Method for Treating Wastewater and Device for Treating Wastewater for Same

Abstract

Disclosed herein is a method for treating wastewater and a device for treating wastewater for the same. A treatment method for parlor wastewater/biomass liquid digestate is provided with, in a cleaning facility provided with at least a mixing tank-reaction tank-sludge dehydrator-(neutralization tank)-biological treatment tank: a step for adding a dewatering aid having an Mp value (moisture content evaluation) of Mp (cake moisture content)≤55 or 55-70 to parlor wastewater/biomass liquid digestate of water to be treated in the mixing tank; next, a step for adding a flocculant to the water to be treated in the reaction tank and forming floc that is maximum (10 mm ϕ or greater) to large (5-10 mm ϕ) and that includes emulsified components and microparticle components in the floc containing the oil and fat portions and calcium in discarded milk or in the biomass liquid digestate; a step for eliminating the floc with the sludge dehydrator and simultaneously separating into the supernatant liquid from which the floc has been eliminated and dehydrated cake with a moisture content of 55% or less or 55-70%; and next, a step for carrying out biological treatment by introducing the supernatant liquid into the biological treatment tank.

Claims

1-10. (canceled)

11. A method for treating wastewater, the wastewater being parlor wastewater or biomass liquid digestate, the method comprising: a step of adding a specific dewatering aid having a performance of an Mp value (Moisture percentage value; moisture content evaluation) of Mp (cake moisture content)≤55 to Mp (cake moisture content)=55 to 70 and a flocculant having an ability to form flocs (Flock: floc-shaped precipitate) to wastewater, which is water to be treated, to form extra-large (ϕ 10 mm or more) flocs; a step of separating into desorbed liquid (supernatant) from which flocs including oils, fats, and calcium contained in milk waste/flocs including an emulsified component and a fine particle component contained in biomass liquid digestate have been removed by removing the flocs and, at the same time, performing dewatering with a sludge dewatering machine and in which 60% to 78% on average of BOD of the raw water (water to be treated) has been removed, and a dewatered cake with a moisture content of 55% or less to 55% to 70%; and then a step of loading the desorbed liquid into a biological treatment tank (aeration tank) and performing biological treatment.

12. The treatment method according claim 11, comprising: a step of adding the specific dewatering aid to the parlor wastewater/biomass liquid digestate, which is the water to be treated, in a mixing tank in a purification facility equipped with at least the mixing tank-a reaction tank-a sludge dewatering machine-(a neutralization tank)-a biological treatment tank; a step of then adding a flocculant having an ability to form flocs to the water to be treated in the reaction tank to form extra-large (ϕ 10 mm or more) flocs including oils, fats, and calcium contained in the milk waste/flocs including an emulsified component and a fine particle component contained in the biomass liquid digestate; a step of separating into desorbed liquid from which flocs including oils, fats, and calcium contained in the milk waste/flocs including an emulsified component and a fine particle component contained in the biomass liquid digestate have been removed by removing the flocs and, at the same time, performing dewatering with a sludge dewatering machine and in which 60% to 78% on average of BOD of the raw water has been removed, and a dewatered cake with a moisture content of 55% or less to 55% to 70%; and then a step of loading the desorbed liquid into a biological treatment tank (aeration tank) and performing biological treatment.

13. The method according to claim 12, wherein an operation of removing the flocs including fats and calcium contained in the milk waste/flocs including an emulsified component and a fine particle component contained in the biomass liquid digestate is performed before the water to be treated flows into the biological treatment tank.

14. The method according to claim 12, wherein an operation of neutralizing a disinfectant is performed in the neutralization tank, if necessary, before the water to be treated flows into the biological treatment tank (aeration tank).

15. The method according to claim 12, wherein the dewatering aid is added at 0.1% or less (vs. wastewater volume) to the parlor wastewater/biomass liquid digestate which is the water to be treated, in the mixing tank.

16. The method according to claim 12, wherein the flocculant is added at 1% or less (0.2% aqueous solution) to the parlor wastewater/biomass liquid digestate which is the water to be treated, in the reaction tank.

17. A device for treating wastewater for use in the method for treating wastewater according to claim 12, said device comprising, as a constituent component, a purification facility equipped with at least a mixing tank-a reaction tank-a sludge dewatering machine-(a neutralization tank)-a biological treatment tank, and wherein the method comprises (1) a step of adding a special dewatering aid having a performance of an Mp value (moisture content evaluation) of Mp (cake moisture content)≤55 to Mp (cake moisture content)=55 to 70 to parlor wastewater/biomass liquid digestate, which is water to be treated, in the mixing tank; (2) a step of adding a flocculant having an ability to form flocs to the water to be treated in the reaction tank to form extra-large (ϕ 10 mm or more) flocs including oils, fats, and calcium contained in the milk waste/flocs including an emulsified component and a fine particle component contained in the biomass liquid digestate; and (3) a step of separating into desorbed liquid (supernatant) from which flocs including oils, fats, and calcium contained in milk waste/flocs including an emulsified component and a fine particle component contained in biomass liquid digestate have been removed by removing the flocs and, at the same time, performing dewatering with a sludge dewatering machine and in which 60% to 78% on average of BOD of the raw water (water to be treated) has been removed, and a dewatered cake with a moisture content of 55% or less to 55% to 70% are performed, thereby loading the desorbed liquid into the biological treatment tank (aeration tank) and performing biological treatment.

Description

BRIEF DESCRIPTION OF DRAWINGS

[0100] FIG. 1 shows the treatment flow sheet of a parlor wastewater treatment device including a purification facility equipped with a mixing tank-a reaction tank-a sludge dewatering machine-a neutralization tank-a biological treatment tank.

[0101] FIG. 2 shows the aeration tank installation conditions and effects (graph with a small numerical value: Reselber dewatering).

[0102] FIG. 3 shows the aeration tank installation conditions and effects (graph with a small numerical value: Reselber dewatering).

[0103] FIG. 4 is a diagram schematically showing an example of a Reselber dewatering system, wherein a floc separator is optional.

[0104] FIG. 5 is a diagram schematically showing an example of a Reselber dewatering system.

[0105] FIG. 6 shows the treatment flow sheet of a biomass liquid digestate (wastewater) treatment device including a purification facility equipped with a mixing tank-a reaction tank-a sludge dewatering machine-a biological treatment tank.

DESCRIPTION OF EMBODIMENTS

[0106] Next, an embodiment of the present invention will be specifically described based on an example related to parlor wastewater. In the following examples, “/d” and “/day” each indicate a value per “1 day”.

Example 1

[0107] In this example, the equipment used for the treatment of parlor wastewater according to the present invention will be described.

[0108] As shown in FIG. 1, (a parlor building.fwdarw.) a raw water tank.fwdarw.a mixing tank.fwdarw.a reaction tank.fwdarw.a sludge dewatering machine.fwdarw.an adjustment tank.fwdarw.a neutralization tank.fwdarw.a biological treatment tank.fwdarw.a membrane treatment tank.fwdarw.a treated water tank (.fwdarw.drainage) were installed as a BOD-SS load reduction/dewatering and treatment facility for parlor wastewater that is discharged from the parlor building and is complexly contaminated with milk waste, germicidal disinfectant, washing drainage, livestock excreta, and the like.

[0109] In the raw water tank, the volume of one tank was set to W 2.5ϕ×L 9.7 m×H 1.9 m=37.84 m.sup.3 so that the raw water flowing in 24 hours could be dewatered in 8 hours.

[0110] The mixing tank to which the dewatering aid was added had a volume of 576 liters, was made of SUS and was equipped with a 0.4 kw stirrer. The reaction tank to which the flocculant (polymer flocculant) was added had a volume 504 liters, was made of SUS and was equipped with a stirrer controlled by a 0.4 kw inverter.

[0111] The sludge dewatering machine was a screw press-type dewatering machine with an operation time of 8 h/d and a treatment capacity of a BOD removal amount of 150 kg/d (remaining amount 50 kg) and an SS removal amount of 294 kg/d (remaining amount 6 kg). The addition amount of the dewatering aid used was 1% vs. the wastewater volume, and the amount of the flocculant (polymer flocculant) used was 1% as an addition ratio of a 0.2% solution. The flow rate adjustment tank had a volume of one tank of W 2.5ϕ×L 8.8 m×H 2.1 m=37.64 m.sup.3 so that the separated liquid flowing in in 8 hours (dewatering machine operating time) could be fed at 24 H/d.

[0112] The neutralization tank had a volume of 576 liters to have a residence time of 15 min or more with respect to the daily average inflow rate, and was made of SUS and had a volume of one tank of W 0.8ϕ×L 0.8 m×H 0.9 m=0.576 m.sup.3. The biological treatment and membrane treatment tanks as the biological treatment tank were operated intermittently with a blower at 24 H/d, and the volume of one biological treatment tank was W 2.5ϕ×L 7.4 m×H 2.1 m=31.48 m.sup.3, and the volume of one membrane treatment tank was W 2.5ϕ×L 7.4 m×H 2.1 m=32.02 m.sup.3 for a total of 63.5 m.sup.3. The required number of installed membranes was 50/group×4 for a total of 200 with a permeate flow rate of 0.35 m.sup.3/m.sup.2.

