JPS6295192A - Method for flocculating suspended matter in waste water - Google Patents

Abstract

PURPOSE:To form large flocs having high strength by mixing anionic and cationic high-polymer electrolytes, as well as a bivalent metallic salt and ammonium salt, adding the mixture to waste water and adequately adjusting the amt. of both the high-polymer electrolytes to be added. CONSTITUTION:The anionic high-polymer electrolyte (e.g., Na salt of a copolymer of methacrylamide and methacrylic acid) and cationic high-polymer electrolyte (e.g., trialkyl ammoniethyl polymethacrylate salt) as well as the bivalent metallic salt (e.g., Ca chloride) and/or ammonium salt (e.g., ammonium chloride) are mixed. A flocculating agent in which the content of either of the above- mentioned two high-polymer electrolytes is in excess of the amt. of reaction with the suspended matter in waste water is added in the form of an aq. soln. to the waste water so as to react with the waste water. An aq. soln. of the high-polymer electrolytes of the reverse polarities reacting with the above- mentioned excess amt. is then added to the waste water so as to react therewith. As a result, large and highly strong flocs are formed.

Description

[Detailed Description of the Invention] "Industrial Application Field" The present invention relates to an improved flocculation method for treating industrial wastewater, domestic wastewater, etc. with a flocculant to effectively flocculate suspended substances in the wastewater. .

``Prior art'' Conventionally, in order to completely treat wastewater as described above, a method has been used in which an anionic polymer flocculant or a cationic polymer flocculant is added to water alone and reacted with suspended solids, or both. Make sure that the method of sequential addition and reaction is being used.

``Problem to be Solved by the Invention J'' In the above conventional technology, the method of adding the anionic polymer 11 [agent alone] causes the suspended solids to aggregate due to adsorption.
The generated flocs are small and have a low electric current, and the speed of sedimentation and filtration in the next step is slow, and dehydration is often insufficient.Therefore, there is also a method of adding a cationic polymer flocculant alone. The properties and size of 70 Tsuku and its 119 aqueous nature (there are some differences, but they are almost the same, and the method of sequentially adding an anionic polymer flocculant and a cationic polymer flocculant has an excellent flocculating effect, Although it becomes a large floc, the bond strength is weak due to cross-linking adsorption, the strong electric current is low and it is easy to crush, and it is hydrophilic and has poor quick dehydration properties, so it is especially recommended to use raw fabrics such as υ0 pressure filtration and belt press FA. When performing Yusui treatment, the sludge after dewatering has poor peelability from the P cloth, and the dewatering efficiency is also poor.In other words, when the above flocs are dehydrated under pressure, 70 pieces are broken and the dewatering channels between the flocs are broken. is closed and the water inside remains unremoved,
In addition, there are problems in that after crushing, the flocs close the grains of the raw material, aggravating the decline in dewatering efficiency.

The purpose of the present invention is to provide an excellent method for flocculating suspended solids in wastewater to solve these problems.

``Means for Solving the Problems'' The method for flocculating suspended solids in wastewater according to the present invention #i consists of two steps, the first step is to use an anionic polymer electrolyte, a cationic polymer electrolyte, and a divalent metal salt. and or an ammonium salt, and in which the amount of one of the two shoulder molecular electrolytes is in excess of the amount of reaction with the suspended matter in the wastewater is made into an aqueous solution and added to the wastewater. The second step is to react by adding an aqueous solution of a polymer electrolyte of the opposite nature, e, which reacts with the excess l.

When the mixed coagulant is rubbed with the water bath solution V, the anionic polymer electrolyte and the cationic polymer electrolyte are blocked from their ionic properties and co-dissolved in close proximity to each other. When this is added to wastewater, it restores ionicity and becomes a precipitate with a huge molecular weight, taking in suspended matter and producing a large amount of 70 kg. adjustment,
By adding a polymer electrolyte of opposite nature that reacts with the excess, extremely large and strong flocs are produced.

The anionic polymer electrolyte and cationic polymer electrolyte used in the mixed flocculant or used alone can be in the form of liquid, paste, or powder. The mixing ratio of the two in the mixed flocculant is 10:1 to 3:1 and 1:1 as the effective content.
The ratio is 0 to 1:3, and outside this range, it is undesirable to make the amount of one of the polymer electrolytes in excess of the amount of the polymer electrolyte reacting with the suspended solids, and the L-collecting effect will be reduced.

The mixing ratio of the divalent metal salt and/or ammonium salt is 50 to 1000 relative to the total weight of both molecular electrolytes.
%, preferably 100 to 500%, and these are placed in the same container and mixed to obtain a mixed flocculant.

