Method for preparing plant nutrition excitant from excess sludge waste by using hydrogen peroxide and alkali

Abstract

The invention belongs to the technical field of waste resource recycling and reusing, and particularly relates to a method for preparing a plant nutrition excitant from excess sludge waste by using hydrogen peroxide in combination with alkali. The method comprises the following steps: mixing a hydrogen peroxide solution with a certain concentration with residual sludge in proportion; performing constant-temperature culture on the mixture for a certain time at a certain temperature, performing centrifugal filtration, and taking supernate for later use; fully mixing the supernate with alkali according to a certain proportion, stirring at a certain speed under a normal temperature condition, reacting for a certain time, centrifugally filtering, and taking the supernate to obtain the plant nutrition excitant. The excess sludge is treated by hydrogen peroxide in combination with alkali, release of nutrient elements and organic matters is promoted, nutrition is provided for plant growth, and seed germination and plant growth and development are stimulated.

Description

Technical Field

[0001] The invention belongs to the technical field of waste resource recycling and reuse, and specifically relates to a method for preparing plant nutrient stimulants from residual sludge waste by utilizing hydrogen peroxide and alkali. Technical Background

[0002] At present, most of my country's urban sewage treatment plants use biological methods for sewage treatment. Residual sludge is the most common organic waste in the sewage treatment process of this method. As of 2022, my country's annual sludge production is 47.579 million tons. Sludge has the characteristics of high water content, easy corruption, and complex composition. The traditional sludge disposal method is to dehydrate and then landfill or incinerate. Although it can effectively solve the sludge disposal problem, it has problems such as wasting land resources, high energy consumption, and air pollution.

[0003] Residual sludge not only contains a lot of organic matter, such as protein, cellulose, volatile fatty acids, carbohydrates, humic acid, etc., but also contains phosphorus, nitrogen, potassium and other nutrients suitable for plant growth and iron, zinc, magnesium and other trace elements, and has great potential for resource utilization. After the sludge is treated, it can be used as fertilizer, which can not only efficiently utilize the nutrients in the sludge and realize the resource utilization of waste, but also greatly reduce the cost of raw materials in the fertilizer production process and improve economic benefits. Therefore, the fertilizer utilization of sludge has gradually become a hot topic of people in recent years.

[0004] The main method of sludge fertilizer is composting, including aerobic composting and anaerobic composting. In the composting process, high temperature and the physiological and biochemical activities of microorganisms are used to eliminate pathogenic fecal coliform bacteria and passivate heavy metals. Regardless of the composting method, it takes a long time and a long cycle to solve the fecal coliform bacteria and heavy metal problems that limit the fertilizer of sludge.

[0005] As an oxidant with strong oxidizing properties, hydrogen peroxide can quickly and effectively kill viruses and microorganisms in sludge. It can destroy the extracellular polymers (EPS) and cell walls of microorganisms in large quantities in sludge, releasing a large number of nutrients such as N, P, K, as well as organic components such as amino acids, proteins, peptides, and humus. The decomposition products of hydrogen peroxide are water and oxygen, which is not easy to cause secondary pollution.

[0006] At present, the main methods for removing heavy metals include flocculation / coagulation, chemical precipitation, oxidation-reduction, electrodeposition, biosorption, microbial reduction, membrane filtration and other treatment technologies. Among these methods, chemical precipitation, which uses alkali to precipitate heavy metals in the form of insoluble hydroxides to remove them from water bodies, is the most widely used in industry. It has simple process control, rapid reaction, wide application range and low cost, and is considered to be one of the most economical and feasible methods for removing heavy metals. Using hydrogen peroxide combined with alkali to treat residual sludge, produce sludge nutrient stimulants, and promote the fertilizer and resource utilization of residual sludge is a residual sludge resource utilization method with great future application prospects. Summary of the invention

[0007] In view of the above problems, the present invention provides a method for effectively, quickly and safely extracting nutrients required for plant growth from sludge.

[0008] The technical solution adopted by the present invention is: a method for preparing plant nutrient stimulants from residual sludge waste by using hydrogen peroxide and alkali, comprising the following steps:

[0009] Step 1: Mix a certain concentration of hydrogen peroxide solution with the remaining sludge in proportion.

[0010] Step 2: Incubate the mixture in step 1 at a certain temperature for a certain period of time, centrifuge and filter, and take the supernatant for later use.

