Constructed wetland substrate based on building spoil and preparation method thereof

Abstract

The invention discloses a constructed wetland substrate based on building spoil. The constructed wetland substrate comprises the following components: building spoil, clay, water, sodium silicate, hydroxypropyl cellulose sodium and prefabricated foam, the preparation method specifically comprises the following steps: (1) adding water into hydroxypropyl cellulose sodium, sodium silicate, building spoil, clay and lauryl sodium sulfate, and stirring to form uniform slurry; (2) adding a foaming agent into water, and aerating to form uniform and dense bubbles; (3) uniformly stirring and mixing the slurry formed in the step (2) and the step (1), pouring into a mold, covering the surface with a non-woven fabric, and naturally drying or drying in a constant-temperature drying oven; and (4) removing the non-woven fabric after complete drying, demolding, sintering in a tunnel kiln or a resistance furnace, and naturally cooling to obtain a finished product. The material disclosed by the invention has relatively high communication porosity, water storage property and water flow permeability, can meet the adhesion growth requirements of microorganisms and plants, and improves the operation effect of the constructed wetland.

Description

Technical Field

[0001] The invention belongs to the field of artificial wetland substrates, and in particular relates to an artificial wetland substrate based on construction waste and a preparation method thereof. Background Art

[0002] The artificial wetland matrix is ​​an important component of artificial wetlands, and its selection and configuration are one of the keys to pollution reduction in artificial wetlands. Suitable artificial wetland matrix materials can provide good hydraulic conditions for the infiltration of sewage in artificial wetland systems, and at the same time provide a carrier for the attachment and growth of plants and microorganisms, and use the microbial film attached to the surface of the matrix and plant roots to absorb and degrade pollutants, so as to achieve the effect of removing pollutants from sewage.

[0003] Domestic and foreign practices have proved that some infiltration fillers with large specific surface area and rich pore structure, such as activated carbon and zeolite, have excellent pollutant removal performance when used as artificial wetland matrices, but there are limiting factors such as high cost and limited exploitation of natural materials; commonly used porous synthetic materials such as porous suspended balls and polyurethane sponges are mostly used in sewage treatment plants. Their suspended and soft characteristics make them unsuitable for use in outdoor artificial wetlands, and there is also a risk of aging and producing microplastics; many porous inorganic filter materials have been invented this year, but most of them have high requirements for materials and synthesis processes, and are difficult to produce and utilize on a large scale. Summary of the invention

[0004] The technical problem to be solved by the present invention is to provide an artificial wetland matrix based on construction waste and a preparation method thereof in view of the shortcomings of the above-mentioned prior art. The material has high connected porosity, water storage capacity, and water permeability, can meet the attachment and growth requirements of microorganisms and plants, and improve the operation effect of the artificial wetland.

[0005] The technical solution of the present invention to solve the above technical problems is: an artificial wetland matrix based on construction waste, the artificial wetland matrix comprising the following components: construction waste, clay, water, sodium silicate, sodium hydroxypropyl cellulose and prefabricated foam, with a mass ratio of 1.3-1.4: 0-0.3: 1: 0.01: 0.001: 0.01-0.015.

[0006] The present invention further defines the scheme: Preferably, the modulus of the sodium silicate is 2.8-3.0, and the viscosity of the sodium hydroxypropyl cellulose is 200000 mPa.s.

[0007] Preferably, the prefabricated foam is made by adding gas to a foaming agent, and the foaming agent is sodium lauryl sulfate or alkyl polyglycoside 0814.

[0008] The present invention provides a method for preparing an artificial wetland matrix based on construction waste, which specifically comprises the following steps: (1) Add water to sodium hydroxypropyl cellulose, sodium silicate, construction waste, clay, and sodium lauryl sulfate, and stir to form a uniform slurry; (2) Add the foaming agent into the water and add gas to form uniform and dense bubbles; (3) The bubbles formed in step (2) and the slurry formed in step (1) are stirred and mixed evenly, poured into a mold, the surface is covered with non-woven fabric, and dried naturally or in a constant temperature oven; (4) After complete drying, remove the non-woven fabric, demold, and send it into a tunnel kiln or a resistance furnace for sintering. After natural cooling, the finished product is obtained.

