CN111003716A - Comprehensive utilization method of seabed sludge - Google Patents
Comprehensive utilization method of seabed sludge Download PDFInfo
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- CN111003716A CN111003716A CN201911301162.8A CN201911301162A CN111003716A CN 111003716 A CN111003716 A CN 111003716A CN 201911301162 A CN201911301162 A CN 201911301162A CN 111003716 A CN111003716 A CN 111003716A
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Abstract
The invention discloses a method for comprehensively utilizing seabed sludge, which comprises the following steps of pretreating a seabed sludge raw material and then soaking and activating the pretreated seabed sludge raw material by using a sodium hydroxide solution, wherein the concentration range of the sodium hydroxide solution is 5-20%; taking the supernatant after the activation treatment, adjusting the pH value, standing, taking the sediment, washing and drying to obtain humic acid; adding water into the activated lower sediment, performing pyrolysis, cooling the product to room temperature, and performing centrifugal separation to obtain a liquid part and a solid part; washing, drying and sieving the solid part obtained by centrifugal separation to obtain the biochar prepared from the seabed sludge; sending the liquid part obtained by centrifugal separation into an evaporative crystallizer, and carrying out evaporative crystallization to obtain sodium chloride; the method has the advantages of no influence on the environment, simple operation, economy and feasibility, can prepare humic acid, biochar and byproduct sodium chloride from the seabed sludge, changes waste into valuable, and has good economic benefit and environmental benefit.
Description
Technical Field
The invention relates to the field of environmental engineering, in particular to a comprehensive utilization method of seabed sludge.
Background
The coastline of China is long, the area of an offshore silt region is large, abundant seabed silt resources are provided, and silt which is difficult to count is accumulated in water areas of various wharfs and navigation channels along the coast; at present, governments adopt a plurality of silt reducing measures to suck a large amount of silt from the seabed, and the large amount of seabed silt collected by a dredger is transported to deep ocean areas to be dumped or accumulated on the coast to form mudflats, so that the potential application value of the seabed silt is wasted; therefore, how to effectively and reasonably dispose and develop and utilize the excavated seabed sludge is a problem to be faced.
The seabed sludge is rich in humic acid, which is an amorphous polymer organic matter, the molecules of which contain conjugated double bonds, aromatic rings, quinone groups, semiquinone groups and other groups and are natural soil conditioners; humic acid is widely existed in soil, lakes, rivers and oceans, and is a potential organic resource which can be vigorously developed and comprehensively utilized; the common commercial humic acid products in the market at present mainly have two sources, one is mineral humic acid extracted from weathered coal, and the other is biochemical humic acid extracted from straw substances, wherein the mineral humic acid is mainly used. Compared with commercial humic acid, the sludge humic acid has more organic matter types, higher contents of fat substances and nitrogen compounds, lower oxidation degree and better physiological activity than the commercial humic acid.
Meanwhile, the seabed sludge is rich in organic matters and is an ideal source for preparing the biochar. Biochar is charcoal with porous characteristics formed by pyrolyzing biomass, and the low cost and sustainability of the biochar indicate that the biochar is a main environment-friendly material in the future. However, the seabed sludge has the characteristics of high water content and high salinity, the existing sludge carbonization technology for dehydrating and then carbonizing the sludge at high temperature not only increases the production cost, but also does not relate to the problem of high-salinity biomass raw material treatment. Meanwhile, the seabed sludge contains a large amount of salt, and if the carbonization liquid is discharged without treatment, the environment is affected, and effective resources are wasted and fully utilized.
The market needs a method which can comprehensively utilize the seabed sludge and does not affect the environment, and the invention solves the problems.
Disclosure of Invention
In order to solve the defects of the prior art, the invention aims to provide a method for comprehensively utilizing the seabed sludge, which has the advantages of no influence on environment, simple operation, economy and feasibility, can prepare humic acid, biochar and byproduct sodium chloride from the seabed sludge, changes waste into valuable, and has good economic benefit and environmental benefit.
In order to achieve the above object, the present invention adopts the following technical solutions:
a method for comprehensively utilizing seabed sludge comprises the following steps:
after pretreatment of the seabed sludge raw material, soaking and activating the pretreated seabed sludge raw material by using a sodium hydroxide solution, wherein the concentration range of the sodium hydroxide solution is 5-20%, and the mass ratio of the seabed sludge to the sodium hydroxide solution is 1: 4-6;
adjusting the pH value of the activated supernatant to 2-2.4, standing, taking out the sediment, washing and drying to obtain humic acid;
adding water into the activated lower sediment, performing pyrolysis, cooling the product to room temperature, and performing centrifugal separation to obtain a liquid part and a solid part;
washing, drying and sieving the solid part obtained by centrifugal separation to obtain the biochar prepared from the seabed sludge;
and (4) sending the liquid part obtained by centrifugal separation into an evaporative crystallizer, and carrying out evaporative crystallization to obtain sodium chloride.
The comprehensive utilization method of the seabed sludge comprises the following steps: removing impurities, and sieving with 60-80 mesh sieve.
The method for comprehensively utilizing the seabed sludge comprises the following steps: ocean bottom mud, seawater farm sludge, mudflat culture sludge and sludge for dredging and throwing the sea.
