A method for comprehensive resource utilization of agricultural waste and furfural production waste

Abstract

The invention discloses a method for comprehensive resource utilization of agricultural waste and furfural production waste. Alkaline waste liquid and alkaline solid waste residue generated in the process of alkali pretreatment of agricultural waste are respectively mixed with acidic waste liquid and waste residue generated in the process of furfural production, so that the pH of the mixed waste liquid and waste residue reaches a suitable range, and the addition of acid and alkali reagents in the process of pH adjustment is omitted, thereby saving costs. At the same time, liquid organic compound fertilizer, alcohol fuel or organic acid, and dietary fiber protein feed are respectively obtained through waste liquid component preparation and waste residue enzymatic saccharification, thereby realizing synchronous high-value conversion of agricultural waste and furfural residue, zero discharge of waste liquid and waste residue in the high-value production process of agricultural waste and the furfural production process, and increasing benefits, thereby solving the problems of low benefits of high-value agricultural waste off-field and large amount of waste generated in the furfural production process that is difficult to dispose of.

Description

Technical field:

[0001] The invention relates to the field of waste resource utilization and environmental protection, and in particular to a method for comprehensive resource utilization of agricultural waste and furfural production waste. Background technology:

[0002] The high-value conversion of straw into fuel or chemicals after leaving the field is an important way to utilize it as a resource. The biochemical conversion of straw into fuel or chemicals usually requires three key steps: pretreatment, enzymatic hydrolysis and fermentation. There are many pretreatment methods, among which the alkaline method is currently the pretreatment method with the lowest energy consumption. However, the amount of waste liquid generated during the alkaline pretreatment process is large and difficult to dispose of, which has become a technical bottleneck for the high-value conversion and utilization of straw.

[0003] Furfural production mainly uses sulfuric acid as a catalyst. The production process produces a large amount of waste liquid and waste residue, with a mass ratio of 24:13:1 to the furfural product. The waste residue is usually directly burned to provide process heat, and the waste liquid is difficult to dispose of, which has become a pain point in the sustainable development of the furfural industry. Summary of the invention:

[0004] The invention aims to provide a method for comprehensive resource utilization of agricultural waste and furfural production waste, wherein alkaline waste liquid and alkaline solid waste residue generated in the alkali pretreatment process of agricultural waste are respectively mixed with acidic waste liquid and acidic solid waste residue generated in the furfural production process, so that the pH of the mixed waste liquid and waste residue reaches a suitable range, the addition of acid and alkali reagents in the pH adjustment process is omitted, and the cost is saved. Meanwhile, liquid organic compound fertilizer, alcohol fuel or organic acid, and dietary fiber protein feed are respectively obtained through the preparation of waste liquid components and enzymatic saccharification of waste residue, so as to realize the synchronous high-value conversion of agricultural waste and furfural residue, zero discharge of waste liquid and waste residue in the high-value production process of agricultural waste and the furfural production process, and increase of income, and solve the problems of low benefits of high-value agricultural waste off-field and large amount of waste generated in the furfural production process that is difficult to dispose.

[0005] The present invention is achieved through the following technical solutions:

[0006] A method for comprehensive resource utilization of agricultural waste and furfural production waste, the method comprising the following steps:

[0007] (1) collecting agricultural waste, drying it to a moisture content of ≤5wt%, and crushing it to a size of 20 mesh or more; mixing the crushed agricultural waste with 1wt% to 2wt% of KOH or a KOH-urea mixed solution at a solid-liquid ratio of 1:10 to 1:20, treating it at 50°C to 80°C for 2 to 4 hours, and then separating the solid and the liquid to obtain a pre-treated solution and a solid residue I;

[0008] (2) mixing the pre-treated liquid obtained in step (1) with the furfural production waste liquid until the pH is neutral, adding nitrogen fertilizer, phosphorus fertilizer and potassium fertilizer, and adjusting the N:P ratio of the mixed liquid to 1:1. 2 O 5 :K 2 O mass ratio is 1: (0.1 ~ 2): (0.2 ~ 4), prepared into liquid organic compound fertilizer, so that N + P 2 O 5 +K 2 The total O content is not less than 4wt%, and the organic matter content is not less than 35wt%;