[0113] The treated water tank was equipped with a discharge pump (50 A×0.75 kw/1 unit) and a return pump (50 A×0.75 kw/1 unit), the inflow rate was 50 m.sup.3/d, and the volume of one tank was set to W 2.5ϕ×L 2.6 m×H 2.0 m=10.44 m.sup.3 to obtain the required residence time of 30 min or more relative to the daily average inflow rate.

[0114] The aeration blower and membrane blower of the biological treatment/membrane treatment tank were operated, and the amount of oxygen necessary for the biological treatment was determined by the following formula.

O.sub.2 (kg/day)=0.5×BOD load amount (kg/d) . . . (1)+0.07×MLSS concentration (kg/m.sup.3) . . . (2)×biological treatment tank volume (m.sup.3) . . . (3)+4.6×N load amount (kg/d) . . . (4)

[0115] Here, the following settings were used: (1) was BOD 50 kg/d, (2) was N load amount (T-N) 22.5 kg/d, and O.sub.2 (kg/day) was 0.5×50 kg+0.07×4 kg/m.sup.3×63.5 m.sup.3+4.6×22.5=146.2 kg/day.

[0116] The required air amount (dissolution efficiency 5%, 1 m.sup.3/oxygen 0.28 kg) was set to 146.2 kg/day÷0.28 kg/m.sup.3÷0.05=10.443 m.sup.3/day=7.25 m.sup.3/min.

Example 2

[0117] In this example, the (parlor building.fwdarw.) raw water tank.fwdarw.mixing tank.fwdarw.reaction tank.fwdarw.sludge dewatering machine.fwdarw.adjustment tank.fwdarw.neutralization tank.fwdarw.biological treatment tank.fwdarw.membrane treatment tank.fwdarw.treated water tank (.fwdarw.drainage) installed in Example 1 were used, and “pulverized chaff”, which was pulverized chaff (sample) mainly composed of a pulverized product having a particle size of 1 to 100 μm and obtained by pulverizing chaff of vegetable fibers by mechanical shearing was used as the dewatering aid having an Mp value of Mp≤70. Further, in the following examples, “Reselber” (manufactured by Reselber Co., Ltd., product numbers: MT2000, MT5000, MT7000), which is a commercial product equivalent to the above “pulverized chaff”, was used as a sample. In these Reselber products, pulverized cardboard is added to the pulverized chaff as the main component, and the product numbers correspond to the amount of the pulverized cardboard.

[0118] In addition to these Reselber products, for example, commercially available products to which pulverized products such as mug straw, straw and/or corn cob are added to the pulverized chaff as the main component can be obtained as the Reselber products.

[0119] (1) Selection of Flocculant

[0120] Parlor wastewater (TS concentration 0.36%, pH5.84, brown cloudy color) was used as a sample to be tested, Reselber (MT2000) as a sample (commercial product) was added as a dewatering aid at 0.1% (vs. wastewater volume) to 100 ml of the wastewater, each of about 30 types of flocculants (polymer flocculants, and the like) was added, and the reaction was confirmed. For example, 0.05 ml of a flocculant (product number: RB-PT) and 1 ml of a flocculant (product number: RB-C1805) were added, and floc determination was performed.

[0121] The results are shown in Table 1. The determination conditions were A to E: the highest rank to the lowest rank. Since the evaluation of the supernatant liquor was the best A+++ with RB-PT and RB-C1805 among all the product numbers, the flocculants (RB-PT and RB-C1805) were selected from about 30 types of flocculants as flocculants for the dewatering aid Reselber (MT2000) (polymer flocculants suitable for the dewatering aid).

TABLE-US-00001 TABLE 1 Flocculant (1) Flocculant (2) Floc determination Addition Addition Supernatant Overall No. Product amount Product amount liquor Size Hardness Tightness evaluation 1 RB-PT 0.05 ml RB-C1805 1 ml A+++ A− B− B− ◯

[0122] (2) Selection of Dewatering Aid

[0123] Next, in order to select a specific pulverized product that can be used in the present invention as a dewatering aid from the pulverized products obtained by pulverizing vegetable fibers by mechanical shearing, 0.1% (vs. wastewater volume) of each of commercial products (three products: “Reselber MT2000”, “Reselber MT5000”, and “Reselber MT7000” manufactured by Reselber Co., Ltd.) was added to 100 ml of wastewater, and floc determination (supernatant liquor, size, hardness, tightness) and overall evaluation were performed. The results are shown in Table 2. The determination conditions were A to E: highest rank to lowest rank.

[0124] In the evaluation of the supernatant liquor, the highest evaluation of all product numbers was obtained for “Reselber MT5000”, but based on the results of Table 2, it was determined that the evaluation of “Reselber MT2000” was also sufficient, and “Reselber MT2000” was selected as the dewatering aid. Accordingly, in the following dewatering test of the present example, it was decided to use, as the dewatering aid, a commercial product “Reselber (MT2000)” which is equivalent to a pulverized product (sample) composed mainly of a pulverized product having a particle size of 1 to 100 μm that was obtained by pulverizing chaff of vegetable fibers by mechanical shearing.

TABLE-US-00002 TABLE 2 Reselber Floc determination product Supernatant Overall number liquor Size Hardness Tightness evaluation MT2000 A+++ A− B− B− .Math. MT5000 A++++ A− to A B− to B B− to B ◯ MT7000 A+++ A− to A B B ◯

[0125] (3) Dewatering Test

[0126] The dewatering aid “Reselber (MT2000)” was added to 800 ml of wastewater, and 0.4 ml of a flocculant (product number: RB-PT) and 8 ml of a flocculant (product number: RB-C1805) were added to form flocs. The flocs were then put into a dewatering tester equipped with a screw press dewatering machine, and a dewatering test was performed. The separated liquid from which the flocs were removed and the dewatered cake were separated, and the moisture content of the separated dewatered cake was measured. The results are shown in Table 3. As a result of using the specific dewatering aid and the flocculant in combination, the moisture content of the dewatered cake was 54.54%, which is 55% or less. The addition ratio was relative to the wastewater volume.

TABLE-US-00003 TABLE 3 Reselber Flocculant (1) Flocculant (2) Cake Addition Addition Addition moisture Product ratio Product amount Product amount content MT2000 0.10% RB-PT 0.4 ml RB-C1805 8 ml 54.54%

[0127] (4) Water Quality Analysis of Separated Liquid

[0128] The BOD values of the raw water (wastewater before dewatering) and the separated liquid from which flocs were removed in the dewatering test (sometimes referred to as “Reselber-dewatered separated liquid”) were measured with a BOD meter. The results are shown in Table 4. It was confirmed that 78.4% of BOD value (biological oxygen demand) was removed by using the dewatering aid and the specific flocculant in combination. FIG. 2 shows the results obtained in testing the biological treatment tank (aeration tank) installation condition. From the figure, it was found that a stable water treatment effect can be expected by reducing the BOD volume load, reducing the amount of generated sludge, and reducing the amount of required oxygen.

TABLE-US-00004 TABLE 4 Sample name BOD Raw water 4560 mg/l Reselber-dewatered separated  985 mg/l liquid

[0129] (5) Summary

[0130] In the above dewatering test, 78.4% of BOD value was removed from the raw water having a BOD value of 4.560 mg/l, and a dewatered separated liquid having a BOD value of 985 mg/l was obtained. Moreover, in the dewatering test using the specific dewatering aid and the flocculant, the moisture content of the dewatered cake was 54.54%. As a result of the above dewatering test, a suitable dewatering aid was “Reselber, product number: MT2000”, and the addition ratio was 0.1% or less (vs. wastewater volume).

[0131] Further, suitable flocculants were product numbers RB-PT and RB-C1805, and the addition ratios of RB-PT and RB-C1805 were 0.05% and 1% (0.2% aqueous solution), respectively (the amount used relative to 1 m.sup.3 of the wastewater treatment amount was 0.725 kg and 0.02 kg for RB-PT and RB-C1805, respectively).

