Method for promoting sludge dewatering and dissolution based on coupling of natural macromolecular organic matter with iron catalysts catalyzing oxidizing agents

Abstract

The application discloses a method for promoting sludge dewatering and dissolution based on natural macromolecular organic matter coupling iron catalyst catalytic oxidant, which adds humic acid, iron catalyst and sodium percarbonate into residual sludge in a secondary sedimentation tank of a domestic sewage treatment plant, and keeps stirring at room temperature to complete sludge dewatering and dissolution respectively. The method can efficiently and quickly promote sludge dewatering and dissolution based on natural macromolecular organic matter coupling iron catalyst catalytic oxidant, and is more efficient, green and sustainable compared with single oxidation reaction.

Description

TECHNICAL FIELD

[0001] The present application relates to a method for improving sludge dewatering and dissolution, in particular to a method for promoting sludge dewatering and dissolution based on coupling natural macromolecular organic matter with iron catalyst to catalyze oxidant, and belongs to the technical field of solid waste treatment. BACKGROUND

[0002] In recent years, with the intensification of industrialization and urbanization in China, in order to meet the rapid growth of urban sewage treatment demand, sewage treatment facilities are increasing, and sludge, as a byproduct of sewage treatment process, its production also increases. The present situation of large volume of residual sludge (water content > 95%) and coexistence of multiple pollutants (organic micro-pollutants, pathogenic microorganisms, heavy metals, etc.) makes it need higher disposal cost (about 50% of the total operation cost of sewage plant), which becomes a big problem faced by sewage plant.

[0003] Sludge dewatering can reduce the volume of sludge, facilitate subsequent transportation and disposal. Common sludge dewatering methods include physical method (mechanical filter pressing), chemical method (advanced oxidation method) and biological method (microorganism, anaerobic fermentation). Among them, the chemical method is widely studied because of its high efficiency and rapidness. However, the traditional advanced oxidation such as Fenton method is limited in its application due to the generation of iron sludge, strict pH requirement (pH = 3) and high dose of chemicals.

[0004] Therefore, it is urgent to develop a new advanced oxidation method for sludge treatment, which can improve dewatering in a wider pH range and reduce the consumption of chemicals. SUMMARY

[0005] The present application provides a method for promoting sludge dewatering and dissolution based on coupling natural macromolecular organic matter with iron catalyst to catalyze oxidant.

[0006] Technical scheme: The present application provides a method for promoting sludge dewatering and dissolution based on coupling natural macromolecular organic matter with iron catalyst to catalyze oxidant, which comprises the following steps: adding humic acid, iron catalyst and sodium percarbonate to the sludge, and stirring at room temperature to complete the dewatering and dissolution of the sludge.

[0007] Among them, the iron catalyst includes one or more of divalent iron, trivalent iron, iron mineral or zero-valent iron.

[0008] Among them, the stirring reaction time at room temperature is 59-61 min.

[0009] Among them, the concentration of sodium percarbonate is 0-60 mg / g TSS. In the present application, TSS means total solid content of sludge.

[0010] The concentration of the humic acid is 0-40 mg / g TSS.

[0011] The concentration of the divalent iron ion in the iron catalyst is 0-40 mg / g TSS.

[0012] The concentration of the trivalent iron ion in the iron catalyst is 0-40 mg / g TSS.

[0013] The iron mineral is magnetite (Fe3O4).

[0014] The sludge is the residual sludge in the secondary sedimentation tank of a domestic sewage plant.

[0015] The pH of the sludge is the initial pH of the sludge, and does not need to be adjusted.

[0016] The trivalent iron ion is derived from Fe2(SO4)3·xH2O.

[0017] As a preference, the concentration of the trivalent iron ion is consistent with the ferrous ion, being 19.8-20 mg / g TSS, and more preferably, the concentration of the trivalent iron ion is consistent with the ferrous ion, being 20 mg / g TSS.

[0018] As a preference, the concentration of the iron ion contained in the added iron mineral is consistent with the ferrous ion, being 19.9-20.1 mg / g TSS, and more preferably, the concentration of the iron ion contained in the magnetite is consistent with the ferrous ion, being 20 mg / g TSS.