[0011] Step 3: The supernatant obtained in step 2 is fully mixed with alkali in a certain proportion, stirred at a certain speed under normal temperature, reacted for a certain period of time, centrifuged and filtered, and the supernatant is taken to obtain the sludge-based nutrient stimulant.

[0012] Furthermore, a method for preparing plant nutrient stimulants from excess sludge waste using hydrogen peroxide in combination with alkali, wherein the concentration of the hydrogen peroxide solution used in step 1 is 30%.

[0013] Furthermore, a method for preparing plant nutrient stimulants from excess sludge waste using hydrogen peroxide combined with alkali, wherein the volume ratio of hydrogen peroxide solution to excess sludge in step 1 is 1-10:30.

[0014] Furthermore, in a method for preparing plant nutrient stimulants from excess sludge waste using hydrogen peroxide in combination with alkali, the reaction temperature in step 2 is 20-40°C.

[0015] Furthermore, in a method for preparing plant nutrient stimulants from excess sludge waste using hydrogen peroxide in combination with alkali, the constant temperature culture reaction time in step 2 is 100-500 minutes.

[0016] Furthermore, in a method for preparing plant nutrient stimulants from residual sludge waste using hydrogen peroxide and alkali, the rotation speed used during centrifugation in step 2 is 5000-10000r / min.

[0017] Furthermore, a method for preparing plant nutrient stimulants from excess sludge waste using hydrogen peroxide combined with alkali, wherein the alkali in step 3 is a strong alkali such as sodium hydroxide, calcium hydroxide or potassium hydroxide.

[0018] Furthermore, in a method for preparing plant nutrient stimulants from residual sludge waste using hydrogen peroxide combined with alkali, the dosage of the alkali in step 3 is 50-500 mg / L.

[0019] Furthermore, in a method for preparing plant nutrient stimulants from excess sludge waste using hydrogen peroxide in combination with alkali, the stirring speed in step 3 is 100-200 r / min.

[0020] Furthermore, in a method for preparing plant nutrient stimulants from excess sludge waste using hydrogen peroxide in combination with alkali, the stirring time in step 3 is 30-100 minutes.

[0021] Furthermore, in a method for preparing plant nutrient stimulants from residual sludge waste using hydrogen peroxide and alkali, the rotation speed used during centrifugation in step 3 is 5000-10000r / min.

[0022] The sludge-based nutrient stimulant obtained by the present invention is used after being diluted 10-100 times.

[0023] The sludge-based nutrient stimulant obtained by the present invention can be used in different growth stages of plants, such as the seed germination stage, the emergence stage, the growth stage, the heading stage, the fruiting stage, etc.

[0024] The beneficial effects of the present invention are:

[0025] 1. The present invention utilizes hydrogen peroxide in combination with alkali to treat residual sludge, promotes the release of nutrients and organic matter, provides nutrition for plant growth, and stimulates plant growth and development.

[0026] 2. The present invention solves the problem of pathogenic bacteria and heavy metals that limit the fertilizerization of sludge.

[0027] 3. The present invention realizes the resource utilization of surplus sludge.

[0028] 4. The present invention solves the problem of long time consumption in the process of fertilizerization of residual sludge

[0029] 5. The present invention reduces the environmental problems caused by improper disposal of excess sludge. DETAILED DESCRIPTION

[0030] The following examples may provide a more comprehensive understanding of the present invention to those skilled in the art, but are not intended to limit the present invention in any way.

[0031] Example 1

[0032] The effects of hydrogen peroxide solution on the release of nitrogen nutrients in sludge and the removal of heavy metals by sodium hydroxide are as follows:

[0033] 1) The sludge used was taken from the sludge concentration tank of a domestic sewage treatment plant in Shenyang.

[0034] 2) Add 30% hydrogen peroxide solution and sludge at a volume ratio of 4:30, 5:30, and 6:30, and set up sludge without hydrogen peroxide solution as the control group of this experiment, and use distilled water to make up the volume; put the reaction container into a constant temperature water bath oscillator, and react for 240 minutes at 30°C and 100rpm. After the reaction is completed, pour the sludge into a centrifuge tube, centrifuge it at a speed of 5000r / min for 10 minutes, and then take the supernatant.

