CN-122010372-A - Sludge in-situ solidification-denitrification and dephosphorization dual-functional coupling material, and preparation method and application thereof

CN122010372ACN 122010372 ACN122010372 ACN 122010372ACN-122010372-A

Abstract

The invention discloses a sludge in-situ solidification-denitrification and dephosphorization dual-function coupling material and a preparation method and application thereof, and belongs to the technical field of water pollution control. The in-situ sludge is used as a core substrate and is matched with a multi-source mineral-based gelatinizer, a composite denitrification and dephosphorization functional filler, modified biomass fiber and an ecological auxiliary agent. The steel slag/fly ash-based gel system reacts with an alkaline excitant to form a compact framework, the modified fiber constructs a three-dimensional bridging network to improve crack resistance, and the composite functional filler realizes triple purification of 'physical adsorption-chemical precipitation-biodegradation', namely zeolite adsorbs ammonia nitrogen and Fe-K-CT iron carbon filler micro-electrolysis oxidation pollutants, releases iron ion precipitation phosphate and releases a slow-release carbon source to maintain denitrification. The material can be prefabricated into a river channel revetment module, an ecological filtering dam component or a wetland foundation pad layer, so that the on-site resource utilization of sludge and the synchronous promotion of water ecological functions are realized, the engineering cost is obviously reduced, and the ecological system restoration is promoted.

Inventors

YU WEI
WANG HAOTIAN
SHAN HAN
LI ZEDIAN
LIU JUN
DING XIA
MA TAO
LI JIAN

Assignees

安徽久吾天虹环保科技有限公司

Dates

Publication Date: 20260512
Application Date: 20260213

Claims (10)

1. The sludge in-situ solidification-denitrification and dephosphorization dual-function coupling material is characterized by comprising, by mass, 60% -75% of in-situ sludge, 15% -25% of a multi-source mineral-based gelling agent, 5% -10% of a composite denitrification and dephosphorization functional filler, 3% -6% of modified biomass fibers and 1% -3% of an ecological auxiliary agent.
2. The sludge in-situ solidification-denitrification and dephosphorization dual-function coupling material according to claim 1, wherein the in-situ sludge is river or wetland substrate sludge, and the water content is 65% -85%.
3. The sludge in-situ solidification-denitrification and dephosphorization dual-function coupling material according to claim 1, wherein the multi-source mineral-based gelling agent consists of 40% of steel slag, 30% of fly ash, 20% of alkaline activator and 10% of penetrating crystallization agent; the alkaline excitant is formed by mixing sodium silicate and sodium hydroxide according to a mass ratio of 3:1, and the penetrating crystallization agent is formed by compounding sodium silicate and active silicon dioxide micro powder according to a mass ratio of 2:1.
4. The sludge in-situ solidification-denitrification and dephosphorization dual-function coupling material as claimed in claim 1, wherein the composite denitrification and dephosphorization function filler consists of 30% of zeolite powder, 25% of Fe-K-CT iron carbon filler, 25% of modified ceramsite and 20% of slow-release carbon source; The Fe-K-CT iron-carbon filler is prepared by mechanically ball milling zero-valent scrap iron, activated carbon and potassium feldspar powder for 2 hours according to the mass ratio of 5:3:2, and then performing heat treatment for 1 hour under the nitrogen atmosphere at 300 ℃, wherein the modified ceramsite is prepared by soaking commercial ceramsite in a FeCl 3 solution for 12 hours and then drying at 60 ℃, and the slow-release carbon source is polyhydroxyalkanoate particles with the particle size of 0.5-1.5 mm.
5. The sludge in-situ solidification-denitrification and dephosphorization dual-function coupling material according to claim 1, wherein the modified biomass fiber is prepared by soaking straw fiber in 5wt% NaOH solution for 30min, treating the straw fiber with 1wt% silane coupling agent KH550 ethanol solution for 1h, drying and cutting the straw fiber to the length of 8-10 mm.
6. The sludge in-situ solidification-denitrification and dephosphorization dual-function coupling material as claimed in claim 1, wherein the ecological auxiliary agent is composed of 0.5% -1.5% of water-retaining agent and 0.5% -1.5% of compound microbial agent, wherein the compound microbial agent is formed by compounding nitrifying bacteria, denitrifying bacteria and phosphorus accumulating bacteria according to the volume ratio of 1:1:1, and the concentration of viable bacteria is not lower than 1 multiplied by 10 8 CFU/g; The water-retaining agent is sodium polyacrylate crosslinked resin, and the water absorption rate is more than or equal to 300g/g.
7. The sludge in-situ solidification-denitrification and dephosphorization dual-function coupling material as claimed in claim 6, wherein the fixation method of the composite microbial agent comprises the following steps of firstly mixing bacterial liquid with 2% sodium alginate solution according to a ratio of 1:4, dripping the bacterial liquid into 0.1mol/L CaCl 2 solution to form gel beads, immersing the gel beads into 1% chitosan acetic acid solution for crosslinking for 10min, and vacuum drying at 40 ℃ until the water content is less than or equal to 10%.
8. The preparation method of the sludge in-situ solidification-denitrification and dephosphorization dual-function coupling material is characterized by comprising the following steps of: S1, in-situ sludge pretreatment, namely treating river or wetland substrate sludge, wherein the aperture of a screen is 20mm, adding fly ash accounting for 5-10% of the mass of the sludge for adjustment if the water content is more than 75%, and spraying deionized water to the water content of 65-75% if the water content is less than 65%; s2, premixing dry materials, namely dry-mixing the multi-source mineral-based gelatinizing agent, the composite denitrification and dephosphorization functional filler and the modified biomass fiber for 2min at the rotating speed of 30r/min to obtain pretreated sludge; S3, mixing wet materials, namely stirring the pretreated sludge and the ecological auxiliary agent for 3-5 minutes at the rotating speed of 60r/min to obtain castable slurry; s4, in-situ forming, namely pouring the castable slurry into a prefabricated mold, vibrating for 30-60S, and covering geotextile on the surface for moisturizing; s5, naturally curing, namely standing and curing for 7-10 days at the environment temperature of more than or equal to 10 ℃, spraying clear water for 1 time in the morning and evening each day, and removing the die after curing is finished to obtain the dual-function coupling material.
9. The method for preparing the sludge in-situ solidification-denitrification and dephosphorization dual-function coupling material according to claim 8, wherein the composite denitrification and dephosphorization functional filler is added twice, namely zeolite powder and modified ceramsite are added firstly and stirred for 1min, and Fe-K-CT iron carbon filler and slow-release carbon source are added and stirred for 1min.
10. The application of the sludge in-situ solidification-denitrification and dephosphorization dual-function coupling material in a river bank protection module, an ecological filtering dam component and a wetland foundation bed layer is characterized in that the sludge in-situ solidification-denitrification and dephosphorization dual-function coupling material is prepared by the preparation method of any one of claims 8-9; The material is manufactured into a hexahedral module, the size of the hexahedral module is 500mm multiplied by 300mm multiplied by 200mm, a vegetation groove with an inclination angle of 15-25 degrees is formed on the upstream surface, the depth of the vegetation groove is 50-80 mm, the width of the vegetation groove is 60-100 mm, a trapezoidal mortise-tenon structure is arranged on the side surface of the module, the internal porosity of a member is more than or equal to 25%, and the aperture is 2-8 mm; the material is made into porous block bodies, the external dimension is 400mm multiplied by 300mm, the internal porosity is more than or equal to 30%, the pore canal is in a three-dimensional communication network structure, and a staggered joint lap joint mode is adopted when stacking; the material is manufactured into a sheet structure, the thickness of the material is 15-20 cm, the material is paved at the bottom of the wetland and used as a bearing layer, the compressive strength is not lower than 2.5MPa, the compaction degree of the original soil foundation before paving is not less than 90%, and the seam of the cushion layer is subjected to seam pointing treatment by adopting slurry with the same proportion.

