CN101289268B

CN101289268B - Process for dehydrating activated sludge by waste alkaline residue/alkali liquor

Info

Publication number: CN101289268B
Application number: CN2008100736039A
Authority: CN
Inventors: 李肇忠
Original assignee: Individual
Current assignee: Individual
Priority date: 2008-05-30
Filing date: 2008-05-30
Publication date: 2010-07-07
Anticipated expiration: 2028-05-30
Also published as: CN101289268A

Abstract

The invention discloses a method for dewatering activated sludge by utilizing waste alkali slag/alkali liquor. The method of the invention mainly includes that the waste alkali slag/alkali liquor is first added with a certain amount of calcium oxide to be evenly mixed and then injected into the activated sludge which goes through gravity settling, and evenly mixed; fully-dissolved polyacrylamide is then added and evenly mixed; the dry basis ratio of the alkali slag, the calcium oxide, the polyacrylamide and the activated sludge is 25 to 40 : 7 to 13 : 0.12 to 0.25:100; after being fermented and air-dried, the dewatered sludge is served as agricultural fertilizer. The dewatering method of the invention has the advantages of low cost, high efficiency of sludge dewatering, good stability and low content of heavy metal in yielding sludge and achieves the purpose that the waste alkali slag is recycled to treat the waste by the waste; in addition, the alkali slag contains the elements of calcium, magnesium and a small amount of sodium, potassium, chloride and the like, which are necessary for the plant growth and can be used for making fertilizer in the agricultural production.

Description

The method of dehydrating activated sludge by waste alkaline residue/alkali liquor

Technical field:

The present invention relates to solvay soda process and make the method for the application, particularly dehydrating activated sludge by waste alkaline residue/alkali liquor of discarded alkali slag/alkali liquid in the soda industry.

Background technology:

Present dewatering technology of mud, polymer organic floculants such as many employing polyacrylamides, also having with iron system, aluminium is main flocculation agent, external also have report to utilize magnesium salts, zinc salt to make flocculation agent, domestic have enterprise to use lime and iron(ic) chloride, make active sludge produce flocculation and reach the mud-water separation purpose, this method mud extraction heavy metal content is big, and the treatment effect instability.

Chinese patent CN1196033A discloses a kind of utilization in the sulfate pulping production process, the white clay that the causticization green liquor stage obtains carries out the method that glue is handled to residual active sludge, and this method needs to carry out under 75-104 ℃ temperature, and processing condition are had relatively high expectations, power consumption is big, the processing cost height.

Summary of the invention:

The objective of the invention is to provide a kind of method of dehydrating activated sludge by waste alkaline residue/alkali liquor, this method cost is low, and sludge dewatering efficient height, and good stability can solve the problem of high problem of active sludge treatment cost and final recycling.

Using alkali slag/alkali liquid makes the method for activated sludge dehydration be:

(1) in the waste soda residue/alkali lye that fully dissolves the furnishing pasty state, adds calcium oxide earlier, and stir;

(2) mixture with alkali slag/alkali liquid and calcium oxide joins in the active sludge of gravity settling, and stirs;

(3) add again through abundant dissolved polyacrylamide, stir, make

(4) alkaline residue: calcium oxide: polyacrylamide: the butt ratio=25-40 of active sludge: 7-13: 0.12-0.25: 100;

(5) leave standstill the back flocculate precipitate through plate-and-frame filter press press filtration mud extraction;

(6) mud after the dehydration is made agricultural fertilizer through fermented air-dried.

Described butt is than the ratio that is exactly the solid weight of each component anhydrous state.

