Preparation method of starch-based composite flocculant and application thereof

Abstract

The invention discloses a preparation method of a starch-based composite flocculant and application thereof. The method is characterized by taking sodium silicate, aluminium salt and iron salt as main raw materials and water as a reaction solvent to prepare ferro-silico aluminium and compounding an alkaline modified starch solution with the ferro-silico aluminium to prepare the starch-based composite flocculant. The starch-based composite flocculant is mainly applied to printing and dyeing wastewater treatment. The starch-based composite flocculant has the advantages of high decolorization rate and CODCr removal rate, high sedimentation velocity, less sludge quantity and no secondary pollution.

Description

technical field [0001] The invention belongs to the field of water treatment, and in particular relates to a preparation method and application of a starch-based composite flocculant. Background technique [0002] With the promulgation of a series of national and local restrictive policies on the printing and dyeing industry and the continuous rise of water and sewage charges, printing and dyeing enterprises are paying more and more attention to the treatment and reuse of wastewater. However, there are various factors affecting the reuse of printing and dyeing wastewater, the most critical factor of which is chroma. Especially in recent years, the stability of dye structure has been greatly improved, which further increases the difficulty of decolorization. Flocculation is considered to be one of the most extensive and economical decolorization methods at present. Compared with other methods, the flocculation method has low processing cost and small footprint. [0003] Whe...

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Problems solved by technology

[0003] When using traditional inorganic flocculants such as polyaluminum chloride (PAC) and polyferric sulfate (PFS) to treat printing and dyeing wastewater, the amount of sludge is large, and it is difficult to achieve ideal decolorization and COD reduction. Cr In recent years, it has been found in hygiene that the occurrence of Alzheimer's disease is related to the residual accumulation of aluminum ions

Synthetic polymer flocculants such as polyacrylamide have the advantages of less dosage, less influence by coexisting salts, and less sludge generation, but the residual monomers of this type of polymer have "three-induced" effects (teratogenic, Carcinogenic, mutagenic), and difficult to degrade

In order to improve the decolorization efficiency, dicyandiamide-formaldehyde (DCD-HCHO) condensation polymers have been widely used in recent years for decolorization. However, in the application, it was found that the degree of polymerization of such substances is limited, the charge density is low, the molecular weight is small, and the active functional groups are insufficient. The effect is poor, the formation of flocs is small, it is difficult to settle quickly in a short time, and the treatment cost is high. Therefore, in engineering practice, it is often necessary to use it in conjunction with PAC or PFS to achieve the flocculation and decolorization effect. However, due to the combination of PAC or PFS and DCD -The structure of HCHO is not similar, the crystallinity is different, etc., the compatibility between the two is poor, the difficulty of compounding is quite large, and it is often necessary to add in batches