The method for comprehensively utilizing the seabed sludge comprises the steps of taking the upper layer liquid after the activation treatment, regulating the pH value range to be 2-2.4 by using a hydrochloric acid solution, standing, taking sediments, repeatedly washing for 3-6 times by using distilled water, and drying at the drying temperature of 60-80 ℃ for 6-9h to obtain the humic acid.
The comprehensive utilization method of the seabed sludge comprises the following steps of taking activated lower sediment, adding distilled water into the activated lower sediment: the mass ratio of the distilled water is 1: 3-6; putting the mixture into a carbonization furnace, introducing nitrogen for protection, then performing pyrolysis, keeping the temperature for 4-5h after the temperature of the carbonization furnace is raised at the rate of 3-10 ℃/min and the hydrothermal carbonization temperature of 200-280 ℃, and cooling the product to room temperature, and then performing centrifugal separation to obtain a liquid part and a solid part.
The comprehensive utilization method of the seabed sludge comprises the steps of washing the solid part obtained by centrifugal separation for 3-6 times, drying at the drying temperature of 100-.
In the method for comprehensively utilizing the seabed sludge, the liquid part obtained by centrifugal separation is sent into an evaporation crystallizer, the evaporation concentration temperature is 80-100 ℃, the liquid part is taken out when the liquid part is concentrated until crystallization is separated out, and solid-liquid separation is carried out at 40-60 ℃ to obtain sodium chloride crystals; the secondary mother liquor returns to the evaporation equipment again.
The invention has the advantages that:
the raw materials are easy to obtain, the humic acid, the biochar and the byproduct sodium chloride are prepared by using the seabed sludge, the economic benefit and the environmental benefit are good, and the full resource utilization of the seabed sludge is realized;
according to the invention, humic acid is extracted by adopting an alkali dissolution and acid precipitation method, a large amount of mineral elements in the seabed sludge are remained in the lower layer extracted mother liquor, and the biochar is prepared by using the mother liquor, so that the mineral elements contained in the seabed sludge are remained;
the method does not need to carry out dehydration and desalination treatment on the raw materials in the process of changing waste into valuable, and can realize zero emission of the environment;
in the research process, the invention finds that the humic acid and the biochar with higher yield can be obtained only when the concentration of the sodium hydroxide solution is 5-20%.
Detailed Description
The present invention will be described in detail with reference to the following embodiments.
A method for comprehensively utilizing seabed sludge comprises the following steps:
firstly, pretreating a seabed sludge raw material, and then soaking and activating the pretreated seabed sludge raw material by using a sodium hydroxide solution, wherein the concentration range of the sodium hydroxide solution is 5-20%, and the mass ratio of the seabed sludge to the sodium hydroxide solution is 1: 4-6; the pretreatment comprises the following steps: removing impurities, and sieving with 60-80 mesh sieve. The seabed sludge comprises: marine bottom mud, seawater farm sludge, mudflat culture sludge, sludge removal and sea throwing sludge; it should be noted that the seabed sludge may be one of these examples, or a combination of several of them.
And step two, taking the activated lower-layer sediment, adding distilled water, and adding the lower-layer sediment: the mass ratio of the distilled water is 1: 3-6; putting the mixture into a carbonization furnace, introducing nitrogen for protection, then performing pyrolysis, keeping the temperature for 4-5h after the temperature of the carbonization furnace is raised at the rate of 3-10 ℃/min and the hydrothermal carbonization temperature of 200-280 ℃, and cooling the product to room temperature, and then performing centrifugal separation to obtain a liquid part and a solid part;
adding water into the activated lower-layer sediment, performing pyrolysis, cooling the product to room temperature, and performing centrifugal separation to obtain a liquid part and a solid part;
step four, washing the solid part obtained by centrifugal separation for 3-6 times, drying at the drying temperature of 100-120 ℃ for 8-12h, and finally sieving through a sieve of 80-100 meshes to obtain the biochar prepared from the seabed sludge;
step five, sending the liquid part obtained by centrifugal separation into an evaporation crystallizer, wherein the evaporation concentration temperature is 80-100 ℃, taking out the liquid part after concentration until crystallization is separated out, and carrying out solid-liquid separation at 40-60 ℃ to obtain sodium chloride crystals; the secondary mother liquor returns to the evaporation equipment again.
The beneficial effects of the invention are verified by the following experiments, and optimization experiments are carried out:
example 1:
pumping sludge at the bottom of the mudflat culture pond, standing to remove supernatant, filtering a solid part by a 80-mesh sieve, soaking and activating the solid part by 11% of sodium hydroxide solution, wherein the mass ratio of the sludge to the sodium hydroxide solution is 1:4, stirring for 2h, standing for 12h, taking supernatant, regulating the pH value to 2.0 by using hydrochloric acid solution, taking lower-layer sediment after standing, washing for 3 times by using distilled water, and drying to obtain humic acid.
