CN110642484A - Dewatered sludge curing agent - Google Patents
Dewatered sludge curing agent Download PDFInfo
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- CN110642484A CN110642484A CN201910859095.5A CN201910859095A CN110642484A CN 110642484 A CN110642484 A CN 110642484A CN 201910859095 A CN201910859095 A CN 201910859095A CN 110642484 A CN110642484 A CN 110642484A
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- sludge
- curing agent
- water content
- polyvinyl acetate
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- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F11/00—Treatment of sludge; Devices therefor
- C02F11/008—Sludge treatment by fixation or solidification
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- Hydrology & Water Resources (AREA)
- Engineering & Computer Science (AREA)
- Environmental & Geological Engineering (AREA)
- Water Supply & Treatment (AREA)
- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Curing Cements, Concrete, And Artificial Stone (AREA)
- Soil Conditioners And Soil-Stabilizing Materials (AREA)
- Treatment Of Sludge (AREA)
Abstract
The invention discloses a dewatered sludge curing agent which is characterized by comprising the following components in percentage by weight: 55-75% of magnesium oxide; 15-35% of magnesium chloride; 5-15% of polyvinyl acetate. The invention has the beneficial effects that: the formula is simple, the using amount is small, the operation is simple and convenient, and only the sludge and the curing agent need to be mixed according to the mass ratio of 1 (0.08-0.15), and the mixture is spread and aired after being uniformly stirred; the solidified sludge has uniform property, the surface and the internal strength are the same, the surface is not cracked, and the interior is not soft and sticky; the curing speed is high, and the curing effect is good.
Description
Technical Field
The invention relates to the technical field of environmental engineering, in particular to a dewatered sludge curing agent.
Background
The sewage sludge has large amount and high water content, and the water is required to be removed and the strength is increased before the landfill so as to reduce the volume, enhance the stability and reduce the landslide risk.
The general treatment mode is to perform primary dehydration on the sludge with the water content of more than 98% and then perform solidification treatment, while the use amount of the existing solidifying agent is about 20% -35% of the sludge amount, thus greatly increasing the sludge treatment amount and bringing great pressure to landfill sites.
Therefore, the invention of a sludge curing agent with low dosage, low cost and simple ingredients is needed. In particular to dewatered sludge with the water content of less than 85 percent after preliminary dewatering in municipal sewage plants and percolate treatment plants.
In addition, the curing agent in the Chinese patent application CN105254166B, although the adding amount is low, has the problems of complex preparation method, energy consumption in the preparation process and water pollution possibly generated.
Disclosure of Invention
In order to overcome the defects of the prior art, the invention develops a dehydrated sludge curing agent with low dosage and low cost.
In order to realize the purpose of the invention, the adopted technical scheme is as follows:
a dewatered sludge curing agent comprises the following components in percentage by weight:
55-75% of magnesium oxide;
15-35% of magnesium chloride;
5-15% of polyvinyl acetate.
In a preferred embodiment of the invention, the sludge and the curing agent are mixed according to a mass ratio of 1 (0.08-0.15).
The invention has the beneficial effects that:
the formula is simple, the using amount is small, the operation is simple and convenient, and only the sludge and the curing agent need to be mixed according to the mass ratio of 1 (0.08-0.15), and the mixture is spread and aired after being uniformly stirred; the solidified sludge has uniform property, the surface and the internal strength are the same, the surface is not cracked, and the interior is not soft and sticky; the curing speed is high, and the curing effect is good.
Drawings
FIG. 1 is a graph showing the change of unconfined compressive strength with time when 10% of a curing agent is added to 80% water content sludge.
FIG. 2 is a graph showing the effect of polyvinyl acetate on sludge solidification.
FIG. 3 is a graph showing the effect of sodium carboxymethylcellulose on sludge solidification.
FIG. 4 is a graph showing the effect of sodium alginate on sludge solidification.
Fig. 5 is a graph of data from experimental studies.
Detailed Description
The traditional inorganic curing agent has good dehydration effect and low price, but only the inorganic curing agent is used for achieving the landfill effect, the addition amount generally needs to reach more than 25% of the sludge amount, the volume of the landfill sludge is greatly increased, the burden of a landfill site is increased, and therefore, the mode of combining the inorganic curing agent and the organic curing agent is adopted, and the ideal effect can be achieved by ensuring a small amount of addition.