[0009] Preferably, the construction waste is crushed and passed through a 200-mesh sieve.

[0010] Preferably, the mold is a plastic or metal cubic container with a flat bottom opening and a smooth inner wall and a height of 2.5 to 3.5 cm. If a regular-shaped finished product is required, the bottom edge diameter is controlled to be less than 10 cm.

[0011] Preferably, the drying temperature is controlled below 60° C., the sintering temperature should be between 1100° C. and 1150° C., and the holding time at this temperature should be longer than 20 minutes.

[0012] Preferably, the matrix material sample prepared by the above method has an apparent porosity of 56.69%, a volume density of 1.11 g / cm³, and a water absorption rate of 51.09%; after being fully immersed in water at room temperature, the moisture content is 34% after being exposed to air for 8 hours.

[0013] The beneficial effects of the present invention are as follows: the present invention adopts construction waste to realize resource utilization of construction waste, which has the advantages of being cheap and readily available, and can obtain a new artificial wetland matrix material with abundant interconnected pores, high cost performance and good stability through pre-foaming followed by drying and sintering, which can improve the operation efficiency of artificial wetlands and provide a new way of utilizing construction waste; The present invention covers the wet product with non-woven fabric for drying by injection molding, thereby reducing the breakage rate of the blank, and at the same time ensuring that the surface is rough after demoulding and has a large specific surface area. The present invention reduces the amount of foaming agent used in the traditional burning and gas production through the pre-foaming pore generation method, thereby reducing possible tail gas pollution; sodium silicate with a specific modulus and sodium hydroxypropyl cellulose with a specific viscosity are selected as binders, thereby improving the fluidity of the slurry during injection molding and enhancing the strength of the ingredients after drying, making it easy to demould, and at the same time ensuring that the prepared matrix material has good mechanical properties; The artificial wetland matrix material prepared by the present invention has a multi-connected pore structure that can ensure good water permeability and provide ideal hydraulic conditions for sewage treatment; it can provide an effective bacteria-carrying area far higher than that of traditional matrix materials such as gravel, which is conducive to the attachment of microorganisms and improves water intake efficiency. As a lightweight material that does not float and has good water storage capacity, it can meet the normal growth of artificial wetland plants and microorganisms under different water level conditions, avoiding the low water level that may cause plant death in the subsurface and tidal flow wetlands using traditional matrices such as gravel, or the blockage of artificial wetlands caused by laying soil on the surface. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 The appearance of the artificial wetland matrix prepared in Example 1; Figure 2 Scanning electron microscope image of the artificial wetland matrix prepared in Example 1. DETAILED DESCRIPTION

[0015] The present invention can be better understood with reference to the following examples. Example

[0016] This embodiment provides an artificial wetland matrix based on construction waste, which includes the following components: construction waste, water, sodium silicate, sodium hydroxypropyl cellulose and prefabricated foam, with a mass ratio of 1.35:1:0.01:0.001:015.

[0017] The method for preparing the artificial wetland matrix of the above-mentioned construction waste soil specifically comprises the following steps: (1) Accurately weigh 0.2 g of sodium hydroxypropyl cellulose with a viscosity of 200,000 mPa.s, 2 g of commercially available sodium silicate with a modulus of 3.0, and 3 g of sodium dodecyl sulfate, add 200 ml of water, and stir slowly to completely dissolve them without generating obvious bubbles; (2) Accurately weigh 270 g of construction waste soil, add it to the above solution, and vigorously stir it using an automatic mixer until a slurry containing uniform bubbles is formed; (3) Pour the slurry formed in step (2) into a multi-connected plastic mold with a size of 7.9 cm*5.4 cm*2.3 cm, cover the surface with non-woven fabric, and place in a constant temperature oven at 60°C to dry. (4) After complete drying, remove the non-woven fabric, demould, place in a resistance furnace and slowly heat to 1125°C, maintain for 30 minutes, and cool naturally to obtain the finished product.

[0018] The matrix material sample prepared above had an apparent porosity of 60.08%, a bulk density of 0.98 g / cm³, and a water absorption rate of 55.85%. After being fully immersed in water at room temperature, the moisture content was 34% after being exposed to air for 8 hours. Example

[0019] The present embodiment provides an artificial wetland matrix based on construction waste, which includes the following components: construction waste, water, clay, sodium silicate, sodium hydroxypropyl cellulose and prefabricated foam, with a mass ratio of 1.1:1:0.23:0.01:0.001:015.