[0009] (3) the solid residue I obtained in step (1) is mixed with furfural residue to a pH of 4.5 to 5.5, water is added to adjust the solid-liquid ratio to 1:5 to 1:10, cellulase is added to the mixed system in an amount of 20 to 40 FPU / g cellulose, and after enzymatic hydrolysis at 50° C. and 100 to 150 rpm for 48 to 72 h, the temperature is lowered to 30 to 37° C., and nutrients are added, including 0.25 wt % to 0.5 wt % yeast powder, 0.25 wt % to 0.5 wt % peptone, and 0.25 wt % to 0.5 wt % KH 2 PO 4 , 0.01wt%~0.02wt%(NH 4 ) 2 SO 4 and 0.02wt%~0.04wt%MgSO 4 7H 2 O, inoculate the microbial strain, and ferment at 100-150 rpm for 24-48 hours before solid-liquid separation to obtain liquid and solid residue II. The liquid is used to purify the fermentation product, and the solid residue II can be prepared into feed or feed additives.

[0010] The agricultural waste is selected from one of crop straw, corn cobs, bagasse and sweet sorghum residue.

[0011] The mass ratio of KOH to urea in the KOH-urea mixed solution in step (1) is 1:0.5 to 1:2, and the furfural production waste liquid in step (3) comes from a production process in which agricultural waste is catalyzed to prepare furfural using sulfuric acid, phosphoric acid or acetic acid as a catalyst.

[0012] The liquid organic compound fertilizer prepared in step (2) can be used for crops, vegetables, seedlings, flowers and potted plants.

[0013] Preferably, the microorganism introduced in step (3) is a strain of yeast, lactic acid bacteria, etc. that can ferment glucose or xylose, the fermentation product produced is an alcohol fuel or an organic acid, and the obtained solid residue II has a dietary fiber content of more than 60wt% and a crude protein content of more than 10wt%.

[0014] The beneficial effects of the present invention are as follows: the present invention combines the high-value conversion process of agricultural waste with the disposal of waste liquid and waste residue in the furfural production process, realizes the synchronous high-value conversion of agricultural waste and furfural residue, simplifies the disposal procedure of waste liquid generated in the furfural production process, and realizes the resource utilization of waste liquid, which not only saves the cost of waste liquid disposal, but also increases additional income by the prepared liquid organic compound fertilizer. Specific implementation method:

[0015] The following is a further description of the present invention, rather than a limitation of the present invention.

[0016] Embodiment 1:

[0017] (1) collecting agricultural waste rice straw, drying it to a moisture content of ≤5wt%, and crushing it to a size of 20 mesh or more;

[0018] (2) mixing the crushed agricultural waste with 1 wt % KOH solution at a solid-liquid ratio of 1:20, treating at 50° C. for 4 h, and then separating the solid and the liquid to obtain a pretreated solution and a solid residue I;

[0019] (3) The pretreated liquid is mixed with the waste liquid from agricultural waste after furfural is prepared using sulfuric acid as a catalyst (see Xiong Jian et al. Research progress in the preparation of furfural and 5-hydroxymethylfurfural from biomass materials. Modern Chemical Industry, 2022, 42(5): 30-34) until the pH is neutral, and nitrogen fertilizer, phosphorus fertilizer and potassium fertilizer are added to adjust the N:P ratio of the mixed liquid. 2 O 5 :K 2 O mass ratio of 1:0.1:0.2, prepared into liquid organic compound fertilizer, N+P 2 O 5 +K 2 The total O content is not less than 4wt%, and the organic matter content is not less than 35wt%. Compared with the control group without adding the organic fertilizer, the promotion effect on corn growth is manifested in that the growth rate is 38% faster (measured in the length of the aboveground part) and the fresh weight is increased by 32%.

