CN-121974465-A - Composite flocculant for treating wastewater with coexistence of multiple heavy metals and preparation method thereof

Abstract

The invention discloses a composite flocculant for wastewater treatment with coexistence of various heavy metals and a preparation method thereof, belonging to the technical field of wastewater treatment. The composite flocculant comprises modified pectin, modified lac, tartaric acid-bentonite compound, cinnamoyl xylan, galacturonic acid, trehalose-pectase compound and activated zeolite powder, wherein the modified pectin is obtained by modifying pectin by oxalic acid, the modified lac is obtained by modifying lac by lactic acid, the cinnamoyl xylan is prepared by acylating xylan by cinnamic anhydride, and the activated zeolite powder is prepared by activating natural zeolite by sodium bicarbonate solution. According to the invention, through the synergistic effect of the components, core pollutants such as heavy metal, ammonia nitrogen, cyanide, sulfide, tannin and the like in the wastewater can be effectively removed, the floc settling property is improved, the scum generation is reduced, and the pollutant indexes in the treated water body meet the corresponding requirements of farmland irrigation and temporary miscellaneous water.

Inventors

• WANG QIANG
• LI MIN

Assignees

• 成都越山向海新型材料科技有限公司

Dates

Publication Date

20260505

Application Date

20260407

Claims (9)

1. 1. A composite flocculant for treating wastewater with coexistence of multiple heavy metals is characterized by comprising, by weight, 25-30 parts of modified pectin, 18-22 parts of modified shellac, 20-25 parts of tartaric acid-bentonite compound, 10-15 parts of cinnamoyl xylan, 5-10 parts of galacturonic acid, 0.5-1 part of trehalose-pectinase compound and 2-3 parts of activated zeolite powder; wherein the modified pectin is obtained by modifying pectin by oxalic acid, and the carboxyl content of the modified pectin is 12% -15%; the modified lac is obtained by modifying lac with lactic acid; the cinnamoyl xylan is prepared by acylation modification of xylan with cinnamic anhydride, and the substitution degree of the cinnamoyl xylan is 0.15-0.20; The activated zeolite powder is prepared by activating natural zeolite with sodium bicarbonate solution.
2. 2. The composite flocculant for the treatment of wastewater with coexistence of multiple heavy metals according to claim 1, wherein the particle size of the tartaric acid-bentonite composite is 150-200 meshes, and the mass ratio of tartaric acid to bentonite is 1 (8-10).
3. 3. The composite flocculant for the treatment of wastewater with coexistence of multiple heavy metals according to claim 1, wherein the mass ratio of trehalose to pectase in the trehalose-pectase complex is (15-20): 80-85.
4. 4. The composite flocculant for the treatment of wastewater coexisting with multiple heavy metals according to claim 1, wherein the particle size of the activated zeolite powder is 200-300 meshes, the mass fraction of sodium bicarbonate solution is 4-8%, the solid-to-liquid ratio of zeolite to sodium bicarbonate solution is 1 (5-10), and g is ml.
5. 5. The composite flocculant for the treatment of wastewater with coexistence of multiple heavy metals according to claim 1, wherein the mass ratio of xylan to cinnamic anhydride in the cinnamoyl xylan is 1 (0.3-0.5).
6. 6. The composite flocculant for the treatment of wastewater with coexistence of multiple heavy metals according to claim 1, wherein the mass ratio of oxalic acid to pectin in the modified pectin is 1 (12-15).
7. 7. The composite flocculant for the treatment of wastewater with coexistence of multiple heavy metals according to claim 1, wherein the mass ratio of lactic acid to lac in the modified lac is 1 (10-15).
8. 8. A method of preparing a composite flocculant according to any one of claims 1 to 7, comprising the steps of: S1, adding deionized water into a tartaric acid-bentonite compound and stirring to prepare a suspension; S2, mixing the modified pectin and the modified lac, adding the suspension, heating to 40-45 ℃, stirring at constant temperature, cooling to room temperature after stirring, sequentially adding the cinnamoyl xylan, galacturonic acid, trehalose-pectase complex and activated zeolite powder, stirring fully, drying at low temperature under vacuum, and crushing to obtain the flocculant.
9. 9. The method for preparing a composite flocculant according to claim 8, wherein in step S2, the vacuum low temperature drying temperature is <40 ℃.