Principle of work of the present invention is: the alkaline residue that produces in the soda ash manufacturing processed (alkali lye that contains waste residue) contains a large amount of precipitated chalks and compositions such as a certain amount of calcium hydroxide and magnesium hydroxide, add a certain amount of strong basicity calcium oxide in addition again and regulate its pH value to strong basicity enhancing alkaline residue activity, the metal hydroxides colloid surface has positive charge in addition, and the active sludge colloid surface has certain negative charge, calcium hydroxide and magnesium hydroxide colloid positively charged in the alkali lye reach electrical neutralizing effect with electronegative active sludge by coagulation, thereby make the flocculation of active sludge colloidal fine particle deposits yields, and precipitated chalk can play the effect of nucleon in these flocs units, the attached flco that forms thereon of active sludge fine particle thing is easy to precipitation more, add a certain amount of cationic high-molecular organic floculant polyacrylamide more therein, make mud further produce throwing out, reach the purpose of mud-water separation.

Advantage of the present invention is: cost is low, sludge dewatering efficient height, good stability, mud extraction heavy metal content are low, realize the utilizing again to reach the purpose of the treatment of wastes with processes of wastes against one another of discarded alkali slag; Contain the required elements of plant-growth such as calcium, magnesium and a spot of sodium, potassium, chlorine in addition in the alkaline residue, can make fertilizer and be used for agriculture production.

Embodiment:

The invention will be further elaborated below in conjunction with embodiment.

The present invention is fully dissolved fresh alkaline residue to stir into and is added calcium oxide stir (alkali lye that contains waste residue directly adds calcium oxide and stirs after gravity settling concentrates) behind the pasty state by a certain percentage, be added to again stir in the active sludge that Sewage Plant produces after, add again through abundant dissolved polyacrylamide solution (preferred concentration is 0.1%-0.5%), four butts ratio is: alkaline residue: calcium oxide: polyacrylamide: active sludge=25-40: 7-13: 0.12-0.25: 100, leave standstill 5～10min after stirring, under 0.2～1.0MPa pressure, carry out press filtration through plate-and-frame filter press, dwell time is 60～120min, the mud extraction water ratio can reach 49.16%～62.33%, if the mud objectionable impurities after the processing does not exceed standard, be interrupted air blast and spontaneous fermentation through 10～20d, oven dry or shine dry doubling and pulverize after can be directly as a kind of fertilizer application in agriculture production.

If heavy metal content exceeds standard in the active sludge, should carry out pre-treatment earlier and make it to meet national requirements to reduce heavy metal content.

Alkaline residue, calcium oxide, polyacrylamide, active sludge butt ratio are: active sludge, alkaline residue are dried the actual butt weight when reaching the constant weight state in 8～10 hours in 105 degrees centigrade of baking ovens; Polyacrylamide, calcium oxide are pressed the weight of actual weighing.

Embodiment:

Add 12 kilograms in calcium oxide toward the fresh alkaline residue 75 kilograms (water ratio is 45.33%) that just unloads and stir back injection 1300L through abundant spissated active sludge (water ratio 91.55% from plate-and-frame filter press, density 1000g/L) stirred 5 minutes, add polyacrylamide solution 60L (concentration is 0.41%) again, 100) and stir (alkaline residue: calcium oxide: polyacrylamide: active sludge=37.33: 10.92: 0.22:, leave standstill 5min, under 0.5MPa pressure, carry out press filtration through plate-and-frame filter press, dwell time is 70min, and the mud extraction water ratio is 55.36%.Mud is through fully fermentation and natural air drying can be used as agricultural fertilizer after pulverizing.

Claims

1. use the method that solvay soda process is produced the discarded alkali slag that produces in the soda ash process or made activated sludge dehydration the alkali lye that contains alkaline residue, it is characterized in that: comprise the steps:

(1), and stirs earlier at the discarded alkali slag of abundant dissolving furnishing pasty state or contain in the alkali lye of alkaline residue and add calcium oxide;

(2), and stir with discarded alkali slag or contain the alkali lye of alkaline residue and the mixture of calcium oxide joins in the active sludge of gravity settling;

(3) add again through abundant dissolved polyacrylamide, stir, make

(4) alkaline residue: calcium oxide: polyacrylamide: the butt ratio=25-40 of active sludge: 7-13: 0.12-0.25: 100, described butt is than being the ratio of each component anhydrous state solid weight;