CN-121990753-A - Composite conditioning method for improving sludge sedimentation and dehydration performance

Abstract

A compound conditioning method for improving sludge sedimentation and dehydration performance relates to a method for improving sludge sedimentation and dehydration performance. The invention aims to solve the technical problems of insufficient EPS damage, insufficient compactness of flocs, limited sedimentation performance and direct mixing failure of TA and PAM in the prior art when CPAM is used alone to treat sludge. The invention adopts a step-by-step adding strategy that TA is added first and then CPAM is added, thereby avoiding the direct mixing of the TA and CPAM to form an invalid compound, simultaneously fully playing the EPS destructive effect of TA and the bridging flocculation effect of CPAM, and obviously improving the sludge sedimentation and dehydration performance. Under the condition that the CPAM addition amount is reduced by 20% -50% compared with that of single use, the sedimentation performance is improved, and the unification of medicament reduction and effect optimization is realized.

Inventors

• WU CHUANDONG
• LU XINGYU
• WANG JINGHUI
• XIAO JIANJUN
• Qi sai
• LI XIN

Assignees

• 广东粤海水务股份有限公司
• 哈尔滨工业大学水资源国家工程研究中心有限公司
• 哈尔滨工业大学

Dates

Publication Date

20260508

Application Date

20260317

Claims (10)

1. 1. A composite conditioning method for improving the sedimentation and dehydration performances of sludge is characterized by comprising the following steps of adding tannic acid into the sludge in a step-by-step manner, and adding cationic polyacrylamide after full reaction.
2. 2. The composite conditioning method for improving sludge settling and dewatering performance according to claim 1, wherein the molecular weight of the cationic polyacrylamide is 800-2000 ten thousand.
3. 3. The composite conditioning method for improving sludge settling and dewatering performance according to claim 2, wherein the molecular weight of the cationic polyacrylamide is 1200 ten thousand.
4. 4. The composite conditioning method for improving the sedimentation and dehydration performances of sludge, which is characterized in that tannic acid and water are mixed to prepare an aqueous solution, and then the aqueous solution is uniformly dripped or injected into the sludge to react for 1 to 3 minutes under the stirring condition.
5. 5. The composite conditioning method for improving sludge settling and dewatering performance according to claim 4, wherein the mass concentration of the tannic acid aqueous solution is 0.5% -2%.
6. 6. The composite conditioning method for improving sludge settling and dewatering performance according to claim 5, wherein CPAM and water are mixed to prepare an aqueous solution, and after the tannic acid reaction is completed, the aqueous solution of CPAM is added, and then stirred for 1-2 min to form dense flocs.
7. 7. The composite conditioning method for improving sludge settling and dewatering performance according to claim 6, wherein sludge-water separation is realized by standing and settling after the completion of the CPAM reaction.
8. 8. The composite conditioning method for improving sludge settling and dewatering performance according to claim 1, wherein the addition amount of tannic acid is 0.1% -1.5% of the dry sludge.
9. 9. The composite conditioning method for improving sludge settling and dewatering performance according to claim 8, wherein the adding amount of CPAM is 0.01% -0.03% of the dry sludge mass, and the mass ratio of TA to CPAM is (10-40): 1.
10. 10. The composite conditioning method for improving the sedimentation and dehydration performances of sludge according to claim 1, wherein the pH of the sludge is neutral to slightly acidic, and the specific pH is 5.5-7.5.

Description

Composite conditioning method for improving sludge sedimentation and dehydration performance Technical Field The invention relates to a method for improving sludge sedimentation and dehydration performance. Background The water content of the surplus sludge produced by the urban sewage treatment plant is high, and the dehydration is difficult, which is one of the main problems in the sewage treatment process. Extracellular polymers (Extracellular Polymeric Substances, EPS) in the sludge contain a large amount of proteins and polysaccharides to form a stable three-dimensional network structure, and a large amount of bound water is wrapped, so that the sludge has poor sedimentation performance and difficult dehydration. At present, adding flocculant is a common method for improving sludge sedimentation and dewatering performance. Polyacrylamide (PAM) is widely used for its excellent bridging flocculation properties, wherein Cationic PAM (CPAM) combines with negatively charged sludge particles by charge neutralization and bridging to form flocs. However, CPAM alone has limited damage to EPS structure, is difficult to release wrapped bound water, has insufficiently compact floc structure, still has larger volume after sedimentation, increases cost when the addition amount is higher, and can cause the problems of loose flocs and the like due to excessive CPAM. Tannic Acid (TA) is a natural plant polyphenol, has good complexing ability and hydrophilicity, and can destroy EPS structure and release bound water. However, it has been shown that TA and PAM directly mixed in a concentrated solution form an insoluble complex precipitate immediately and completely lose flocculation activity. Therefore, how to achieve effective cooperation of TA and PAM is a technical problem to be solved in the art. Disclosure of Invention The invention aims to solve the technical problems of insufficient EPS damage, insufficient compactness of flocs, limited sedimentation performance and direct mixing failure of TA and PAM in the prior art when CPAM is used alone to treat sludge, and provides a composite conditioning method for improving sludge sedimentation and dehydration performance. The composite conditioning method for improving the sedimentation and dehydration performance of the sludge is carried out by adopting a step-by-step adding mode, namely adding tannic acid into the sludge firstly, fully reacting and then adding cationic polyacrylamide. The invention has the following points: 1. The step-by-step adding strategy is to add TA first and then CPAM, so that ineffective compound is avoided by directly mixing the TA and CPAM, EPS destructive effect of TA and bridging flocculation effect of CPAM are fully exerted, and sludge sedimentation and dewatering performance are remarkably improved; 2. The optimal adding amount range and proportion of TA and CPAM are determined through a large number of experiments, the synergistic effect is strongest when the mass ratio of TA to CPAM is 25:1, and the sedimentation performance is optimal; 3. The low-dose high-efficiency method has the advantages that the sedimentation performance is improved instead under the condition that the CPAM dosage is reduced by 20% -50% compared with the single use, and the unification of medicament reduction and effect optimization is realized. Compared with the prior art, the invention has the following beneficial effects: ① Significantly improves the sedimentation performance SV30 (30 min sedimentation ratio) SV30 can be reduced to 43% at optimum formulation (ta=20 mg/L, cpam=0.8 mg/L), 52.2% lower than control (90%), and further lower than optimum dose CPAM alone (1.2 mg/L, SV 30=44%). SV60 (60 min sedimentation ratio) can be reduced to 35%, which is the lowest value of the whole test, indicating the most thorough sedimentation. ② Synergistic quantitative characterization For objective evaluation of the synergistic effect of the compounding method of the present invention, a synergistic coefficient (SEC) is defined as follows: wherein SV30 is the sludge sedimentation ratio (%), SEC >0 indicates that the compound system has positive synergistic effect, and the larger the numerical value is, the more remarkable the synergistic effect is. Calculated by synergy coefficient (SEC) at cpam=0.8 mg/L SEC reached 15.7% (SV 30 decreased from 51% to 43%) and at cpam=0.5 mg/L SEC reached 10.9% (SV 30 decreased from 64% to 57%). It was demonstrated that there was a significant synergistic effect of TA with CPAM, rather than a simple superposition. ③ Drug reduction CPAM dosage can be reduced from 1.2mg/L to 0.8mg/L when independently used, and the amplitude is reduced by 33%, and under TA synergy, the sedimentation effect of low-dose CPAM (0.8 mg/L) can be better than that of high-dose CPAM (1.2 mg/L). ④ Optimization of floc structure The sedimentation kinetics study shows that although the initial sedimentation of the compound group is slightly slower than that of the indep