阅读说明：本技术 一种利用水体修复植物聚草制备富磷水热炭及制备方法 (Phosphorus-rich hydrothermal carbon prepared from water body restoration plants and grass gathering and preparation method ) 是由 崔孝强 陈冠益 颜蓓蓓 马文超 程占军 林法伟 钟磊 于 2019-08-08 设计创作，主要内容包括：本发明公开了一种利用水体修复植物聚草制备富磷水热炭及制备方法,该富磷水热炭的制备方法,包括：(1)将收获的聚草除杂后洗净风干,并烘干和粉碎过筛；(2)取粉碎后的聚草和水以1:5～1:15的质量比例加入到水热反应器中,在200～260℃下保温1～3h进行水热炭化；(3)炭化后冷却至室温,取出物料过滤,将固体产物烘干后粉碎,即得富磷水热炭。本发明以水体修复植物聚草作为原料进行水热炭的制备,该方法操作便捷且绿色环保,实现了水体修复植物废弃物的无害化处置,有效地避免了二次污染；同时本发明所制备的水热炭含有很高的磷钾含量,可以作为良好的土壤添加剂,实现了水体修复植物的高值资源化利用。(The invention discloses a phosphorus-rich hydrothermal carbon prepared by utilizing water restoration plants to gather grass and a preparation method thereof, wherein the preparation method of the phosphorus-rich hydrothermal carbon comprises the following steps: (1) removing impurities from the harvested poly grass, cleaning, air drying, crushing and sieving; (2) adding the crushed poly grass and water into a hydrothermal reactor according to the mass ratio of 1: 5-1: 15, and carrying out hydrothermal carbonization at the temperature of 200-260 ℃ for 1-3 h; (3) cooling to room temperature after carbonization, taking out the materials, filtering, drying and crushing the solid product to obtain the phosphorus-rich hydrothermal carbon. The method takes the water body repairing plant poly grass as the raw material to prepare the hydrothermal carbon, is convenient to operate, is green and environment-friendly, realizes harmless treatment of the water body repairing plant waste, and effectively avoids secondary pollution; meanwhile, the hydrothermal carbon prepared by the method has high phosphorus and potassium content, can be used as a good soil additive, and realizes high-value resource utilization of water restoration plants.)

1. A method for preparing phosphorus-rich hydrothermal carbon by utilizing water body restoration plants and grass gathering is characterized by comprising the following steps:

(1) Removing impurities from the harvested poly grass, cleaning, air drying, crushing and sieving;

(2) Adding the crushed poly grass and water into a hydrothermal reactor according to the mass ratio of 1: 5-1: 15, and carrying out hydrothermal carbonization at the temperature of 200-260 ℃ for 1-3 h;

(3) Cooling to room temperature after carbonization, taking out the materials, filtering, drying the solid product and then crushing to obtain the hydrothermal carbon.

2. The method according to claim 1, wherein the drying temperature in step (1) is 65 to 85 ℃.

3. The preparation method according to claim 1, wherein in the step (2), the ratio of the dry weight of the biomass of the restoration plant to the mass of water is 1: 5-1: 10.

4. The preparation method according to claim 1, wherein in the step (2), the temperature rise rate of the hydrothermal carbonization is 1-5 ℃/min, and the temperature is kept for 1-2 h after the temperature is raised to 220-260 ℃.

5. The method according to claim 1, wherein the water body restoration plant is a common plant of artificial wetland of plantain, canna or droughhaired bevel.

6. The method for preparing the phosphorus-rich hydrothermal carbon by utilizing the water body restoration plant poly-grass method as claimed in claim 1, wherein the total phosphorus content of the hydrothermal carbon is 18.4-30.4mg/g, and the total potassium content is 20.6-32.7 mg/g.

Technical Field

The invention relates to the field of resource utilization of solid wastes and environmental protection, in particular to resource utilization of water body restoration plants, and particularly relates to a method for resource utilization of water body restoration plants through hydrothermal carbonization.

