阅读说明：本技术 一种用于污泥堆肥处理的生物炭及其制备方法 (Biochar for sludge composting and preparation method thereof ) 是由 荆亚超 刘海洋 李飞 岳朴杰 谷小兵 白玉勇 于 2020-01-14 设计创作，主要内容包括：本发明涉及污泥处理技术领域,尤其涉及一种用于污泥堆肥处理的生物炭及其制备方法。一种生物炭,包括如下重量组分的原料：铁粉1-2份和污泥50-200份。一种生物炭的制备方法,包括以下步骤：将铁粉与污泥混合；在绝氧且含有氢气的气氛下,将加入铁粉的污泥加热分解,获得零价铁污泥生物炭；将零价铁污泥生物炭加热升温后,向零价铁污泥生物炭内通入活性气体,即得生物炭。利用该方法制备的生物炭,能够降低污泥中存在的重金属和多氯联苯、多环芳烃、卤代烃等有机物污染物的活性,并能有效减轻污泥发酵过程产生的臭气。解决目前采用好氧堆肥方式处理污泥,难以有效去除污泥中存在的重金属以及有机污染物,且发酵过程中会产生大量臭气的问题。(The invention relates to the technical field of sludge treatment, in particular to biochar for sludge composting treatment and a preparation method thereof. The biochar comprises the following raw materials in parts by weight: 1-2 parts of iron powder and 50-200 parts of sludge. A preparation method of biochar comprises the following steps: mixing iron powder and sludge; heating and decomposing the sludge added with the iron powder in an oxygen-free atmosphere containing hydrogen to obtain zero-valent iron sludge biochar; heating the zero-valent iron sludge biochar, and introducing active gas into the zero-valent iron sludge biochar to obtain the biochar. The biochar prepared by the method can reduce the activity of heavy metal and organic pollutants such as polychlorinated biphenyl, polycyclic aromatic hydrocarbon, halogenated hydrocarbon and the like in sludge, and can effectively reduce odor generated in the sludge fermentation process. Solves the problems that the sludge is treated by adopting an aerobic composting mode at present, heavy metals and organic pollutants in the sludge are difficult to be effectively removed, and a large amount of odor is generated in the fermentation process.)

1. The biochar is characterized by comprising the following raw materials in parts by weight: 1-2 parts of iron powder and 50-200 parts of sludge.

2. The biochar of claim 1,

the iron powder is prepared by crushing the iron-containing waste and sieving the crushed iron-containing waste through a 100-200-mesh sieve;

the organic matter content of the sludge is 50-80%, and the weight content of nitrogen and phosphorus is not higher than 5%.

3. A process for the preparation of biochar as claimed in claims 1-2, characterized in that it comprises the following steps:

s1, mixing iron powder and sludge;

s2, heating and decomposing the sludge added with the iron powder in an oxygen-free hydrogen-containing atmosphere to obtain zero-valent iron sludge biochar;

s3, heating the zero-valent iron sludge biochar, and introducing active gas into the zero-valent iron sludge biochar for modification to obtain biochar;

the active gas is one or more of water vapor or carbon dioxide.

4. The method for preparing biochar according to claim 3, wherein in step S2, the temperature of the thermal decomposition is 400-600 ℃ and the time is 2-4 hours.

5. The method for preparing biochar according to claim 4, wherein the step S3 specifically comprises:

heating the zero-valent iron sludge biochar to the temperature of 750-850 ℃, and introducing steam into the zero-valent iron sludge biochar for modification to obtain the biochar.

6. Use of biochar prepared by the method of claims 3-5 in the treatment of sludge.

7. A method for treating sludge by using the biochar prepared by the method of claims 3-5, which is characterized by comprising the following steps:

mixing biochar with sludge to be treated according to a mass ratio of 1: (15-20) uniformly mixing the raw materials in proportion, and fermenting to obtain the sludge reaching the standard;

and/or adding part of the standard-reaching sludge and the biochar into the newly-treated sludge for sludge treatment.

8. The method for treating sludge according to claim 7, wherein the method comprises:

mixing biochar with sludge to be treated according to a mass ratio of 1: (15-20) uniformly mixing the raw materials in proportion, and fermenting to obtain sludge reaching the standard;

taking part of the sludge meeting the standard as clinker, uniformly mixing the biochar, the clinker and the sludge to be newly treated according to the mass ratio of 1 (5-15) to (15: 20), and then fermenting again.

9. The method for treating sludge according to any one of claims 7 to 8, wherein the temperature of the fermentation is 50 ℃ to 65 ℃ and the fermentation period is 15 to 20 days.

Technical Field

The invention relates to the technical field of sludge treatment, in particular to biochar for sludge composting treatment and a preparation method thereof.

