Phosphorus recovery from biocar obtained after gasification

Abstract

The invention relates to phosphorus recovery from biochar obtained after gasification. In the method of the invention, phosphorus recovery is provided from biochar ash obtained from different biomass sources. In said method of phosphorus recovery from biochar, a different leaching method is applied, and low concentrations of mineral acid are used under microwave digestion.

Description

[0001] PHOSPHORUS RECOVERY FROM BIOCAR OBTAINED AFTER GASIFICATION

[0002] Technical Field of the Invention

[0003] The invention relates to phosphorus recovery from biochar obtained after gasification. In the method of the invention, phosphorus recovery is provided from biochar ash obtained from different biomass sources.

[0004] State of the Art

[0005] Phosphorus is obtained from rocks in nature. However, it is predicted that the reserves of phosphate rocks will be depleted within a period of 60-70 years. Due to the limited natural phosphorus resources in the world, research on phosphorus recovery from wastewater, sludge and other waste materials is gaining momentum. It is important that the phosphorus recovery method is simple, functional and suitable in terms of investment cost. There is phosphorus at very significant levels in biochar ash. Biochar ash is an important source compared to sewage sludge in terms of phosphorus and other microelements and can be used as a secondary phosphorus raw material source. Biochar, which is the solid product obtained after the gasification process, can be evaluated both as a product and as a qualified waste. Thus, a high value-added material can be obtained from biochar. The phosphoric acid and nitric acid used in phosphorus recovery ensure that the phosphorus in the products is dissolved and transferred to the liquid phase.

[0006] In the state of the art, heavy metal levels are high in the current methods used to ensure phosphorus recovery. In the state of the art, phosphorus recovery processes such as ashdec method, phoskraft, thermophos, recophos, leachphos, Ecophos, SESAL-Phos or polferash are available. Although there is high phosphorus recovery in these processes, it is known that investment and operating costs are high. The potential to damage the soil, operational difficulties, equipment supply problems, high chemical consumption and high investment costs are also disadvantages of phosphorus recovery methods. Therefore, in the state of the art, the problems of high heavy metal levels, the possibility of damaging the soil, operational difficulties, equipment supply problems, high chemical consumption and high investment costs cannot be prevented in phosphorus recovery methods.

[0007] Due to the limitations and inadequacies of the solutions in the state of the art, the high levels of heavy metals in the methods used in phosphorus recovery, the possibility of damaging the soil, operational difficulties, equipment supply problems, high chemical consumption and high investment costs, it has become necessary to make developments in the relevant field.

[0008] Brief Description and Aims of the Invention

[0009] The invention relates to phosphorus recovery from biochar obtained after gasification. In the method of the invention, phosphorus recovery is provided from biochar ash obtained from different biomass sources. In said method of phosphorus recovery from biochar, a different leaching method is applied, and low concentrations of mineral acid are used under microwave digestion.

[0010] One of the aims of the invention is to provide a method that will reduce the cost of phosphorus recovery. In said phosphorus recovery method, since the biochar obtained after gasification is used, the cost of phosphorus recovery is also reduced by minimising the high chemical consumption.

[0011] Another aim of the invention is to contribute to waste management within the scope of zero waste studies in phosphorus recovery. Since the biochar used in the invention is a solid by-product obtained in gasification processes, waste evaluation is provided.

[0012] Another aim of the invention is to facilitate the development of soil conditioners to be used in infertile and unusable soils for soil reclamation. By means of the phosphorus content of the biochar obtained with said method, it can be used directly as a soil conditioner.

[0013] Another aim of the invention is to contribute to waste use in the fertiliser industry. The green waste, pomace and sewage sludge samples used in said method can be used in the production of phosphorus fertiliser, thus contributing to waste use in the fertiliser industry.