Adding deionized water into the lower sediment after the activated sludge is soaked in 11% sodium hydroxide solution, wherein the ratio of the deionized water to the lower sediment is as follows: the mass ratio of the deionized water is 1:4, and the mixture is placed in a high-pressure reaction kettle for hydrothermal carbonization reaction. Before the temperature of the reaction kettle is increased, nitrogen is introduced into the reaction chamber for 15min through a gas phase pipe, and then the gas valve is screwed down to enable the reaction chamber to be in a closed state. In the hydrothermal carbonization process, the reaction kettle is heated to 200 ℃ by a voltage of 220V, the temperature is kept constant for 4h by a closed container, and the product is centrifugally separated after being cooled to room temperature.
And (3) repeatedly washing the solid part obtained by centrifugal separation with distilled water for 3 times, then drying in a drying oven at 105 ℃ for 8h, and sieving with a 80-mesh sieve to obtain the biochar prepared from the mudflat culture mud. Evaporating and concentrating the liquid part obtained by centrifugal separation in a rotary evaporator at 85 deg.C, taking out when crystal is separated out, and performing solid-liquid separation at 45 deg.C to obtain sodium chloride crystal.
Example 2:
collecting seabed sludge collected by a dredger, standing to remove supernatant, filtering a solid part by a 80-mesh sieve, soaking and activating by using 14% sodium hydroxide solution, stirring for 3h, standing for 12h, taking supernatant liquid, regulating the pH value to 2.2 by using hydrochloric acid solution, standing, taking lower-layer sediment, washing for 3 times by using distilled water, and drying to obtain humic acid.
Adding deionized water into the lower sediment after the activated sludge is soaked in a 14% sodium hydroxide solution, wherein the ratio of the deionized water to the lower sediment is as follows: the mass ratio of the deionized water is 1:3, and the mixture is placed in a high-pressure reaction kettle for hydrothermal carbonization reaction. Before the temperature of the reaction kettle is increased, nitrogen is introduced into the reaction chamber for 15min through a gas phase pipe, and then the gas valve is screwed down to enable the reaction chamber to be in a closed state. In the hydrothermal carbonization process, the reaction kettle is heated to 220 ℃ by a voltage of 220V, the temperature is kept constant for 5 hours by a closed container, and the product is centrifugally separated after being cooled to room temperature.
And (3) repeatedly washing the solid part obtained by centrifugal separation with distilled water for 3 times, then drying in an oven at 110 ℃ for 8h, and sieving with a 80-mesh sieve to obtain the biochar prepared from the mudflat culture mud. Evaporating and concentrating the liquid part obtained by centrifugal separation in a rotary evaporator at 90 deg.C, taking out when crystal is separated out, and performing solid-liquid separation at 50 deg.C to obtain sodium chloride crystal.
Example 3:
collecting seabed sludge collected by a dredger, standing to remove supernatant, filtering a solid part by a 80-mesh sieve, soaking and activating the solid part by 17% sodium hydroxide solution, stirring for 3h, standing for 12h, taking supernatant, regulating the pH value of the supernatant to 2.4 by hydrochloric acid solution, standing, taking lower-layer sediment, washing for 4 times by distilled water, and drying to obtain humic acid.
Adding deionized water into the lower sediment after 17% sodium hydroxide solution is used for soaking activated sludge, wherein the ratio of the lower sediment to the activated sludge is as follows: the mass ratio of the deionized water is 1:5, and the mixture is placed in a high-pressure reaction kettle for hydrothermal carbonization reaction. Before the temperature of the reaction kettle is increased, nitrogen is introduced into the reaction chamber for 15min through a gas phase pipe, and then the gas valve is screwed down to enable the reaction chamber to be in a closed state. In the hydrothermal carbonization process, the reaction kettle is heated to 240 ℃ by a closed container at 220V, the temperature is kept constant for 4.5h, and the product is centrifugally separated after being cooled to room temperature.
And (3) repeatedly washing the solid part obtained by centrifugal separation with distilled water for 4 times, then drying in an oven at 110 ℃ for 9h, and sieving with a 80-mesh sieve to obtain the biochar prepared from the mudflat culture mud. Evaporating and concentrating the liquid part obtained by centrifugal separation in a rotary evaporator at 90 deg.C, taking out when crystal is separated out, and performing solid-liquid separation at 50 deg.C to obtain sodium chloride crystal.
Example 4:
pumping sludge at the bottom of the mudflat culture pond, standing to remove supernatant, filtering a solid part by a 80-mesh sieve, soaking and activating the solid part by 5% of sodium hydroxide solution, wherein the mass ratio of the sludge to the sodium hydroxide solution is 1:4, stirring for 2h, standing for 12h, taking supernatant, regulating the pH value to 2.2 by using hydrochloric acid solution, standing, taking lower-layer sediment, washing for 4 times by using distilled water, and drying to obtain humic acid.
Adding deionized water into the lower sediment after soaking activated sludge in 5% sodium hydroxide solution, wherein the ratio of the lower sediment to the activated sludge is as follows: the mass ratio of the deionized water is 1:6, and the mixture is placed in a high-pressure reaction kettle for hydrothermal carbonization reaction. Before the temperature of the reaction kettle is increased, nitrogen is introduced into the reaction chamber for 15min through a gas phase pipe, and then the gas valve is screwed down to enable the reaction chamber to be in a closed state. In the hydrothermal carbonization process, the reaction kettle is heated to 260 ℃ by a closed container at 220V, the temperature is kept constant for 4 hours, and the product is centrifugally separated after being cooled to room temperature.
