KR100551250B1 - Solidifying agent for sewage or wastewater sludge and covering material for waste reclamation land prepared using this - Google Patents

Abstract

 The present invention relates to a solidifying agent for solidifying sewage and wastewater sludge, and a cover material produced by using the same. More specifically, using a paraffin and an inorganic binder simultaneously solidifies sewage and wastewater sludge having inorganic and organic solidification characteristics. The present invention relates to a solidifying agent, and solidified sewage and wastewater sludge using the same as a cover material, road auxiliary base material, or construction aggregate used in a landfill.

The solidifying agent of the present invention is paraffin 24.0 to 56.0% by weight, inorganic binder 24.0 to 56.0% by weight, stearic acid 2.0 to 10.0% by weight, polyvinyl alcohol 2.0 to 10.0% by weight, carboxymethyl cellulose 2.0 to 10.0% by weight and sodium hydroxide, hydroxide It is made by mixing water with a mixture comprising 0.1 to 3.0% by weight of potassium or a mixture thereof and 5.0 to 20.0% by weight of vinyl acetate resin, wherein the solidifying agent is dehydrated sewage, wastewater sludge or concentrated sewage sludge. 3 to 25 wt% of the total weight is mixed to dry to prepare an auxiliary base material.

Solidification of sewage and wastewater sludge using the solidifying agent of the present invention does not significantly increase the weight and volume of the waste, and it is stable in the long term because no harmful substances are eluted, and it also utilizes the solidified sludge as an auxiliary base material. Can be reduced.

Sewage sludge, wastewater sludge, hardener, paraffin, lime, auxiliary base material, cover material

Description

Solidifying agent for solidifying sewage and wastewater sludge and covering material manufactured by using the same {SOLIDIFYING AGENT FOR SEWAGE OR WASTEWATER SLUDGE AND COVERING MATERIAL FOR WASTE RECLAMATION LAND PREPARED USING THIS}

The present invention relates to a solidifying agent for solidifying sewage and wastewater sludge, and a cover material produced by using the same. More specifically, using a paraffin and an inorganic binder simultaneously solidifies sewage and wastewater sludge having inorganic and organic solidification characteristics. The present invention relates to a solidifying agent, and solidified sewage and wastewater sludge using the same as a cover material, road auxiliary base material, or construction aggregate used in a landfill.

Sludge refers to a mud-like substance formed by sedimentation of sewage in water during sewage and wastewater treatment. Sludge is difficult to transport and handle due to its contaminants and high water content.

Currently, many of the sludges generated are dependent on landfilling and dumping at sea.In the case of landfilling, not only landfills are lacking, but leachate is generated and groundwater is contaminated. This is a serious problem, causing red tide, and costly to transport sludge to the ocean.

In addition, sludge treatment methods such as incineration, composting, stabilization / solidification treatment, etc. have been proposed. There are many limitations and difficulties in incineration or composting due to high water content in the sludge generated.

The stabilization / solidification method for sewage and wastewater sludge has been recently developed in various ways. Finally, the sludge is finally fixed in a matrix or a constant film is formed to suppress and block the leaching of heavy metals to the outside, and It is a treatment to improve the mechanical properties.

Stabilization / solidification techniques are divided into inorganic and organic processes.

The inorganic process is a method of solidifying waste by using inorganic as a solidifying agent, and cement or lime is generally used as a solidifying agent, which is inexpensive but has an inexpensive advantage, but increases the weight and volume of the waste, and in the long term, There is a risk of elution. In addition, in the case of cement, when the waste contains a large amount of organic matter, the improvement effect is significantly reduced, and in the case of lime, it takes a considerable time before the treatment effect is expressed.

The organic process is a method of treating wastes using thermoplastic or thermosetting resins, which are expensive due to high material cost, high energy consumption, initial facility investment and skilled technology, and incurs secondary environmental pollution. Dioxins and incineration residues are caused by the problem.

In particular, high-functional wastes, such as sewage and wastewater sludge, do not mix well with the solidifying agent, which makes it difficult to stabilize / solidify the sludge, which may be well mixed with high-functional wastes, thereby promoting solidification of sewage and wastewater sludge. The development of a hardener was required.

Accordingly, the present inventors have studied carefully and developed a solidifying agent that mixes well with moisture sewage and wastewater sludge and promotes solidification, and furthermore, dehydrated sludge (water content ratio of about 75%) as well as concentration before dehydration. It was able to solidify sludge (about 98% water content), and developed solidified sewage / wastewater sludge to be used as cover material or aggregate for road subbases used in landfills.