[0019] Dewatering mechanism: the ferrous ion can activate sodium percarbonate to generate hydroxyl radicals, thereby destroying the sludge floc and the extracellular polymeric substance, releasing bound water and intracellular water, and at the same time, the ferrous ion is oxidized to trivalent iron ion as a flocculant to improve sludge dewatering. However, this reaction requires strict acidic conditions (pH=3), and consumes more chemicals, so the present application introduces the natural macromolecular organic matter humic acid to complex the soluble iron ion, increases the circulation of the ferrous ion and the trivalent iron ion, generates more hydroxyl radicals, improves sludge dewatering and dissolution, and at the same time, reduces the consumption of chemicals and widens the pH range of the reaction system.

[0020] Beneficial effects: compared with the prior art, the present application has the following significant advantages: the natural macromolecular organic matter humic acid coupled with the iron catalyst in the present application significantly promotes sludge dewatering and dissolution. Moreover, the addition of the natural macromolecular organic matter overcomes the strict acidic reaction conditions, increases the circulation of the ferrous ion and the trivalent iron ion, and reduces the input of chemicals. The method has obvious effects, strong feasibility, is environmentally friendly, and has good practical application value. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1 This is a diagram illustrating the effect of Example 1 on promoting sludge dewatering;

[0022] Figure 2 This is a diagram illustrating the effect of Example 2 on promoting sludge dewatering;

[0023] Figure 3 This is a diagram illustrating the effect of Example 3 on promoting sludge dewatering;

[0024] Figure 4 The graph shows the effect of Comparative Examples 1, 2, 3, and 4 on promoting sludge dewatering.

[0025] Figure 5 The graph shows the effect of comparative examples 5, 6, 7, and 8 on promoting the dissolution and release of proteins from sludge.

[0026] Figure 6 The graph shows the effect of comparative examples 5, 6, 7, and 8 on promoting the dissolution and release of polysaccharides from sludge.

[0027] Figure 7 The graph shows the effect of comparative examples 5, 6, 7, and 8 on promoting the release of dissolved organic carbon from sludge. Detailed Implementation

[0028] The technical solution of the present invention will be further described below with reference to the accompanying drawings.

[0029] The sludge source for the secondary sedimentation tank was residual sludge from the secondary sedimentation tank of a municipal wastewater treatment plant in Changsha City. After settling for 24 hours, the supernatant was removed, and sand, gravel, and debris were removed using a 60-mesh sieve. The sludge was stored at 4℃. All experiments were completed within one month. The sludge pH was 7.2±0.1, the total solids content was 33.45±0.52 g / L, the volatile solids content was 14.24±0.45 g / L, and the specific resistance was (9.29±0.12)×10⁻⁶. 12 The concentrations of the sample were as follows: m / kg, water content 96.69%, capillary absorption time 123.6 ± 1.32 s, protein concentration 63.63 mg / L, polysaccharide concentration 21 mg / L, dissolved organic carbon concentration 60.1 mg / L, and ammonia nitrogen (NH4). + The concentration was 52.8 mg / L, and the soluble phosphorus (PO4) content was... 3- The concentration of ions was 9.22 mg / L, and the concentration of humic acid was 50.9 mg / L.

[0030] Preparation of 1 mol / L sulfuric acid: Take 5.4 ml of 98% concentrated sulfuric acid with a pipette, dilute with ultrapure water and bring the volume to 100 ml.

[0031] Preparation of humic acid solution: Humic acid was prepared at a concentration of 60 g / L.

[0032] Ferrous ions were added at 0, 10, 20, 40 mg / g TSS, calculated as FeSO4-7H2O.

[0033] Ferric ions were added at 20 mg / g TSS, calculated as Fe2(SO4)3-xH2O (analytical pure, CAS: 15244-10-7).

[0034] Zero-valent iron was added at 20 mg / g TSS, calculated as reduced iron powder containing iron ion concentration.

[0035] Magnetite was added at 20 mg / g TSS, calculated as Fe3O4 containing iron ion concentration.