Background

Sludge is a solid precipitate produced during sewage treatment. Along with the acceleration of the urbanization process, the treatment capacity of urban sewage is increasing day by day, and the generation amount of sludge is also increased sharply. The sludge contains rich nutrient elements such as organic matter nitrogen, phosphorus and the like, and also contains harmful substances such as heavy metals, organic pollutants or pathogens with more types and different contents. In order to prevent secondary environmental pollution caused by sludge, it must be properly treated and disposed.

The sludge treatment mode mainly comprises aerobic composting, anaerobic digestion, drying incineration and the like. Wherein, the sludge is treated by anaerobic digestion, drying incineration and other modes, and the problems of low efficiency, serious pollution and the like exist. Compared with anaerobic digestion and drying incineration modes, the aerobic composting mode is adopted to treat the sludge, the efficiency is higher, and the pollution is less, so the aerobic composting becomes the most important mode for stabilizing treatment and safe disposal of the sludge at present. Aerobic composting refers to the process of utilizing aerobic microorganisms to ferment under aerobic conditions to biodegrade organic matters in sludge to generate decomposed sludge with stable properties. However, the aerobic composting method has the following disadvantages:

in the sewage treatment process, heavy metals, organic pollutants and the like are easily enriched in the sludge, and the land utilization of the sludge is influenced. The aerobic composting method is adopted to treat the sludge, although the content of harmful substances such as heavy metals, organic pollutants and the like in the sludge can be reduced to a certain extent, the treated sludge still has great toxicity.

In addition, the aerobic composting method needs to carry out independent composting on the sludge, the air permeability of a pile body is poor, the pile needs to be turned frequently, the energy consumption is high, the fermentation time is long, a large fermentation bin is needed, and the occupied area is large. In addition, a large amount of odor is generated in the fermentation process, which causes secondary pollution.

Disclosure of Invention

The invention aims to solve the technical problems that heavy metals and organic pollutants in sludge are difficult to effectively remove and a large amount of odor is generated in the fermentation process when the sludge is treated by adopting an aerobic composting mode at present.

The technical scheme for solving the technical problems is as follows:

the biochar comprises the following raw materials in parts by weight: 1-2 parts of iron powder and 50-200 parts of sludge.

Iron powder can be prepared by using cheap materials such as iron sheets, scrap iron, shaving scraps and the like. Iron powder as zero-valent iron has a low standard electrode potential (E0(Fe/Fe) ═ 0.44V), has reducibility, and can reduce the activity of heavy metals and also reduce organic pollutants such as polychlorinated biphenyls, polycyclic aromatic hydrocarbons, halogenated hydrocarbons, and the like.

The biological carbon with strong adsorbability can be prepared by taking the sludge as a raw material. The method mixes the reductive iron powder and the strong adsorptive charcoal, and adds the mixture into a sludge reactor, thereby not only improving the ventilation and oxygen supply effects of the sludge stack to be treated, but also absorbing the odor generated in the sludge fermentation process and secondarily decomposing the odor in the fermentation stack.

The biochar prepared by using the iron powder and the sludge as raw materials can remove heavy metal and organic pollutants such as polychlorinated biphenyl, polycyclic aromatic hydrocarbon, halogenated hydrocarbon and the like in the sludge, and can effectively remove odor generated in the sludge fermentation process.

Further, the iron powder is prepared by crushing the iron-containing waste and sieving the crushed iron-containing waste through a 100-mesh and 200-mesh sieve; the organic matter content of the sludge is 50-80%, and the weight content of nitrogen and phosphorus is not higher than 5%.

Iron-containing waste materials such as iron sheets, iron filings, shaving scraps and the like are crushed and sieved by a sieve with 100-mesh and 200-mesh sieve, and the prepared iron powder has larger surface area and active reducibility. Sludge with the organic matter content of 50% -80% is selected as a raw material, so that the prepared biochar can be ensured to have strong adsorption capacity. The content of nitrogen and phosphorus is lower than 5 percent, thereby not only providing fertilizer for land utilization of sludge, but also avoiding the over-high content of nitrogen and phosphorus

A preparation method of biochar comprises the following steps:

s1, mixing iron powder and sludge;

s2, heating and decomposing the sludge added with the iron powder in an oxygen-free hydrogen-containing atmosphere to obtain zero-valent iron sludge biochar;

s3, heating the zero-valent iron sludge biochar, and introducing active gas into the zero-valent iron sludge biochar to obtain biochar;

the active gas is one or more of water vapor or carbon dioxide.

Iron powder is reducing and easily oxidized. The iron powder and the sludge are mixed under the oxygen-deficient and reductive hydrogen-containing environment, so that the reducibility of the iron powder can be ensured. After the sludge is heated and decomposed, the sludge can be pyrolyzed and deformed. Under the condition of further increasing the temperature, activating gas (water vapor or carbon dioxide) is introduced to form porous biochar, so that the adsorption of the biochar is enhanced. The biochar prepared by the method has adsorbability and reducibility, can reduce heavy metals in sludge and adsorb organic pollutants in the sludge and odor generated in the sludge fermentation process.