[0035] 3) Sodium hydroxide was added to the sludge supernatant obtained in the previous step. The dosage of sodium hydroxide was 50, 100, 300, and 500 mg / L. At the same time, the sludge supernatant without sodium hydroxide was set as the control group of this experiment. The reaction was stirred at a speed of 100 r / min for 60 min using a mechanical stirring device. After the reaction was completed, the liquid was poured into a centrifuge tube and centrifuged at a speed of 5000 r / min for 10 min to obtain the supernatant.

[0036] 4) The ammonia nitrogen content in the supernatant was measured by Nessler's reagent spectrophotometry to characterize the release effect of sludge nitrogen nutrients. The results showed that the ammonia nitrogen content in the supernatant of the control group without the addition of hydrogen peroxide solution was 65.55 mg / L, and the ammonia nitrogen content in the supernatant with a volume ratio of 30% hydrogen peroxide solution to sludge of 4:30, 5:30, and 6:30 was 122.38, 157.49, and 156.45 mg / L, respectively, which was 86.70%, 140.26%, and 138.67% higher than that of the control group. Ammonia nitrogen can provide the necessary nitrogen elements for plant growth and provide the necessary nutritional support for the synthesis of proteins, nucleic acids, etc. in plants. The content of metal Pb in the supernatant was measured by atomic absorption spectrophotometry to characterize the removal effect of heavy metals. The results showed that the Pb content in the control group without sodium hydroxide was 0.250 mg / L, and the Pb content in the sludge supernatant with 50, 100, 300, and 500 mg / L sodium hydroxide was 0.194, 0.144, 0.105, and 0.079 mg / L, respectively, which was 22.4%, 42.4%, 58%, and 68.4% lower than that in the control group without sodium hydroxide. When lead enters the human body, it will damage the nervous system, digestive system, liver, kidneys, etc., causing problems such as hypertension and cardiovascular disease. The results showed that the use of hydrogen peroxide combined with sodium hydroxide to treat sludge can significantly increase the content of plant nutrient element nitrogen in the sludge supernatant and reduce the content of heavy metals that threaten plant growth. The sludge-based nutrient stimulus obtained by using hydrogen peroxide combined with sodium hydroxide to treat sludge has a high fertilizer value.

[0037] Example 2

[0038] The effects of different sludge nutrient stimulant dosages on seed germination rate are as follows:

[0039] 1) The sludge used was taken from the sludge concentration tank of a domestic sewage treatment plant in Shenyang.

[0040] 2) Add 30% hydrogen peroxide solution and sludge at a volume ratio of 5:30, place the reaction container in a constant temperature water bath oscillator, and react for 300 minutes at 25°C and 100 rpm. After the reaction is completed, pour the sludge into a centrifuge tube and centrifuge it at a speed of 5500r / min for 10 minutes to obtain the supernatant.

[0041] 3) Sodium hydroxide was added to the sludge supernatant obtained in the previous step, and the amount of sodium hydroxide added was 500 mg / L. The reaction was stirred at a speed of 120 r / min for 80 min using a mechanical stirring device. After the reaction was completed, the liquid was poured into a centrifuge tube and centrifuged at a speed of 5500 r / min for 10 min to obtain the supernatant.

[0042] 4) Place two pieces of filter paper in a petri dish to store water, and place a certain number of Chinese cabbage seeds evenly on the filter paper.

[0043] 5) Dilute the sludge nutrient stimulant obtained in step 3 by 20 and 10 times respectively and spray it on the culture dish until the filter paper is soaked, cover the culture dish with plastic wrap to keep it moist, pierce holes after covering to keep air circulation, and then place the culture dish in an incubator and calculate the seed germination rate after culturing at 25°C for 3 days.

[0044] 6) As a control group, distilled water was sprayed on the culture dish until the filter paper was soaked, and the culture dish was covered with plastic wrap to keep it moist. After covering, holes were pierced to maintain air circulation. The culture dish was then placed in an incubator and cultured at 25°C for 3 days before calculating the seed germination rate.

[0045] 7) The seed germination rate of the control group with distilled water was 89.3% after three days, and the seed germination rates of the 20- and 10-fold diluted sludge nutrient stimulants were 92% and 94.6%, respectively, which were 3% and 5.9% higher than the control group. The results showed that the sludge-based nutrient stimulant obtained by treating sludge with hydrogen peroxide and sodium hydroxide can significantly increase the seed germination rate. The sludge-based nutrient stimulant obtained by treating sludge with hydrogen peroxide and sodium hydroxide has a high fertilizer value.

