JPS6017440B2 - Method for manufacturing soil improvement material using activated sludge as raw material - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a soil improvement material (active humus), and more specifically, it involves treating cellulose organic matter such as waste fibers in waste liquid discharged from a pulp and paper mill by a biological treatment method. Plant fiber scum is added to the activated sludge containing precipitated cellulose, lignin, and bacterial protein, and after the water is squeezed, fly ash is added and mixed to create soil that contains characteristic elements that deodorize without changing microbial activity. This invention relates to a method for producing improved materials.

Conventionally, for processing organic sludge that does not contain harmful substances into fertilizer, raw wastewater is usually processed through a natural concentration process such as a settling tank or a thickener, and then a forced thickener with a simple structure such as a far thickener or pressure thickener is used. to make thickened sludge with a moisture content of about 90%,
This is further subjected to a high-performance dehydrator to dehydrate it to about 70% moisture, and then goes through a drying process to form dry sludge with a moisture content of about 50 to 60%, but sludge with a moisture content of about 90% is used. If you dehydrate it using an expensive dehydrator such as a high-performance vacuum filtration machine, pressure filtration machine, or centrifugal dehydrator,
In addition to the heavy load on machinery and equipment, the manufacturing process becomes complicated and requires a lot of time and effort when turning into fertilizer, resulting in increased expenses and high costs, which is a major issue in the fertilizer industry.

The present invention was proposed in order to solve the above-mentioned conventional problems, and an appropriate amount of vegetable fiber scum is added to activated sludge with a water content of about 96% obtained from raw wastewater by a biological treatment method (aerobic treatment). The first feature is to provide a simple and effective water extraction method that allows activated sludge with a moisture content of about 65% to be obtained at a time by applying it to a screw press with a simple structure. The present invention is characterized in that a mixture of the concentrated activated sludge mixed with fly ash to the extent that it does not change the activity of microorganisms (ie, bacterial cell growth) is transferred to a rotary fermenter or the like and aged.

Next, the method for producing the soil improvement material of the present invention will be explained in detail.
Organic substances such as waste fibers in organic wastewater from pulp and paper mills are subjected to physical and chemical treatments during the production process, and if we look at their properties from a fertilizer perspective, firstly, the composition of carbohydrates is ideal. It is.

That is, cellulose is the main component, and lignin is less than one-third. Second, the shape is fine and homogeneous.
That is, it is easily decomposed by microorganisms, and a homogeneous product can be obtained that exhibits a fertilizer effect.

Third, it can be mixed with any fertilizer. That is, it is chemically inert and does not cause any chemical changes to the mixed fertilizer, so it can be used in combination with any fertilizer. Fourth, it includes various feature elements. The constituent elements contained in a large amount of washing water are retained in abundance due to the adsorption properties of cellulose. As mentioned above, cellulose organic matter such as waste fibers in the waste water of pulp and paper mills has properties suitable for making fertilizers, and is also released in large quantities from the mills, some of which can be recovered and reused. However, around 70% of it is fine fibers or powdery cellulose that pass through a 150-mesh wire mesh, so it is difficult to bottle it, and it is stored in a vast sedimentation tank as a so-called sedimentation tank method. Only supernatant water that complies with discharge water regulation standards is released into rivers. For example, in the case of a pulp and paper mill where wastewater is treated at a rate of 30,000/day, the SS at the entrance of the settling tank is 350 to 4.
0 ground. p. m, this sedimentation pond rule is 10 m per day.
Since the amount reaches ~12 tons, it is possible to industrially produce a sufficient amount of organic fertilizer from pulp and paper mill waste by utilizing the large amount of sedimentation ponds that have been accumulated in the past.

In known sewage treatment methods that biologically treat sewage or organic wastewater, the activated sludge produced emits a bad odor, so it is either incinerated after dehydration and drying, or mixed with soil and disposed of in a landfill, etc. However, in the present invention, activated sludge produced by biological treatment of organic wastewater from pulp and paper mills, etc. is squeezed to a moisture content of 60 to 70%, and then pulverized coal combustion ash (fly ash), which has strong deodorizing properties, is used. to an extent that does not cause any change in microbial activity, preferably about 1% by weight, and the moisture content is 50%.
%, and then in order to ensure smooth rotting of this mixture and uniform quality, it is sent to a Danow-type rotary fermenter, where it is aerated for a certain period of time, and a rope is added to support the growth of microorganisms. After that, aerobic fermentation is carried out and aging is carried out to approximately 30 to 40% carbon content, and once this process is completed, the above operation can be continued or for one day depending on the need for storage and transportation of the product. The method is to dry the microorganisms by leaving them in the air at 40° C. or below for 6 days to make them inactive or in suspended animation, thereby producing active rot.