[0036] Example 1 Catalysis of sodium percarbonate by ferrous ions under acidic conditions to improve sludge dewatering and dissolution

[0037] First, 150 ml of residual sludge was weighed into a beaker with a volume of 250 ml, and stirred at room temperature at a stirring speed of 300 revolutions per minute. 1 mol / L sulfuric acid was continuously added to maintain the pH of the sludge at 3, and after 5 minutes, FeSO4-7H2O was added (corresponding to ferrous ion concentrations of 0, 10, 20, 40 mg / g TSS, denoted as S0, S10, S20 and S40), and stirring was continued and the pH was maintained at 3, and after 5 minutes, sodium percarbonate was added (corresponding to sodium percarbonate concentrations of 0, 10, 20, 40, 60 mg / g TSS, denoted as F0, F10, F20, F40 and F60), and stirring was continued and the pH was maintained at 3, and the process was continued for 60 minutes. In this part of the experiment, a gradient experiment of sodium percarbonate was performed for each ferrous ion concentration, a total of 24 experiments, and each experiment was repeated three times. Finally, 5 ml of sludge was taken from each, and the capillary suction time of the sludge was measured using a capillary suction time tester, and the results are shown in Table 1. Figure 1 Figure 1 As can be seen, under acidic conditions (pH = 3), the treatment of sludge with ferrous ions or sodium percarbonate alone deteriorated the dewatering effect of the sludge as the concentration increased, while the combined use of ferrous ions and sodium percarbonate promoted the dewatering of the sludge.

[0038] Example 2 Catalysis of sodium percarbonate by ferrous ions of different concentrations coupled with humic acid to improve sludge dewatering and dissolution

[0039] ​First, 0.69 ml of humic acid solution (corresponding to a humic acid concentration of 10 mg / g TSS) was mixed with FeSO4·7H2O (corresponding to ferrous ion concentrations of 0, 10, 20, and 40 mg / g TSS, denoted as S0, S10, S20, and S40) in centrifuge tubes and chelated by shaking for 1 hour. Then, 150 ml of sludge was measured into a 250 ml beaker and stirred at 300 rpm at room temperature. Without adjusting the pH, the pre-chelated humic acid and ferrous ion solutions were added, and the mixture was stirred at 300 rpm for 5 minutes. Sodium percarbonate (corresponding to sodium percarbonate concentrations of 0, 10, 20, 40, and 60 mg / g TSS, denoted as F0, F10, F20, F40, and F60) was added, and stirring continued for 60 minutes. 5 ml of sludge was then taken, and the capillary absorption time, a sludge dewatering index, was measured using a capillary absorption time meter. The results are as follows: Figure 2 As shown. By Figure 2 It is evident that, under conditions without pH adjustment and with the addition of humic acid, ferrous ion treatment alone promotes sludge dewatering with increasing concentration, while sodium percarbonate treatment alone deteriorates sludge dewatering with increasing concentration. The combination of the two treatments shows deterioration of sludge dewatering at low ferrous ion concentrations (less than 20 mg / g TSS) and promotion of sludge dewatering at high ferrous ion concentrations (greater than 20 mg / g TSS).

[0040] Example 3: Improving sludge dewatering based on sodium percarbonate catalysis using humic acid of different concentrations coupled with ferrous ions.

[0041] First, 0, 0.85, 0.69, 3.39, and 6.76 ml of humic acid solution (corresponding to humic acid concentrations of 0, 5, 10, 20, and 40 mg / g TSS) were mixed with 20 mg / g TSS ferrous ions in centrifuge tubes and chelated by shaking for 1 hour. Then, 150 ml of sludge was measured into a 250 ml beaker and stirred at 300 rpm at room temperature. Without adjusting the pH, the pre-chelated humic acid and ferrous ion solution was added, and the mixture was stirred at 300 rpm for 5 minutes. Sodium percarbonate (corresponding to a sodium percarbonate concentration of 20 mg / g TSS) was then added, and stirring continued for 60 minutes. 5 ml of sludge was then taken, and the capillary absorption time (a sludge dewatering index) was measured using a capillary absorption time meter. The results are as follows: Figure 3 As shown. By Figure 3 It can be seen that as the concentration of added humic acid increases, the effect of sludge dewatering is first promoted and then inhibited. The sludge dewatering effect is best when the concentration of humic acid is 10 mg / g TSS.

