Production of magnesium ammonium phosphate fertilizer from municipal sewage sludge by the sonoleaching process

Abstract

Solid waste management is a pressing environmental issue due to rapid urbanization and population growth. Researchers are turning to organic farming as a solution to resource depletion. Disposing of sewage sludge can lead to environmental degradation and the spread of diseases. Developing a cost-effective phosphate fertilizer from sewage sludge would benefit water and sewage companies, as well as farmers and agricultural companies. Producing a low-cost phosphate fertilizer from sewage sludge with sonoleaching method, could address environmental pollution and provide economic benefits.

Description

Production of magnesium ammonium phosphate fertilizer from municipal sewage sludge by the sonoleaching process

[0001] The project aims to produce magnesium ammonium phosphate as a slow-release fertilizer using an ultrasonic method from urban sewage sludge. The process involves gathering, drying, burning, and decomposing the sludge, followed by separating heavy metals and extracting phosphorus to form struvite crystals. This innovative approach addresses the environmental issues caused by sewage sludge accumulation and provides an economical fertilizer source for farmers.

[0002] C05F 7 / 00

[0003] US5252116 - Organic base fertilizer from municipal sewage sludge

[0004] A process for producing a granular fertilizer product from biological or municipal sewage sludge is described. This process involves (1) gently blending the biological sludge with sufficient lime-containing material (preferably lime kiln dust) to raise the pH of the blended material to at least 11 pH units, and preferably at least 12 pH units, in such a manner as to avoid or prevent the formation of a slurry; (2) then conditioning the blended materials at a temperature of 180. degree. F. and a pH of at least 11, and preferably at least 12, for a time sufficient to effectively kill or otherwise destroy a significant percentage of the pathogens present in the sludge; (3) blending the conditioned sludge with a second lime-containing material (preferably cement kiln dust or fly ash) and a binder (preferably lignosulfonate); (4) then agglomerating the blended materials to form pellets or granules; (5) drying the pellets or granules to a moisture content of less than 15 weight percent; (6) and curing the dried pellets or granules at ambient temperatures for a time sufficient for the pellets or granules to develop sufficient physical strength to be used as a fertilizer. The product of this invention can be used directly as a low-grade fertilizer or, if desired, additional nutrients or other additives can be added to upgrade its fertilizer value.

[0005] The invention above differs from the present invention in its method for producing fertilizer from sewage sludge, as this invention uses the sonoleaching method for this aim.

[0006] US20090314046A1- Production of a high phosphorus fertilizer product

[0007] This invention is related to methods for the production of high-phosphorus fertilizer products from waste products. In particular, the method describes the production of liquid and dry fertilizer products produced from the incineration of wastewater treatment sludges utilizing biological phosphorus removal (Bio-P). The fertilizers produced can be used interchangeably for commercial purposes either directly as a fertilizer product, or mixed with other conventional products to produce custom blended fertilizers for particular purposes.

[0008] The mentioned invention is a method for producing fertilizer from wastewater, while our invention uses the Sonoleaching method for this aim, and the invention above uses the incineration method.

[0009] The invention presents the sonoleaching method for processing sewage sludge and optimizing it in the form of magnesium ammonium phosphate sediment, which could be used as fertilizer.

[0010] Today, managing waste has become one of the biggest environmental crises caused by fast population growth and urbanization. Furthermore, the increasing trend of destruction of water resources, soil, and the environment in the world has encouraged researchers to do organic farming in recent years. Leaving the sewage sludge in the environment ends up in environmental destruction, due to having perishable materials, pathogenic microbes, and ova, as well as spreading infectious diseases. Thus, in case this project succeeds, water and sewage companies will welcome that because it solves the problem of accumulation and burial of sewage sludge, as well as producing an economical chemical fertilizer which could be used by the farmers and farming companies, in a wide range. Considering the high price of the apatite sources and the final price of produced and imported Phosphorus fertilizers, achieving this cheap fertilizer source, helps almost all the farmers and also lessens the environmental pollution, due to the extraction of the phosphor from the sewage sludge, and so it has a significant importance in national level. However, the goal of this invention is to produce magnesium ammonium phosphate with an ultrasonic method from sewage sludge that could be used as a slow-release fertilizer that can be used with high speed for crops, farming products, and ornamental plants, without harming them.Solution of problem

[0011] The urban sewage sludge was first gathered from a city. Then a sample of untreated sewage was first under the temperature of 105 centigrade degrees for about 12 to 24 hours and then it was dried in the oven, crushed, and then passed through the mesh sieve size 10. It was then burnt in an electric oven with a temperature range of 600- 900 centigrade degrees for 2 to 6 hours and dried at room temperature. For the decomposition of the sludge element of the raw sewage and its ash, the amount of 0 / 025 grams of the ash was heated by adding 4 milliliters of NHO3200 microliters of HF, and 4 milliliters of H2O mixed in a reaction media and in 150 centigrade degrees for an hour. The solution is passed through the Watman grade 42 filter paper after being cooled. Then to determine the heavy metals, an ICP device was used, and for measuring the phosphor, the ascorbic acid-molybdenum blue spectrophotometric method was used.

[0012] 1)To prepare acid with a biological source, farming products that are rich in citric acid are used and in this case, Citrus lemon L has been used for leaching. The lime was provided from the gardens in the south of the country, and to remove the seeds and the palps, they were centrifuged at 3000 ppm for 15 minutes and the concentration of the organic acids was measured with a liquid chromatography device(HPLC).