And (3) repeatedly washing the solid part obtained by centrifugal separation with distilled water for 5 times, then drying in an oven at 105 ℃ for 10h, and sieving with a 80-mesh sieve to obtain the biochar prepared from the mudflat culture mud. Evaporating and concentrating the liquid part obtained by centrifugal separation in a rotary evaporator at 90 deg.C, taking out when crystal is separated out, and performing solid-liquid separation at 60 deg.C to obtain sodium chloride crystal.
Example 5:
pumping sludge at the bottom of a seawater farm, standing to remove supernatant, filtering a solid part by using a 80-mesh sieve, soaking and activating the solid part by using 20% sodium hydroxide solution, wherein the mass ratio of the sludge to the sodium hydroxide solution is 1:5, stirring for 2h, standing for 12h, taking supernatant, regulating the pH value of the supernatant to 2.4 by using hydrochloric acid solution, taking lower-layer sediment after standing, washing for 5 times by using distilled water, and drying to obtain humic acid.
Adding deionized water into the lower sediment after the activated sludge is soaked in 20% sodium hydroxide solution, wherein the ratio of the deionized water to the lower sediment is as follows: the mass ratio of the deionized water is 1:4, and the mixture is placed in a high-pressure reaction kettle for hydrothermal carbonization reaction. Before the temperature of the reaction kettle is increased, nitrogen is introduced into the reaction chamber for 15min through a gas phase pipe, and then the gas valve is screwed down to enable the reaction chamber to be in a closed state. In the hydrothermal carbonization process, the reaction kettle is heated to 280 ℃ by a closed container at 220V, the temperature is kept constant for 5 hours, and the product is centrifugally separated after being cooled to room temperature.
And (3) repeatedly washing the solid part obtained by centrifugal separation with distilled water for 6 times, then drying in an oven at 110 ℃ for 10h, and sieving with a 80-mesh sieve to obtain the biochar prepared from the mudflat culture mud. Evaporating and concentrating the liquid part obtained by centrifugal separation in a rotary evaporator at 90 deg.C, taking out when crystal is separated out, and performing solid-liquid separation at 50 deg.C to obtain sodium chloride crystal.
Example 6:
pumping sludge at the bottom of a seawater farm, standing to remove supernatant, filtering a solid part by using a 80-mesh sieve, soaking and activating the solid part by using 8% sodium hydroxide solution, wherein the mass ratio of the sludge to the sodium hydroxide solution is 1:6, stirring for 2h, standing for 12h, taking supernatant, regulating the pH value of the supernatant to 2.0 by using hydrochloric acid solution, taking lower-layer sediment after standing, washing for 5 times by using distilled water, and drying to obtain humic acid.
Adding deionized water into the lower sediment after the activated sludge is soaked in 8% sodium hydroxide solution, wherein the ratio of the lower sediment to the activated sludge is as follows: the mass ratio of the deionized water is 1:5, and the mixture is placed in a high-pressure reaction kettle for hydrothermal carbonization reaction. Before the temperature of the reaction kettle is increased, nitrogen is introduced into the reaction chamber for 15min through a gas phase pipe, and then the gas valve is screwed down to enable the reaction chamber to be in a closed state. In the hydrothermal carbonization process, the reaction kettle is heated to 200 ℃ by 220V voltage, the temperature is kept constant for 4.5h by a closed container, and the product is centrifugally separated after being cooled to room temperature.
And (3) repeatedly washing the solid part obtained by centrifugal separation with distilled water for 3 times, then drying in an oven at 110 ℃ for 11h, and sieving with a 80-mesh sieve to obtain the biochar prepared from the mudflat culture mud. Evaporating and concentrating the liquid part obtained by centrifugal separation in a rotary evaporator at 80 deg.C, taking out when crystal is separated out, and performing solid-liquid separation at 55 deg.C to obtain sodium chloride crystal.
Example 7:
collecting seabed sludge collected by a dredger, standing to remove supernatant, filtering a solid part by a 80-mesh sieve, soaking and activating the solid part by 8% sodium hydroxide solution, stirring for 3h, standing for 12h, taking supernatant, regulating the pH value of the supernatant to 2.4 by hydrochloric acid solution, standing, taking lower-layer sediment, washing for 6 times by distilled water, and drying to obtain humic acid.
Adding deionized water into the lower sediment after the activated sludge is soaked in 8% sodium hydroxide solution, wherein the ratio of the lower sediment to the activated sludge is as follows: the mass ratio of the deionized water is 1:6, and the mixture is placed in a high-pressure reaction kettle for hydrothermal carbonization reaction. Before the temperature of the reaction kettle is increased, nitrogen is introduced into the reaction chamber for 15min through a gas phase pipe, and then the gas valve is screwed down to enable the reaction chamber to be in a closed state. In the hydrothermal carbonization process, the reaction kettle is heated to 220 ℃ by a voltage of 220V, the temperature is kept constant for 4h by a closed container, and the product is centrifugally separated after being cooled to room temperature.