[0042] Comparative Example 1: Improved Sludge Dewatering Based on Humic Acid Coupled with Ferrous Iron Catalysis and Sodium Percarbonate

[0043] Four systems were compared in this experiment, namely, divalent iron alone, divalent iron catalyzed sodium percarbonate, divalent iron coupled with humic acid catalyzed sodium percarbonate, and divalent iron catalyzed sodium percarbonate under the condition of pH = 3, denoted as Fe(II), Fe(II) / SPC, Fe(II) / SPC / HA, and Fe(II) / SPC / pH = 3. 0.69 ml of humic acid solution (corresponding to a humic acid concentration of 10 mg / g TSS) was mixed with 20 mg / g TSS divalent iron ions in a centrifuge tube, and shaken for 1 hour to form a pre-mixed iron ion and humic acid. The experiment was carried out in a 250 ml beaker, with a sludge volume of 150 ml, and stirring was carried out at room temperature at a stirring speed of 300 revolutions / minute. The experimental steps were as follows: Fe(II): 20 mg / g TSS divalent iron ions were added to the beaker, stirred at 300 revolutions / minute, and the pH was not adjusted for 60 minutes; Fe(II) / SPC: 20 mg / g TSS divalent iron ions were added to the beaker, stirred at 300 revolutions / minute for 5 minutes, then 0.093 g of sodium percarbonate (corresponding to a sodium percarbonate concentration of 20 mg / g TSS) was added, and stirring was continued for 60 minutes without adjusting the pH; Fe(II) / SPC / HA: pre-mixed iron ion and humic acid were added to the beaker, stirred at 300 revolutions / minute for 5 minutes, then 0.093 g of sodium percarbonate (corresponding to a sodium percarbonate concentration of 20 mg / g TSS) was added, and stirring was continued for 60 minutes without adjusting the pH; Fe(II) / SPC / pH = 3: 1 mol / L sulfuric acid was continuously added to the beaker to maintain the pH of the sludge at 3, then 20 mg / g TSS divalent iron ions were added after 5 minutes, and stirring was continued while maintaining the pH at 3, then 0.093 g of sodium percarbonate (corresponding to a sodium percarbonate concentration of 20 mg / g TSS) was added after 5 minutes, and stirring was continued while maintaining the pH at 3, and the process lasted for 60 minutes. After each system ended, 5 ml of sludge was taken, and the capillary suction time of the sludge was measured using a capillary suction time tester, and the results are shown in Table 1. Figure 4

[0044] Example 2: Improving sludge dewatering based on humic acid coupled with trivalent iron catalyzed sodium percarbonate

[0045] ​Four systems were compared in this experiment, which were ferric iron, ferric iron catalyzed sodium percarbonate, ferric iron coupled with humic acid catalyzed sodium percarbonate and ferric iron catalyzed sodium percarbonate under the condition of pH = 3, which were recorded as Fe(III), Fe(III) / SPC, Fe(III) / SPC / HA and Fe(III) / SPC / pH = 3. 0.69 ml of humic acid solution (corresponding to a humic acid concentration of 10 mg / g TSS) was mixed with 20 mg / g TSS ferric ion in a centrifuge tube, and shaken for 1 hour to form a pre-mixed ferric ion and humic acid. The experiment was carried out in a 250 ml beaker, the sludge volume was 150 ml, and the stirring speed was 300 rpm at room temperature. The experimental steps were as follows: Fe(III): 20 mg / g TSS ferric ion was added to the beaker, stirred at 300 rpm for 60 minutes, and the pH was not adjusted; Fe(III) / SPC: 20 mg / g TSS ferric ion was added to the beaker, stirred at 300 rpm for 5 minutes, then 0.093 g of sodium percarbonate (corresponding to a sodium percarbonate concentration of 20 mg / g TSS) was added, and the stirring was continued for 60 minutes, and the pH was not adjusted; Fe(III) / SPC / HA: pre-mixed ferric ion and humic acid were added to the beaker, stirred at 300 rpm for 5 minutes, then 0.093 g of sodium percarbonate (corresponding to a sodium percarbonate concentration of 20 mg / g TSS) was added, and the stirring was continued for 60 minutes, and the pH was not adjusted; Fe(III) / SPC / pH = 3: 1 mol / L sulfuric acid was continuously added to the beaker to maintain the pH of the sludge at 3, then 20 mg / g TSS ferric ion was added, and the stirring was continued and the pH was maintained at 3, then 0.093 g of sodium percarbonate (corresponding to a sodium percarbonate concentration of 20 mg / g TSS) was added, and the stirring was continued and the pH was maintained at 3, and the process lasted for 60 minutes. After each system ended, 5 ml of sludge was taken, and the capillary suction time of the sludge was measured by a capillary suction time tester. The results are shown in Figure 4 .