An object of the present invention is to provide a solidifying agent for sewage and wastewater sludge which can remove the solidifying inhibitory elements around the solid object to promote solidification and easily solidify.

Another object of the present invention is to solidify sewage and wastewater sludge with the above-mentioned solidifying agent and to use it as a cover material, road auxiliary base material or construction aggregate used in waste landfill.

Still another object of the present invention is to reduce environmental pollution by recycling sewage and wastewater sludge, which is difficult to dispose of.

Hereinafter, the solidifying agent for solidifying the sewage and wastewater sludge of the present invention and the cover material prepared by using the same will be described in detail.

The solidifying agent of the present invention is paraffin 24.0-56.0 wt%, inorganic binder 24.0-56.0 wt%, stearic acid 2.0-10.0 wt%, polyvinyl alcohol 2.0-10.0 wt%, carboxymethylcellulose 2.0-10.0 wt% and sodium hydroxide, hydroxide It is characterized by consisting of a mixture of water or a mixture comprising potassium or 0.1 to 3.0% by weight thereof.

Paraffin is a colorless or white substance consisting of straight chain hydrocarbon mixtures that can be obtained by dewaxing petroleum feedstocks with the general formula C _n H _{2n + 2} . Paraffin has 16-40 carbon atoms, and mostly 20-30. Paraffins of up to 5 carbon atoms per molecule are gases at room temperature, those of 5 to 15 carbon atoms are liquid and chained paraffins containing more than 15 carbon atoms are solids.

As the paraffin used in the present invention, a water-soluble paraffin obtained by emulsifying a solid paraffin is used. The solid paraffin, a carbon compound, is a chain-like (aliphatic) hydrocarbon that is insoluble in water. The solid paraffin is dissolved in water by OH ⁻ by mixing an additive with heating → an emulsifier → esterification.

Water-soluble paraffins help adhesion and hydrogen bonding between homogeneous or heterogeneous molecules. In particular, water-soluble paraffins act to catalyze the surface area and promote solidification by using absorbent materials and absorbing properties.

In addition, a water-soluble paraffin is a RCOOH and ROH and ion exchange, which are attached to the mineral particles surrounding action proceeds Ca ⁺² ion and by removing RCOOH and ROH to interfere with reaction of toripja near toripja Ca ⁺² ions are directly reacted with toripja Let's do it. By this ion exchange action, it is stably hardened and increases adhesion and particle density to maximize chemical bonding force between particles. Therefore, it is possible to overcome the disadvantages of existing cement in treating sludge with high organic content and high water content.

In addition, the water-soluble paraffin is excellent in water resistance and elasticity, and the hardening occurs continuously even after a long time to prevent long-term aging, thereby increasing the durability of the treatment.

In addition, the calcium silicate hydrate is produced by the silicon silicate mixture in the mixed product of water-soluble paraffins to react with lime to improve the pozzolanic reaction.

In the present invention, lime and water-soluble paraffins combine to promote absorption and exothermic reactions, and at the same time, monovalent ions such as Na ⁺ and K ^{+ in} water-soluble paraffins and divalent ions of Ca ⁺² of lime are exchanged so that particles are aggregated and paraffin-specific. The capture effect of

In the solidifying agent of the present invention, paraffin is contained in an amount of 24.0 to 56.0% by weight based on 100% by weight of the solidifying agent mixture to be mixed. When paraffin is included in less than 24.0% by weight, there is a disadvantage in that the binding force between the mixed components is not sufficient, and when included in excess of 56.0% by weight, there is a problem that it is not economical without any special improvement effect.

The inorganic binder functions to bind the mixed components, and the inorganic binder which is preferably used in the solidifying agent of the present invention is cement, lime or a mixture thereof. However, the inorganic binder in the present invention is not limited to the above-described inorganic binders, and all commercially available inorganic binders may be used.

In the solidifying agent of the present invention, the inorganic binder is included in 24.0 to 56.0% by weight based on 100% by weight of the mixture. When the inorganic binder is included in less than 24.0% by weight, there is a disadvantage in that the binding strength between the mixed components is not sufficient.When the inorganic binder is included in an amount exceeding 56.0% by weight, the weight becomes heavy and the content of other particles, especially paraffin, is reduced, thereby causing the effect of collecting particles. There is a problem falling.