Further, the step S2 specifically includes: heating the sludge added with the iron powder to 400-600 ℃ for decomposition, wherein the decomposition duration is 2-4 hours, and obtaining the zero-valent iron sludge biochar.

At the temperature of 400-600 ℃, the sludge added with the iron powder is subjected to continuous pyrolysis reaction for 2-4 hours, and the prepared zero-valent iron sludge biochar has strong adsorbability.

Further, the step S3 specifically includes:

heating to 750-;

after the temperature is further increased, activated gas steam is introduced into the zero-valent iron sludge biochar, so that the biochar can form a porous structure, and the adsorption surface area of the biochar is enlarged. In addition, the water vapor is used as the activating gas, so that the environment is not influenced.

Application of the biochar prepared by the method in sludge treatment.

The biological carbon provided by the invention is applied to sludge treatment, can reduce the toxicity of sludge and remove odor generated by sludge fermentation.

A method of treating sludge, comprising the steps of:

mixing biochar with sludge to be treated according to a mass ratio of 1: (15-20) uniformly mixing the raw materials in proportion, and fermenting to obtain the sludge reaching the standard;

and/or adding part of the standard-reaching sludge and the biochar into the newly-treated sludge for sludge treatment.

According to the mass ratio of 1: (15-20), uniformly mixing the biochar provided by the invention with sludge to be treated, and fermenting. The sludge treated by the method has the heavy metal removal rate of 76.9 percent and the organic pollutant removal rate of 71.4 percent, and basically eliminates the odor generated by sludge fermentation.

And/or adding part of the sludge reaching the standard and the biochar into the sludge to be newly treated, wherein the sludge reaching the standard contains beneficial flora for sludge fermentation, so that the sludge fermentation speed can be increased, and the sludge treatment efficiency is improved.

Further, mixing the biochar with sludge to be treated according to a mass ratio of 1: (15-20) uniformly mixing the raw materials in proportion, and fermenting to obtain sludge reaching the standard;

taking part of the sludge meeting the standard as clinker, uniformly mixing the biochar, the clinker and the sludge to be newly treated according to the mass ratio of 1 (5-15) to (15: 20), and then fermenting again. .

The standard-reaching sludge is rich in sludge fermentation flora, and the biochar, clinker and the sludge to be newly treated are uniformly mixed according to the mass ratio of 1 (5-15) to (15: 20) and then fermented, so that the removal rate of heavy metals and organic pollutants can be further improved.

Furthermore, the fermentation temperature is 50-65 ℃, and the fermentation period is 15-20 days.

The fermentation temperature is adjusted to 50-65 ℃, and after fermentation for 15-20 days, the removal rate of heavy metals exceeds 77%, and the removal rate of organic pollutants exceeds 72%.

Compared with the prior art, the biochar provided by the invention takes iron powder and sludge as raw materials, the iron powder can be prepared from iron sheet, scrap iron or shaving and other iron metals, and the sludge can be municipal sludge. The method has the advantages of multiple raw material acquisition ways, low price, high efficiency, environmental friendliness and the like. The biochar prepared by using the iron powder and the sludge as raw materials can remove heavy metals, polychlorinated biphenyl, polycyclic aromatic hydrocarbon, halogenated hydrocarbon and other organic pollutants in the sludge, and can effectively remove odor generated in the sludge fermentation process.

The preparation method of the biochar provided by the invention is characterized in that iron powder and sludge are mixed under an oxygen-deficient hydrogen-containing environment, and activated gas is introduced for activation after heating and decomposition. The prepared biochar has adsorbability and reducibility, can reduce heavy metals in sludge and adsorb organic pollutants in the sludge and odor generated in the sludge fermentation process.

The invention also provides a method for treating sludge by using the biochar, which comprises the following steps of: (15-20) fermenting after uniformly mixing. The removal rate of heavy metals of the treated sludge exceeds 77 percent, the removal rate of organic pollutants exceeds 72 percent, and the odor generated by sludge fermentation is basically eliminated.

Drawings

FIG. 1 is a graph showing the effect of sludge treatment in example 1 and comparative example 1;

FIG. 2 is a graph showing the effect of sludge treatment in example 2 and comparative example 2;

FIG. 3 is a graph showing the effect of sludge treatment in example 3 and comparative example 3.

Detailed Description

The principles and features of this invention are described below in conjunction with the following drawings, which are set forth by way of illustration only and are not intended to limit the scope of the invention.

In the description of the present invention, it is to be understood that the terms "upper", "lower", "center", "inner", "outer", "top", "bottom", and the like, indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, and are only for convenience in describing the present invention and simplifying the description, but do not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and thus, should not be construed as limiting the present invention.

In the description of the present invention, it should be noted that, unless otherwise explicitly specified or limited, the terms "mounted," "connected," and "connected" are to be construed broadly, e.g., as meaning either a fixed connection, a removable connection, or an integral connection; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meanings of the above terms in the present invention can be understood in specific cases to those skilled in the art.