[0132] The results obtained in the evaluation of supernatant liquor (turbid.fwdarw.transparent), evaluation of flocs (“size”: flocs are not formed, small (ϕ 3 mm or less), medium (ϕ 3 to 5 mm), large (ϕ 5 to 10 mm), and extra-large (ϕ 10 mm or more); “hardness”: soft.fwdarw.hard; “tightness”: loose.fwdarw.tight), E to A rank evaluation, and evaluation of presumed (expected) cake moisture content are summarized in Table 5. The results obtained in evaluation of BOD value and supernatant liquor, evaluation of flocs, rank evaluation, and evaluation of cake moisture content in the dewatering test have confirmed that with the present invention, flocs in which insoluble substances containing harmful substances are aggregated can be easily removed and the purified liquid phase can be purified to the extent such that the liquid can be discarded into the river. Further, the present invention is not limited to the case where the dewatering aid having an Mp 55 is used, and the results on the BOD value, evaluation of supernatant liquor, evaluation of flocs, and cake moisture content have confirmed that flocs in which insoluble substances containing harmful substances are aggregated can be easily removed and the purified liquid phase can be purified to the extent such that the liquid can be discarded (drained) into the river also when the dewatering aid having an Mp=55 to 70 is used, in the same manner as in the case where the dewatering aid having an Mp≤55 is used.

TABLE-US-00005 TABLE 5 Presumed cake Supernatant Hard- Tight- Evalua- moisture liquor Size ness ness tion content Transparent Extra- Hard Tight A 55% or less large (ϕ 10 mm or more) ↑ Large (ϕ 5 ↑ ↑ B 55% to 70% to 10 mm) | Medium (ϕ 3 | | C 70% to 80% to 5 mm) ↓ Small (ϕ 3 ↓ ↓ D 80% to 90% mm or less) Turbid No flocs Soft Loose E 90% or more

Example 3

[0133] In the present example, pulverized chaff (pulverized chaff composed mainly of a pulverized product having a particle size of 1 to 10 μm and obtained by pulverizing chaff of vegetable fibers by mechanical shearing) was used as the specific dewatering aid. Further, in the below-described example, “Reselber” (manufactured by Reselber Co., Ltd., product number: MT2000, and the like), which is a commercially available product equivalent to the “pulverized chaff”, was used as a sample.

[0134] (1) Selection of Flocculant

[0135] “Reselber (MT2000)” as a sample (commercial product) was added as a dewatering aid at 0.1% (vs. wastewater volume) to 100 ml of parlor wastewater (TS concentration 1.92%, pH 4.56, white cloudy color), each of about 30 types of polymer flocculants (0.2% aqueous solution) was added, and the reaction was confirmed. The results are shown in Table 6. When the reaction was confirmed, the evaluation of the supernatant liquor in the floc determination was the best, A to A+, with RB-C1805 among all the product numbers. Therefore, the flocculant (RB-C1805) was selected from about 30 types of flocculants as the polymer flocculant suitable for the dewatering aid Reselber (MT2000).

TABLE-US-00006 TABLE 6 Flocculant (1) Flocculant (2) Floc determination Addition Addition Supernatant Overall No. Product amount Product amount liquor Size Hardness Tightness evaluation 1 RB-C1805 6 ml — — A to A+ B+ B B ◯

[0136] (2) Selection of Dewatering Aid

[0137] Next, in order to select, as a dewatering aid, a specific pulverized product that can be used in the present invention from the pulverized products obtained by pulverizing vegetable fibers by mechanical shearing, commercially available products (three products: “Reselber MT2000”, “Reselber MT5000” and “Reselber MT7000” manufactured by Reselber Co., Ltd.), were added at 0.1% (vs. wastewater volume) of each to 100 ml of parlor wastewater and floc determination was performed. The results are shown in Table 7. When the reaction was confirmed, in the floc determination (supernatant liquor, size, hardness, tightness), the evaluation of the supernatant liquor was A to A+ which was the highest evaluation of all product numbers. Therefore, “MT2000” was selected as the dewatering aid.

[0138] Accordingly, in the following dewatering test of the present example, it was decided to use, as the dewatering aid, a commercial product “Reselber (MT2000)” which is equivalent to a pulverized product (sample) composed mainly of a pulverized product having a particle size of 1 to 100 μm that was obtained by pulverizing chaff of vegetable fibers by mechanical shearing.

TABLE-US-00007 TABLE 7 Reselber Floc determination product Supernatant Overall number liquor Size Hardness Tightness evaluation MT2000 A to A+ B+ B B .Math. MT5000 A B+ B B ◯ MT7000 A B+ B B ◯

[0139] (3) Dewatering Test

[0140] The dewatering aid “Reselber (MT2000)” was added at 0.10% (vs. wastewater volume) to 500 ml of parlor wastewater, and 30 ml of a flocculant (product number: RB-C1805) was added to form flocs. The flocs were then put into a dewatering tester (pressurization area 81 cm.sup.2, pressure/holding time variable), a dewatering test was performed, the separated liquid from which the flocs were removed and the dewatered cake were separated, and the moisture content of the separated dewatered cake was measured. As for the dewatering pressurization and holding time, a screw press dewatering machine was used. The results are shown in Table 8. As a result of using the specific dewatering aid and the flocculant in combination, the moisture content of the dewatered cake was 35.60%, which is 55% or less.

TABLE-US-00008 TABLE 8 Reselber Flocculant (1) Flocculant (2) Cake Addition Addition Addition moisture Product ratio Product amount Product amount content MT2000 0.10% RB-C1805 30 ml — — 35.60%

[0141] (4) Water Quality Analysis of Separated Liquid

[0142] The BOD values of the raw water (wastewater before dewatering) and the separated liquid from which flocs were removed in the dewatering test (sometimes referred to as “Reselber-dewatered separated liquid”) were measured with a BOD meter. The results are shown in Table 9. As a result of using the dewatering aid and the flocculant in combination, 78.8% of BOD value was removed from the BOD value (12,300 mg/l) of the raw water, and a separated liquid having a BOD value of 2700 mg/l was obtained. FIG. 3 shows the results obtained in testing the biological treatment tank (aeration tank) installation condition. From the figure, it was found that a stable water treatment effect can be expected by reducing the BOD volume load, reducing the amount of generated sludge, and reducing the amount of required oxygen.

TABLE-US-00009 TABLE 9 Sample name BOD Raw water 12,300 mg/l Reselber-dewatered separated 2700 mg/l liquid

[0143] (5) Summary

[0144] In the above dewatering test, 78% of BOD value was removed from the raw water having a BOD value of 12,300 mg/l, and a dewatered desorbed water having a BOD value of 2,700 mg/l was obtained. As a result of using the specific dewatering aid and the flocculant, the moisture content of the dewatered cake was 35.6%. As a result of the above dewatering test, a suitable dewatering aid was “Reselber, product number: MT2000”, and the addition ratio was 0.1% or less; 1 kg or less was used (vs. wastewater volume) for 1 m.sup.3 of wastewater treatment amount. The product number of a suitable flocculant was RB-C1805, and the addition ratio was 6%; 0.12 kg was used (0.2% aqueous solution) for 1 m.sup.3 of wastewater treatment amount.

[0145] [Evaluation of Supernatant Liquor, Evaluation of Flocs and Evaluation of Cake Moisture Content]

[0146] The results obtained in the evaluation of supernatant liquor (turbid.fwdarw.transparent), evaluation of flocs (“size”: flocs are not formed, small (ϕ 3 mm or less), medium (ϕ 3 to 5 mm), large (ϕ 5 to 10 mm), and extra-large (ϕ 10 mm or more); “hardness”: soft.fwdarw.hard; “tightness”), E to A rank evaluation, and evaluation of presumed (expected) cake moisture content are summarized in Table 10. In the dewatering test, the supernatant liquor was transparent (the size of the flocs was extra-large (ϕ 10 nm or more)), and the moisture content of the dewatered cake was 35.6% which is 55% or less. Further, the present invention is not limited to the case where the dewatering aid having an Mp≤55 is used, and it was confirmed that the supernatant liquor was substantially transparent (the size of the flocs was large (ϕ 5 to 10 nm)), the moisture content of the dewatering cake was within the range of 55% to 70%, and the purified liquid phase could be purified to the extent such that the liquid could be discarded into the river even when using a dewatering aid having an Mp=55 to 70.

TABLE-US-00010 TABLE 10 Predicted cake Supernatant Hard- Tight- Evalua- moisture liquor Size ness ness tion content Transparent Extra- Hard Tight A 55% or less large (ϕ 10 mm or more) ↑ Large (ϕ 5 ↑ ↑ B 55% to 70% to 10 mm) | Medium (ϕ 3 | | C 70% to 80% to 5 mm) ↓ Small (ϕ 3 ↓ ↓ D 80% to 90% mm or less) Turbid No flocs Soft Loose E 90% or more

[0147] Next, an embodiment of the present invention will be specifically described based on an example related to biomass liquid digestate. In the following examples, “/D”, “/day”, and “/d” each indicate a value per “1 day”.

Example 4

[0148] In this example, a wastewater treatment device equipped with at least a raw water tank-a mixing tank-a reaction tank-an adjustment tank-a sludge dewatering machine-(a neutralization tank)-a biological treatment tank (aeration tank)-a membrane treatment tank-a treated water tank-a dilution water tank-a disinfection tank will be specifically described as a wastewater treatment device (facility) to be used for the treatment of a biomass power generation liquid digestate of the present invention.