[0014] Another aim of the invention is to enable the production of phosphorus fertiliser in both liquid and solid phases. In said method, the products that are broken down by adding low amounts of phosphoric acid and nitric acid are precipitated with calcium hydroxide (Ca(OH)2) and ammonia (NH3) and thus, the production of phosphorus fertiliser in both liquid and solid phases is made possible. The phosphorus fertilisers produced with the phosphorus obtained in said method contain valuable micronutrients such as iron (Fe), chromium (Cr), molybdenum (Mo), manganese (Mn) or copper (Cu), which are necessary for proper plant growth. Liquid fertiliser can be applied as injection or spraying into the soil, while solid fertiliser can be applied as subsoil layer spreading or above-ground spreading.

[0015] Said method aims to recover phosphorus from biochar obtained from the gasification process and thus provide a method that will reduce the cost in phosphorus recovery, to use biochar as a direct soil conditioner with its phosphorus content, to enable the production of phosphorus fertiliser in both liquid and solid phases, and to contribute to waste utilisation in phosphorus recovery.

[0016] Detailed Description of the Invention

[0017] The invention relates to phosphorus recovery from biochar obtained after gasification. In the method of the invention, phosphorus recovery is provided from biochar ash obtained from different biomass sources. In said method of phosphorus recovery from biochar, a different leaching method is applied, and low concentrations of mineral acid are used under microwave digestion.

[0018] Said method of phosphorus recovery from biochar provides a high phosphorus recovery (PO4-P) compared to the current studies in the state of the art. It is possible to produce dicalcium phosphate (CaHPCU) and diammonium phosphate ((NH^HPC ), which have many areas of use, by providing phosphorus recovery with the method applied within the scope of the invention.

[0019] In said phosphorus recovery from biochar, two different approaches are applied, namely microwave application and mixing with acid, and phosphorus recovery is provided from biochar samples.

[0020] The phosphorus recovered with said method can be used in solid or liquid phase fertiliser production. Method of mixed biochar ash sample with acid for phosphorus recovery from biochar, which is the subject of the invention, comprises the process steps of: i. obtaining 4 different biochars by gasifying the biomass obtained from sewage sludge, olive pomace, green waste and their mixture in the updraft gasification reactor, ii. weighing of biochar samples, iii. adding phosphoric acid (H3PO4) solution and nitric acid (HNO3) solution onto biochar samples, iv. shaking the samples in a mixer in closed and non-interacting containers, v. completing the volume of samples taken into falcon tubes, vi. centrifuging the tubes to settle solid particles, vii. filtering the emerging falcon tubes, viii. precipitating the filtered samples by diluting them with calcium hydroxide (Ca(OH)2) and ammonia (NH3) solutions, ix. adjusting the pH value of the solutions to the range of 7-9, and x. filtering the precipitated part.

[0021] In an embodiment of the invention, method of mixing biochar ash sample with acid for phosphorus recovery from biochar comprises the process steps of: i. obtaining 4 different biochars by gasifying the biomass obtained from sewage sludge, olive pomace, green waste and their mixture in the updraft gasification reactor, ii. weighing of biochar samples as 1 grams, iii. adding 2 mL of 2.7 M phosphoric acid (H3PO4) solution and 3 mL of 2.7M nitric acid (HNO3) solution to the samples to give an acid / mass ratio of 0.60, iv. shaking the samples in a mixer in closed and non-interacting containers at 140 rpm for 2 hours, v. completing the volume of samples taken into falcon tubes to 14 mL, vi. centrifuging the tubes at 9000 rpm for 4 minutes to settle the solid particles, vii. filtering he resulting falcon tubes through Polyvinylidene fluoride (PVDF) 0.45 pm filters, viii. taking 1 mL of the samples and diluting these 10 times and precipitating with calcium hydroxide (Ca(OH)2) and ammonia (NH3) solutions, ix. adjusting the pH value of the solutions to the range of 7-9, and x. passing the precipitated part through 0.20 pm filters.