[0046] Example 3: Improving sludge dewatering based on humic acid coupled with zero-valent iron catalyzed sodium percarbonate

[0047] Four systems were compared in this experiment, which were zero-valent iron, zero-valent iron catalyzed sodium percarbonate, zero-valent iron coupled with humic acid catalyzed sodium percarbonate and zero-valent iron catalyzed sodium percarbonate under pH = 3 conditions, denoted as ZVI, ZVI / SPC, ZVI / SPC / HA and ZVI / SPC / pH = 3. The experiment was carried out in a 250 ml beaker, the sludge volume was 150 ml, and the stirring was carried out at room temperature with a stirring speed of 300 rpm. The experimental steps were as follows: Fe3O4: 20 mg / g TSS of reducing iron powder was added to the beaker, stirred at 300 rpm for 60 minutes, and the pH was not adjusted; ZVI / SPC: 20 mg / g TSS of reducing iron powder was added to the beaker, stirred at 300 rpm for 5 minutes, then 0.093 g of sodium percarbonate (corresponding to a concentration of 20 mg / g TSS of sodium percarbonate) was added, and the stirring was continued for 60 minutes without adjusting the pH; ZVI / SPC / HA: 0.69 ml of humic acid solution (corresponding to a concentration of 10 mg / g TSS of humic acid) was added to the beaker, stirred at 300 rpm for 5 minutes, then 20 mg / g TSS of reducing iron powder was added, and the stirring was continued for 5 minutes, then 0.093 g of sodium percarbonate (corresponding to a concentration of 20 mg / g TSS of sodium percarbonate) was added, and the stirring was continued for 60 minutes without adjusting the pH; ZVI / SPC / pH = 3: 1 mol / L of sulfuric acid was continuously added to the beaker to maintain the pH of the sludge at 3, then 20 mg / g TSS of reducing iron powder was added after 5 minutes, and the stirring was continued while maintaining the pH at 3, then 0.093 g of sodium percarbonate (corresponding to a concentration of 20 mg / g TSS of sodium percarbonate) was added after 5 minutes, and the stirring was continued while maintaining the pH at 3, and the process lasted for 60 minutes. After each system ended, 5 ml of sludge was taken, and the capillary suction time of the sludge was measured by a capillary suction time tester, and the results are shown in Figure 4 .

[0048] Example 4: Improving sludge dewatering based on humic acid coupled with magnetite catalyzed sodium percarbonate

[0049] The experiment was carried out in four systems for comparison, which were magnetite alone, magnetite catalytic sodium carbonate, magnetite coupling humic acid catalytic sodium carbonate and pH = 3 conditions under the treatment of magnetite catalytic sodium carbonate, marked as Fe3O4, V / SPC, Fe3O4 / SPC / HA and Fe3O4 / SPC / pH = 3. The experiment was carried out in 250ml beaker, the sludge volume was 150ml, and the stirring was carried out at room temperature, the stirring speed was 300r / min. The experimental steps were as follows: Fe3O4: 20mg / g TSS Fe3O4 was added to the beaker, 300r / min, stirring and lasting for 60 minutes, without adjusting pH; Fe3O4 / SPC: 20mg / g TSS Fe3O4 was added to the beaker, 300r / min, stirring for 5 minutes, then 0.093g sodium carbonate (corresponding to the concentration of sodium carbonate 20mg / g TSS) was added, continue to stir and last for 60 minutes, without adjusting pH; Fe3O4 / SPC / HA: 0.69ml humic acid (corresponding to the concentration of humic acid 10mg / g TSS) solution was added to the beaker, 300r / min, stirring for 5 minutes, then 20mg / g TSS Fe3O4 was added, continue to stir for 5 minutes, then 0.093g sodium carbonate (corresponding to the concentration of sodium carbonate 20mg / g TSS) was added, continue to stir and last for 60 minutes, without adjusting pH; Fe3O4 / SPC / pH = 3: 1mol / L sulfuric acid was continuously added to the beaker to keep the pH of the sludge at 3, 5 minutes later, 20mg / g TSS Fe3O4 was added, continue to stir and keep the pH at 3, 5 minutes later, 0.093g sodium carbonate (corresponding to the concentration of sodium carbonate 20mg / g TSS) was added, continue to stir and keep the pH at 3, the process lasted for 60 minutes. After each system ended, 5ml sludge was taken, and the capillary suction time of sludge dewatering index was measured by capillary suction time tester, and the results were shown in Figure 4 .