[0020] (4) The solid residue I and the furfural residue were mixed to pH 4.5, water was added to adjust the solid-liquid ratio to 1:10, cellulase was added to the mixed system in an amount of 40 FPU / g cellulose, and the solid-liquid separation was carried out after enzymatic hydrolysis at 50° C. and 100 rpm for 48 h, the temperature was lowered to 30° C., and nutrients were added, including 0.25 wt% yeast powder, 0.25 wt% peptone, and 0.25 wt% KH 2 PO 4 、0.01wt%(NH 4 ) 2 SO 4and 0.02wt%MgSO 4 7H 2 O, the yeast strain was inoculated, and the solid-liquid separation was carried out after fermentation at 100 rpm for 24 h to obtain liquid and solid residue II. The ethanol concentration in the liquid was 15 g / L, and the dietary fiber content of the solid residue II was 65 wt%, and the crude protein content was 10 wt%.

[0021] Embodiment 2:

[0022] (1) collecting agricultural waste corn cobs, drying them to a moisture content of ≤5 wt%, and crushing them to a size of 20 mesh or more;

[0023] (2) mixing the crushed agricultural waste with a 2 wt % KOH-urea mixed solution (KOH to urea mass ratio is 1:1) at a solid-liquid ratio of 1:15, treating at 80° C. for 2 h, and then separating the solid and liquid to obtain a pretreated solution and a solid residue I;

[0024] (3) The pretreated liquid was mixed with the waste liquid from agricultural waste after furfural was prepared using phosphoric acid as a catalyst (Xiong Jian et al. Research progress in the preparation of furfural and 5-hydroxymethylfurfural from biomass materials. Modern Chemical Industry, 2022, 42(5): 30-34.) until the pH was neutral, and nitrogen fertilizer, phosphorus fertilizer and potassium fertilizer were added to adjust the N:P ratio of the mixed liquid. 2 O 5 :K 2 O mass ratio is 1:1:2, and liquid organic compound fertilizer is prepared to make N+P 2 O 5 +K 2 The total O content is not less than 4wt%, and the organic matter content is not less than 35wt%. Compared with the control group without adding the organic fertilizer, the growth promotion effect on tobacco is manifested in that the growth rate is 42% faster (measured in the length of the aboveground part) and the fresh weight is increased by 35%.

[0025] (4) The solid residue I and the furfural residue were mixed to a pH of 5.0, water was added to adjust the solid-liquid ratio to 1:5, cellulase was added to the mixed system in an amount of 20 FPU / g cellulose, and the solid-liquid separation was carried out after enzymatic hydrolysis at 50° C. and 150 rpm for 72 h, the temperature was lowered to 30° C., and nutrients were added, including 0.5 wt % yeast powder, 0.5 wt % peptone, and 0.5 wt % KH 2 PO 4 、0.02wt%(NH 4 ) 2 SO 4 and 0.04wt%MgSO 4 7H 2O, the yeast strain was inoculated, and the solid-liquid separation was carried out after fermentation at 150rpm for 48h to obtain liquid and solid residue II. The ethanol concentration in the liquid was 40g / L, and the dietary fiber content of the solid residue II was 70wt%, and the crude protein content was 12wt%.

[0026] Embodiment 3:

[0027] (1) collecting agricultural waste sugarcane bagasse, drying it to a moisture content of ≤5wt%, and crushing it to a size of 20 mesh or more;

[0028] (2) mixing the crushed agricultural waste with 2 wt % KOH solution at a solid-liquid ratio of 1:10, treating at 80° C. for 2 h, and then separating the solid and the liquid to obtain a pretreated solution and a solid residue I;

[0029] (3) The pretreated liquid was mixed with the waste liquid from agricultural waste prepared with acetic acid as a catalyst to produce furfural (Xiong Jian et al. Research progress in the preparation of furfural and 5-hydroxymethylfurfural from biomass materials. Modern Chemical Industry, 2022, 42(5): 30-34) until the pH was neutral, and nitrogen fertilizer, phosphorus fertilizer and potassium fertilizer were added to adjust the N:P ratio of the mixed liquid. 2 O 5 :K 2 O mass ratio of 1:2:4, prepared into liquid organic compound fertilizer, N+P 2 O 5 +K 2 The total O content is not less than 4wt%, and the organic matter content is not less than 35wt%. Compared with the control group without adding the organic fertilizer, the growth promotion effect on tomato seedlings is manifested in that the growth rate is 42% faster (measured in the length of the aboveground part) and the fresh weight is increased by 37%.