In this case, instead of leaving it in the air, artificial treatments such as low-temperature drying, low-temperature holding, and freezing may be applied to bring the microorganisms into suspended animation and efficiently produce active humus. Of course, heating, heat rays, or short wave irradiation such as ultraviolet rays may be used as appropriate to kill all or a limited percentage of the microorganisms. Note that the mixture of activated sludge and fly ash can be deposited for a certain period of time without being sent to the Dannow rotary fermenter, and the mixture can be matured to a carbon content of 30 to 40%. Aerobic fermentation either stops or becomes anaerobic fermentation, so care must be taken when changing the sediment to make the distribution of air and moisture uniform.

In this case, it is necessary to completely switch over using a shovel loader or the like at least once every few days.

In addition to deodorizing activated sludge by mixing fly atshu, this mixture also removes poppy, element, iron, boron, lime, magnesia, which are poor soil elements in activated sludge.
Valuable ingredients such as manganese and molybdenum are added to make it a high-quality soil improvement material. The activated sludge in the thickening tank collected from the settling tank is more than 96% water, so when water is squeezed out using a screw press, it is best to remove 10-15% of the water, leaving the water content at 80-85%. Because it is in the form of a slurry, it is inconvenient to handle, and it has too much water to be used as a base material for compost, so it is dried to reduce the water content to 60 to 70%.
It was adjusted to 0%. However, since activated sludge emits a bad odor, this drying work is not easy. Therefore, the present inventor conducted an experiment by adding fiber scum (short fibers floating in wastewater are commonly called in the paper industry) to the activated sludge in the thickening tank in order to flocculate the activated sludge in the thickening tank and promote thickening. When I tried it out, I was surprised to find that by adjusting the amount of scum added, I was able to freely adjust the amount of water expressed using just a screw press (
50-70%) I was able to discover what I could do and achieve my desired goal. This improvement in water leakage is due to the increase in the solid content in the slurry sludge due to the addition of scum, and the fact that each fiber of the added scum becomes a flocculation of the sludge bones, which acts as a filtration platform and resists the squeezing of the screw. The sludge that coagulates around the core of the scum fibers introduced into the screw press together with water is guided by water into the small water holes in the press chest and is caught in a screen-like bed (filter). This is thought to be due to the physical phenomenon of forming a bed (bed) and filtering out water. By the way, looking at the filtration condition of the screw press, almost all of the screw press filtration holes are covered with sludge flocs with fiber scum as the core, and water is coming out from the ruptures. Sludge with fiber scum as its core. It can be seen that the blocks form a filter bed. In the case of producing compost according to the present invention, a suspension in which 4 parts of fiber scum is dispersed in 96 parts of slurry activated sludge with a water content of 96% is mixed into the activated sludge slurry at a weight ratio of 25%. Possibly moisture content 60
~70% activated sludge can be easily obtained, and when the amount of scum suspension medium (fiber scum) mixed into the activated sludge slurry is increased, it becomes a so-called hard sludge with a water content of about 50%. The experimental results confirmed that sludge suitable for disposal or incineration could be obtained.

As mentioned above, sludge mixed with fiber scum forms a filter bed in the filtration holes, so it does not flow out. Water walking crabs are very good.
Furthermore, although there is only a small amount of fiber scum remaining in the squeezed sludge, since it is mainly made of cellulose, if microorganisms multiply, the fiber scum itself will gradually decompose and become rotten, making it difficult to use activated sludge-based compost. It will also make the effect permanent.

Furthermore, by mixing fiber scum, the amount of polymer that is normally added to coagulate sludge can be reduced by approximately 50%. In addition, in pulp and paper mills, it is of course possible to adjust the wastewater containing floating scum and add it to the activated sludge in the thickening tank, without preparing a separate dispersion of scum in water. It is.