[0149] In the raw water tank, the actual volume of one tank was set to W 8.0 m×L 8.0 m×H 2.2 m=140.8 m.sup.3 to obtain a volume for 1 day or more with respect to the planned throughput. One raw water auxiliary pump: 50 A×0.75 kw 200 V, one raw water pump: 80 A×2.2 kw 200 V, one raw water tank stirring blower: 65 A×3.7 kw 200 V, and 16 aeration stirring devices (disk type) were installed in the raw water tank.

[0150] The pre-treatment Reselber dewatering equipment had a treatment amount: 140.0 m.sup.3/D, a load amount: BOD amount 420.0 kg/day, a removal amount: BOD 420.0 kg/D×83.3%=349.8 kg/d (remaining amount 70.2 kg/d), SS: 2100.0 kg/D×98.0%=2058.0 kg/d (remaining amount 42.0 kg/d).

[0151] The following mechanical equipment was installed. One sewage metering device: made of FRP, 90° triangular weir (weighing only); one mixing/reaction tank apparatus: made of SUS, W 900 mm×L 1800 mm×H 1260 mm, actual volume 0.81 m.sup.3/tank×2 tanks; two stirrers 200 to 300 rpm×0.75 kw×200 V (one of them is inverter controlled); two floc separators: made of SUS, 0.2 kw×200 V, equipped with special clogging prevention mechanism and automatic cleaning device; two screw press dewatering machines (RSP-300Y type) (inverter controlled): liquid contact unit, made of SUS, equipped with fixed-type automatic washing device, 1.5 kw×200 V; and two dewatered cake transfer conveyor; made of SUS, U200 type×5 m×0.75 kw×200 V.

[0152] The amount of generated dewatered cake was (140.0 m.sup.3/d×2.1%)÷(1-0.7)=9.8 t/D, where the raw water concentration was 2.1% and the moisture content of the dewatered cake was 70%. The amount of the flocculation aid (Reselber MT-2000) used was 140.0 m.sup.3/D×0.1%=140.0 kg/D with 0.1% addition vs. the liquid. The amount of the polymer flocculant used was 140.0 m.sup.3/D×10.5%×0.5%=73.5 kg/D, with 10.5%, vs. the liquid, of the flocculant 1 added at 0.5% concentration, and the 0.5% dissolution concentrated liquid was 73.5 kg÷0.5%=14.7 m.sup.3/D; and 140.0 m.sup.3/D×21%×0.2%=58.8 kg/D, 21%, vs. the liquid, of the flocculant 2 added at 0.2% concentration, and the 0.2% concentrated liquid was 58.8 kg÷0.2%=29.4 m.sup.3/D.

[0153] The adjustment tank had an actual volume of W 2.4 m×L 5.0 m×H 4.0 m=48.0 m.sup.3 in order to supply wastewater flowing in over 22 hours in 24 hours. In the adjustment tank, one adjustment pump: 50 A×0.75 kw 200 V, one adjustment tank aeration stirring blower: 50 A×2.2 kw 200 V, and six aeration stirring devices (disk type) were installed.

[0154] The biological treatment tank was of an intermittent operation system, and the required volume was set to 140.0 m.sup.3/D×500 mg/l÷0.2 kg.Math.BOD/m.sup.3.Math.day=350.0 m.sup.3 in order to keep the inflow BOD load at 0.2 kg.Math.BOD/m.sup.3 or less. The actual volumes were W 5.0 m×L 6.6 m×H 4.0 m=132.0 m.sup.3, W 4.2 m×L 6.6 m×H 4.0 m=110.88 m.sup.3, W 3.0 m×L 6.6 m×H 4.0 m=79.2 m.sup.3, and W 5.0 m×L 4.0 m×H 4.0 m (membrane treatment tank)=80.0 m.sup.3 for a total of 402.08 m.sup.3. The required air amount was O.sub.2=(0.8×70.2 kg/D)÷(0.07×5 kg/m.sup.3×402.08 m.sup.3)=196.89 kg/d, O.sub.2=196.89 kg/d÷0.49 kg/m.sup.3÷0.04=10,045.5 m.sup.3/d=10.1 m.sup.3/min.

[0155] In the membrane treatment tank, the required number of membranes was set to 140.0 m.sup.3/D÷0.275 m.sup.3/m.sup.2.Math.D÷0.8 m.sup.2/membrane÷0.8 H=796 membranes, and the number of membrane bases used was set to 200 membranes/base×4 bases=800 membranes in order to obtain a permeate flow rate of 0.275 m.sup.3/m.sup.2.Math.D at 24 H/D (operation for 8 min−cleaning for 2 min). The amount of air required for membrane treatment was set to 10 L/min×800 membranes=8.0 m.sup.3/min so that the air amount per membrane was 10 L/min. The return circulation ratio was set to 5 times or more. In the membrane treatment tank, four submerged membrane separators: pore size 0.1 to 0.4 μm, 200 membranes/base, 4 bases; two membrane blowers: 65 A×45 kPa×4.1 m.sup.3/min×5.5 kW; one return circulation pump: 50 A×1.5 kw; and two membrane treatment water pumps: 40 A×0.75 kw (onshore corrosion resistant type) were installed.

[0156] The treated water tank had a required volume of 140.0 m.sup.3/D<5.84 m.sup.3/h×12 hours=70.08 m.sup.3 and an actual volume of W 1.8 m×L (6.6 m+5.9 m)×H 3.5 m=78.75 m.sup.3 in order to ensure the volume enabling storage of water that was membrane-treated for 12 hours. One treated water transfer pump 65 A×2.2 kw was installed in the treated water tank.

[0157] The dilution water tank had a required volume of 70 m.sup.3/D and an actual volume of W 4.5 m×L 5.0 m×H 3.5 m=79.0 m.sup.3 in order to ensure the volume enabling storage of dilution water (well water+membrane treated water) sufficient for one day. One dilution water transfer pump 65 A×2.2 kw (solenoid valve 40 A for well water) was installed in the dilution water tank.

[0158] The disinfection tank equipment had a treatment amount of 140.0 m.sup.3/D. The required chlorine amount was set to 140.0 m.sup.3/D×10 mg/L×10.sup.−3=1.40 kg/D, 1.40 kg/D+70%=2.0 kg/D in order to obtain an injection of 10 mg/L with respect to the treatment amount. One sterilizer (hypochlorous acid tablet dissolution method, PVC type, 15 kg type) was installed in the disinfection tank equipment.

Example 5

[0159] In the present example, the raw water tank-mixing tank-floc separator-screw press dewatering machine-adjustment tank-metering tank-biological treatment tank (aeration tank)-membrane treatment tank-treated water tank-dilution water tank-disinfection tank (.fwdarw.outflow) (see FIG. 6) installed in Example 4 were used, and “pulverized chaff”, which was pulverized chaff (sample) mainly composed of a pulverized product having a particle size of 1 to 100 μm and obtained by pulverizing chaff of vegetable fibers by mechanical shearing, was used as the dewatering aid having an MP value (moisture content evaluation) of MP (cake moisture content)≤70. Further, in the following example, “Reselber” (manufactured by Reselber Co., Ltd., product numbers: MT2000, MT5000, MT7000), which is a commercial product equivalent to the above “pulverized chaff”, was used as a sample. In these Reselber products, pulverized cardboard is added to the pulverized chaff as the main component, and the product numbers correspond to the amount of the pulverized cardboard.

[0160] In addition to these Reselber products, for example, commercially available products (manufactured by Reselber Co., Ltd.) to which pulverized products such as mug straw, straw and/or corn cob are added to the pulverized chaff as the main component can be obtained as the Reselber products.

[0161] (1) Selection of Flocculant

[0162] Biomass power generation liquid digest [water quality after pretreatment, pH value: 7.5-8.5, BOD value: 500 mg/l (removal ratio 83.3%), SS value: 300 mg/l (removal ratio 98.0%)] was used as a sample to be treated, Reselber (MT2000) as a sample (commercial product) was added as a dewatering aid at 0.1% (vs. wastewater volume) to 100 ml of the sludge, each of about 30 types of flocculants (polymer flocculants, and the like) was added, and the reaction was confirmed. For example, a flocculant (product number: RB-C1805) was added at an addition ratio of 46%, and floc determination was performed.

[0163] The results are shown in Table 11. The determination conditions were A to E: the highest rank to the lowest rank. Since the evaluation of the supernatant liquor was the best A++ with the flocculant RB-C1805 among all the product numbers, the flocculants (RB-C1805) was selected from about 30 types of flocculants as a flocculant for the dewatering aid Reselber (MT2000) (polymer flocculant suitable for the dewatering aid).