And (3) repeatedly washing the solid part obtained by centrifugal separation with distilled water for 3 times, then drying in an oven at 110 ℃ for 12h, and sieving with a 80-mesh sieve to obtain the biochar prepared from the mudflat culture mud. Evaporating and concentrating the liquid part obtained by centrifugal separation in a rotary evaporator at 85 deg.C, taking out when crystal is separated out, and performing solid-liquid separation at 50 deg.C to obtain sodium chloride crystal.
Example 8:
pumping sludge at the bottom of a seawater farm, standing to remove supernatant, filtering a solid part by using a 80-mesh sieve, soaking and activating the solid part by using 20% sodium hydroxide solution, wherein the mass ratio of the sludge to the sodium hydroxide solution is 1:5, stirring for 2h, standing for 12h, taking supernatant, regulating the pH value of the supernatant to 2.0 by using hydrochloric acid solution, taking lower-layer sediment after standing, washing for 6 times by using distilled water, and drying to obtain humic acid.
Adding deionized water into the lower sediment after the activated sludge is soaked in 20% sodium hydroxide solution, wherein the ratio of the deionized water to the lower sediment is as follows: the mass ratio of the deionized water is 1:3, and the mixture is placed in a high-pressure reaction kettle for hydrothermal carbonization reaction. Before the temperature of the reaction kettle is increased, nitrogen is introduced into the reaction chamber for 15min through a gas phase pipe, and then the gas valve is screwed down to enable the reaction chamber to be in a closed state. In the hydrothermal carbonization process, the reaction kettle is heated to 240 ℃ by a closed container at 220V, the temperature is kept constant for 4.5h, and the product is centrifugally separated after being cooled to room temperature.
And (3) repeatedly washing the solid part obtained by centrifugal separation with distilled water for 3 times, then drying in an oven at 110 ℃ for 8h, and sieving with a 80-mesh sieve to obtain the biochar prepared from the mudflat culture mud. Evaporating and concentrating the liquid part obtained by centrifugal separation in a rotary evaporator at 80 deg.C, taking out when crystal is separated out, and performing solid-liquid separation at 45 deg.C to obtain sodium chloride crystal.
Example 9:
collecting seabed sludge collected by a dredger, standing to remove supernatant, filtering a solid part by a 80-mesh sieve, soaking and activating the solid part by 5% sodium hydroxide solution, stirring for 3h, standing for 12h, taking supernatant, regulating the pH value of the supernatant to 2.2 by hydrochloric acid solution, standing, taking lower-layer sediment, washing 3 times by distilled water, and drying to obtain humic acid.
Adding deionized water into the lower sediment after soaking activated sludge in 5% sodium hydroxide solution, wherein the ratio of the lower sediment to the activated sludge is as follows: the mass ratio of the deionized water is 1:5, and the mixture is placed in a high-pressure reaction kettle for hydrothermal carbonization reaction. Before the temperature of the reaction kettle is increased, nitrogen is introduced into the reaction chamber for 15min through a gas phase pipe, and then the gas valve is screwed down to enable the reaction chamber to be in a closed state. In the hydrothermal carbonization process, the reaction kettle is heated to 260 ℃ by a closed container at 220V, the temperature is kept constant for 5 hours, and the product is centrifugally separated after being cooled to room temperature.
And (3) repeatedly washing the solid part obtained by centrifugal separation with distilled water for 3 times, then placing the solid part in a drying oven at 110 ℃ for drying for 9 hours, and sieving the dried solid part with a 80-mesh sieve to obtain the biochar prepared from the mudflat culture mud. Evaporating and concentrating the liquid part obtained by centrifugal separation in a rotary evaporator at the temperature of 95 ℃, taking out the liquid part when crystals are separated out, and performing solid-liquid separation at the temperature of 50 ℃ to obtain sodium chloride crystals.
Example 10:
pumping sludge at the bottom of the mudflat culture pond, standing to remove supernatant, filtering a solid part by a 80-mesh sieve, soaking and activating the solid part by 11% of sodium hydroxide solution, wherein the mass ratio of the sludge to the sodium hydroxide solution is 1:4, stirring for 2h, standing for 12h, taking supernatant, regulating the pH value to 2.0 by using hydrochloric acid solution, taking lower-layer sediment after standing, washing for 4 times by using distilled water, and drying to obtain humic acid.
Adding deionized water into the lower sediment after the activated sludge is soaked in 11% sodium hydroxide solution, wherein the ratio of the deionized water to the lower sediment is as follows: the mass ratio of the deionized water is 1:6, and the mixture is placed in a high-pressure reaction kettle for hydrothermal carbonization reaction. Before the temperature of the reaction kettle is increased, nitrogen is introduced into the reaction chamber for 15min through a gas phase pipe, and then the gas valve is screwed down to enable the reaction chamber to be in a closed state. In the hydrothermal carbonization process, the reaction kettle is heated to 280 ℃ by a closed container at 220V, the temperature is kept constant for 4 hours, and the product is centrifugally separated after being cooled to room temperature.