Description

Sludge in-situ solidification-denitrification and dephosphorization dual-functional coupling material, and preparation method and application thereof Technical Field The invention relates to the technical field of water pollution control, in particular to a sludge in-situ solidification-denitrification and dephosphorization dual-function coupling material, a preparation method and application thereof. Background The current water ecological management and engineering construction face three core problems. Firstly, the sludge disposal pressure is high, more and more sludge is deposited at the bottoms of river channels and wetlands, and the traditional dredging-outward transporting-landfill mode not only occupies precious land resources, but also is easy to cause secondary pollution, and the dredging, transportation and subsequent disposal costs are high. Secondly, engineering materials cannot meet ecological requirements, traditional structural materials such as concrete and masonry stone are produced in different places and transported to a construction site for a long distance, so that the cost is increased, ecological connection between water and land can be cut, and the effect of purifying water quality cannot be exerted at all. Finally, the cost superposition caused by single function, such as materials specially used for denitrification and dephosphorization as filter materials and floating island carriers, needs additional paving construction, and cannot be matched with materials playing a role of structural support, so that the engineering complexity is improved, and the cost is greatly increased. Patent CN118495771a discloses a sludge treatment slow-release material and a treatment method, and the surface of an iron-carbon micro-electrolysis filler is coated with a water-soluble slow-release film, so that ferrous ions are slowly released in the sludge, and then persulfate is catalytically activated to generate free radicals, so that oxidative degradation of nitrogen-containing organic matters is realized, and ferric ions react with phosphate to generate ferric phosphate precipitation, so that the effect of synchronously removing nitrogen, phosphorus and heavy metals is achieved. Although the scheme has certain denitrification and dephosphorization capability, the core of the scheme is an added slow release medicament, the structure molding or mechanical property construction of the material is not involved, the scheme cannot be used as an engineering structure body, and the scheme is not suitable for in-situ curing application scenes. At present, the research on preparing the denitrification or dephosphorization functional material by recycling the sludge is also carried out in the industry, but the material function integration is also provided with an obvious short plate. On one hand, the slow-release medicament material has no structural support capability although being capable of realizing purification by chemical reaction, and cannot be cured and formed in situ, and on the other hand, the pyrolytic carbon-based adsorption material has good dephosphorization effect, but the preparation process has high energy consumption, is in powder form, and hardly meets the requirements on the mechanical property and the construction convenience of the material in engineering application. More importantly, the two technologies cannot combine the functions of 'in-situ solidification' and 'denitrification and dephosphorization' in the same material system, so that two works of structure construction and water quality purification can be respectively carried out in actual engineering, thereby not only increasing the complexity of the system, but also improving the comprehensive cost. Therefore, the development of a material capable of being formed in situ under normal temperature or low temperature conditions is urgent, the material has enough mechanical strength and can be used for high-efficiency denitrification and dephosphorization, and the aim of synchronously improving the on-site resource utilization and water ecological functions of the sludge is fulfilled by the material with double functions. Disclosure of Invention The invention aims to provide a sludge in-situ solidification-denitrification and dephosphorization dual-function coupling material, which solves the problems of high sludge outward transportation treatment cost, and system redundancy caused by independent construction of engineering structure and ecological function rupture and denitrification and dephosphorization units in the prior art. The second purpose of the invention is to provide a preparation method of the sludge in-situ solidification-denitrification and dephosphorization dual-function coupling material, which is used for preparing the sludge in-situ solidification-denitrification and dephosphorization dual-function coupling material. The invention further aims to provide application of the sludge in-situ solidification-denitri