[0050] From Figure 4 the comparative example 1, comparative example 2, comparative example 3, comparative example 4, it can be seen that under the condition of not adjusting pH, the humic acid coupling ferric ion catalytic sodium carbonate system has the best dewatering effect, and the capillary suction time is equivalent to the acidic condition, which is reduced by 52% compared with the original sludge.

[0051] Comparative example 5 is based on humic acid coupling ferrous iron catalytic sodium carbonate to improve sludge dissolution

[0052] Four systems were compared in this experiment, namely, divalent iron alone, divalent iron catalyzed sodium percarbonate, divalent iron coupled with humic acid catalyzed sodium percarbonate, and divalent iron catalyzed sodium percarbonate under the condition of pH = 3, denoted as Fe(II), Fe(II) / SPC, Fe(II) / SPC / HA, and Fe(II) / SPC / pH = 3. 0.69 ml of humic acid solution (corresponding to a humic acid concentration of 10 mg / g TSS) was mixed with 20 mg / g TSS divalent iron ions in a centrifuge tube, and shaken for 1 hour to form a pre-mixed iron ion and humic acid. The experiment was carried out in a 250 ml beaker, with a sludge volume of 150 ml, and stirring was carried out at room temperature at a stirring speed of 300 revolutions / minute. The experimental steps were as follows: Fe(II): 20 mg / g TSS divalent iron ions were added to the beaker, stirred at 300 revolutions / minute, and the pH was not adjusted for 60 minutes; Fe(II) / SPC: 20 mg / g TSS divalent iron ions were added to the beaker, stirred at 300 revolutions / minute for 5 minutes, then 0.093 g of sodium percarbonate (corresponding to a sodium percarbonate concentration of 20 mg / g TSS) was added, and stirring was continued for 60 minutes without adjusting the pH; Fe(II) / SPC / HA: the pre-mixed iron ion and humic acid were added to the beaker, stirred at 300 revolutions / minute for 5 minutes, then 0.093 g of sodium percarbonate (corresponding to a sodium percarbonate concentration of 20 mg / g TSS) was added, and stirring was continued for 60 minutes without adjusting the pH; Fe(II) / SPC / pH = 3: 1 mol / L sulfuric acid was continuously added to the beaker to maintain the pH of the sludge at 3, then 20 mg / g TSS divalent iron ions were added, stirring was continued and the pH was maintained at 3, then 0.093 g of sodium percarbonate (corresponding to a sodium percarbonate concentration of 20 mg / g TSS) was added, stirring was continued and the pH was maintained at 3, and the process lasted for 60 minutes. After each system was completed, 20 ml of sludge was taken, centrifuged at 2000 g for 10 minutes, and the supernatant was filtered with a 0.45 um filter membrane. The concentrations of polysaccharide and protein in the supernatant were determined by the phenol-sulfuric acid method and the Folin phenol method, respectively. The concentration of dissolved organic carbon in the supernatant was detected by a TOC detector, and the results are shown in Table 1. Figure 5 、 6 、7.

[0053] Example 6: Improving sludge solubilization based on humic acid coupled with trivalent iron catalyzed sodium percarbonate

[0054] Four systems were compared in this experiment, which were ferric iron, ferric iron catalyzed sodium percarbonate, ferric iron coupled with humic acid catalyzed sodium percarbonate and ferric iron catalyzed sodium percarbonate under the condition of pH = 3, which were recorded as Fe(III), Fe(III) / SPC, Fe(III) / SPC / HA and Fe(III) / SPC / pH = 3. 0.69 ml of humic acid solution (corresponding to a humic acid concentration of 10 mg / g TSS) was mixed with 20 mg / g TSS ferric ion in a centrifuge tube, and shaken for 1 hour to form a pre-mixed ferric ion and humic acid. The experiment was carried out in a 250 ml beaker, the sludge volume was 150 ml, and the stirring speed was 300 rpm at room temperature. The experimental steps were as follows: Fe(III): 20 mg / g TSS ferric ion was added to the beaker, stirred at 300 rpm for 60 minutes, and the pH was not adjusted; Fe(III) / SPC: 20 mg / g TSS ferric ion was added to the beaker, stirred at 300 rpm for 5 minutes, then 0.093 g of sodium percarbonate (corresponding to a sodium percarbonate concentration of 20 mg / g TSS) was added, and the stirring was continued for 60 minutes, and the pH was not adjusted; Fe(III) / SPC / HA: pre-mixed ferric ion and humic acid was added to the beaker, stirred at 300 rpm for 5 minutes, then 0.093 g of sodium percarbonate (corresponding to a sodium percarbonate concentration of 20 mg / g TSS) was added, and the stirring was continued for 60 minutes, and the pH was not adjusted; Fe(III) / SPC / pH = 3: 1 mol / L sulfuric acid was continuously added to the beaker to maintain the pH of the sludge at 3, then 20 mg / g TSS ferric ion was added, and the stirring was continued and the pH was maintained at 3, then 0.093 g of sodium percarbonate (corresponding to a sodium percarbonate concentration of 20 mg / g TSS) was added, and the stirring was continued and the pH was maintained at 3, and the process lasted for 60 minutes. After each system was completed, 20 ml of sludge was taken, centrifuged at 2000 g for 10 minutes, and the supernatant was filtered with a 0.45 um filter membrane. The concentrations of polysaccharide and protein in the supernatant were determined by phenol-sulfuric acid method and Folin phenol method, respectively. The concentration of dissolved organic carbon in the supernatant was detected by TOC detector, and the results are shown in Tables 1-4. Figure 5 、 6 、7.