[0013] 2)The Sonoleaching test: The response surface methodology has been used to analyze the effects of the four main elements (10- 70 percent of the volume percent), the wastewater sludge concentration( the solid to liquid portion) (0 / 2 to 4 percent of the volume-weight percentage), ultrasonic power(50- 200 watt) and time (0-120 minutes) was used in optimizing the Sonoleaching process.

[0014] Separating the heavy metals extracting the phosphor and recovering that in the form of struvite:

[0015] To separate the heavy metals from the final product of the Sonoleaching process, different amounts from 0 / 01 to 0 / 2 grams per milliliter of ion-exchange resin, have been added to 25 milliliters of washing solution. Then the solution was stirred with the speed of 200 revolutions per minute for 30 minutes and then the heavy metals concentration before and after the use of ion exchange resin was measured. The efficiency of eliminating the heavy metals and phosphor in the form of extracted metal content is calculated based on the formula below:

[0016] The efficiency of eliminating heavy metals= 1- ( the content of the extracted metal) (the total amount of the metals) × 100

[0017] For sedimentation of the magnesium ammonium phosphate in the form of crystals, magnesium chloride (MgCl2.6H2O, 100%) and ammonium chloride (NH4Cl, 99.8%) as the source of magnesium and ammonium were used. First, magnesium chloride will be added to a 50-milliliter of prepared solution which does not contain heavy metals. Then, by using Sodium hydroxide, the solution’s pH is adjusted, and, ammonium chloride is used for sediment / sedimentation After that, the mixture is immediately stirred with an electric stir for 15 minutes and then it is centrifuged with 3600 revolutions per minute, for 10 minutes. The crystal-form fertilizer with the 1:1:1 ratio of magnesium, ammunoim, and phosphate is resulted in pH=9 / 5. To analyze the formation of the desired fertilizer crystals, the resulting sediments are dried at a temperature of 55 centigrade degrees for 72 hours and then the ICP device is used to determine the heavy metals and to measure the phosphor, the ascorbic acid-molybdenum blue spectrophotometric method was used. Also to analyze the morphology changes method, the sediments resulting from the sonoleaching process were photographed by SEM and EDX.

[0018] Different ratios of the magnesium ammonium phosphate fertilizer (s) with commercial phosphor fertilizer (p) including 100 to zero(S100:p0) were used. 75 to 25(s75:p25 ), 50 to 50(s50:p50), 25 to 75(s25:p75), and 100 to zero (s0:p100) was used. For this aim, a pot study was done randomly with 4 different applications of phosphor levels (zero, 50,100, and 150 kilograms of phosphor per hectare). Planting wheat was repeated 3 times in limestone soil.Advantage effects of the invention

[0019] – magnesium ammonium phosphate is a white crystalline solid, granular, odorless, and sludge-free material

[0020] – it can be used as a slow-release fertilizer with a high consumption speed for Crops, garden, and ornamental plants, without harming the roots of the plants

[0021] – the existence of ammonium and magnesium in this fertilizer has made it a more efficient fertilizer than the commercial samples for the crops, as the ammonium and magnesium participate in synthesizing chlorophyll.

[0022] : illustrates the chart of the process

[0023] : it shows different stages of sewage sludge processingExamples

[0024] [Table. 1]: this table shows the extraction of phosphor from the sewage sludge ash, based on the response surface methodology

[0025] [ Diagram. 1]: This diagram shows the process of sonoleaching and the optimized process of extracting phosphor based on the experiments

[0026]

[0027] [Table. 2]: this table shows the elimination of the existing impurity in the leachate, produced from leaching by Cation Exchange Resins

[0028] [Table. 3]: this table shows the recovering percent of phosphor as magnesium ammonium phosphate based on the response surface methodology

[0029] [diagram. 2]: It shows the optimizing product of magnesium ammonium phosphate

[0030]

[0031] [ picture. 3]: it shows the SEM image of the magnesium ammonium phosphate fertilizer

[0032]

[0033] [picture. 4]: it shows the EDS microanalysis of synthesized magnesium ammonium phosphate

[0034]

[0035] [Table. 4]: commercial phosphate fertilizer (p) including 100 to zero(S100:p0) was used. 75 to 25(s75:p25 ), 50 to 50(s50:p50), 25 to 75(s25:p75), and 100 to zero (s0:p100) was used. For this aim, a pot study was done randomly with 4 different applications of phosphor levels (zero, 50,100, and 150 kilograms of phosphor per hectare)

[0036] magnesium ammonium phosphate fertilizer could be synthesized based on the organizations’ needs and organs like the governor's office, municipality, farming, and environmental organizations, particularly by farmers. Ammonium phosphate could reduce the pollution caused by disposing of sewage sludge in soil and water and decrease the import of phosphorous fertilizers to the least. This fertilizer compound could be used in farming lands, greenhouses, and gardens, to provide a part of the required food ingredients, specifically the required phosphor of the soil and plants, as well as improve the physical, chemical, or biological properties of the soil in form of fertilizer and strip planting.

Claims

A process for extracting phosphor from municipal sewage sludge by sonoleaching and optimizing it in the form of magnesium ammonium phosphate sediment.According to the claim. 1, the extraction of phosphor from sewage sludge was optimized with the sonoleaching process.According to the claim. 2, the synthesized fertilizer increases the absorption of phosphor in wheat.

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