Example 1
A dewatered sludge curing agent is prepared from 65% of magnesium oxide, 15% of magnesium chloride and 15% of polyvinyl acetate through mixing, and mixing uniformly, namely: curing agent 1: 0.06 percent of the water content is added into the dewatered sludge with the water content of 80 percent, and the mixture is placed in a room after being uniformly stirred.
The sludge solidification effect is as follows: when the sludge is aged for 7 days, the water content of the solidified sludge is 63.92 percent, and the unconfined compressive strength is 81.2 KPa.
Example 2
A dewatered sludge curing agent is prepared from 55% of magnesium oxide, 32% of magnesium chloride and 13% of polyvinyl acetate through uniformly mixing, and mixing the following raw materials in percentage by weight: curing agent 1: 0.11 of the water content is added into the dewatered sludge with the water content of 80 percent, and the mixture is placed in a room after being uniformly stirred.
The sludge solidification effect is as follows: when the sludge is aged for 7 days, the water content of the solidified sludge is 58.78 percent, and the unconfined compressive strength is 110.3 KPa.
Example 3
A dewatered sludge curing agent is prepared from 68% of magnesium oxide, 23% of magnesium chloride and 9% of polyvinyl acetate through mixing, and mixing uniformly, mixing the following components in percentage by weight: curing agent 1: 0.11 of the water content is added into the dewatered sludge with the water content of 80 percent, and the mixture is placed in a room after being uniformly stirred.
The sludge solidification effect is as follows: when the sludge is aged for 7 days, the water content of the solidified sludge is 59.32%, and the unconfined compressive strength is 104.2 KPa.
Compared with CN201710998984.0, the sludge curing agent is prepared by mixing three components of high alumina cement, portland cement and dihydrate gypsum, can meet the landfill requirement, and needs to be added in a weight ratio of 20-30%. Compared with the prior art, the invention has simple formula, can directly purchase materials, does not need processing, and is convenient and quick.
The development principle of the invention is as follows:
after preliminary screening, three organic curing agents of sodium alginate, polyvinyl acetate and sodium carboxymethylcellulose are combined with a magnesium oxide and magnesium chloride inorganic curing agent to carry out a curing test, and the unconfined compressive strength result is found to be as follows: polyvinyl acetate > sodium alginate > sodium carboxymethylcellulose; the water content is more than sodium carboxymethylcellulose and more than sodium alginate and polyvinyl acetate; the inside and the outside of the solidified sludge added with the polyvinyl acetate are uniform, the surface of the solidified sludge added with the sodium alginate is full of cracks, the solidified sludge added with the sodium carboxymethyl cellulose is full of cracks, and the shell is hard and the inside of the shell is sticky and soft. Polyvinyl acetate was therefore identified as a preferred organic curing agent formulation.
The addition amount of the organic curing agent is unchanged (1%), the addition amount of the inorganic curing agent is changed, and when the water content of the sludge is 80%:
when 3 percent (based on the wet weight of the original sludge as 100 percent) of inorganic curing agent is added, the water content is 68.938 percent after the mixture is kept still for 7 days;
when 5% of inorganic curing agent is added, standing for 7d until the water content is 66.490;
when 10% of inorganic curing agent is added, the water content is 61.212% after standing for 7d, and the unconfined compressive strength is obviously enhanced along with the increase of the addition amount.
Therefore, for the sludge with the water content of 80%, about 10% of inorganic curing agent is added to enable the sludge to meet the landfill requirement within 7 days, if the initial water content of the sludge is higher or the reduction of the water content is accelerated, the dosage of the curing agent can be increased as required, and conversely, the dosage can be reduced; however, if the amount of the additive is too high, the difficulty in stirring the sludge and the curing agent is increased, which is not favorable for uniform mixing.