Stearic acid is a surfactant, which is a kind of fatty acid. It has a carboxyl group on the hydrophilic head and a carbon ring on the hydrophobic tail, so that it becomes a catalyst for paraffin to dissolve well in water as it is mixed with paraffin. It works to improve.

In the solidifying agent of the present invention, stearic acid is included in an amount of 2.0 to 10.0% by weight based on 100% by weight of the mixture. When the stearic acid is included in less than 2.0% by weight is not sufficient waterproof and trapping effect, when contained in more than 10.0% by weight there is a problem in reducing the content of other components, paraffin or inorganic binder to reduce the inter-particle bonding.

Polyvinyl alcohol is obtained by dissolving vinyl acetate in alcohol and saponifying by adding alkali, which is used for adhesives, thickeners, varnishes, colloidal stabilizers, cement coatings and the like. This serves to combine the components to be mixed to improve mechanical properties and increase water tightness.

In the solidifying agent of the present invention, the polyvinyl alcohol is included in an amount of 2.0 to 10.0% by weight based on 100% by weight of the mixture. When the polyvinyl alcohol is included in less than 2.0% by weight, the binding strength is weak, and when included in excess of 10.0% by weight, there is a problem that is not economical without a special improvement effect.

Carboxymethylcellulose (CMC) is a white solid made by reacting alkali cellulose with chloroacetic acid salts and is a water-soluble cellulose having 0.8 or less sodium glycolate and ether groups per cellulose molecular unit (C6). It is used for grass feeding of textile products and is formulated in detergents to enhance the cleaning effect. It is used for medicine, cosmetics, and food industry. It has the property of preventing mold or rot, allowing for long-term storage. In particular, carboxymethyl cellulose in the present invention acts as an emulsifier to emulsify the paraffins.

In the solidifying agent of the present invention, the carboxymethylcellulose is included in an amount of 2.0 to 10.0% by weight based on 100% by weight of the mixture. When carboxymethyl cellulose is included in less than 2.0% by weight is an anti-corruption effect is insufficient and when included in excess of 10.0% by weight there is a problem that is not economical without a special improvement effect.

In the solidifying agent of the present invention, sodium hydroxide (NaOH), potassium hydroxide (KOH) or a mixture thereof is included in an amount of 0.5 to 3.0% by weight based on 100% by weight of the solidifying agent mixture. It acts as an accelerator and is highly soluble and well soluble in water so that materials mixed with the present hardener are easily mixed.

The solidifying agent of the present invention may be prepared in liquid, gel, or powder form depending on the purpose of solidification and the purpose of use.

In the solidifying agent of the present invention, an organic synthetic polymer of 5.0 to 20.0% by weight based on 100% by weight of the solidifying agent mixture may be added to prepare a liquid solidifying agent. The organic synthetic polymer preferably used in the present invention is vinyl acetate resin. It is highly dispersible in water, allowing the mixed components to mix well.

In the solidifying agent of the present invention, the silicone solidifying agent may be prepared by further containing 1.0 to 15.0% by weight of silicone based on 100% by weight of the solidifying agent mixture.

Further, in the solidifying agent of the present invention, a powdered solidifying agent can be prepared by further mixing the solidified powder with the gelling solidifying agent.

The powdered solidifying agent is further mixed with the gelled solidifying agent to form a powder, and is prepared by mixing the gel-solidifying agent and the solidified powder in a ratio of 1: 1 to 2.5.

The solid powder may be paper-making powder, gypsum or a mixture thereof.

The solidified powder most preferably used in the present invention is that both paper powder and gypsum are used, wherein the ratio of paper powder and gypsum is 1: 0.8 to 1.2.

The papermaking powder is paper milled and includes papermaking dust from the paper mill.

Paper dust is mixed with a gel solidifying agent in a predetermined ratio within the above range and dried, and then a proportion of gypsum is mixed to prepare a powder solidifying agent.

The amount of water used in the preparation of the solidifying agent of the present invention is an amount of paraffin, an inorganic binder, stearic acid, polyvinyl alcohol, carboxymethyl cellulose and sodium hydroxide and / or potassium hydroxide are mixed in a predetermined ratio, and an appropriate ratio is formulated according to the use. to be. Thus the amount of water blended can be determined empirically or by theoretical or iterative practice to one skilled in the art. Preferably the amount of water used is from 200 to 500% by weight relative to 100% by weight of the mixture to be mixed.