As described in detail above, according to the present invention, by adding plant fiber scum to activated sludge with a moisture content of 96% or more produced from organic wastewater by a biological treatment method, water is absorbed by one-stage water extraction using a screw press with a simple structure. Since activated sludge with a yield of about 65% can be obtained, it does not require the complicated process and troublesome two-stage water extraction process used for the treatment of fertilized sludge, and it also eliminates the need for the complicated process of two-stage water extraction and troublesome labor that was used for the treatment of fertilized sludge. Since a high-performance dewatering machine is not used, the cost of producing this type of sludge can be reduced.Moreover, in the present invention, fly ash is mixed into this activated sludge to the extent that it does not inhibit microbial activity (bacterial growth). However, since this is fed into a rotary fermentation tank or the like to mature, when this is applied to a cultivator, it becomes humic in the soil faster than raw sludge, and becomes a humic sludge in the soil. It accumulates in the soil and has effects such as enhancing soil fertility, assisting in soil improvement, and aiding the growth of crops.Examples are given below, but they do not limit the scope of the present invention. isn't it.

Example 1 SS250 waste liquid from a pulp and paper mill (residual liquid obtained by recovering a portion of spilled waste fibers) was introduced into a neutralization tank, and a P.O. After being neutralized on day 7,
Add a small amount of urea and ammonium phosphate (nutrients for microorganisms) to this (160k each for a waste liquid inflow of 12,000〆/D).
9,80k9) and then add 0.9,80k9) of agglomerate polymer.
The activated sludge is mixed with 25% of the sludge and introduced into the aeration tank, where it is aerobically treated with the mixed microorganisms (in the case of continuous operation, the returned sludge is used as seed), and then the precipitated activated sludge is collected in the settling tank. The fiber scum is collected in a thickening tank, mixed with 4% suspended water of fiber scum and 25% of slurry-like activated sludge, and this mixed solution is sent to a screw press using a pump to produce 300 kg/day of wet activated sludge with a water content of 65%. Obtained.

10% by weight of fly ash is mixed into this wet sludge,
After feeding this mixture into a kneader and adjusting the water content to about 50%, it was fed into a Danow type rotary fermenter and aged for 3 days while air was fed into the activated slag 24 with a carbon content of 30 to 40%.
0 kg/day was produced. The analysis results of this product (analysis by Japan Fertilizer Inspection Association) are shown in Table 1. No.
Table 1 Example 2 Add water to the precipitation heterogeneity to determine the concentration of the dispersoid, that is, S
The activated sludge was adjusted to S400 (the concentration is adjustable) and pumped up in the same manner as in Example 1, yielding 300 k9/day.

I tried to increase the raw material concentration (SS) to about twice that of the previous example, but I could only obtain about the same amount. Therefore, it seems that the amount was reduced compared to the raw material of Example 1. 1% by weight of fly ash was mixed with the above activated sludge, deposited in the air for 10 days, changed over and aged with a shovel loader every 3 days, and turned into activated sludge with a moisture content of 40% 240k9/
Manufactured days. As a result, it was revealed that sedimentation ponds with a large amount of sedimentation and abandonment can be used as raw materials for active septic tanks, although the crawling rate is not good.

Note that the first and second embodiments described above represent the results of experience conducted in the wastewater treatment plant described in the third embodiment shown in the drawings.

Example 3 In the figure, 1 is an introduction waterway (or a conduit for precipitation heteronomy) from a waste waterway that has a valve factory and a paper mill on the same site,
2 is a neutralization tank, and since kraft pulp is manufactured by an alkaline method in this example, neutralization is performed with sulfuric acid.

Reference numeral 3 is a metering weir which supplies microbial nutrients suitable for the flow rate from a phosphoric acid tank 4 and a urea tank 5 depending on the amount of wastewater passing per unit time.

6 is an aeration tank, which is partitioned by a partition wall 7 in the center, and a lotus is passed through the bottom of the partition wall 7. In the primary aeration tank 6, microorganisms mixed in are used to decompose cellulose in the wastewater and utilize intermediate metabolites of the decomposition. Floating organic matter that has been synthesized (i.e., bacterial cell growth) and has become humic to some extent is collected in the secondary aeration tank 62 as the wastewater flows.
By repeating the decomposition and synthesis, the organic matter in the wastewater becomes activated sludge and flows into the settling tank 8 from the bottom through the overflow port 63 of the secondary aeration tank 62 together with water.