And (3) repeatedly washing the solid part obtained by centrifugal separation with distilled water for 4 times, then drying in an oven at 105 ℃ for 10h, and sieving with a 80-mesh sieve to obtain the biochar prepared from the mudflat culture mud. Evaporating and concentrating the liquid part obtained by centrifugal separation in a rotary evaporator at 90 deg.C, taking out when crystal is separated out, and performing solid-liquid separation at 60 deg.C to obtain sodium chloride crystal.
Example 11:
pumping sludge at the bottom of a seawater farm, standing to remove supernatant, filtering a solid part by using a 80-mesh sieve, soaking and activating the solid part by using 14% sodium hydroxide solution, wherein the mass ratio of the sludge to the sodium hydroxide solution is 1:5, stirring for 3h, standing for 12h, taking supernatant, regulating the pH value of the supernatant to 2.2 by using hydrochloric acid solution, taking lower-layer sediment after standing, washing for 5 times by using distilled water, and drying to obtain humic acid.
Adding deionized water into the lower sediment after the activated sludge is soaked in a 14% sodium hydroxide solution, wherein the ratio of the deionized water to the lower sediment is as follows: the mass ratio of the deionized water is 1:3, and the mixture is placed in a high-pressure reaction kettle for hydrothermal carbonization reaction. Before the temperature of the reaction kettle is increased, nitrogen is introduced into the reaction chamber for 15min through a gas phase pipe, and then the gas valve is screwed down to enable the reaction chamber to be in a closed state. In the hydrothermal carbonization process, the reaction kettle is heated to 240 ℃ by a closed container at 220V, the temperature is kept constant for 4.5h, and the product is centrifugally separated after being cooled to room temperature.
And (3) repeatedly washing the solid part obtained by centrifugal separation with distilled water for 3 times, then drying in an oven at 105 ℃ for 11h, and sieving with a 80-mesh sieve to obtain the biochar prepared from the mudflat culture mud. Evaporating and concentrating the liquid part obtained by centrifugal separation in a rotary evaporator at 85 deg.C, taking out when crystal is separated out, and performing solid-liquid separation at 55 deg.C to obtain sodium chloride crystal.
Example 12:
pumping sludge at the bottom of the mudflat culture pond, standing to remove supernatant, filtering a solid part by a 80-mesh sieve, soaking and activating the solid part by 17% of sodium hydroxide solution, wherein the mass ratio of the sludge to the sodium hydroxide solution is 1:6, stirring for 2h, standing for 12h, taking supernatant, regulating the pH value to 2.4 by using hydrochloric acid solution, taking lower-layer sediment after standing, washing for 6 times by using distilled water, and drying to obtain humic acid.
Adding deionized water into the lower sediment after 17% sodium hydroxide solution is used for soaking activated sludge, wherein the ratio of the lower sediment to the activated sludge is as follows: the mass ratio of the deionized water is 1:4, and the mixture is placed in a high-pressure reaction kettle for hydrothermal carbonization reaction. Before the temperature of the reaction kettle is increased, nitrogen is introduced into the reaction chamber for 15min through a gas phase pipe, and then the gas valve is screwed down to enable the reaction chamber to be in a closed state. In the hydrothermal carbonization process, the reaction kettle is heated to 260 ℃ by a closed container at 220V, the temperature is kept constant for 5 hours, and the product is centrifugally separated after being cooled to room temperature.
And (3) repeatedly washing the solid part obtained by centrifugal separation with distilled water for 4 times, then drying in an oven at 105 ℃ for 12h, and sieving with a 80-mesh sieve to obtain the biochar prepared from the mudflat culture mud. Evaporating and concentrating the liquid part obtained by centrifugal separation in a rotary evaporator at the temperature of 90 ℃, taking out the liquid part until crystals are separated out, and performing solid-liquid separation at the temperature of 55 ℃ to obtain sodium chloride crystals.
The data in table 1 below are the results of the humic acid and biochar yield analysis on the above-described seafloor sludge prepared using methods conventional in the art, and are particularly seen in the data in table 1.
TABLE 1
As can be seen from the data in table 1, humic acid and biochar can be produced simultaneously by using the comprehensive utilization method of the seabed sludge. Compared with the prior art, the sodium hydroxide solution provided by the invention has the concentration of 5-20% to obtain high-yield humic acid and biochar, and the utilization degree of the seabed sludge is improved.
The scope of the invention is further verified by the following comparative examples:
comparative example 1:
pumping sludge at the bottom of the mudflat culture pond, standing to remove supernatant, filtering a solid part by a 80-mesh sieve, soaking and activating the solid part by using 3% sodium hydroxide solution, wherein the mass ratio of the sludge to the sodium hydroxide solution is 1:4, stirring for 2h, standing for 12h, taking supernatant, regulating the pH value to 1.8 by using hydrochloric acid solution, taking lower-layer sediment after standing, washing for 3 times by using distilled water, and drying to obtain humic acid.
