Method for recycling extracellular polymers and removing heavy metal ions from excess sludge

A technology of extracellular polymers and heavy metal ions, which is applied in the field of extracellular polymer recovery and heavy metal ion removal in excess sludge. It can solve the problems of narrow applicable pH range, difficult separation of extracellular polymers, and large consumption of raw materials.

Active Publication Date: 2019-02-22
BEIJING UNIV OF CIVIL ENG & ARCHITECTURE
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

Humic acid adsorbent is a kind of natural adsorbent, common lignite, peat and bottom mud, etc., but it is still in the research and development stage, with low adsorption (exchange) capacity, narrow applicable pH value range, mechanical strength, etc. Low-level problems make it difficult to apply on a large scale; polymer adsorbents mainly include synthetic resins, ion exchange fibers, chitosan and their derivatives, etc. Although their adsorption capacity is high, they need to consume a large amount of raw materials and high production costs; biological materials The adsorbent is mainly bacteria, algae and some cell extracts. Compared with other adsorbents, it has the advantages of high treatment efficiency, low investment, low operating cost, and less secondary pollution. However, because microorganisms are selective to heavy

Method used

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  • Method for recycling extracellular polymers and removing heavy metal ions from excess sludge
  • Method for recycling extracellular polymers and removing heavy metal ions from excess sludge
  • Method for recycling extracellular polymers and removing heavy metal ions from excess sludge

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Experimental program
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Effect test

Embodiment 1

[0039] image 3 It shows that when the dead-end filter cake membrane filtration method is adopted, the Pb concentration at different initial concentrations will increase with the filtration. 2+ change in the removal rate. It can be seen from the figure that at a certain amount of extracellular polymer filter cake (100mL, 0.1g / L extracellular polymer solution at filtration pressure p 1 = filter cake formed when filtering at 100kPa) In the case of filter cake membrane filtration on Pb 2+ The removal rate is a function of the initial concentration, with the Pb 2+ Concentration increased, showing a downward trend; but when dealing with Pb 2+ When the concentration is 10μM, although the removal rate decreases continuously with the filtration, the removal rate still remains above 90%. Due to the certain adsorption sites of extracellular polymer filter cake, the higher the Pb 2+ The initial concentration showed a correspondingly lower absolute removal rate. With continuous membr...

Embodiment 2

[0041] Figure 4 It shows that the filtration membrane with extracellular polymer filter cake layer (also referred to as filter cake membrane) formed by 100mL extracellular polymer solution with a concentration of 0.1-0.5g / L has an initial concentration of 10μM Pb 2+ solution removal rate. Depend on Figure 4 It can be seen that when the concentration of the extracellular polymer solution is greater than or equal to 0.2g / L, along with the filtration (until the filtrate volume per unit filtration area is 10cm), the Pb 2+ The removal rate is constant and maintained above 99%; it shows that the concentration of the extracellular polymer that forms the extracellular polymer filter cake layer is increased, that is, the amount of extracellular polymer in the extracellular polymer filter cake layer is increased (sorbent quality), can significantly increase the Pb 2+ This also shows that the coupling technology of extracellular polymer recovery and heavy metal ion removal of the pr...

Embodiment 3

[0043] The present invention is passing through the filter membrane that has extracellular polymer filter cake layer in carrying out concentration recovery process, such as figure 1 As shown, the filtration rate of the filter membrane with the extracellular polymer filter cake layer decreased significantly (ie, the fouling of the filter membrane was serious). In order to reduce the fouling of the filter membrane (filter resistance of the filter membrane), calcium ions (Ca 2+ )Methods. Figure 5 The filtration behavior of the extracellular polymer solution along with the filtration is shown when adding and not adding calcium ions, where the abscissa is the volume of liquid filtered per unit filtration area, and the ordinate is the reciprocal of the filtration speed (the larger the value, the The smaller the filtration speed); the results showed that the decline of filtration speed was significantly slowed down when calcium ions were added, that is, the filtration resistance wa...

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Abstract

The invention relates to a method for recycling extracellular polymers and removing heavy metal ions from excess sludge. The method comprises the following steps: S1, desorbing the extracellular polymers on the surfaces of cell bodies in the excess sludge into a water-dissolved state; then, reducing suspended substances after desorption of the extracellular polymers to obtain an extracellular polymer solution; S2, filtering the extracellular polymer solution by using a filtration membrane so as to form an extracellular polymer filter cake layer on the upper surface of the filtration membrane and obtain the filtration membrane with the extracellular polymer filter cake layer; S3, filtering a water solution containing the heavy metal ions by using the filtration membrane with the extracellular polymer filter cake layer. By the method, the operation is simple, and the excess sludge can be reduced by recycling the extracellular polymers in the excess sludge; meanwhile, the two steps of concentrating and recycling the extracellular polymers and removing the heavy metal ions in the excess sludge are coupled, so that the problem that the extracellular polymers adsorbing the heavy metal ions are difficultly separated from water is avoided.

Description

technical field [0001] The invention relates to the technical field of sewage treatment, in particular to a method for recycling extracellular polymers in excess sludge and removing heavy metal ions. Background technique [0002] Resource recovery is an inevitable direction for the future development of sewage treatment. At present, the most commonly used sewage treatment technology is the activated sludge method, however, a large amount of excess sludge generated during the activated sludge treatment process is an urgent problem to be solved. The remaining sludge is mainly composed of cell bodies and extracellular polymers, and the extracellular polymers account for 10-40% of the dry weight of the sludge. Extracellular polymers mainly include the secretions of microbial cells, cell autolysis or some substances shed from the cell surface, including polysaccharides, proteins, nucleic acids, phospholipids, humus, etc., among which polysaccharides and proteins are the main com...

Claims

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Application Information

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IPC IPC(8): C02F1/44C02F1/28C02F101/20
CPCC02F1/286C02F1/44C02F2101/20
Inventor 曹达啟方晓敏宋鑫郝晓地
Owner BEIJING UNIV OF CIVIL ENG & ARCHITECTURE
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