TABLE-US-00011 TABLE 11 Flocculant (1) Flocculant (2) Floc determination Addition Addition Supernatant Overall No. Product ratio Product ratio liquor Size Hardness Tightness evaluation 1 RB-C1805 46% — — A++ A B B ◯

[0164] (2) Selection of Dewatering Aid

[0165] Next, in order to select a specific pulverized product that can be used in the present invention as a dewatering aid from the pulverized products obtained by pulverizing vegetable fibers by mechanical shearing, 0.1% (vs. sludge volume) of each of three commercial products “Reselber MT2000”, “Reselber MT5000”, and “Reselber MT7000” (manufactured by Reselber Co., Ltd.) was added to 100 ml of sludge, and floc determination (supernatant liquor, size, hardness, tightness) and overall evaluation were performed. The results are shown in Table 12. The determination conditions were A to E: the highest rank to the lowest rank.

[0166] When the reaction was confirmed, in the evaluation of the supernatant liquor in the floc determination, the highest evaluation A+++ of all product numbers was for MT7000, and Reselber MT7000 was selected as the dewatering aid. Accordingly, in the following dewatering test of the present example, it was decided to use, as the dewatering aid, a commercial product “Reselber (MT7000)” which is equivalent to a pulverized product (sample) composed mainly of a pulverized product having a particle size of 1 to 100 μm that was obtained by pulverizing chaff of vegetable fibers by mechanical shearing.

TABLE-US-00012 TABLE 12 Reselber Floc determination product Supernatant Overall number liquor Size Hardness Tightness evaluation MT2000 A++ A B B MT5000 A++ A B+ to A− B+ to A− MT7000 A+++ A B+ B+ ◯

[0167] (3) Dewatering Test

[0168] The dewatering aid “Reselber (MT7000)” was added to 600 ml of sludge, and a flocculant (product number: RB-C1805) was added at an addition ratio of 46% (vs. sludge volume, 0.2% aqueous solution) to form flocs. The flocs were then put into a dewatering tester equipped with a screw press dewatering machine, and a dewatering test was performed. The separated liquid from which the flocs were removed and the dewatered cake were separated, the moisture content of the separated dewatered cake was measured, and water quality analysis of the desorbed water was performed. The dewatering pressure and holding time were set on the assumption of a screw press dewatering machine. The results are shown in Table 13. When 0.1% of the Reselber was added, the moisture content of the dewatered cake was 59.03%.

TABLE-US-00013 TABLE 13 Reselber Flocculant (1) Flocculant (2) Cake Addition Addition Addition moisture Product ratio Product ratio Product ratio content MT7000 0.1% RB-C1805 46% — — 59.03%

[0169] (4) Water Quality Analysis of Separated Liquid

[0170] Water quality analysis (analysis of BOD, COD, SS, T-N) of raw water (water before dewatering) and the separated liquid in the above dewatering test (may be described as “Reselber-dewatered separated liquid”) were performed by a public institution. The results are shown in Table 14. It was confirmed that Reselber dewatering removed BOD at 86.5%, COD at 91.8%, SS at 99.8%, and T-N at 54%.

TABLE-US-00014 TABLE 14 Sample name BOD COD SS T-N Raw water 2600 mg/l 8000 mg/l 13,000 mg/l 3700 mg/l Reselber-  350 mg/l  660 mg/l 28 mg/l 1700 mg/l dewatered separated liquid

[0171] (5) Summary

[0172] It was confirmed that the Reselber dewatering demonstrated significant reduction in all items of water quality analysis of the separated liquid. This proves that the construction cost of the purification tank can be significantly reduced. It was confirmed that the Reselber dewatering reduced the cake moisture content to 59.3%, and upon comparison with the total amount of industrial wastewater fraction that is presently cannot be treated and is discarded, the amount was 1/18 of the present amount.

[0173] Further, a suitable flocculant was product number RB-C1805, and the addition ratio thereof was 46% (vs. sludge volume, 0.2% aqueous solution). The suitable Reselber was product number MT7000, and the addition ratio was 0.1% (vs. sludge volume).

[0174] The results obtained in the evaluation of supernatant liquor: (turbid.fwdarw.transparent), evaluation of flocs (A to E, “size”: flocs are not formed, small (ϕ 3 mm or less), medium (ϕ 3 to 5 mm), large (ϕ 5 to 10 mm), and extra-large (ϕ 10 mm or more); “hardness”: soft.fwdarw.hard; “tightness”: loose.fwdarw.tight), the presumed (expected) cake moisture content: 90% or more, 80% to 90%, 70% to 80%, 55% to 70%, and 55% or less are summarized in Table 15.

[0175] According to the dewatering test, the supernatant liquor was transparent (the size of the flocs was extra-large (ϕ 10 mm or more)), and the moisture content of the dewatered cake was 59.3% which is within 55% to 70%. Further, the present invention is not limited to the case where the dewatering aid having an MP (cake moisture content)≤55 is used, and it was confirmed that the purified liquid phase can be purified to the extent such that the liquid can be discarded into the river also when the dewatering aid having MP (cake moisture content)=55% to 70% is used, provided that the supernatant liquor is almost transparent (the size of the flocs is large (ϕ 5 to 10 mm)) and if the moisture content of the dewatered cake is in the range of 55% to 70%.

TABLE-US-00015 TABLE 15 Floc determination table Presumed cake Supernatant Hard- Tight- Evalua- moisture liquor Size ness ness tion content Transparent Extra- Hard Tight A 55% or less large (ϕ 10 mm or more) ↑ Large (ϕ 5 ↑ ↑ B 55% to 70% to 10 mm) | Medium (ϕ 3 | | C 70% to 80% to 5 mm) ↓ Small (ϕ 3 ↓ ↓ D 80% to 90% mm or less) Turbid No flocs Soft Loose E 90% or more

Example 6

[0176] In the present example, the sample was purified using digested sludge from a municipal (K city) sewage treatment plant as a target sample.

[0177] (1) Selection of Flocculant

[0178] Reselber MT2000 was added at 0.1% (vs. sludge volume) to 100 ml of a sludge [sample properties; TS (solid matter) concentration: 1.33%, pH: 7.25, appearance: black turbid color, odor: charcoal odor, fibrous material (100 mesh): 5.2%/ss, fibrous material (200 mesh): 14.2%/ss], each of about 30 kinds of flocculants (including K city-designated flocculants) was added, and the reaction was confirmed. The results are shown in Table 16.

TABLE-US-00016 TABLE 16 Flocculant Floc determination Addition Addition Supernatant Overall No. Product amount ratio vs. TS liquor Size Hardness Tightness evaluation 1 K city- 12 ml 1.8% A− to A A− to A B− B− ◯ designated flocculant

[0179] When the reaction was confirmed, since it was B− in the evaluation of “Tightness” in the floc determination, the flocculant designated by the local government (K city) was selected.

[0180] (2) Selection of Reselber

[0181] Each of three kinds of Reselber MT2000, MT5000, and MT7000 was added to 100 ml of sludge at 0.1% (vs. sludge capacity), and the reaction was confirmed. The results are shown in Table 17.

TABLE-US-00017 TABLE 17 Reselber Floc determination product Supernatant Overall number liquor Size Hardness Tightness evaluation MT2000 A− A− B− to B B− to B .Math. MT5000 A− to A A− to A B− to B B− ◯ MT7000 A B+ to B− B− ◯ A−

[0182] Reselber MT2000 for which the evaluation of “tightness” in the floc determination was the best among all the products when the reaction was confirmed was selected.

[0183] (3) Dewatering Test

[0184] Reselber MT2000 was added to 500 ml of sludge, and a polymer flocculant (0.2% aqueous solution) was added to form flocs. The flocs were then put into a dewatering tester (pressurization area 81 cm.sup.2, pressure/holding time variable), a dewatering test was performed, and the moisture content of the discharged dewatered cake was measured. The dewatering pressure and holding time were set on the assumption of a screw press dewatering machine. The results are shown in Table 18.

TABLE-US-00018 TABLE 18 Sample name SS T-P Raw water 11,000 mg/l 510 mg/l Reselber-dewatered separated 42 mg/l 97 mg/l liquid (Reselber 0.1%, flocculant designated by K city) Reselber-dewatered separated 27 mg/l 97 mg/l liquid (Reselber 0.3%, flocculant designated by K city) Reselber-dewatered separated 35 mg/l 110 mg/l liquid (Reselber 0.1%, flocculant selected by us) Reselber-dewatered separated 26 mg/l 99 mg/l liquid (Reselber 0.3%, flocculant selected by us)

[0185] When 0.04% of Reselber (addition ratio 3% vs. TS) was added, the cake moisture content was 78.67%. When 0.1% of Reselber (addition ratio 7.5% vs. TS) was added, the cake moisture content was 74.18%. When 0.3% of Reselber (addition ratio 22.5% vs. TS) was added, the cake moisture content was 69.92%.

[0186] (4) Water Quality Analysis of Desorbed Water

[0187] The SS value and T-P value of raw water (water before dewatering) and after desorption in the dewatering test were measured by a public institution. The results are shown in Table 19.