This sedimentation tank 8 is provided with a sedimentation groove 9 having an annular cross section at the center of the bottom, and an inflow tube 1 that stands upright from the bottom at the center of the sedimentation groove 9.
0 is provided, and the wastewater containing activated sludge from the aeration tank 62 rises up the vertical cylinder 10 and is fed into the settling tank 8 from its upper end 10'. The waste water is discharged into the river from an overflow ditch 8' provided around the settling tank 8, but the activated sludge sinks as it is into the settling ditch 9 of the settling tank. Reference numeral 11 denotes an activated sludge thickening tank, and the activated sludge is introduced into the thickening tank 11 through a pipe 12 conveyed to the settling groove 9 and collected into the thickening tank 11 by a pump P.

Reference numeral 13 denotes a scum tank, in which a solution in which scum is dispersed in water is collected and sent to a thickening tank by a pump P2, where it is mixed in an appropriate amount into the activated sludge of the scum.

This liquid mixture is sent to the screw press 14 by the pump P3, and the fly ash f is mixed with the squeezed activated sludge, which is sent to the kneader 15, and then sent to the Danow type rotary fermentation tank 16. Therefore, this equipment automatically collects organic matter from the wastewater as activated sludge using the constantly flowing wastewater as a medium, then squeezes the water, mixes in fly ash, and matures it in a rotary fermenter to pulp. Activated septic can be easily obtained from paper mill wastewater, and its working mechanism can be made simple and reliable.

In addition, 17 is a coagulant polymer tank, 18 is a rope floating blade of a neutralization tank, 19 is a sulfuric acid tank, 20, 21 is an aeration mechanism (aeration) of an aeration tank, 22 is a return sludge pipe for seeds, 2
3 is a scum inlet, 24 is a water pipe, v is a valve, and 25 is a thickening blade.

Next, the implementation results of the present invention are as shown below. 1 example,
These are the results of cultivating 4. Matsuna in saprophyte volcanic ash and examining the growth yield and amount of nitrogen and phosphoric acid absorbed.

Although the average plant height was the same in each plot, the yield increased in the compost plot according to the invention.

The absorption results showed that the inventive compost plot had a high utilization of nitrogen, while the general compost plot showed a high utilization of phosphoric acid, which may be due to the large amount of fertilizer applied. These are the results of a study on the fertilizing effect of two cases, daikon radish grown in a highland field at an altitude of 860 m, with general compost.

There was no difference in the growth process, but at harvest time, the compost plot of the present invention was superior in plant height, seed diameter, and root weight, showing a yield increase index of 103.

Yield is per IQ. 3 Examples: In order to understand the fertilizing effect of perennial plants, the following are the results of a study on 3-year-old Kaizuka Ibuki in a field with accumulated loam soil.

The plot in which the compost of the present invention was used was superior in terms of enlargement of lateral trunks and elongation of tree height, and the amount of new shoot growth reached 1.8 times, confirming the development of roots of perennial plants.

[Brief explanation of drawings]

The drawing is a diagrammatic explanatory diagram of an apparatus for carrying out the present invention. 2... Neutralization tank, 3... Measuring girth, 6.・・・
...Primary aeration tank, 62 secondary aeration tank, 8...
... Sedimentation basin, 9 ... Sedimentation groove, 10 ...
Inflow upright rare, 11...Concentrator tank, 13...Scum tank, 14...Screw press, 15...
Hawk mixing machine, 16...Rotary fermentation tank.

Claims (1)

[Claims] 1. Vegetable fiber scum is added to slurry-like activated sludge produced by biological treatment from organic wastewater of a pulp and paper mill, and the water is squeezed to a moisture content of 60 to 70%. A soil improvement characterized by comprising a step of mixing ~30% by weight and adjusting the water content to about 50%, and a step of feeding this mixture into a pile or rotary fermenter and aging it to a carbon content of 30 to 40%. Manufacturing method of wood. 2. The soil improvement material according to claim 1, which uses activated sludge produced from an organic suspension obtained by adding water to sedimentation pond slag of a pulp and paper mill and stirring to adjust the concentration of dispersoids. manufacturing method.