Background

Since the middle of the 20 th century, with the acceleration of industrialization and urbanization, the population number is rapidly increased, and the situation of water eutrophication in China is becoming more severe. According to the '2017 Chinese environmental condition publication' published by the ministry of ecological environment of China in 2018, about 30.3% of reservoirs and lakes in China are in eutrophication state, water eutrophication becomes the main reason of water quality type water shortage in China, and the restoration of eutrophic water is imminent. In recent years, the high-efficiency composite ecological wetland system is widely concerned by people due to the characteristics of low cost, high efficiency and environmental friendliness, and mainly utilizes a composite system consisting of a substrate, microorganisms and aquatic plants to purify eutrophic water through multiple coordination effects of adsorption, filtration, precipitation, plant absorption, microorganism decomposition and the like. However, although the water body can be purified by the application of the water body restoration plants, if the plants are harvested irregularly, not only the water quality purification efficiency is affected, but also the nutrient salts absorbed by the plants are returned to the water again along with the falling of the dry branches and leaves, so that the secondary pollution of the water body is caused. Therefore, in the efficient operation and maintenance of the ecological wetland, the harvesting treatment of the restoration plants is an essential link, and the key point is that how to treat a large amount of restoration plant residues is more important. In addition, the resource utilization of abundant nutrient elements enriched in the repair plants has important significance for improving the soil productivity and increasing the crop yield.

The water body restoration plants are rich in a large amount of phosphorus, the content of the phosphorus is higher than that of common crop straws by one order of magnitude, and the phosphorus can be used as a soil fertilizer additive and has high agricultural value. However, most of phosphorus in the water body restoration plant biomass is water-soluble, and if the plant biomass is directly returned to the field, a large amount of phosphorus is easily leached under the action of rainwater and irrigation water, so that a large amount of nutrients are lost, agricultural non-point source pollution is caused, and the risk of water body eutrophication is aggravated again. Therefore, it is very critical how to effectively fix the phosphorus in the water body restoration plants and prepare products with high added values. Biochar is a stable carbon-rich porous solid substance generated by pyrolysis of waste biomass under the condition of oxygen isolation, and has wide application in carbon fixation and emission reduction, soil improvement, crop yield increase, environmental remediation and other aspects in recent years. Among them, biochar is a soil additive, which can improve soil fertility and further increase crop yield, and has been widely noticed by people in recent years. However, there is no selectivity in raw materials for preparing the agricultural biochar at present, and even some raw materials deficient in nutrient elements are used for preparing the agricultural biochar, and the soil improvement and crop yield increase effects are not good. Therefore, the preparation of biochar rich in nutrient elements, such as phosphorus-rich biochar, is imminent, and the targeted improvement of poor nutrient element type low-yield farmland soil can be realized, so that the purpose of increasing the yield of crops is realized. As mentioned above, the phosphorus-rich biochar prepared by using phosphorus-rich water body repairing plants can realize harmless treatment of plant repairing wastes and can also produce biochar which is needed urgently and directionally contains rich nutrient elements. The existing preparation method of the biochar mainly adopts a pyrolysis method and a hydrothermal method, the pyrolysis method requires higher temperature, so that the energy consumption is higher, and the requirement on the water content of raw materials is higher; compared with the prior art, the hydrothermal method mainly utilizes the energy of water in a subcritical or supercritical state, requires lower temperature and is suitable for treating biomass with higher water content, particularly water eutrophication restoration plants mainly comprising aquatic plants. However, the preparation of phosphorus-rich hydrothermal carbon by hydrothermal carbonization of water body restoration plants has not been reported in the prior art. Therefore, if the phosphorus-rich hydrothermal carbon can be prepared by using the water body remediation plant biomass wastes, the win-win goal of harmless treatment and resource utilization of the wastes can be realized, and meanwhile, the end technical support is provided for the industrialized development of the ecological wetland.

Disclosure of Invention

The invention aims to provide a method for recycling eutrophic water restoration plants by hydrothermal carbonization, which adopts a hydrothermal carbonization technology to treat the water restoration plants and obtain hydrothermal carbon rich in phosphorus.