The solidifying agent of the present invention is prepared by mixing the mixed components in the most suitable ratio according to the characteristics of the object to be solidified, that is, water content, contamination concentration, treatment method after solidification.

The solidifying agent of the present invention is obtained by adding predetermined water to a stirrer and heating it to 70-100 ° C., followed by mixing with stearic acid, paraffin, cement, carboxymethyl cellulose, polyvinyl alcohol and sodium hydroxide and / or potassium hydroxide and stirring. . In addition, the mixture may be prepared by mixing any one of organic synthetic polymers, silicones or solid powders with an additional ratio.

The solidifying agent of the present invention is mixed with the concentrated sludge or the dewatered sludge treated in the sewage and wastewater treatment plant at an appropriate ratio and dried to solidify the sludge.

That is, when 3 to 25% by weight of the solidifying agent of the present invention is mixed according to the conventional method with respect to the total weight of the concentrated or dehydrated sewage and wastewater sludge, the sewage and wastewater sludge is solidified. do. Drying can be fanned for natural drying or quick drying. Dry solidified sludge is used as a cover material for a waste disposal plant, aggregate for road subbases, or aggregate for construction.

The solidifying agent of the present invention can solidify not only dehydrated sewage and wastewater sludge but also concentrated sewage and wastewater sludge. In other words, in the sewage and wastewater sludge treatment, the sewage and wastewater sludge treatment can be made simpler by solidifying using the concentrated sludge which has not undergone the dehydration treatment step.

Through the following examples, comparative examples and test examples will be described in more detail the hardener and cover material of the present invention.

Example 1 Preparation of Liquid Solidifying Agent

2200 cc of water was added to the stirrer and heated until it reached 90 ° C., and the stirrer was operated to rotate slowly. 60 g of stearic acid, 400 g of paraffin, 400 g of cement, 50 g of carboxymethylcellulose, 70 g of polyvinyl alcohol, 10 g of sodium hydroxide and 10 g of potassium hydroxide were added to the stirrer and stirred to prepare a liquid hardener.

Example 2 Preparation of Gel-Based Solidifying Agent

10 g of silicone was added to the liquid solidifying agent prepared in Example 1 and stirred to prepare a gel solidifying agent.

Example 3 Preparation of Powdery Solidifying Agent

1000 g of papermaking dust was added to the gel-forming solidifier prepared in Example 2, stirred and dried, and then 1000 g of gypsum was added and mixed to prepare a powder-based solidifying agent.

Example 4 Preparation of Cover Material

1000g of concentrated sludge treated by aerobic microorganisms in a sewage treatment plant was prepared in three containers. 200 g of solidifying agents (a), gels (b) and powders (c) prepared in Examples 1, 2 and 3, respectively, were put in a container containing the concentrated sludge, mixed for 2 hours, and then naturally dried for 2 days. Sludge (A, B, C) was obtained.

Comparative Example 1

1000 g of concentrated sludge treated by aerobic microorganisms was prepared in a sewage treatment plant. 200 g of lime was added to the concentrated sludge, followed by mixing for 2 hours, followed by air drying for 2 days to obtain solidified sludge.

Test Example 1 pH Test

Four beakers containing 25 ml of distilled water were prepared, 5 g of each of the solidified sludges (A, B, and C) prepared in Example 4 and 5 g of the raw sludge were mixed in each of the beakers, and the glass electrode was put thereinto measure the pH value. The pH measurement results are shown in Figure 1.

Figure 1 pH change of sludge treated with solidifying agent of the present invention

Sludge must maintain pH value over 12 after 24 hours to get the effect of killing pathogens, preventing rot and suppressing odor. As shown in Figure 1, the pH value of raw sludge was about 8 alkaline. The solidified sludges A, B and C all had pH values of 12 or more. This confirmed that the solidified sludge of the present invention has the effect of killing and preventing rot and odor of pathogens.

Test Example 2 Melting Test

Into two beakers containing 500 ml of distilled water, 10 g of raw sludge and 10 g of sludge (C) solidified with the solidified powder (c) obtained in Example 4 were allowed to stand for 30 days, and then the submerged sludge solidified product. The state of and turbidity of water were investigated.