The addition amount of the inorganic curing agent is unchanged (10%), the dosage of the polyvinyl acetate organic curing agent is changed, and when 0.5% of the inorganic curing agent is added, the water content is 65.503% after the polyvinyl acetate organic curing agent is kept still for 7 d; when 1% is added, standing for 7d until the water content is 65.695%; when 1.5% is added, the water content 65.442 is still kept for 7d, the unconfined compressive strength increases with the addition amount, but the change amplitude is not obvious like the water content. Therefore, from the viewpoint of cost reduction, the amount of polyvinyl acetate to be added can be selected to be small.
In the invention, 5-15% is relative to 100% of the curing agent, namely, the polyvinyl acetate accounts for 5-15% of the total components; the amount of polyvinyl acetate used here is 0.5%/1%/1.5% of the amount of wet sludge, relative to the amount of wet sludge.
The magnesium oxychloride cement is made up by using light-burned magnesium oxide (MgO) and magnesium chloride (MgCl)2) Water (H)2O) the air-hardening gelled material formed according to a certain proportion has quick hardening characteristic, so that magnesium oxide and magnesium chloride are adopted as curing agents and can react with moisture in the sludge to form a crystalline phase, thereby enabling the sludge to achieve the curing effect;
1. experimental research shows that when the molar ratio of the magnesium oxide to the magnesium chloride is 8.76-10.3, a good mechanical effect can be achieved (as shown in figure 5).
2. The total amount of the inorganic curing agent is kept unchanged, the molar ratio of the magnesium oxide to the magnesium chloride is changed, the unconfined compressive strength is shown in figure 5, and the mechanical strength is higher when the molar ratio is 4/1 and 10/1. 4/1, 7/1 and 10/1 are selected for further experiments, and the experimental results are as follows: when the magnesium oxide/magnesium chloride is 4/1, the unconfined compressive strength is 14.931; when the magnesium oxide/magnesium chloride is 7/1, the unconfined compressive strength is 13.792; when the molar ratio of magnesium oxide/magnesium chloride is about 10/1, the mechanical strength of the solidified sludge is optimum because the unconfined compressive strength is 15.182 when the magnesium oxide/magnesium chloride ratio is 10/1.
The polyvinyl acetate can be used for preparing an adhesive and can also be used as a water coagulant, so that the polyvinyl acetate can be used as an organic curing agent to be added into sludge, can achieve the effects of increasing viscosity and adsorbing and bridging, is favorable for the combination of an inorganic curing agent and the sludge, and further enhances the curing effect.
Claims (2)
1. The dewatered sludge curing agent is characterized by comprising the following components in percentage by weight:
55-75% of magnesium oxide;
15-35% of magnesium chloride;
5-15% of polyvinyl acetate.
2. The dewatered sludge solidifying agent according to claim 1, wherein: the sludge and the curing agent are mixed according to the mass ratio of 1 (0.08-0.15).
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
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| CN201910859095.5A CN110642484A (en) | 2019-09-11 | 2019-09-11 | Dewatered sludge curing agent |
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| CN201910859095.5A CN110642484A (en) | 2019-09-11 | 2019-09-11 | Dewatered sludge curing agent |
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Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1220980A (en) * | 1991-01-29 | 1999-06-30 | C·F·沙夫 | Beton product |
| CN101260230A (en) * | 2007-03-07 | 2008-09-10 | 许培圣 | Hot-pressing forming artificial stone material and preparation method thereof |
| CN102503328A (en) * | 2011-09-30 | 2012-06-20 | 北京旷世达资源环境工程发展中心 | Universal rock and soil curing agent and preparation method thereof |
| CN105314817A (en) * | 2014-08-01 | 2016-02-10 | 蒋华 | Treatment method for dewatered sludge of domestic sewage treatment plant |
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2019
- 2019-09-11 CN CN201910859095.5A patent/CN110642484A/en active Pending
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1220980A (en) * | 1991-01-29 | 1999-06-30 | C·F·沙夫 | Beton product |
| CN101260230A (en) * | 2007-03-07 | 2008-09-10 | 许培圣 | Hot-pressing forming artificial stone material and preparation method thereof |
| CN102503328A (en) * | 2011-09-30 | 2012-06-20 | 北京旷世达资源环境工程发展中心 | Universal rock and soil curing agent and preparation method thereof |
| CN105314817A (en) * | 2014-08-01 | 2016-02-10 | 蒋华 | Treatment method for dewatered sludge of domestic sewage treatment plant |
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