Adding deionized water into the lower sediment after the activated sludge is soaked in 11% sodium hydroxide solution, wherein the ratio of the deionized water to the lower sediment is as follows: the mass ratio of the deionized water is 1:4, and the mixture is placed in a high-pressure reaction kettle for hydrothermal carbonization reaction. Before the temperature of the reaction kettle is increased, nitrogen is introduced into the reaction chamber for 15min through a gas phase pipe, and then the gas valve is screwed down to enable the reaction chamber to be in a closed state. In the hydrothermal carbonization process, the reaction kettle is heated to 200 ℃ by a voltage of 220V, the temperature is kept constant for 4h by a closed container, and the product is centrifugally separated after being cooled to room temperature.
Comparative example 2:
collecting seabed sludge collected by a dredger, standing to remove supernatant, filtering a solid part by a 80-mesh sieve, soaking and activating the solid part by 25% sodium hydroxide solution, stirring for 3h, standing for 12h, taking supernatant, regulating the pH value of the supernatant to 2.6 by hydrochloric acid solution, standing, taking lower-layer sediment, washing 3 times by distilled water, and drying to obtain humic acid.
Adding deionized water into the lower sediment after the activated sludge is soaked in a 14% sodium hydroxide solution, wherein the ratio of the deionized water to the lower sediment is as follows: the mass ratio of the deionized water is 1:3, and the mixture is placed in a high-pressure reaction kettle for hydrothermal carbonization reaction. Before the temperature of the reaction kettle is increased, nitrogen is introduced into the reaction chamber for 15min through a gas phase pipe, and then the gas valve is screwed down to enable the reaction chamber to be in a closed state. In the hydrothermal carbonization process, the reaction kettle is heated to 220 ℃ by a voltage of 220V, the temperature is kept constant for 5 hours by a closed container, and the product is centrifugally separated after being cooled to room temperature.
Comparative example 3:
collecting seabed sludge collected by a dredger, standing to remove supernatant, filtering a solid part by a 80-mesh sieve, soaking and activating the solid part by 30% sodium hydroxide solution, stirring for 3h, standing for 12h, taking supernatant, regulating the pH value of the supernatant to 1.8 by hydrochloric acid solution, standing, taking lower-layer sediment, washing for 4 times by distilled water, and drying to obtain humic acid.
Adding deionized water into the lower sediment after 17% sodium hydroxide solution is used for soaking activated sludge, wherein the ratio of the lower sediment to the activated sludge is as follows: the mass ratio of the deionized water is 1:5, and the mixture is placed in a high-pressure reaction kettle for hydrothermal carbonization reaction. Before the temperature of the reaction kettle is increased, nitrogen is introduced into the reaction chamber for 15min through a gas phase pipe, and then the gas valve is screwed down to enable the reaction chamber to be in a closed state. In the hydrothermal carbonization process, the reaction kettle is heated to 240 ℃ by a closed container at 220V, the temperature is kept constant for 4.5h, and the product is centrifugally separated after being cooled to room temperature.
Comparative example 4:
pumping sludge at the bottom of the mudflat culture pond, standing to remove supernatant, filtering a solid part by a 80-mesh sieve, soaking and activating the solid part by using 3% sodium hydroxide solution, wherein the mass ratio of the sludge to the sodium hydroxide solution is 1:4, stirring for 2h, standing for 12h, taking supernatant, regulating the pH value to 2.6 by using hydrochloric acid solution, taking lower-layer sediment after standing, washing for 4 times by using distilled water, and drying to obtain humic acid.
Adding deionized water into the lower sediment after soaking activated sludge in 5% sodium hydroxide solution, wherein the ratio of the lower sediment to the activated sludge is as follows: the mass ratio of the deionized water is 1:6, and the mixture is placed in a high-pressure reaction kettle for hydrothermal carbonization reaction. Before the temperature of the reaction kettle is increased, nitrogen is introduced into the reaction chamber for 15min through a gas phase pipe, and then the gas valve is screwed down to enable the reaction chamber to be in a closed state. In the hydrothermal carbonization process, the reaction kettle is heated to 260 ℃ by a closed container at 220V, the temperature is kept constant for 4 hours, and the product is centrifugally separated after being cooled to room temperature.
Comparative example 5:
pumping sludge at the bottom of a seawater farm, standing to remove supernatant, filtering a solid part by using a 80-mesh sieve, soaking and activating the solid part by using 25% sodium hydroxide solution, wherein the mass ratio of the sludge to the sodium hydroxide solution is 1:5, stirring for 2 hours, standing for 12 hours, taking supernatant, regulating the pH value of the supernatant to 1.8 by using hydrochloric acid solution, taking lower-layer sediment after standing, washing for 5 times by using distilled water, and drying to obtain humic acid.
Adding deionized water into the lower sediment after the activated sludge is soaked in 20% sodium hydroxide solution, wherein the ratio of the deionized water to the lower sediment is as follows: the mass ratio of the deionized water is 1:4, and the mixture is placed in a high-pressure reaction kettle for hydrothermal carbonization reaction. Before the temperature of the reaction kettle is increased, nitrogen is introduced into the reaction chamber for 15min through a gas phase pipe, and then the gas valve is screwed down to enable the reaction chamber to be in a closed state. In the hydrothermal carbonization process, the reaction kettle is heated to 280 ℃ by a closed container at 220V, the temperature is kept constant for 5 hours, and the product is centrifugally separated after being cooled to room temperature.