[0046] Example 3

[0047] The effects of different sludge nutrient stimulant dosages on plant growth during the seedling stage are as follows:

[0048] 1) The sludge used was taken from the sludge concentration tank of a domestic sewage treatment plant in Shenyang.

[0049] 2) Add 30% hydrogen peroxide solution and sludge at a volume ratio of 5:30, place the reaction container in a constant temperature water bath oscillator, and react for 360 minutes at 35°C and 100 rpm. After the reaction is completed, pour the sludge into a centrifuge tube, centrifuge at 6000 r / min for 10 minutes, and then take the supernatant.

[0050] 3) Sodium hydroxide was added to the sludge supernatant obtained in the previous step, and the amount of sodium hydroxide added was 500 mg / L. The reaction was stirred at a speed of 140 r / min for 100 min using a mechanical stirring device. After the reaction was completed, the liquid was poured into a centrifuge tube and centrifuged at a speed of 6000 r / min for 10 min to obtain the supernatant.

[0051] 4) Plant the pakchoi seeds in a pot for cultivation. After the seedlings emerge, dilute the sludge nutrient stimulus obtained in step 3 by 20 and 10 times respectively and spray the plants until the soil is soaked. At the same time, set the plants only treated with distilled water as a control group, and measure the growth of the plants after 10 days.

[0052] 5) The plant height of the control group treated with distilled water was 3 cm after 10 days, while the plant height of the pakchoi treated with 20- and 10-fold diluted sludge nutrient stimulants was 3.3 and 3.8 cm, respectively, an increase of 10% and 26%, respectively. The results show that the sludge-based nutrient stimulant obtained by treating sludge with hydrogen peroxide and sodium hydroxide can significantly promote plant growth. The sludge-based nutrient stimulant obtained by treating sludge with hydrogen peroxide and sodium hydroxide has a high fertilizer value.

Claims

1. A method for preparing plant nutrient stimulants from excess sludge waste using hydrogen peroxide combined with alkali, characterized in that: Here is how: Step 1: Mix a certain concentration of hydrogen peroxide solution with the remaining sludge in proportion; Step 2: The mixture of step 1 is cultured at a certain temperature for a certain period of time, and then centrifuged and filtered to take the supernatant for later use; Step 3: The supernatant obtained in step 2 is fully mixed with alkali in a certain proportion, stirred at a certain speed under normal temperature, reacted for a certain period of time, centrifuged and filtered, and the supernatant is taken.

2. The method for preparing plant nutrient stimulants from excess sludge waste using hydrogen peroxide and alkali according to claim 1, characterized in that: In step 1, the concentration of the hydrogen peroxide solution used is 30%.

3. The method for preparing plant nutrient stimulants from excess sludge waste using hydrogen peroxide and alkali according to claim 1, characterized in that: In step 1, the volume ratio of hydrogen peroxide solution to residual sludge is 1-10:

30.

4. The method for preparing plant nutrient stimulants from excess sludge waste using hydrogen peroxide and alkali according to claim 1, characterized in that: In step 2, the reaction temperature is 20-40°C.

5. The method for preparing plant nutrient stimulants from excess sludge waste using hydrogen peroxide and alkali according to claim 1, characterized in that: In step 2, the constant temperature culture reaction time is 100-500 minutes.

6. The method for preparing plant nutrient stimulants from excess sludge waste using hydrogen peroxide and alkali according to claim 1, characterized in that: In step 2, the rotation speed used during centrifugation is 5000-10000 r / min.

7. The method for preparing plant nutrient stimulants from excess sludge waste using hydrogen peroxide and alkali according to claim 1, characterized in that: In step 3, the base is sodium hydroxide, calcium hydroxide or potassium hydroxide.

8. The method for preparing plant nutrient stimulants from excess sludge waste using hydrogen peroxide and alkali according to claim 1, characterized in that: In step 3, the dosage of the alkali is 50-500 mg / L.

9. The method for preparing plant nutrient stimulants from excess sludge waste using hydrogen peroxide and alkali according to claim 1, characterized in that: In step 3, the stirring speed is 100-200 r / min, and the stirring time is 30-100 min.

10. The method for preparing plant nutrient stimulants from excess sludge waste using hydrogen peroxide and alkali according to claim 1, characterized in that: In step 3, the rotation speed used during centrifugation is 5000-10000 r / min.