CN109721200B

CN109721200B - Method for treating salted kelp brine

Info

Publication number: CN109721200B
Application number: CN201910150244.0A
Authority: CN
Inventors: 梁永胜; 邢岳松; 梁永明; 窦晓霞; 苗深义; 张进奎
Original assignee: Weihai Rentai Biotechnology Co ltd
Current assignee: Weihai Rentai Biotechnology Co ltd
Priority date: 2019-02-28
Filing date: 2019-02-28
Publication date: 2021-08-31
Anticipated expiration: 2039-02-28
Also published as: CN109721200A

Abstract

The invention relates to a method for treating salted kelp brine, which solves the technical problem that the existing salted kelp brine cannot be effectively treated and comprises the step of filtering fresh kelp salted brine; flocculation and coagulation; a salt preparation step; preparing a seaweed extract; the method can be widely applied to the field of treatment of the salted kelp brine.

Description

Method for treating salted kelp brine

Technical Field

The invention relates to the field of sewage treatment, in particular to a treatment method.

Background

The processing and production of the salted kelp in China are mainly concentrated in coastal areas such as Shandong, Fujian, Liaoning and the like. Blanching the fresh kelp by hot water at 80-90 ℃, and then mixing with salt for dehydration to obtain the salted kelp. A large amount of kelp salting brine is generated in the process of processing salted kelp, and the wastewater is generally directly discharged into the sea without any treatment.

Researches show that the salted kelp brine which is desalted by adding salt contains a large amount of organic substances such as protein, trehalose gum, fucoidin and mannitol besides a large amount of sodium chloride, so that the serious COD (chemical oxygen demand) of the salted water exceeds the standard. The kelp salinization brine is directly discharged into the sea, and can cause serious seawater pollution.

The method for treating the high-salinity kelp salinized brine does not have a good treatment method at present; the method can not extract salt with higher purity by concentration without removing protein and other organic substances in brine, and can only dry the salt in the sun or directly discharge the salt in the open air. If the waste water is directly discharged, the sea area is polluted; if the salt is sunned in the open air, the land is polluted.

Disclosure of Invention

The invention aims to solve the technical problem that the existing method cannot effectively treat the kelp salinization brine, and provides the kelp salinization brine treatment method which is simple in process, strong in operability and low in cost.

In order to achieve the aim, the invention provides a method for treating saline brine for blanching fresh kelp, which comprises the following steps:

1. filtering fresh kelp salinized brine: conveying the fresh kelp blanching salinized brine into a raw material water tank by a water pump, conveying the raw material water from the raw material water tank to a bag filter by the water pump for filtering, wherein the mesh number of a filtering screen is 80-120 meshes, filtering impurities in the raw material water, and pumping the filtrate into a filtrate tank;

2. flocculation and coagulation: adding a composite flocculant and a polymerizer, uniformly stirring, standing for flocculation, wherein in the process, almost all organic matters such as protein and the like in the salted brine are flocculated and separated out from the brine, and simultaneously removing peculiar smell and COD in the salted brine of the kelp; the flocculating agent and the polymerizing agent are both self-made. The preparation method comprises the following steps: taking porous stone powder and 30 g of powder, adding 70 g of water into the powder, soaking the powder for 10 minutes, shearing the powder into paste at a high speed of 3000 r/min, adding the paste into brine according to the proportion of 1-10% of the brine, preferably 5-10%, stirring and mixing the mixture uniformly, and adsorbing proteins and other organic matters in the brine by the pasty porous stone powder; the polymerization agent is compounded by cation (polyvinyl amide) and iron ion (ferric chloride), 8 parts of ferric chloride and 2 parts of cation; adding 0.1-1% of brine, preferably 0.5-1% of brine, stirring and mixing for 30 minutes, aggregating the flocculant absorbed with protein into compact floccule, separating out from water, and filtering out by a filter screen of 200 meshes.

3. Preparation of salt

Filtering the flocculated and polymerized brine by a packing auger filter to separate clear liquid from flocculated slag. And filtering to obtain brine clear liquid, pumping the brine clear liquid into a double-effect evaporation concentrator through a water pump for concentration, putting the brine clear liquid into a cooling crystallizer after the Baume degree of a concentrated solution reaches 1.2, and cooling and crystallizing to form salt.

4. Preparation of seaweed extract

The filter residue obtained by filtering is separated, dehydrated, purified and dried to obtain an extract which mainly contains seaweed protein, trehalose gum, fucoidin, mannitol, iodine, potassium salt and other substances and is a high-quality raw material for preparing the seaweed protein fertilizer.

The invention has the advantages that the flocculant and the polymerizer can effectively remove protein and other organic matters in the brine soaked by kelp, and can also extract salt and seaweed extract from waste brine, so that the brine discharge can be prevented and pollution to sea areas can be caused, and the prepared seaweed extract can be used as a high-quality raw material for preparing seaweed protein fertilizer, thereby having better economic benefit and achieving the effect of environment-friendly discharge.