TABLE-US-00019 TABLE 19 Reselber Flocculant Addition Addition Addition Cake Product ratio ratio Product Addition ratio moisture number vs. volume vs. TS number amount vs. TS content MT2000 0.04% 3.0% Flocculant 60 ml 1.8% 78.67% designated by K city MT2000 0.10% 7.5% Flocculant 60 ml 1.8% 74.18% designated by K city MT2000 0.30% 22.5% Flocculant 60 ml 1.8% 69.92% designated by K city

[0188] (5) SS Recovery Rate

[0189] The SS recovery rate was 99.6% when 0.1% of Reselber was added (addition ratio 7.5% vs. TS) and the flocculant designated by the local government (K city) was used, 99.75% when 0.3% of Reselber was added (addition ratio 22.5% vs. TS) and the flocculant designated by the local government (K city) was used, 99.7% when 0.1% of Reselber was added (addition ratio 7.5% vs. TS) and the polymer flocculant (0.2% aqueous solution) was used, and 99.76% when 0.3% of Reselber was added (addition ratio 22.5% vs. TS) and the polymer flocculant (0.2% aqueous solution) was used.

[0190] (6) T-P Recovery Rate

[0191] The T-P recovery rate was 81% when 0.1% of Reselber was added (addition ratio 7.5% vs. TS) and the flocculant designated by the local government (K city) was used, 81% when 0.3% of Reselber was added (addition ratio 22.5% vs. TS) and the flocculant designated by the local government (K city) was used, 78.4% when 0.1% of Reselber was added (addition ratio 7.5% vs. TS) and the polymer flocculant (0.2% aqueous solution) was used, and 80.6% when 0.3% of Reselber was added (addition ratio 22.5% vs. TS) and the polymer flocculant (0.2% aqueous solution) was used.

[0192] (7) Summary

[0193] With the preferred Reselber product number MT2000, the addition ratio was 0.04% to 0.3% (vs. sludge capacity), and the addition ratio vs. TS was 3% to 22.5% (0.4 kg to 3 kg were used vs. sludge amount of 1 m.sup.3). Further, with the preferred flocculant product number designated by the local government (K city), the addition ratio was 12% (0.2% aqueous solution), and the addition ratio vs. TS was 1.8% (0.24 kg was used vs. sludge amount of 1 m.sup.3).

[0194] With the preferred flocculant product number designated by the local government (K city), the addition ratio was 12% (0.2% aqueous solution), and the TS addition ratio vs. TS (0.24 kg was used vs. sludge amount of 1 m.sup.3) was 1.8%. The Reselber dewatering resulted in the cake moisture content of 69.92% to 78.67%, the SS recovery ratio of 99.6% to 99.75%, and the T-P recovery ratio of 81%.

[0195] Evaluation of supernatant liquor was turbid.fwdarw.transparent, evaluation of flocs was: “size”: flocs are not formed, small (ϕ 3 mm or less), medium (ϕ 3 to 5 mm), large (ϕ 5 to 10 mm), and extra-large (ϕ 10 mm or more); “hardness”: soft.fwdarw.hard; “tightness”: loose.fwdarw.tight, overall “evaluation” was E to A, and “presumed (predicted) cake moisture content” was 90% or more, 80% to 90%, 70% to 80%, 55% to 70%, and 55% or less (see Table 5).

Example 7

[0196] In this example, it was verified whether the cake moisture content could be reduced by dewatering treatment of biomass liquid digestate.

[0197] (1) Confirmation of Sludge Properties

[0198] A biomass liquid digestate (wet methane fermentation liquid digestate of food waste raw material [sample properties; TS (solid matter) concentration: 5.49%, pH: 7.59, appearance: black turbid, odor: nitrification odor]) was used as a target sample.

[0199] (2) Dewatering Test

[0200] The dewatering aid Reselber (MT2000) was added to 300 ml of sludge, and a polymer flocculant A (0.2% aqueous solution) was added to form flocs. The flocs were then put into a dewatering tester (pressurization area 81 cm.sup.2, pressure/holding time variable), a dewatering test was performed, and the moisture content of the discharged dewatered cake was measured. The dewatering pressure and holding time were set to 2000 G and 1 min on the assumption of a centrifuge and to 490 kPa and 5 min on the assumption of a screw press machine. The results are shown in Table 20.

TABLE-US-00020 TABLE 20 Assumed Sludge Reselber Flocculant Cake dewatering amount to Product Addition Product Addition moisture machine be dewatered number ratio number amount content Centrifuge 300 ml MT2000 0.05% Our 66 ml 77.62% flocculant A Screw press 300 ml MT2000 0.05% Our 66 ml 67.92% flocculant A

[0201] As a result of adding Reselber MT2000 and polymer flocculant A (0.2% aqueous solution) and dewatering on the assumption of a centrifuge, the cake moisture content was 77.62%. Further, as a result of adding Reselber MT2000 and polymer flocculant A (0.2% aqueous solution) and dewatering on the assumption of a screw press machine, the cake moisture content was 67.92%. There was almost no leakage of SS into the separated liquid in the test on the assumption of a centrifuge, and a small amount of leakage in the test on the assumption of a screw press machine.

[0202] (3) Summary

[0203] With the Reselber dewatering, the cake moisture content in the test on the assumption of a centrifuge was 77.62%, and dewatering to 75% or less by the centrifuge was considered impossible due to a low dewatering pressure. Further, in the test on the assumption of a screw press machine, the cake moisture content was 67.92%, and it was determined that dewatering to 75% or less was possible with the screw press machine.

Example 8

[0204] In this example, the dewatering treatment of a liquid digestate generated in a biomass power generation facility was performed.

[0205] As a sample, a liquid digestate of biomass power generation [sludge before solid-liquid separation; TS (solid matter) concentration: 4.36%, pH: 7.51, appearance: black turbid, odor: nitrification odor, sludge after solid separation; TS (solid matter) concentration: 1.04%, pH: 8.14, appearance: brown, odor: nitrification odor] was used, and a dewatering treatment test of the liquid digestate was performed. There was a difference of 4 times or more between the TS (solid matter) concentration before and after solid-liquid separation.

[0206] (1) Selection of Flocculant

[0207] The dewatering aid Reselber MT2000 was added to 100 ml of sludge, about 20 types of flocculants were added, compatibility between the Reselber and sludge was confirmed, and the reaction was confirmed in order to select the product number. The results are shown in Table 21. In the sludge before and after the solid-liquid separation, the compatible flocculant had the same product number. There was a difference of 1.6 times between the addition amount of flocculant in the sludge before and after solid-liquid separation.

TABLE-US-00021 TABLE 21 Flocculant (1) Flocculant (2) Floc determination Specimen Addition Addition Supernatant Overall name Product amount Product amount liquor Size Hardness Tightness evaluation Sludge Our 68 ml — — A A B to B+ B to B+ before flocculant A solid- liquid separation Sludge Our 43 ml — — A A− to A B− to B B− to B after flocculant A solid- liquid separation

[0208] (2) Dewatering Test

[0209] Reselber (MT2000) was added at an addition ratio of 0.05% (vs. wastewater volume) to the sludge, and the polymer flocculant A was added to form flocs. The flocs were then put into a dewatering tester (pressurization area 81 cm.sup.2, pressure/holding time variable), a dewatering test was performed, and the moisture content of the discharged dewatered cake was measured. The dewatering pressure and holding time were set to 480 kPa and 5 min on the assumption of a screw press dewatering machine. The results are shown in Table 22.

TABLE-US-00022 TABLE 22 Amount of Reselber Flocculant (1) Flocculant (2) Cake Specimen sludge to Product Addition Product Addition Product Addition moisture name be dewatered number ratio number amount number amount content Sludge 500 ml MT2000 0.05% Our 340 ml — — 69.01% before flocculant A solid- liquid separation Sludge 700 ml MT2000 0.05% Our 300 ml — — 73.88% after flocculant A solid- liquid separation

[0210] (Sludge Before Solid-Liquid Separation)

[0211] As a result of adding Reselber MT2000 and 340 ml of polymer flocculant A (0.2% aqueous solution) to 500 ml of sludge and dewatering on the assumption of a screw press machine, the cake moisture content was 69.01%.

(Sludge after solid-liquid separation)

[0212] As a result of adding Reselber MT2000 and 300 ml of polymer flocculant A (0.2% aqueous solution) to 700 ml of sludge and dewatering on the assumption of a screw press machine, the cake moisture content was 73.88%.

[0213] (3) Water Quality Analysis

[0214] Water quality analysis of raw wastewater (water before dewatering) and separated liquid in dewatering test was performed. T-N was determined by a public institution, and BOD was determined with a BOD meter. The results are shown in Table 23.