[0022] In order to both recover phosphorus from biochar ash and increase the fertiliser value of the liquid product to be obtained, the recovery of phosphorus was investigated by using low concentrations of nitric acid at different temperatures and pressures under microwave digestion for different periods without the need for any additional processing, and the temperature, pressure, and time values under the developed digestion conditions were optimised according to the type and concentration of acid applied. In phosphorus recovery, the phosphorus-based mass balance was taken into account, and the amount of phosphorus recovered from biochar ash obtained from different biomass sources and the fertiliser value of the resulting liquid product were determined.

[0023] In the microwave digestion application for phosphorus recovery from biochar, which is the subject of the invention; microwave application is carried out with a mixture of hydrochloric acid (HCI) and nitric acid (HNO3) of the biochar ash sample obtained from the gasification process.

[0024] In addition, wet extraction is carried out with a mixture of phosphoric acid (H3PO4) and nitric acid (HNO3) of the biochar ash sample for phosphorus recovery from the biochar, which is the subject of the invention.

[0025] In one embodiment of the invention, an extraction is carried out in a microwave digester device with a mixture of hydrochloric acid (HCI) and nitric acid (HNO3) from a sample of biochar ash weighed as 1 g.

[0026] In another embodiment of the invention, a wet extraction is carried out with a mixture of phosphoric acid (H3PO4) and nitric acid (HNO3) from 1 g of biochar ash.

[0027] Micronutrient elements and heavy metal analyses were carried out in liquid products. In addition, a precipitation process was applied with calcium hydroxide (Ca(OH)2) and ammonia (NH3) solutions. The precipitated part in the pH range of 7-9 was passed through 0.20 pm filters and phosphorus was determined by the tin chloride method by working at appropriate dilution rates and providing the necessary dilution rates to the prepared samples.

Claims

CLAIMS1. Method for recovering phosphorus from biochar obtained after gasification, comprising the process steps of: i. obtaining 4 different biochars by gasifying the biomass obtained from sewage sludge, olive pomace, green waste and their mixture in the updraft gasification reactor, ii. weighing of biochar samples, iii. adding phosphoric acid (H3PO4) solution and nitric acid (HNO3) solution onto biochar samples, iv. shaking the samples in a mixer in closed and non-interacting containers, v. completing the volume of samples taken into falcon tubes, vi. centrifuging the tubes to settle solid particles, vii. filtering the emerging falcon tubes, viii. precipitating the filtered samples by diluting them with calcium hydroxide (Ca(OH)2) and ammonia (NH3) solutions, ix. adjusting the pH value of the solutions to the range of 7-9, and x. filtering the precipitated part.

2. A method according to claim 1 , comprising the steps of: i. obtaining 4 different biochars by gasifying the biomass obtained from sewage sludge, olive pomace, green waste and their mixture in the updraft gasification reactor, ii. weighing of biochar samples as 1 grams, iii. adding 2 mL of 2.7 M phosphoric acid (H3PO4) solution and 3 mL of 2.7M nitric acid (HNO3) solution to the samples to give an acid / mass ratio of 0.60, iv. shaking the samples in a mixer in closed and non-interacting containers at 140 rpm for 2 hours, v. completing the volume of samples taken into falcon tubes to 14 mL, vi. centrifuging the tubes at 9000 rpm for 4 minutes to settle the solid particles,vii. filtering he resulting falcon tubes through Polyvinylidene fluoride (PVDF) 0.45 pm filters, viii. taking 1 mL of the samples and diluting these 10 times and precipitating with calcium hydroxide (Ca(OH)2) and ammonia (NH3) solutions, ix. adjusting the pH value of the solutions to the range of 7-9, and x. passing the precipitated part through 0.20 pm filters.

3. Method for phosphorus recovery from biochar obtained after gasification by microwave extraction, comprising the application of microwave extraction of the biochar ash sample obtained from the gasification process with a mixture of hydrochloric acid (HCI) and nitric acid (HNO3).

4. A method according to claim 3, comprising the application of microwave extraction of 1 g of biochar ash with a mixture of hydrochloric acid (HCI) and nitric acid (HNO3) in a microwave digester device.