Figure 2 Dissolution test of sludge

As shown in Fig. 2, the one-sludge (a) dissolves and dissolves in water over time, but the sludge (b) solidified with the solidifying agent of the present invention retains its solidified form even after a long time. Could. This is because the particles are collected by the coating due to the formation of the paraffin coating and are stable by maintaining a solidified form for a long time.

Test Example 3 Repeated Batch Dissolution Test

One sludge, 10 g of each of the solidified sludge (C) and the solidified sludge obtained in Comparative Example 1 were prepared with the solidified powder (c) obtained in Example 4. These were placed in a beaker containing 100 g of distilled water adjusted to pH 5.6 to 6.3 with hydrochloric acid, mixed, and shaken at room temperature for 6 hours. After the solid-liquid separation using a centrifuge to extract the supernatant, the eluted heavy metals were analyzed using AAS (Atomic Absorption Spectrometry) and the results are shown in Table 1.

Table 1

Dissolution frequency One Sludge Lime Treated Sewage Sludge Sewage sludge treated with powder solidifying agent   Cadmium (Cd) One 0.04 0.04 0.00 2 0.04 0.04 0.00 3 0.05 0.05 0.00 4 0.05 0.05 0.00 5 0.05 0.05 0.00   Pb One 0.70 0.60 0.10 2 0.40 0.60 0.30 3 0.60 0.60 0.10 4 0.00 0.00 0.20 5 0.00 0.10 0.30   Copper (Cu) One 0.00 4.60 1.80 2 0.00 1.00 0.10 3 0.00 0.50 0.00 4 0.00 0.00 0.00 5 0.00 0.00 0.00   Chrome (Cr) One 0.00 0.00 0.00 2 0.00 0.00 0.00 3 0.00 0.00 0.00 4 0.00 0.00 0.00 5 0.00 0.00 0.00

As shown in Table 1, chromium was not detected for all samples, copper and lead showed high concentrations only at the beginning of elution, and concentrations decreased rapidly in the second and third times. It was eluted. Copper was not eluted from the raw sludge but elution was observed in the sewage sludge treated with lime and the solidifying agent of the present invention because it is re-eluted under strong alkali conditions. Copper was eluted at 4.60 ppm when treated with lime, but when treated with the solidifying agent of the present invention, 1.80 ppm was released within the standard value. Overall, it was found that there was a heavy metal elution delay effect when treated with the solidifying agent of the present invention.

 Test Example 4 Long-Term Continuous Dissolution Test

10 g of sludge (C) solidified with a solidifying agent in powder form (c) obtained in Example 4 was added to an elution apparatus (surface area 0.0079 m ² ), and 0.5 liter / time of distilled water simulating artificial rainfall was introduced once a week for 6 months. It was carried out continuously. The pH, heavy metal concentration and COD of the effluent were measured at 1 month intervals and the results are shown in Table 2.

TABLE 2

Primary (initial) 2nd (January) 3rd (from February) 4th (from April) 5th (June) Waste Management Act pH 12.4 11.2 10.4 9.8 9.6 - CD Not detected Not detected 0.01 Not detected Not detected 0.3 Pb 0.20 0.11 0.05 Not detected Not detected 3 Cu 0.05 Not detected Not detected Not detected Not detected 3 Cr Not detected 0.02 Not detected Not detected Not detected 1.5 COD 169 84 47 21.2 12.8 -

As shown in Table 2, the pH of the sludge solidified with the solidifying agent of the present invention decreased to 9.6 after 6 months from the initial 12.6 and COD decreased to 12.8 after 6 months from the initial 169. In addition, cadmium and chromium were not detected in the initial heavy metal concentrations, but a small amount of copper and lead were eluted, but not detected after 4 months, and the sludge solidified with the solidifying agent of the present invention was confirmed to be environmentally harmless.

Then, the utilization of using the solidified sludge of the present invention as a cover material or road auxiliary base material was tested.

Test Example 5 Strength Characteristics

Uniaxial compressive strength was performed according to KS F 2314. The solidified sludge prepared by mixing the solidifying agent in the mixing ratio of 10%, 15%, and 20% with respect to the total weight of the sewage sludge was compacted into three layers by using PVC pipe having a diameter of 5 cm and a height of 10 cm, respectively. A soft clay machine with a maximum load of 50 kg was used as a strain control method to maintain a loading rate of 1 mm / min.

