganic coagulation component and an aggregate auxiliary component. Note that this production method is an example, and the inorganic coagulant of the present invention may be formed by another method. In short, it is only necessary to form a powder in which the inorganic coagulation component and the aggregate are mixed. Thus, an inorganic flocculant in which the inorganic flocculant and the aggregate are mixed in an appropriate amount can be obtained.

The above-mentioned appropriate amount means that the inorganic coagulation component is blended in an amount of 2 to 10 parts by weight with respect to 10 parts by weight of the aggregate. With this amount, the inorganic aggregating component can always exhibit a stable aggregating force without lowering the aggregating force, and can quickly perform solid-liquid separation. Incidentally, if the amount of the aggregate is too large or too small with respect to the inorganic aggregate component, solid-liquid separation becomes difficult. For example, when the amount of the inorganic aggregate component exceeds 10 parts by weight with respect to 10 parts by weight of the aggregate, the amount of the aggregate is too small, the function of neutralizing the water quality is weakened, and the aggregating power of the inorganic aggregate component is reduced. At the same time, it becomes difficult to settle down, and the amount of cement as aggregate that precipitates on the sludge surface is insufficient, so that sludge and flocs tend to rise. In addition, the aggregated inorganic component is aggregate 1
If the amount is less than 2 parts by weight with respect to 0 parts by weight, the amount of aggregate is too large with respect to the inorganic agglomerated component, whereby the water quality becomes extremely alkaline and the cohesive strength is reduced. In any case, if the amount of the inorganic coagulation component and the aggregate is not appropriate, coagulation is hindered.

The amount of the aggregate auxiliary component may be appropriately adjusted according to the ionic state contained in the wastewater.
The amount of the aggregate auxiliary component was 3 parts per 10 parts by weight of the aggregate.
It is advisable to mix up to 30 parts by weight. By blending this amount of aggregate auxiliary component, it is possible to control the function of inorganic coagulation component and aggregate, and to show more stable coagulation force and ease of sedimentation for sludge and wastewater treatment, and to perform solid-liquid separation. Can be. Incidentally, the aggregate auxiliary component here does not indicate silica, gypsum or the like contained in the cement component, but is further compounded separately from the cement component. In addition, it is a matter of course that calcium sulfate may be used as the anhydrous gypsum instead of natural gypsum.

As an example of the inorganic coagulant of the present invention which is made into a powder using such an inorganic coagulant or an aggregate, an inorganic coagulant mixed in the ratio shown in Table 1 is shown.

[0016]

[Table 1]------------------------------------------------------------------------------------------------------------ Blend):---------------------------------------------------------------------------------------------------------- −−−−−−−−−−−−−−− Aggregate auxiliary component: Silica: 40 parts by weight: Sulfuric acid band:: Anhydrite:: (Blended in the same amount):----------- −−−−−−−−−−−−−−−−−−−−−

[0017]

EXAMPLES Hereinafter, examples will be described in which marine sludge is coagulated and solid-liquid separated using the inorganic coagulant of the present invention. In this example, an inorganic coagulant mixed in the ratio shown in Table 1 was used.

The dredged sea sludge was collected, and the mixing condition of the sea sludge and seawater was adjusted to prepare four types of aqueous solutions having different SS concentrations. The SS concentration of these four aqueous solutions is
6844 mg / l, 14863 mg / l, 3 respectively
3522 mg / l and 55135 mg / l. Then, 200 ml of each of these aqueous solutions was placed in a beaker, and after adding a prescribed amount of the inorganic flocculant of the present invention,
Stirred at pm for 5 minutes. Here, the prescribed amount of the inorganic coagulant is 250 mg, 500 mg,
1000 mg and 2000 mg were used. 100 ml of this aqueous solution was dispensed into a measuring cylinder, and the solid-liquid separation state of an undiluted aqueous solution to which no inorganic coagulant was added and an aqueous solution to which a prescribed amount of each inorganic coagulant was added was observed. Then, the degree of transparency of the supernatant liquid and the amount of sedimented floc were checked, and the time until the supernatant liquid became almost transparent and the amount of floc accumulated almost did not increase was observed. Table 2 shows the solid-liquid separation state of the aqueous solution.
It was as follows.

[0019]

Table 2----------------------------------------------------------------------------------------------------------------- ppm):: 250: 500: 1000: 2000 ----------------------------------------------------------- 6844: E: B: A: A : A −−−−−−−−−−−−−−−−−−−−−−−−−−−−−− 14863: X: D: C: B: A −−−−−−−− ----------------------------------------------------------- 33522: X: D: D: C: B ---------------- −−−−−−−−−−−−−−− 55153: X: E: D: D: C −−−−−−−−−−−−−−−−−−−−−−−−−−−−− −−−−− Solid-liquid separation state A = separated within 2 minutes B = within 4 minutes Without significant turbidity remains X = Most solid-liquid separation in E = 6 min turbidity slightly remains at D = 6 min separated by C = within 6 minutes of release

In the examples, when the inorganic flocculant of the present invention was added to marine sludge, floc was quickly formed and settled. Although the degree of sedimentation and the size of floc differed depending on the SS concentration and the amount of the added inorganic coagulant, the aqueous solution to which the inorganic coagulant was added was almost completely solid-liquid separated within a few minutes. On the other hand, the aqueous solution of the stock solution hardly separated into solid and liquid. In recovering floc from the solid-liquid separated aqueous solution, filter paper (ADV) was collected from a measuring cylinder.
No. manufactured by ANTEC When suction filtration was performed using 101) as a filter, the aqueous solution to which the inorganic flocculant had been added could easily recover flocs without collapse, and the filtrate was almost transparent. On the other hand, the aqueous solution of the stock solution passed through the filter paper with almost no suspended solids recovered, and the filtrate became considerably turbid. The test was omitted for sludge of rivers and lakes, as compared to marine sludge, because the components in seawater were not included and solid-liquid separation was easier.

[0021]

As described above, the inorganic flocculant of the present invention comprises an inorganic flocculant and an aggregate, cement is used as the aggregate, and the inorganic flocculant is added to 10 parts by weight of the aggregate.
10 to 10 parts by weight and in powder form, for dewatering and drainage of marine sludge, adjust the water quality from around the inorganic coagulation component, form flocs without lowering the cohesion, and stabilize As well as exerting cohesive force, solid-liquid separation can be performed quickly. In addition, one or both of aluminum oxide and sodium carbonate are used for the inorganic coagulation component, and the aggregate is mainly composed of cement and the aggregate auxiliary component is silica, sulfate band, and anhydrite. By having any one or all,
By controlling the formation of flocs and the degree of sedimentation, solid-liquid separation can be achieved with more stable cohesion.

Claims (2)

[Claims] 1. An aggregate comprising an inorganic aggregate component and an aggregate, cement is used as the aggregate, and the inorganic aggregate component is 2 to 10 parts by weight with respect to 10 parts by weight of the aggregate, and is in powder form. Inorganic flocculant. 2. The inorganic coagulation component is one or both of aluminum oxide and sodium carbonate, and the aggregate is a cement containing a main component of the aggregate and silica, a sulfate band, and an anhydrous gypsum as an auxiliary component of the aggregate. The inorganic coagulant according to claim 1, wherein the inorganic coagulant has any one or all of them.