TABLE-US-00023 TABLE 23 Specimen name BOD T-N After solid- Raw water (water 1320 mg/l 2000 mg/l liquid before dewatering) separation Separated liquid in 480 mg/l 1300 mg/l Reselber dewatering Removal ratio 63.6% 35.0% Before Raw water (water 2420 mg/l solid-liquid before dewatering) separation Separated liquid in 400 mg/l Reselber dewatering Removal ratio 83.5%

[0215] (Sludge Before Solid-Liquid Separation)

[0216] Here, 63.6% of BOD was removed to 480 mg/l by the Reselber dewatering. T-N remained at a removal rate of 35%. Most of the remaining nitrogen was considered ammoniacal nitrogen.

(Sludge after Solid-Liquid Separation)

[0217] Here, 83.5% of BOD was removed to 400 mg/l by the Reselber dewatering.

[0218] (4) Summary

[0219] Since the Reselber dewatering treatment reduced BOD to ⅓, it became clear that the planned installation capacity of the biological treatment tank (aeration tank) can be ⅓ that in the case where the raw water is treated as is. In addition, it was found that after the cake moisture content has reached the first half of 70%, subsequent treatment can be easily performed, and planning of composting and industrial waste disposal is facilitated.

Example 9

[0220] In this example, a liquid digestate (high concentration) of biomass power generation was used, and the dewatering treatment of the liquid digestate was performed.

[0221] As a sample, a liquid digestate of biomass power generation [properties of wastewater; TS (solid matter) concentration: 81.17%, pH: 8.05, appearance: dark brown, odor: low nitrification odor] was used. The TS (solid matter) concentration was very high at 8%, and in subsequent tests, a 2-fold diluted sample was used.

[0222] (1) Dewatering Test

[0223] The dewatering aid Reselber (MT2000) was added at an addition ratio of 0.05% (vs. wastewater volume) to 300 ml of wastewater, and the flocculant A or B was added to form flocs. The flocs were then put into a dewatering tester (pressurization area 81 cm.sup.2, pressure/holding time variable), a dewatering test was performed, and the moisture content of the discharged dewatered cake was measured. The dewatering pressure and holding time were set to 480 kPa and 5 min on the assumption of a screw press dewatering machine. The results are shown in Table 24.

TABLE-US-00024 TABLE 24 Reselber Flocculant (1) Flocculant (2) Flocculant (3) Cake Product Addition Product Addition Product Addition Product Addition moisture number ratio number amount number amount number amount content MT2000 0.05% Our 60 ml Flocculant B 120 ml — — 61.10% flocculant A of this firm

[0224] As a result of adding Reselber MT2000, the flocculant A in an addition amount of 60 ml (0.5% aqueous solution), and the flocculant B in an addition amount of 120 ml (0.2% aqueous solution) and dewatering on the assumption of a screw press machine, the cake moisture content was 61.1%.

[0225] (2) Water Quality Analysis

[0226] BOD measurement of raw wastewater (water before dewatering) and separated liquid in the dewatering test was performed using a BOD meter. The results are shown in Table 25.

[0227] In the Reselber dewatering, 82.2% of BOD was removed to 535 mg/l. According to visual confirmation, SS was almost removed. The dilution ratio of the raw water was preferably 2 times or more. In the Reselber dewatering treatment, the cake moisture content was 61.1% and 82.2% of BOD was removed to 535 mg/l.

TABLE-US-00025 TABLE 25 Specimen name BOD Raw wastewater (water before dewatering) 3010 mg/l Separated liquid in Reselber dewatering  535 mg/l (water after dewatering) Removal ratio 82.2%

Example 10

[0228] In this example, a test was conducted to see how much the BOD and SS concentrations could be lowered and how much the cake moisture content could be lowered by subjecting the biomass liquid digestate to Reselber dewatering treatment. FIG. 4 schematically shows an example of the Reselber dewatering system used in this example. In the figure, a floc separator is shown as an option.

[0229] As the wastewater of the sample to be treated, a biomass liquid digestate [sample properties; TS (solid matter) concentration: 4.17%, pH: 7.50, appearance: dark brown, odor: nitrification odor] was used, and a dewatering test and a water quality analysis test of the sample were conducted.

[0230] (1) Dewatering Test

[0231] The dewatering aid Reselber (MT2000) was added at 0.30% (vs. wastewater volume) to 500 ml of wastewater, and 150 ml of flocculant A (0.5% aqueous solution) in an amount of and 350 ml of flocculant B (0.2% aqueous solution) were added to form flocs. A water quality analysis test of the later stage was performed for the water fraction as desorbed water, the solid matter was put into a dewatering tester (pressurization area 81 m.sup.2, pressure/holding time variable), a dewatering test was performed, and the moisture content of the discharged dewatered cake was measured. The dewatering pressure and holding time were set to 480 kPa and 5 min on the assumption of a screw press dewatering machine. The results are shown in Table 26.

TABLE-US-00026 TABLE 26 Reselber Flocculant (1) Flocculant (2) Flocculant (3) Cake Product Addition Product Addition Product Addition Product Addition moisture No. number ratio number amount number amount number amount content 1 MT2000 0.10% Flocculant A 150 ml Flocculant B 350 ml — — 71.95%

[0232] As shown in the table, as a result of adding Reselber MT2000, adding the flocculants A and B, and dewatering, the cake moisture content was 71.95%. The addition amount of the flocculant varies depending on the biomass raw material, but in the case of a biomass liquid digestate derived from cow dung and chicken dung, the addition amount tends to increase.

[0233] (2) Water Quality Analysis Test

[0234] The measurement of BOD, SS (suspended substance), phosphorus, and nitrogen in raw wastewater (water before dewatering) and the dewatered liquid in the dewatering test was performed by a public institution (environmental measurement agency). The results are shown in Table 27.

TABLE-US-00027 TABLE 27 Specimen name BOD SS Raw wastewater (water before dewatering) 4300 mg/l 26,000 mg/l Separated liquid in Reselber dewatering  410 mg/l 25 mg/l (water after dewatering) Removal ratio 90.5% 99.9%

[0235] Here, 90.5% of BOD of the raw wastewater (water before dewatering) was removed, the BOD of the dewatered separated liquid changed from 4300 mg/l to 410 mg/l, and it was confirmed that excellent Reselber water treatment effect was demonstrated. Further, 99% of the SS of the raw wastewater (water before dewatering) was removed, the SS of the dewatered separated liquid changed from 26,000 mg/l to 25 mg/l, and was confirmed that excellent Reselber water treatment effect was also demonstrated in this respect.

[0236] By the Reselber dewatering, 90.5% of BOD of the raw wastewater (water before dewatering) was removed, and 99.9% of SS of the Reselber separated liquid was removed to 25 mg/l. Moreover, the cake moisture content was a low value of 71.95%. From these values, it was confirmed that the Reselber dewatering of the biomass liquid digestate can be performed with high efficiency in both dewatering and water treatment performance.

[0237] (3) Summary

[0238] It was confirmed that the moisture content of the dewatered cake was lowered to 75% to 65% by the Reselber dewatering treatment, and the moisture content could be freely set by increasing/decreasing the addition amount of Reselber. According to the water quality analysis test of the Reselber-dewatered separated liquid, 95% on average of phosphorus in the Reselber-dewatered separated liquid was removed, 95% on average of SS (suspended substance) was removed, 60% on average of BOD was removed, and 60% on average of nitrogen was removed. It was confirmed that the dewatering system using Reselber can be used as a water recycling technique in a water treatment system.

Example 11

[0239] In this example, the liquid digestate generated in biomass power generation was tested for how much BOD can be lowered and how much the cake dewatering ratio can be lowered by subjecting the liquid digestate to the Reselber dewatering treatment. A Reselber dewatering system similar to the Reselber dewatering system used in Example 7 was used.

[0240] (1) Dewatering Test

[0241] The dewatering aid Reselber (MT2000) and 90 ml of the polymer flocculant A (0.2% aqueous solution) were added to 500 ml of sludge to form flocs. The flocs were put into a dewatering tester (pressurization area 81 cm.sup.2, pressure/holding time variable), a dewatering test was performed, and the moisture content of the discharged cake was measured. The dewatering pressure and holding time were set to 480 kPa and 5 min on the assumption of a screw press dewatering machine. The results are shown in Table 28.

TABLE-US-00028 TABLE 28 Reselber Flocculant (1) Flocculant (2) Flocculant (3) Cake Product Addition Product Addition Product Addition Product Addition moisture number ratio number amount number amount number amount content MT2000 0.30% Our 90 ml — — — — 72.75% flocculant A

[0242] As shown in the table, as a result of adding 0.30% (vs. wastewater volume) of Reselber MT2000 and 90 ml of polymer flocculant A (0.2% aqueous solution) and performing dewatering on the assumption of a screw press machine, the cake moisture content was 72.75%.