Detailed Description

The technical solution of the present invention will be described in detail with reference to examples.

Example 1

A method for treating saline brine generated by blanching fresh kelp specifically comprises the following steps:

1. flocculation and coagulation of fresh kelp salinized brine

Taking 1 ton of kelp salinization brine, pumping the kelp salinization brine into a flocculation tank through a water pump, adding a composite flocculant and a polymerization agent, uniformly stirring, and standing for flocculation; the composite flocculant is made of porous stone powder macromolecular sieve material, when in use, water with the mass percentage concentration of 30% is prepared, the flocculant is expanded into paste through high-speed shearing of 3000 r/min, and is mixed with kelp salinization brine according to 5% of the mass of the brine; simultaneously remove the peculiar smell and COD in the kelp salinization brine.

The mass percentage concentration of organic matters such as protein and the like in the brine after flocculation filtration is reduced from the original 2 percent to about 0.1 percent; COD is reduced by about 2000 times.

2. Preparation of salt

And (3) pumping the filtered clear brine liquid into a double-effect evaporation concentrator through a water pump for concentration, putting the concentrated brine liquid into a cooling crystallizer after the Baume degree of the concentrated brine liquid reaches 1.2, and cooling and crystallizing the brine liquid to form salt. The crystal can be crystallized when the Baume degree reaches 1.2, and the crystal is not crystallized when the Baume degree is lower than 1.2; above 1.2, the particles become hard lumps.

3. Preparation of seaweed extract

Filtering to obtain aggregated floc, diluting with water, centrifuging, crushing to separate protein and other organic matters from flocculant, and settling with centrifugal settling machine to separate clear liquid from flocculant; concentrating the separated clear liquid by a concentrator until the solid content reaches 35%, and spray drying to obtain a powdery extract. The obtained extract mainly contains seaweed protein, trehalose gum, fucoidin, mannitol, iodine, potassium salt and other substances, and is a high-quality raw material for preparing seaweed protein fertilizer; the settled flocculant residue is used for preparing fertilizer.

Finally, the treatment method provided by the invention can realize the purpose of zero emission of the kelp brine. The matter extracted from the filtered aggregate flocculate contains trehalose gum, dunaliella salina polysaccharide, mannitol, iodine, amino acid, gibberellin, etc. and is used in compounding special fertilizer with the functions of promoting metabolism, promoting photosynthesis, strengthening plant body, raising resistance, preventing diseases and pests, etc.

The following table shows the effect of different flocculant and polymerizer additions on the removal of organic materials such as proteins and COD.

Note: the addition amounts of the flocculating agent and the polymerization agent are the mass percent of the brine.

As can be seen from the table above, when the added flocculating agent accounts for 5% and 10% of the mass of the brine; meanwhile, when the added polymerization agent accounts for 0.5 percent and 1 percent of the mass of the brine, the effect of removing organic matters is best.

When the mass percentage of the added flocculating agent in the brine is 5 percent and 10 percent; meanwhile, when the added polymerization agent accounts for 0.5%, 1% and 0.1% of the mass of the brine, the effect of reducing COD is best.

Claims

1. A method for treating salted kelp brine is characterized by comprising the following steps:

(1) conveying the fresh kelp blanching salinized brine into a raw material water tank by a water pump, conveying the raw material water from the raw material water tank to a bag filter by the water pump for filtering, filtering impurities in the raw material water, and pumping a filtrate into a filtrate tank;

(2) adding a flocculating agent and a polymerizing agent, stirring uniformly, and standing for flocculation;

(3) filtering the flocculated liquid obtained in the step (2) by using a packing auger filter to separate clear liquid from flocculated slag; filtering clear liquid, pumping the clear liquid into a double-effect evaporation concentrator through a water pump for concentration, putting the concentrated clear liquid into a cooling crystallizer, and cooling and crystallizing the concentrated clear liquid into salt;

(4) adding water to dilute the aggregated floc obtained by filtering in the step (3), centrifuging and crushing to separate organic matters from the flocculant, and then settling the flocculant by a centrifugal settling machine to separate clear liquid; concentrating the separated clear liquid by a concentrator, and spray drying to obtain a powdery extract;

in the step (2), the flocculating agent is porous stone powder, is soaked in water, is sheared into paste at a high speed, is added into brine, and is stirred and mixed uniformly;

in the step (2), the polymerizer is prepared by compounding polyvinyl amide and ferric chloride;

in the step (2), the addition amount of the flocculating agent accounts for 5-10% of the mass percentage of the brine; the addition amount of the polymerization agent accounts for 0.5-1% of the mass percentage of the brine.

2. The method for treating the brine of salted kelp as claimed in claim 1, wherein the clear solution obtained by filtering in the step (3) is concentrated in a double-effect evaporation concentrator by a water pump, and the concentrated solution is cooled and crystallized to form salt after the Baume degree of the concentrated solution reaches 1.2.