CN106966766B

CN106966766B - Method for preparing fertilizer by treating bean dreg black mud through hydrothermal carbonization

Info

Publication number: CN106966766B
Application number: CN201710216125.1A
Authority: CN
Inventors: 张镭; 高玉军; 王建宏; 周业剑; 唐军义; 施耐德克劳迪娅; 马克布特曼
Original assignee: Beijing Shunhong Jinjian Environment Technology Development Co ltd
Current assignee: Beijing Shunhong Jinjian Environment Technology Development Co ltd
Priority date: 2017-04-05
Filing date: 2017-04-05
Publication date: 2021-03-26
Anticipated expiration: 2037-04-05
Also published as: CN106966766A

Abstract

The invention provides a method for preparing a fertilizer by carrying out hydrothermal carbonization treatment on bean dreg black mud, which is characterized in that two acid catalysts are added in two steps, namely, acetic acid is added before the bean dreg black mud enters a reactor, and concentrated sulfuric acid is added into the reactor in the midway of the reaction.

Description

Method for preparing fertilizer by treating bean dreg black mud through hydrothermal carbonization

Technical Field

The invention relates to the field of soybean protein production and pollutant treatment, and provides a method for preparing a fertilizer by treating bean dreg black mud through hydrothermal carbonization.

Background

The soybean protein is generally protein derived from soybean, has amino acid composition similar to that of milk, does not contain cholesterol, contains peculiar active ingredients such as isoflavone and the like, and has high nutritional value. Because the soybean protein has the advantages, the preparation raw materials are low in cost and easy to obtain, the preparation technology is relatively simple, the development of the domestic soybean protein preparation industry is rapid, and the number of domestic large soybean protein production enterprises is nearly hundreds and medium-sized enterprises is more by 2015.

The basic process of the soybean protein production of domestic enterprises at present is as follows: low temperature leaching-alkali dissolution-acid precipitation-centrifugation-spray drying or enzyme treatment, wherein a large amount of bean dregs (about 5 tons of bean dregs per ton of protein) are generated after alkali dissolution, and a large amount of waste water (about 20 tons of waste water with high COD and BOD per ton of protein) is generated after acid precipitation and centrifugation. If not properly disposed of, it can cause serious pollution problems, and if not fully utilized, it can be a significant waste of resources.

At present, the main direction of the bean dregs is to feed factories, and the wastewater is mainly treated by sewage factories. Because the bean dregs have high water content and are extremely easy to decay, and the bean dregs can be directly used as feed or are inconvenient to process, the bean dregs can be directly used as fertilizer or even discarded in many times. Sludge generated by the precipitation of the wastewater for producing the soybean protein, namely the bean dreg black mud, has the problems of large occupied area, pollution and the like no matter in composting and landfill. The ideal state of reduction, harmlessness, stabilization and recycling of the comprehensive treatment and utilization distance of the waste produced in the production process of the soybean protein has a great difference.

Disclosure of Invention

The applicant further optimizes the hydrothermal carbonization treatment process and tries to expand the application range thereof on the basis of introducing German Buttmann hydrothermal carbonization treatment technology to construct equipment and actually operating and treating sludge (Beijing, Yanzhou, Jining and the like) of urban domestic sewage plants. In experiments, the applicant finds that the hydrothermal carbonization technology can be completely used for treating the bean dregs and the bean dregs black mud, can effectively reduce the water content of the bean dregs and the bean dregs black mud, and can improve the nutrient element composition of the bean dregs and the black mud. The existing hydrothermal carbonization catalyst type and adding mode (adding concentrated sulfuric acid once before entering a reactor) are changed into two times of stepwise addition (adding acetic acid before entering the reactor, and adding concentrated sulfuric acid into the reactor midway during the reaction), so that the water content of the product can be better improved, the better reduction/preservation effect can be realized, and the protein/effective nitrogen and phosphorus content can be improved.

The 'bean dreg black mud' in the invention refers to sludge generated by precipitation of wastewater generated in the production process of soybean protein.