Comparative example 6:
pumping sludge at the bottom of a seawater farm, standing to remove supernatant, filtering a solid part by using a 80-mesh sieve, soaking and activating the solid part by using a 4% sodium hydroxide solution, wherein the mass ratio of the sludge to the sodium hydroxide solution is 1:6, stirring for 2h, standing for 12h, taking supernatant, regulating the pH value of the supernatant to 2.6 by using a hydrochloric acid solution, taking lower-layer sediment after standing, washing for 5 times by using distilled water, and drying to obtain humic acid.
Adding deionized water into the lower sediment after the activated sludge is soaked in 8% sodium hydroxide solution, wherein the ratio of the lower sediment to the activated sludge is as follows: the mass ratio of the deionized water is 1:5, and the mixture is placed in a high-pressure reaction kettle for hydrothermal carbonization reaction. Before the temperature of the reaction kettle is increased, nitrogen is introduced into the reaction chamber for 15min through a gas phase pipe, and then the gas valve is screwed down to enable the reaction chamber to be in a closed state. In the hydrothermal carbonization process, the reaction kettle is heated to 200 ℃ by 220V voltage, the temperature is kept constant for 4.5h by a closed container, and the product is centrifugally separated after being cooled to room temperature.
The data in table 2 below are the results of the humic acid and biochar yield analysis of the seafloor sludge preparation in the comparative examples, and in particular the data in table 2.
Table 2:
as can be seen from the data in tables 1 and 2, the present invention provides a method for simultaneously producing humic acid and biochar from seabed sludge, and the yield of humic acid and biochar is high only within the technical scope of the present invention.
The raw materials are easy to obtain, and the seabed sludge is utilized to prepare humic acid, biochar and byproduct sodium chloride and recycle sodium phosphate, so that the method has good economic benefit and environmental benefit, and realizes the full utilization of the seabed sludge as resources; the method can realize zero emission of the environment in the process of changing waste into valuable.
The foregoing illustrates and describes the principles, general features, and advantages of the present invention. It should be understood by those skilled in the art that the above embodiments do not limit the present invention in any way, and all technical solutions obtained by using equivalent alternatives or equivalent variations fall within the scope of the present invention.
Claims (7)
1. A method for comprehensively utilizing seabed sludge is characterized by comprising the following steps:
after pretreatment of the seabed sludge raw material, soaking and activating the pretreated seabed sludge raw material by using a sodium hydroxide solution, wherein the concentration range of the sodium hydroxide solution is 5-20%, and the mass ratio of the seabed sludge to the sodium hydroxide solution is 1: 4-6;
adjusting the pH value of the activated supernatant to 2-2.4, standing, taking out the sediment, washing and drying to obtain humic acid;
adding water into the activated lower sediment, performing pyrolysis, cooling the product to room temperature, and performing centrifugal separation to obtain a liquid part and a solid part;
washing, drying and sieving the solid part obtained by centrifugal separation to obtain the biochar prepared from the seabed sludge;
and (4) sending the liquid part obtained by centrifugal separation into an evaporative crystallizer, and carrying out evaporative crystallization to obtain sodium chloride.
2. The method for comprehensively utilizing the seabed sludge as claimed in claim 1, wherein the pretreatment comprises: removing impurities, and sieving with 60-80 mesh sieve.
3. The method for comprehensively utilizing the seabed sludge as claimed in claim 1, wherein the seabed sludge comprises: ocean bottom mud, seawater farm sludge, mudflat culture sludge and sludge for dredging and throwing the sea.
4. The method for comprehensively utilizing seabed sludge as claimed in claim 1, wherein the humic acid is obtained by taking the activated supernatant, adjusting the pH value to 2-2.4 with hydrochloric acid solution, standing, taking sediment, washing with distilled water repeatedly for 3-6 times, and drying at 60-80 ℃ for 6-9 h.
5. The method for comprehensively utilizing the seabed sludge as claimed in claim 1, wherein the activated lower sediment is taken and added with distilled water, and the lower sediment: the mass ratio of the distilled water is 1: 3-6; putting the mixture into a carbonization furnace, introducing nitrogen for protection, then performing pyrolysis, keeping the temperature for 4-5h after the temperature of the carbonization furnace is raised at the rate of 3-10 ℃/min and the hydrothermal carbonization temperature of 200-280 ℃, and cooling the product to room temperature, and then performing centrifugal separation to obtain a liquid part and a solid part.
6. The method as claimed in claim 1, wherein the solid part obtained by centrifugal separation is washed for 3-6 times, dried at 100-120 ℃ for 8-12h, and sieved with 80-100 mesh sieve to obtain the biochar prepared from the seabed sludge.
7. The method for comprehensively utilizing the seabed sludge as claimed in claim 1, wherein the liquid part obtained by centrifugal separation is sent to an evaporative crystallizer, the evaporative concentration temperature is 80-100 ℃, the liquid part is taken out when the liquid part is concentrated until crystallization is separated out, and solid-liquid separation is carried out at 40-60 ℃ to obtain sodium chloride crystals; the secondary mother liquor returns to the evaporation equipment again.
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