Method for recovery of extracellular polymers in excess sludge and removal of heavy metal ions

Abstract

The invention relates to a method for recovering extracellular polymers in excess sludge and removing heavy metal ions, comprising the following steps: S1, desorbing extracellular polymers on the surface of cell bodies in excess sludge to become water-soluble; then, Remove the suspended matter after extracellular polymer desorption, and obtain the extracellular polymer solution; S2: filter the extracellular polymer solution with a filter membrane, thereby forming an extracellular polymer filter cake layer on the upper surface of the filter membrane , and obtain a filter membrane with an extracellular polymer filter cake layer; S3: adopt a filter membrane with an extracellular polymer filter cake layer to filter the aqueous solution containing heavy metal ions. The invention is simple to operate, and can reduce the excess sludge by recovering the extracellular polymer in the excess sludge; at the same time, the two steps of concentration and recovery of the extracellular polymer in the excess sludge and the removal of heavy metal ions are coupled, thereby avoiding adsorption The problem of difficult separation of extracellular polymers of heavy metal ions from water was solved.

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...

AI Technical Summary

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 metals, it is difficult to find A universal microorganism that adsorbs various heavy metal ions, and the strain selection is time-consuming, the adsorption capacity and selectivity are low, and the production cost is high

[0004] At present, after various physical or chemical methods, the moisture content of the extracellular polymer solution obtained from the excess sludge is close to 100%, and the traditional drying methods such as freeze drying, high temperature evaporation, electrospray drying, etc. are directly used to prepare the extracellular polymer solution. material powder, which consumes a lot of energy

In addition, as a biopolymer adsorbent, the biggest problem faced in the practical application process is that the extracellular polymer adsorbed various heavy metal ions is difficult to separate from the aqueous solution.

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