Types of anionic polymer electrolytes include sodium salts of copolymers of acrylamide or methacrylamide and acrylic acid or methacrylic acid, and sodium acrylamide-2-methylpropanesulfonate copolymers; examples of cationic polymer electrolytes include Cation modified products of methacrylic acid ester polymers and copolymers [e.g., poly(trialkyl methacrylate (also d-dialkyl monobenzyl)) ammonioethyl salt, diethylaminoethyl methacrylate/triethylaminoethyl methacrylate/acrylamide copolymer, methacrylate ff1N-N'-dibrukylaminoalkyl/acrylamide copolymer, chloride copolyalkylene/polyamine of trialkylaminoalkyl methacrylate/acrylamide copolymer and its conductor [e.g., polyethyleneimine, alkylated polyalkylenepolyamine] Examples of divalent metal salts include calcium chloride, calcium nitrate, and magnesium chloride, and examples of ammonium salts include ammonium chloride, ammonium sulfate, ammonium oxalate, ammonium carbonate, and ammonium nitrate.

Before treating wastewater, the properties of the wastewater, i.e., the type, concentration, and pH of suspended solids, are measured in advance, and the mixed flocculant is prepared by measuring the types of anionic polymer electrolyte and cationic polymer electrolyte, and the following. It is preferable to select a mixing ratio in which either one of the two contains an excess amount of the reactant with the suspended solids in the wastewater. To dissolve the mixed flocculant in water as a preliminary step in the tX1 stage before adding it to wastewater, it is best to adjust the total of both molecular electrolytes to 0.2 to 5.0 Total amount of salt and/or ammonium salt 05-20.0% preferably 1.0-1
It is important to adjust it so that it is 0.0%, o,
If it is less than 5X, the anionic polymer electrolyte and the cationic polymer electrolyte will react and all the precipitates will be formed.
．． If it is 0% or more, the nonionic polymer electrolyte becomes nonionic and is masked again after adding the flocculant to the wastewater to return to the anionic state, and the specific cationic polymer electrolyte remains unmasked for the entire time it takes to react. is delayed. An aqueous solution of this mixed flocculant is added to the wastewater and reacts with the suspended solids to form flocs. At this time, it is preferable to adjust the total amount of the anionic polymer electrolyte and cationic polymer electrolyte to be 0.05 to 5.00% by weight based on the suspended solids. Next, as a preliminary step for treatment with a reverse polymer electrolyte in @2 steps, the polymer electrolyte is dissolved in total water to form an aqueous solution of 0.1 to 3Xa degree, and the excess polymer electrolyte is removed. The amount is calculated in advance, a corresponding amount of t is added, and the reaction is caused to produce extremely large and strong flocs.

"Operation" In the first stage of treatment, as a preliminary step, the mixed flocculant is dissolved in water to create an aqueous solution, and the anionic polymer electrolyte is
It reacts with a valent metal salt, an ammonium salt, or both, and becomes nonionized, and retains its hydrophilicity.The cationic groups of the parent cationic polymer/IL electrolyte are masked by the ammonium ions of the ammonium salt, and the polymer electrolytes are separated from each other. They do not react and come close to each other and become co-soluble.

Next, when this aqueous solution f: is added to wastewater, the divalent metal ions react with the suspended matter or are diluted, so that the bond with the nonionized polymer electrolyte is weakened and finally broken, so that the molecular electrolyte is The ammonium ion that was masking the co-dissolved cationic polymer 71 reacts with the suspended matter or is diluted, so the masking is released and the co-dissolved cationic polymer 71 becomes a cationic polymer electrolyte. Because of this, the polymer electrolyte reacts with the suspended solids while proceeding with the precipitation reaction.For this reason, the reaction between adjacent polymer electrolytes causes the polymer chains to intertwine and become macromolecules. As it precipitates, it takes in all the suspended solids and agglomerates them to form a large 70 pieces.
One of the excess polyelectrolytes still remains unreacted. In the two-step process, when an aqueous solution of a polymer electrolyte, which reacts with the excess and has the opposite properties, is added, the precipitation reaction with the excess increases, taking in the flocs and making them grow larger and larger. , and form a flock with high strength.

"Example" (1) Wastewater of M chemical company (turbidity a degree 600W/i%
pH 6, 8), as a first step, the sodium salt of the anionic polyelectrolyte methacrylamide methacrylic acid copolymer, the cationic polyelectrolyte polymethacrylate trialkylammonioethyl salt, and the metal salt of 2f1fi. A mixed flocculant (indicated by M in Table 1) prepared by mixing calcium in a ratio of 4:1:5 was dissolved in water K% by the method shown in mf to obtain each o, sX-o, 2X, and 1. An OX co-solution was prepared, and this was added to wastewater at a rate of addition of anionic polymer electrolyte of 1.2X/ss, thionic polymer electrolyte of o, and 3X/ss. Former #i
The amount was in excess of the amount reacted with the suspended solids. When I processed this, a fairly large 70 pieces were generated. Next, in the second step, the cationic polymer electrolyte diethylaminoethyl methacrylate/triethylaminoethyl methacrylate salt acrylamide copolymer (indicated by 81 in Table 1) is made into a 0.2N aqueous solution and the addition rate to the wastewater is , 3N/8
The results shown in Table 1 were obtained.