[0055] Example 7: Improving sludge solubilization based on humic acid coupled with zero-valent iron catalyzed sodium percarbonate

[0056] Four systems were compared in this experiment, which were zero-valent iron, zero-valent iron catalyzed sodium percarbonate, zero-valent iron coupled with humic acid catalyzed sodium percarbonate, and zero-valent iron catalyzed sodium percarbonate under pH = 3 conditions, denoted as ZVI, ZVI / SPC, ZVI / SPC / HA, and ZVI / SPC / pH = 3. The experiment was carried out in a 250 ml beaker, the sludge volume was 150 ml, and the stirring was carried out at room temperature with a stirring speed of 300 rpm. The experimental steps were as follows: Fe3O4: 20 mg / g TSS of reducing iron powder was added to the beaker, stirred at 300 rpm for 60 minutes, and the pH was not adjusted; ZVI / SPC: 20 mg / g TSS of reducing iron powder was added to the beaker, stirred at 300 rpm for 5 minutes, then 0.093 g of sodium percarbonate (corresponding to a concentration of 20 mg / g TSS of sodium percarbonate) was added, and the stirring was continued for 60 minutes without adjusting the pH; ZVI / SPC / HA: 0.69 ml of humic acid solution (corresponding to a concentration of 10 mg / g TSS of humic acid) was added to the beaker, stirred at 300 rpm for 5 minutes, then 20 mg / g TSS of reducing iron powder was added, and the stirring was continued for 5 minutes, then 0.093 g of sodium percarbonate (corresponding to a concentration of 20 mg / g TSS of sodium percarbonate) was added, and the stirring was continued for 60 minutes without adjusting the pH; ZVI / SPC / pH = 3: 1 mol / L of sulfuric acid was continuously added to the beaker to maintain the pH of the sludge at 3, then 20 mg / g TSS of reducing iron powder was added after 5 minutes, and the stirring was continued while maintaining the pH at 3, then 0.093 g of sodium percarbonate (corresponding to a concentration of 20 mg / g TSS of sodium percarbonate) was added after 5 minutes, and the stirring was continued while maintaining the pH at 3, and the process lasted for 60 minutes. After each system ended, 20 ml of sludge was taken, centrifuged at 2000 g for 10 minutes, and the supernatant was filtered with a 0.45 um filter membrane, and the concentrations of polysaccharide and protein in the supernatant were determined by phenol-sulfuric acid method and Folin phenol method, respectively. The concentration of dissolved organic carbon in the supernatant was detected by a TOC detector, and the results are shown in Tables 1-4. Figure 5 、 6 、7.