Description

Composite flocculant for treating wastewater with coexistence of multiple heavy metals and preparation method thereof Technical Field The invention belongs to the technical field of wastewater treatment, and particularly relates to a composite flocculant for wastewater treatment with coexistence of various heavy metals and a preparation method thereof. Background Mountain Gao Gu is deep, the topography is broken in mountain and valley regions of mountain and Chuangan juncture, small ecological immigration points in the region, temporary domestic water (such as toilet flushing, farm tool cleaning, courtyard cleaning and the like) of remote forest-protecting stations and scattered farmers and the mixed water of the water of mountain stream ditch water and shallow groundwater of peripheral farmlands are used as main water sources. The area has two typical pollution types, namely livestock and poultry raising activities scattered along the line are mainly carried out on cattle, sheep and poultry, raising wastewater is overflowed from the ground surface and is converged into a stream ditch, and the scattered abandoned mine points and smelting remains left by history, including lead zinc mine, small coal kilns, tail mine piles of mercury mine, goats, simple smelting waste slag piles and a waste furnace body. The effective seepage prevention measures are not adopted for the points for a long time, and each time in rainy season, the rainwater is leached to slag and rock stratum to form leaching water containing low-concentration heavy metals, and the leaching water is converged along with the channels to form a combined pollution system. Because the simple treatment methods of complex water components, precipitation, simple filtration and the like and the treatment technology of inorganic flocculating agents such as polyaluminium chloride and the like are poor in adaptability, the water cannot be treated to the basic water quality requirements of farmland irrigation and temporary miscellaneous water, and further potential influences are formed on the safety of regional farmland irrigation and the safety of temporary domestic miscellaneous water, so that heavy metal pollution of soil can be aggravated, the growth of crops is influenced, and the water can be infiltrated into human bodies through skin contact, so that adverse effects are caused on the health of the human bodies. The primary difficulty in treating such complex polluted water is the stable complex formed by heavy metals and humic acid. The historical left-over mine points and smelting remains in the area are leached by rainwater in a rainy season, low-concentration heavy metal ions such as lead (0.05-0.2 mg/L), zinc (0.1-0.5 mg/L), cadmium (0.005-0.02 mg/L) and mercury (0.001-0.003 mg/L) are released to a water body, and humic acid is generated after the fallen leaves of the broad-leaved forest in the mountain area are decomposed. The complex-state heavy metals are difficult to capture by conventional flocculating agents, cannot be removed through natural sedimentation, and cannot effectively remove heavy metals in the water body, so that the use safety of regional farmland irrigation and temporary miscellaneous water is threatened. The second problem is the interference of ammonia nitrogen carried by the cultivation wastewater to a heavy metal complexing system. After the wastewater generated by the regional dispersed livestock and poultry cultivation is converged into a stream ditch, ammonia nitrogen is brought in, the concentration in dry season is maintained at 0.8-2.5mg/L, the concentration in rainy season is influenced by surface flooding superposition, and the concentration can be increased to 3.0-5.2mg/L. Under the action of rock stratum leaching, the water body is weak acid, and ammonia nitrogen mainly exists in an ammonium ion form in the environment. The coordination capability difference of the ammonium ions and the heavy metal ions is large, the low-concentration ammonium ions have no obvious competitive interference on the heavy metal-humic acid complex, the complex structure is difficult to damage, the heavy metal dissociation is difficult to be promoted, but the ionic strength of the water body can be indirectly changed, so that the floccules formed by the conventional flocculant are loose and the sedimentation performance is poor. In addition, the synergistic pollution of ammonia nitrogen and heavy metals further aggravates the water quality deterioration, the conventional treatment cannot remove both types of pollutants, the treatment efficiency is finally caused to slide down, and the basic water quality requirements of farm irrigation and temporary miscellaneous water cannot be met. The third difficulty is the difficult degradation characteristics of the metal cyanide complex. The small-sized gold ore in the area adopts the cyanide gold extraction process, after the ore point is shut down, the residual medicament can slowly release t