For comparison, as a conventional method, methacrylamide/methacrylic acid copolymer (methacrylamide/methacrylic acid copolymer) was used alone (C in Table 1).
1-1) at an addition rate of 1.8%/8 days, and sodium salt of methacrylamide/methacrylic acid copolymer 0.9/BS and trialkylammonioethyl polymethacrylate salt Q , 99f;/SS was sequentially added (
(indicated by C, -2 in Table 1) is shown.

Table 1 Compared to the conventional aggregation method, the flocculation method of this example had significantly superior filtration ability, good SS removal rate, and very low moisture content of the cake. Also, the peelability of the cake from the oven cloth using the oven cloth belt press was good, and there was no clogging of the oven cloth.

(2) Anionic polymer electrolyte acrylamide/acrylic acid co-heavy metal using excess sludge (@turbidity @lf:1too~/), pH 6,8) from activated sludge treatment of factory wastewater of D Food Company as the first step. An agglomerate formed by mixing the sodium salt of , the trialkylammonioethyl polymethacrylate salt of a cationic polymer electrolyte, the divalent metal salt chloride, and the ammonium salt ammonium sulfate i in a ratio of 1:4:2:3. The agent (indicated by M2 in Table 2) was dissolved in water according to the method described above to obtain 0.2%, 0.8%, 0.4X and 0.6X co-solutions, which were added to wastewater at an addition rate. The anionic polymer electrolyte was added to the skin at a concentration of 2%/SS, and the cationic polymer electrolyte was added at a concentration of 8X/8s. The latter was in excess of the amount of reaction with suspended solids. When processed using this method, quite large flocs were generated. Next, in the second step, the anionic polymer electrolyte methacrylic acid
A copolymer of methacrylic acid (indicated by 82 in Table 2) was added to 0.
2N aqueous solution added to wastewater at a rate of 0.3X/8 days K
The following results were obtained as shown in Table 2. For comparison, as a conventional method, poly(trialkylammonioethyl methacrylate) [t-single C (indicated by c2-1 in Table 2) was treated at an addition rate of 7.3X/SS and the following case and acrylamide-acrylic acid copolymer were prepared. 0.65% sodium salt of
/SS and polymethacrylic acid trialkylammonioethyl salt 65X/s8 are sequentially added (indicated by C2-2 in Table 2).

Table 2 The flocculation method of this example has an extremely large filtration capacity and a high SS removal rate compared to the conventional flocculation method, and since the water contained in the flocs is easily separated, the water content of the cake after filtration is low.

"Effects of the Invention" The method of coagulating suspended solids in wastewater of the present invention is as described above.
As a step, an anionic polymer electrolyte and a cationic polymer electrolyte are mixed with a divalent metal salt and/or an ammonium salt, and one of the two corner molecular electrolytes reacts with suspended matter in wastewater. Using a flocculant in excess of the amount,
When this is dissolved in water as a preliminary work, it can be dissolved uniformly without precipitation, and when this aqueous solution is added to wastewater, the molecular electrolytes at both corners return to their original ionicity, and the effective reaction described above occurs. Then, in the second step, when all the reverse polyelectrolytes are added, the above reaction is amplified and occurs, resulting in very large, strong, and non-viscous flocs, which are difficult to use in the next screen. Solid-liquid separation processing such as filtration processing, press water squeezing processing using furnace cloth, roll press processing, and centrifugal dehydration processing can be carried out effectively, resulting in excellent processing capacity, high recovery rate of suspended solids, and dewatering. The moisture content of the resulting cake is low, and the molecular electrolytes at both ends of the mixed flocculant are easy to adjust. Especially when using filter cloth, the processing ability is extremely good, and the It has many effects such as good removability and less clogging of furnace cloth.

Claims (1)

[Claims] It is made by mixing an anionic polymer electrolyte and a cationic polymer electrolyte with a divalent metal salt and/or an ammonium salt, and the amount of either of the above-mentioned polymer electrolytes is equal to that of suspended solids in wastewater. In wastewater, the flocculant in excess of the reaction amount is made into an aqueous solution and added to the wastewater to react, and then an aqueous solution of a reverse polymer electrolyte that reacts with the excess amount is added and reacted. Flocculation method of suspended solids.