[0243] (2) Water Quality Analysis Test

[0244] The measurement of the raw wastewater (water before dewatering) and the separated liquid obtained in the dewatering test was performed using a BOD meter (Central Kagaku Corp., OxiTop System). The results are shown in Table 29. The Reselber dewatering reduced the BOD of 6920 mg/l of the raw wastewater (water before dewatering) by half to the BOD of 3450 mg/l of the Reselber-dewatered separated liquid (water after dewatering).

TABLE-US-00029 TABLE 29 Specimen name BOD Raw wastewater (water before dewatering) 6920 mg/l Separated liquid in Reselber dewatering 3450 mg/l (water after dewatering)

[0245] It was confirmed that by reducing by half the BOD of raw wastewater (water before dewatering) by the Reselber dewatering treatment, the volume of the biological treatment tank (aeration tank) planned by design became half that in the case where the raw water is treated as is. In addition, it was found that after the cake moisture content reaches the first half of 70%, subsequent treatment can be easily performed, and planning of composting and industrial waste disposal is facilitated.

[0246] (3) Summary

[0247] It was confirmed that the moisture content of the dewatered cake was lowered to 75% to 65% by the dewatering treatment. According to the water quality analysis test of the Reselber-dewatered separated liquid, 95% on average of phosphorus was removed, 95% on average of SS (suspended substance) was removed, 60% on average of BOD was removed, and 60% on average of nitrogen was removed. It was confirmed that the Reselber dewatering system can be used as a recycling technique in a water treatment system.

Example 12

[0248] In this example, the liquid digestate of biomass power generation was subjected to dewatering treatment to measure the cake moisture content and perform a water quality analysis test of the Reselber-dewatered separated liquid.

[0249] In this example, sludge [sludge properties; TS (solid matter) concentration: 2.73%, pH: 7.63, appearance: dark black brown color, smell: low rot odor] was used, and the sludge dewatering test and water quality analysis [phosphorus, SS (suspended substance), BOD, nitrogen] of the Reselber-dewatered separated liquid were performed. FIG. 2 schematically shows an example of the reseller dewatering system plant used in this example.

[0250] (1) Dewatering Test

[0251] The dewatering aid Reselber (MT2000) was added at 0.10% (vs. sludge volume) and a polymer flocculant (0.2% aqueous solution) was added to 800 ml of sludge to form flocs. The flocs were put into a dewatering tester (pressurization area 81 cm.sup.2, pressure/holding time variable), a dewatering test was performed, and the moisture content of the discharged cake was measured. The dewatering pressure and holding time were set to 480 kPa and 5 min on the assumption of a screw press dewatering machine. The results are shown in Table 30.

TABLE-US-00030 TABLE 30 Reselber Flocculant (1) Flocculant (2) Flocculant (3) Cake Product Addition Product Addition Product Addition Product Addition moisture No. number ratio number amount number amount number amount content 1 MT2000 0.10% Existing 100 ml — — — — 72.11% product (1.5% vs. TS)

[0252] As shown in the table, as a result of adding 0.1% of Reselber MT2000 and 100 ml (1.5% vs. TS) of the polymer flocculant (existing product) and dewatering on the assumption of a screw press, the cake moisture content was 72.11%. Although the original sludge could be easily dewatered, it was confirmed that the addition of Reselber almost eliminates SS leakage and leads to subsequent advancement of fermentation. As a result of adding Reselber and dewatering, the moisture content of the cake was 72.11%, and it was confirmed that further reduction was possible by increasing the addition amount.

[0253] (2) Water Quality Analysis Test

[0254] A water quality analysis test of the Reselber-dewatered separated liquid was conducted. The resultant dewatering effect was that 95% on average of phosphorus was removed, 95% on average of SS (suspended substance) was removed, 60% on average of BOD was removed, and 60% on average of nitrogen was removed. It was confirmed that the moisture content can be freely set by increasing or decreasing the Reselber addition amount. It was confirmed that the Reselber dewatering system can be used as a recycling technique in a water treatment system.

Example 13

[0255] In this example, it was investigated how much the cake moisture content can be reduced by the sludge dewatering treatment of ink washing wastewater.

[0256] In this example, ink washing wastewater sludge [sludge properties; TS (solids concentration): 0.45%, pH: 6.24, appearance: black turbid, slightly transparent color, odor: mineral oily odor] was used, and the Reselber dewatering test and water quality analysis test [phosphorus, SS (suspended substance), BOD, nitrogen] of the Reselber-dewatered separated liquid were performed.

[0257] (1) Dewatering Test

[0258] The dewatering aid Reselber (MT2000) was added at 0.3% (vs. sludge volume) to 800 ml of sludge and the polymer flocculant A (0.2% aqueous solution) was added at 75 ml to form flocs. The flocs were put into a dewatering tester (pressurization area 81 cm.sup.2, pressure/holding time variable), and the moisture content of the discharged cake was measured. The dewatering pressure and holding time were set to 960 kPa and 10 min on the assumption of a filter press dewatering machine, and 480 kPa and 5 min on the assumption of a screw press machine. The results of the dewatering test are shown in Table 31.

TABLE-US-00031 TABLE 31 Assumed Reselber Flocculant (1) Flocculant (2) Flocculant (3) Cake dewatering Product Addition Product Addition Product Addition Product Addition moisture machine number ratio number amount number amount number amount content Filter MT2000 0.3% Our 75 ml — — — — 72.74% press flocculant A Screw MT2000 0.3% Our 75 ml — — — — 77.54% press flocculant A

[0259] As shown in the table, as a result of adding Reselber MT2000 and the polymer flocculant A and dewatering on the assumption of a filter press, the cake moisture content was 72.74%. As a result of dewatering on the assumption of a filter press, the cake moisture content was 77.54%. Because of the Reselber dewatering, the cake moisture content was 72.74% to 77.54% and was reduced by 15% to 20% or more from the current level. This reduced the dewatered cake amount to ⅓ of the current level.

[0260] (2) Dewatering Effect

[0261] It was confirmed that the moisture content can be freely set by increasing or decreasing the Reselber addition amount, and the following water treatment effect was also confirmed: 95% on average of phosphorus was removed, 95% on average of SS (suspended substance) was removed, 60% on average of BOD was removed, and 60% on average of nitrogen was removed. It was confirmed that the Reselber dewatering system can be used as a recycling technique in a water treatment system.

INDUSTRIAL APPLICABILITY

[0262] As described in detail above, the present invention relates to a method of treating parlor wastewater/biomass liquid digestate and a device for treating water for same, and has the following industrial applicability. 1) In the present invention, the attention is focused on fats and calcium contained in parlor wastewater including washing water and disinfectant of milking equipment, water washed away from the floor of the milking facility, washing drainage, cow manure, milk waste, and the like, in particular, the milk waste, in order to remove the fats and calcium efficiently before the fats and calcium flow into an aeration tank, a specific dewatering aid having an Mp value of Mp≤70, more specifically Mp≤55 to Mp=55 to 70 and a flocculant are used in combination so that the formation of flocs including the fats and calcium contained in the milk waste, floc removal/dewatering and neutralization of disinfectant in the neutralization tank are performed simultaneously, thereby making it possible to implement the biological treatment in the biological treatment tank (aeration tank); 2) By using the specific dewatering aid and the flocculant in combination, it is possible to drain the parlor wastewater in a form that satisfies the general drainage standards established by the Water Pollution Control Law; 3) the dewatered cake generated as a residue can be reused in composting facilities; and 4) a method for efficiently biologically treating parlor wastewater and a wastewater treatment device (facility) therefor can be provided. Further, in the present invention, 5) the attention is focused, in particular, on an emulsified component and a fine particle component contained in a biomass liquid digestate, in order to remove the emulsified component and the fine particle component efficiently before the emulsified component and the fine particle component flow into an aeration tank, a specific dewatering aid having an Mp value (moisture content evaluation) of Mp (cake moisture content)≤70, more specifically, Mp (cake moisture content)≤55 to Mp (cake moisture content)=55 to 70 and a flocculant are used in combination so that the formation of flocs including the emulsified component and the fine particle component contained in the biomass liquid digestate and floc removal/dewatering are performed, thereby making it possible to implement the biological treatment in the biological treatment tank (aeration tank); 6) by using the specific dewatering aid and the flocculant in combination, it is possible to drain the biomass liquid digestate in a form that satisfies the general drainage standards established by the Water Pollution Control Law; 7) it is possible to provide a method for efficiently biologically treating a biomass liquid digestate and a wastewater treatment device (facility) therefor; 8) the present invention enables separation into the separated liquid from which extra-large (ϕ 10 mm or more) to large (ϕ 5 to 10 mm) flocs have been removed and a dewatered cake with a moisture content of 70% or less, more specifically, a moisture content of 55% or less to 55% to 70%, and 78% or less of BOD of the raw water can be removed; and 9) a stable water treatment effect can be expected by reducing the BOD volume load, reducing the amount of generated sludge, and reducing the amount of required oxygen.