On the one hand, the method for preparing the fertilizer by treating the bean dreg black mud through hydrothermal carbonization comprises the following steps:

a. collecting bean dreg black mud;

b. sending the bean dreg black mud to a reactor, and adding acetic acid during the process;

c. carrying out hydrothermal carbonization reaction in a reactor, and adding concentrated sulfuric acid during the hydrothermal carbonization reaction;

d. collecting the produced biological carbon slurry;

e. and (4) pressing and dehydrating, crushing and bagging to obtain a fertilizer finished product.

In a further aspect, the concentrated sulfuric acid used in the method is 98% concentrated sulfuric acid and the acetic acid is glacial acetic acid.

In a further aspect, the process uses concentrated sulfuric acid in an amount of 0.5-1% (v/v) and acetic acid in an amount of 1-2% (v/v).

In a further aspect, the process uses concentrated sulfuric acid in an amount of 0.5% (v/v) and acetic acid in an amount of 1.5% (v/v).

In a further aspect, the hydrothermal carbonization temperature is 150-.

In a further aspect, the hydrothermal carbonization temperature is 150 ℃, the pressure is 20bar, and the time is 120 minutes.

In a further aspect, the hydrothermal carbonization is carried out by adding concentrated sulfuric acid until one-fourth of the expected reaction time.

And in the step d, the generated biological carbon slurry is collected through a pressure relief system under the condition of ensuring the operation pressure of the system, the heat of the biological carbon slurry is received through a heat exchange system in the period, the obtained heat is used for preheating the black mud in the step b through a front heat exchange system, and the carbon slurry is depressurized through a pressure relief system and then is delivered to a buffer storage tank under residual pressure.

In a further aspect, the pressure in the reactor is provided by a sludge pump.

Drawings

FIG. 1 is a complete process flow diagram of a sludge hot water carbonization treatment technology. In the figure: 1. feed hopper, 2, the mud force (forcing) pump, 3, preceding heat exchanger system, 4, heat recovery, 5, 1# catalyst throw with some, 6, the reactor, 7, back heat exchanger system, 8, the pressure relief system, 9, the carbon thick liquid storehouse, 10, sheet frame dewatering device, 11, waste water treatment (option), 12, 1# catalyst throw with the pump, 13, 2# catalyst throw with the pump, 14, the biological charcoal heat conduction oil furnace, 15, the filtrating storage tank, 16, the mud feed bin, A, the bean dregs black mud of moisture content 85%, B, precipitate repayment (optional), C, the water return mill water inlet after handling, D, the biological charcoal cake.

FIG. 2 is an external view of an apparatus (3000 ton year capacity) used by the applicant for actually treating okara.

Detailed Description

Example 1 treatment of Black mud from okara

The bean dreg black mud sample source is as follows: the black mud obtained by precipitating the wastewater produced by Shandong Xingshi Soy biology Limited company has the water content of about 85 percent.

The treatment process of the invention comprises the following steps:

a. collecting bean dreg black mud by using a closed spiral;

b. sending the bean dreg black mud to a reactor, adding 1.5% (v/v) of glacial acetic acid in the reactor, and preheating the black mud by using a previous heat exchange system;

c. carrying out hydrothermal carbonization reaction in a reactor, wherein the hydrothermal carbonization temperature is 150 ℃, the pressure is 20bar, the time is 120 minutes, 0.5% (v/v) of 98% concentrated sulfuric acid is added when the reaction is carried out for about 30 minutes, and the pressure in the reactor is provided by a sludge pump;

d. collecting the generated biological carbon slurry by a pressure relief system under the condition of ensuring the operating pressure of the system, and cooling and recovering heat by a post heat exchange system in the period;

e. pressing and dehydrating to obtain the charcoal cake.

Control treatment procedure 1:

the basic treatment process is the same as the treatment process of the invention, wherein no acid catalyst is added, and the hydrothermal carbonization temperature is adjusted to 200 ℃, the pressure is adjusted to 30bar, and the time is adjusted to 150 minutes.