A method for preparing phosphorus-rich hydrothermal carbon by utilizing water restoration plants and grass comprises the following specific steps:

(1) Removing impurities from the harvested poly grass, cleaning, air drying, crushing and sieving;

(2) Adding the crushed poly grass and water into a hydrothermal reactor according to the mass ratio of 1: 5-1: 15, and carrying out hydrothermal carbonization at the temperature of 200-260 ℃ for 1-3 h;

(3) Cooling to room temperature after carbonization, taking out the materials, filtering, drying and crushing the solid product to obtain the phosphorus-rich hydrothermal carbon.

The proper drying temperature in the drying process of the water restoration plant biomass has an important influence on the form and the water content of the biomass and the existence form of phosphorus in the biomass, and further influences the hydrothermal carbonization effect of the biomass, and the conditions are researched and tested to determine that the drying temperature in the step (1) is preferably 65-85 ℃.

the hydrothermal carbonization mainly utilizes the energy of water in a subcritical or supercritical state to realize the carbonization of biomass, so the control of the proportion of water and biomass in a reaction system is very critical; under the condition of an equivalent biomass system, the biomass carbonization is incomplete due to the fact that the pressure of the reaction system is too low and the energy is insufficient due to too low added water amount, otherwise, unnecessary energy consumption in the reaction process is increased due to too high water amount, conditions are researched and tested, and the mass ratio of the poly-grass to the water in the step (2) is determined to be 1: 5-1: 15, preferably 1: 5-1: 10.

the hydrothermal carbonization time, temperature and heating rate are used as key factors influencing the properties of the hydrothermal carbon, and the hydrothermal carbonization time, temperature and heating rate are correspondingly optimized according to the purpose of the prepared target hydrothermal carbon. Too low temperature and too short time can cause insufficient hydrothermal carbonization of the biomass, thereby influencing the development of surface functional groups and pores of the biomass; conversely, too high a temperature and too long a reaction time may result in too low a yield of hydrothermal carbon, decomposition of functional groups, and additional energy consumption. In addition, the purpose of the test is to realize resource recovery of phosphorus in the water body restoration plant, so that the distribution ratio of solid-phase hydrothermal carbon and liquid-phase products of phosphorus in a reaction system at different temperatures is also an important consideration index. The conditions are researched and tested, and it is determined that in the step (2), the temperature rise speed of the hydrothermal carbonization is 1-5 ℃/min, the temperature is raised to 200-260 ℃, then the temperature is kept for 1-3 h, and preferably the temperature is raised to 220-260 ℃ and the temperature is kept for 1-2 h.

The invention also provides the phosphorus-rich hydrothermal carbon prepared by the preparation method.

the pH value of the phosphorus-rich hydrothermal carbon is 5.2-6.2, the ash content is 21.0-24.7%, and the carbon content is 46.7-53.2%; the total potassium content of the hydrothermal carbon is 20.6-32.7mg/g, the total phosphorus content is 18.4-30.4mg/g, and the solid phase phosphorus recovery rate is 95.2-102.3%.

Compared with the prior art, the invention has the beneficial effects that:

(1) The method utilizes the hydrothermal carbonization technology to carry out harmless treatment on the eutrophic water body restoration plants, and effectively avoids secondary pollution caused by returning dead branches and fallen leaves of plants rich in nitrogen and phosphorus to the water body, thereby improving the purification efficiency of the ecological wetland on the eutrophic water body at the tail end and providing technical support for the industrial development of the ecological wetland.

(2) The invention realizes harmless treatment of the waste plant biomass for water body remediation, emphasizes resource recovery of the rich phosphorus, has the phosphorus recovery rate of more than 95 percent, prepares high-value phosphorus-rich hydrothermal carbon, can be used as an additive for low-phosphorus and low-yield soil, and has great application potential in the fields of energy and environment.

(3) The invention realizes harmless treatment of the waste biomass of the water restoration plant, and simultaneously stably seals and preserves carbon in the biomass waste, reduces carbon dioxide emission, and has remarkable ecological benefit.

(4) The technology for preparing the phosphorus-rich hydrothermal carbon by utilizing the water body restoration plants and the poly grass has the advantages of low energy consumption, environmental protection, low cost and high efficiency, and can fulfill the aims of harmless treatment and resource utilization of wastes and realize win-win of environmental protection and resource utilization.

Detailed Description