[0020] The method for preparing the artificial wetland matrix of the above-mentioned construction waste soil specifically comprises the following steps: (1) Accurately weigh 0.2 g of sodium hydroxypropyl cellulose with a viscosity of 200,000 mPa.s, 2 g of commercially available sodium silicate with a modulus of 3.0, 220 g of construction waste, 50 g of clay, and 3 g of sodium dodecyl sulfate, add 160 ml of water, and stir to form a uniform slurry; (2) Accurately measure 2 ml of alkyl polyglycoside 0814 (liquid product with a content of 50%), add 40 ml of water, and add gas to form uniform and dense bubbles; (3) The bubbles formed in step (2) and the slurry formed in step (1) are stirred and mixed evenly, poured into a plastic mold with a height of 3 cm, the surface is covered with non-woven fabric, and dried naturally; (4) After complete drying, the non-woven fabric is removed, the mold is removed, and the product is sent to a tunnel kiln at 1100°C for firing to obtain the finished product.

[0021] The matrix material sample prepared above had an apparent porosity of 56.69%, a bulk density of 1.11 g / cm³, and a water absorption rate of 51.09%. After being fully immersed in water at room temperature, the moisture content was 30% after being exposed to air for 8 hours.

[0022] In addition to the above embodiments, the present invention may also have other implementation modes. Any technical solution formed by equivalent replacement or equivalent transformation falls within the protection scope required by the present invention.

Claims

1. An artificial wetland matrix based on construction waste, characterized by: The artificial wetland matrix comprises the following components: construction waste soil, clay, water, sodium silicate, sodium hydroxypropyl cellulose and prefabricated foam, with a mass ratio of 1.3-1.4:0-0.3:1:0.01:0.001:0.01-0.

015.

2. The artificial wetland matrix based on construction waste according to claim 1, characterized in that: The modulus of the sodium silicate is 2.8-3.0, and the viscosity of the sodium hydroxypropyl cellulose is 200000 mpa.s.

3. The artificial wetland matrix based on construction waste according to claim 1, characterized in that: The prefabricated foam is made by adding gas to a foaming agent, and the foaming agent is sodium lauryl sulfate or alkyl polyglycoside 0814.

4. A method for preparing an artificial wetland matrix based on construction waste according to any one of claims 1 to 3, characterized in that: The specific steps include: (1) Add water to sodium hydroxypropyl cellulose, sodium silicate, construction waste, clay, and sodium lauryl sulfate, and stir to form a uniform slurry; (2) Add the foaming agent into the water and add gas to form uniform and dense bubbles; (3) The bubbles formed in step (2) and the slurry formed in step (1) are stirred and mixed evenly, poured into a mold, the surface is covered with non-woven fabric, and dried naturally or placed in a constant temperature oven; (4) After complete drying, remove the non-woven fabric, demold, and send it into a tunnel kiln or a resistance furnace for sintering. After natural cooling, the finished product is obtained.

5. The method for preparing an artificial wetland matrix based on construction waste according to claim 4, characterized in that: The construction waste soil is crushed and passed through a 200-mesh sieve.

6. The method for preparing an artificial wetland matrix based on construction waste according to claim 5, characterized in that: The mold is a plastic or metal cubic container with a flat bottom opening and a smooth inner wall and a height of 2.5 to 3.5 cm. If a regular-shaped finished product is required, the bottom edge diameter is controlled to be less than 10 cm.

7. The method for preparing an artificial wetland matrix based on construction waste according to claim 6, characterized in that: The drying temperature is controlled below 60°C, the sintering temperature should be between 1100°C and 1150°C, and the holding time at this temperature should be longer than 20 minutes.

8. The method for preparing an artificial wetland matrix based on construction waste according to claim 7, characterized in that: The matrix material sample prepared by the above method has an apparent porosity of 56.69%, a volume density of 1.11 g / cm³, and a water absorption rate of 51.09%. After being fully immersed in water at room temperature, the moisture content is 34% after being exposed to air for 8 hours.

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