Control treatment procedure 2:

the basic process is the same as the process of the present invention, wherein only 1.5% of 98% concentrated sulfuric acid is added as a single catalyst in step b.

Control treatment procedure 3:

the basic treatment process is the same as the treatment process of the invention, wherein only 1.5 percent of 98 percent concentrated sulfuric acid is added as a single catalyst in the step b, and the hydrothermal carbonization temperature is adjusted to 200 ℃, the pressure is adjusted to 30bar, and the time is adjusted to 150 minutes.

Control treatment Process 4

The basic process is the same as the process of the invention, wherein, in step b, 98% concentrated sulfuric acid is added for 1%, and in step c, when the reaction is carried out for 30 minutes, 80% concentrated nitric acid is added as a catalyst,

the above treatment was carried out using the same equipment and the same black mud loading (1.5 tons).

Example 2 comparison of the effects of the treatment methods in example 1

Measuring the water content, effective nitrogen content (alkali diffusion method) and effective phosphorus content (molybdenum-antimony colorimetric method)

The result shows that compared with the existing hydrothermal carbonization method, the method can more effectively reduce the water content of the black mud so as to better realize sludge reduction, and simultaneously prolong the storage time (the data is shown in example 3); shortening the reaction time (better than

controls

1 and 3, which have longer reaction times); the effective nitrogen and phosphorus contents in the product are effectively improved to realize better fertilizer effect (even if the difference of water content is eliminated, the effective nitrogen and phosphorus contents of the product of the method are obviously higher than those of the contrast, which is probably caused by a better wall-breaking decomposition process generated by adding two acids step by step); as can be seen from comparison with control 4, the effect of adopting the weak acid and the strong acid is even better than that of pure strong acid (low water content, high nitrogen content and slightly low phosphorus content) for the bean dreg raw material. The method of the invention has no obvious difference from the prior hydrothermal carbonization treatment technology in the aspects of construction and operation cost (the acid types are increased but the total volume is unchanged).

Example 3 actual fertilizer preparation and use

The moisture content of the charcoal cake obtained by plate pressing dehydration is low, and the charcoal cake is suitable for transportation and storage/composting for a certain time. The original sludge can be fermented to generate extremely unpleasant smell after being stacked in the open air for about 3 days, the operator can not access the original sludge without protection, and the treated carbon cake can not generate obvious odor after being stacked in the open air for 30 days.

In the radish potting experiment, when the charcoal cake prepared by the method in example 1 is applied as an organic fertilizer in an amount of 1.5% of the weight of dry soil, the growth condition (growth speed and size of underground parts) of the radish is obviously better than that of the non-fertilized group.

Claims

1. A method for preparing a fertilizer by treating bean dreg black mud through hydrothermal carbonization comprises the following steps:

a. collecting bean dreg black mud;

d. collecting the produced biological carbon slurry;

e. pressing and dehydrating, crushing and bagging to obtain a fertilizer finished product; wherein the used concentrated sulfuric acid is 98% concentrated sulfuric acid, and the acetic acid is glacial acetic acid; the adding amount of concentrated sulfuric acid is 0.5% v/v, and the adding amount of acetic acid is 1.5% v/v; the hydrothermal carbonization temperature is 150 ℃, the pressure is 20bar, and the time is 120 minutes; concentrated sulfuric acid was added when the hydrothermal carbonization proceeded for one-fourth of the expected reaction time.

2. The method according to claim 1, wherein the generated biochar slurry is collected by a pressure relief system under the condition of ensuring the operating pressure of the system in the step d, heat of the biochar slurry is received by a heat exchange system in the period, the obtained heat is used for preheating the black mud in the step b by a front heat exchange system, and the carbon slurry is depressurized by a pressure relief system and then is delivered to a buffer storage tank under the residual pressure.

3. A process according to claim 1 or 2, wherein the pressure in the reactor is provided by a sludge pump.