[0030] (4) The solid residue I and the furfural residue were mixed to a pH of 5.5, water was added to adjust the solid-liquid ratio to 1:5, and cellulase was added to the mixed system in an amount of 20 FPU / g cellulose. After enzymatic hydrolysis at 50° C. and 150 rpm for 72 h, the solid and liquid were separated, the temperature was lowered to 37° C., and nutrients were added, including 0.5 wt% yeast powder, 0.5 wt% peptone, and 0.5 wt% KH 2 PO 4 、0.02wt%(NH 4 ) 2 SO 4 and 0.04wt%MgSO 4 7H 2 O, inoculated with lactic acid strains, and fermented at 150rpm for 48h before solid-liquid separation to obtain liquid and solid residue II. The lactic acid concentration in the liquid was 70g / L, and the dietary fiber content of the solid residue II was 72wt%, and the crude protein content was 15wt%.

Claims

1. A method for comprehensive resource utilization of agricultural waste and furfural production waste, characterized in that: The method comprises the following steps: (1) collecting agricultural waste, drying it to a moisture content of ≤5wt%, and crushing it to a size of 20 mesh or more; mixing the crushed agricultural waste with 1wt% to 2wt% of KOH or a KOH-urea mixed solution at a solid-liquid ratio of 1:10 to 1:20, treating it at 50°C to 80°C for 2 to 4 hours, and then separating the solid and the liquid to obtain a pre-treated solution and a solid residue I; (2) mixing the pretreated liquid obtained in step (1) with the furfural production waste liquid until the pH is neutral, adding nitrogen fertilizer, phosphorus fertilizer and potassium fertilizer, and adjusting the mass ratio of N:P2O5:K2O in the mixed liquid to be 1:(0.1-2):(0.2-4), to prepare a liquid organic compound fertilizer, so that the total content of N+P2O5+K2O is not less than 4wt%, and the organic matter content is not less than 35wt%; (3) the solid residue I obtained in step (1) is mixed with furfural residue to a pH of 4.5 to 5.5, water is added to adjust the solid-liquid ratio to 1:5 to 1:10, cellulase is added to the mixed system in an amount of 20 to 40 FPU / g cellulose, and after enzymatic hydrolysis at 50° C. and 100 to 150 rpm for 48 to 72 h, the temperature is lowered to 30 to 37° C., and nutrients are added, with the total mass percentage being 100%, including 0.25 wt % to 0.5 wt % yeast powder, 0.25 wt% to 0.5wt% peptone, 0.25wt% to 0.5wt% KH2PO4, 0.01wt% to 0.02wt% (NH4)2SO4 and 0.02wt% to 0.04wt% MgSO4·7H2O, then inoculate the microbial strain, ferment at 100 to 150rpm for 24 to 48h and separate the solid and liquid to obtain liquid and solid residue II, the liquid is used to purify the fermentation product, and the solid residue II is prepared into feed or feed additive.

2. The method according to claim 1, characterized in that: The agricultural waste is selected from one of crop straw, corn cobs, bagasse and sweet sorghum residue.

3. The method according to claim 1, characterized in that The mass ratio of KOH to urea in the KOH-urea mixed solution in step (1) is 1:0.5 to 1:

2.

4. The method according to claim 1, characterized in that: The liquid organic compound fertilizer prepared in step (2) is used for crops.

5. The method according to claim 1, characterized in that: The microorganism introduced in step (3) is a strain that can ferment glucose or xylose.

6. The method according to claim 1, characterized in that The fermentation product produced in step (3) is one of alcohol fuel and organic acid.

7. The method according to claim 1, characterized in that The solid residue II obtained in step (3) has a dietary fiber content of more than 60wt% and a crude protein content of more than 10wt%.