Figure 3 Uniaxial Compressive Strength of Sludge Treated with Solidifying Agent of the Present Invention

As shown in Figure 3, the uniaxial compressive strength of the raw sludge showed a low strength of 0.05 (1 day) to 0.18 (28 days) kg / cm 2. The uniaxial compressive strength that can run the construction machine is 0.5kg / ㎠ or more, the sludge solidified using the solidifying agent of the present invention exhibited strength of more than 0.5kg / ㎠ at all compounding ratios after 7 days of curing, the road of the waste carrier It appeared to be able to play a role. This is due to the separation of fine clay and colloidal components by ion exchange and pozzolanic reaction by CaO, etc. among the solidifying agents, and the sludge is improved to high quality soil. Increasing the high purity, and also because of the hardenability of the paraffin, the strength of the sludge is increased.

Test Example 6 Permeability Analysis

Permeability test was conducted in accordance with KS F 2322. It was carried out using a rigid wall permeable mold having a diameter of 5 cm and a height of 6 cm and using the same sample as in Test Example 5.

Fig. 4 Permeability Per Day of Sludge Treated with Solidifying Agent of the Present Invention

As shown in Figure 4, the permeability coefficient decreased as the solidifying agent formulation and curing days increased. The raw material sludge showed a permeability coefficient of 4-5 X 10 ^-5 cm / sec, but the 28-day permeability coefficient of the sludge solidified using the solidifying agent of the present invention was 4-6 X 10 ^-6 cm / sec. It can be seen that the fold reduced.

Permeability coefficients for daily and intermediate cover of waste landfills are not clearly defined, but are based on low permeability clay or clay sand. Generally, the permeability coefficient of clay soil is 1 X 10 ^{-5 to} 1 X 10 ^-7. cm / sec. The permeability coefficient of the sludge solidified by the solidifying agent of the present invention was found to satisfy the permeability coefficient criteria of landfill cover material at 1 × 10 ^{−5 to} 1 × 10 ⁻⁶ cm / sec.

Although specific embodiments of the present invention have been described above, it is obvious that the sewage sludge solidifying agent of the present invention and the cover material prepared by using the same may be variously modified and implemented by those skilled in the art.

For example, although the mixing ratio of each component is specified in the said Example, the mixing ratio may change according to a use use.

However, such modified embodiments should not be individually understood from the technical spirit or the prospect of the present invention, and such modified embodiments should fall within the appended claims of the present invention.

As described above, the solidifying agent of the present invention, unlike cement or lime used as a conventional solidifying agent, does not significantly increase the weight and volume of the waste during solidifying the waste, and converts the contaminant solidified with the inorganic binder back to paraffin. By collecting, the solid is stable in the long term and no harmful substances are eluted from the solid.

In addition, the solidifying agent of the present invention can easily solidify not only dehydrated sewage and wastewater sludge, but also concentrated sewage and wastewater sludge, so that sewage and wastewater sludge can be treated more simply and at a lower cost. It can be used as road subsidiary materials or construction aggregates, and can reduce environmental pollution by recycling waste.

Claims (6)

Paraffin 24.0-56.0 wt%, Inorganic binder 24.0-56.0 wt% cement, lime or mixtures thereof, 2.0-10.0 wt% stearic acid, 2.0-10.0 wt% polyvinyl alcohol, 2.0-10.0 wt% carboxymethylcellulose, sodium hydroxide A solidifying agent for solidifying sewage and wastewater sludge, characterized by mixing water with a mixture comprising 0.1 to 3.0 wt% of potassium hydroxide or a mixture thereof and 5.0 to 20.0 wt% of vinyl acetate resin. The method according to claim 1, A solidifying agent for solidifying sewage and wastewater sludge, characterized in that the mixture further comprises 1.0 to 15.0% by weight of silicon to form a gel. The method according to claim 2, The solidified powder is further mixed with the mixture to form a powder, the solidifying agent for solidifying the sewage and wastewater sludge, characterized in that the mixing ratio of the mixture and the solidified powder is 1: 1 to 2.5. The method according to claim 3, And said solidified powder is papermaking powder, gypsum, or a mixture thereof, wherein said solidifying powder solidifies sewage and wastewater sludge. The solidifying agent according to any one of claims 1 to 4 and dried dehydrated sewage sludge or concentrated sewage sludge, 3 to 25% by weight of a solidifying agent is mixed with respect to the total weight of the dewatered sewage sludge or concentrated sewage sludge. The method according to claim 5, The cover material is used as a road auxiliary base material or construction aggregate Covering materials.