[0057] Example 8: Improvement of sludge solubilization by humic acid coupled with magnetite catalyzed sodium percarbonate

[0058] The experiment was carried out in four systems for comparison, which were magnetite, magnetite catalytic sodium carbonate, magnetite coupling humic acid catalytic sodium carbonate and pH = 3 conditions under the treatment of magnetite catalytic sodium carbonate, marked as Fe3O4, V / SPC, Fe3O4 / SPC / HA and Fe3O4 / SPC / pH = 3. The experiment was carried out in a 250ml beaker, the sludge volume was 150ml, and the stirring was carried out at room temperature, the stirring speed was 300r / min. The experimental steps were as follows: Fe3O4: 20mg / g TSS Fe3O4 was added to the beaker, 300r / min, stirring and lasting for 60 minutes, without adjusting pH; Fe3O4 / SPC: 20mg / g TSS Fe3O4 was added to the beaker, 300r / min, stirring for 5 minutes, then 0.093g sodium carbonate (corresponding to the concentration of sodium carbonate 20mg / g TSS) was added, continue to stir and last for 60 minutes, without adjusting pH; Fe3O4 / SPC / HA: 0.69ml humic acid (corresponding to the concentration of humic acid 10mg / g TSS) solution was added to the beaker, 300r / min, stirring for 5 minutes, then 20mg / g TSS Fe3O4 was added, continue to stir for 5 minutes, then 0.093g sodium carbonate (corresponding to the concentration of sodium carbonate 20mg / g TSS) was added, continue to stir and last for 60 minutes, without adjusting pH; Fe3O4 / SPC / pH = 3: 1mol / L sulfuric acid was continuously added to the beaker to keep the pH of the sludge at 3, 5 minutes later, 20mg / g TSS Fe3O4 was added, continue to stir and keep the pH at 3, 5 minutes later, 0.093g sodium carbonate (corresponding to the concentration of sodium carbonate 20mg / g TSS) was added, continue to stir and keep the pH at 3, the process lasted for 60 minutes. After each system ended, 20ml sludge was taken, 2000g centrifuged for 10 minutes, the supernatant was filtered with 0.45um filter membrane, the concentration of polysaccharide and protein in the supernatant was determined by phenol-sulfuric acid method and Folin phenol method respectively. The concentration of dissolved organic carbon in the supernatant was detected by TOC detector, and the results are shown in Figure 5 、 6 、7.

[0059] Figure 5 Figure 5, figure 6, figure 7 and figure 8 are the effect diagrams of sludge dissolution and release of protein promotion of comparative example 5, comparative example 6, comparative example 7 and comparative example 8; it can be seen from Figure 5 that under the condition of not adjusting pH, the dissolution effect of humic acid coupling magnetite catalytic sodium carbonate system on sludge is the best, the dissolved protein in the supernatant is increased by 5.5 times compared with the original sludge. Figure 6 Figure 5, figure 6, figure 7 and figure 8 are the effect diagrams of sludge dissolution and release of protein promotion of comparative example 5, comparative example 6, comparative example 7 and comparative example 8; it can be seen from Figure 6It can be seen that under the condition of not adjusting pH, the humic acid coupled magnetite catalytic sodium carbonate system has the best effect on sludge dissolution, and the dissolved polysaccharide in the supernatant is 4 times that of the original sludge. Figure 7 The effect of sludge dissolution and release of dissolved organic carbon promotion of Comparative Example 5, Comparative Example 6, Comparative Example 7, Comparative Example 8 is shown in the figure. Figure 7 It can be seen that under the condition of not adjusting pH, the humic acid coupled magnetite catalytic sodium carbonate system has the best effect on sludge dissolution, and the dissolved polysaccharide in the supernatant is 4 times that of the original sludge.

Claims

1. A method for promoting sludge dewatering and solubilization based on coupling of natural macromolecular organic matter with iron catalysts catalyzing oxidizing agents, characterized in that, It comprises the following steps: The dewatering and dissolution of the sludge are completed by adding humic acid, iron catalyst and sodium percarbonate into the sludge and stirring at room temperature, the iron catalyst is magnetite, the concentration of the sodium percarbonate is 20 mg / g TSS, the concentration of the humic acid is 10 mg / g TSS, and the magnetite is added in the form of Fe3O4 containing iron ion concentration of 20 mg / g TSS.

2. The method for promoting sludge dewatering and solubilization by natural macromolecular organic matter coupled iron catalyst catalytic oxidation agent according to claim 1, characterized in that, The reaction time of the stirring at room temperature is 59-61 min.

3. The method for promoting sludge dewatering and solubilization by natural macromolecular organic matter coupled iron catalyst catalytic oxidation agent according to claim 1, characterized in that, The sludge is residual sludge in a secondary sedimentation tank of a domestic sewage plant.

4. The method for promoting sludge dewatering and solubilization by natural macromolecular organic matter coupled iron catalyst catalytic oxidation agent according to claim 1, characterized in that, The pH of the sludge is the initial pH value of the sludge.

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