DD292218A5 - METHOD FOR SEPARATING SOLIDS SUSPENDED IN WATER - Google Patents

Abstract

Process for the separation of suspended solids in water at levels of 10 4 to 101 g / l, which is used in the treatment of water and in the purification of municipal and industrial wastewater, as well as in separation processes. For this purpose, a highly branched copolymer of dimethyl diallyl ammonium chloride high molecular weight is added with a proportion of crosslinking comonomer from 0.1 to 3.0 mol% in amounts of 0.05 to 2%, based on the solids content of the suspension. After flocculation, the solids are separated in a known manner. Solids; flocculation; Separation; water-soluble organic polymers; Poly (dimethyl diallyl ammonium chloride)}

Description

Field of application of the invention

The invention relates to a process for the removal of suspended in water inorganic and / or organic solids. It can be used in the treatment of water as well as in the treatment of municipal and industrial wastewater and in technical separation processes.

Characteristic of the known state of the art

The separation of inorganic or organic solids suspended in water is a widely used process. It has gained great importance in drinking water treatment, domestic water production and the purification of municipal and industrial wastewater. Such phase separations also occur within technical processes, eg. As in the mineral processing in mining.

To accelerate the separation of the phases and the sedimentation of the solids, water-soluble organic polymers are frequently added as flocculants to the suspension to be separated. This can increase the throughput in an existing plant. Furthermore, by the use of these flocculants an improved separation efficiency, d. H. a higher degree of separation of the suspended materials and thus achieved an increased purity of the water. The flocculants used are water-soluble cationic, anionic or nonionic polymers. The cationic water-soluble polymers include homopolymer such as. Polyethyleneimine or polydimethyl-diallyl-ammonium chloride) or polymeric quaternary esters or amides of acrylic acid or copolymers containing cationic groups, e.g. B. corresponding copolymers of acrylamides. Usually, 0.2 to 2% of the flocculant, based on the solids content of the suspension, are used (Ullmann, Encyclopadie der technischen Chemie, 4th Edition, Verlag Chemie, Volume 6, p. 442).

To improve the separation processes in wastewater treatment, poly (dimethyl-diallyl-ammonium chloride) (poly-DMDAAC) is used (E. Blitz, W. Czysz, wastewater technology, Springer-Verlag, Berlin 1984, p. 574). U.S. Patent 3,171,805 and British Patent Specification No. 1084540 also describe the use of poly-DMDAAC for water purification. In the purification of water with inorganic iron or aluminum salts, improved deposition of the hydroxide sludge can be achieved with poly-DMDAAC (Ch.Wandrey, W. Jaeger, J.Wotzka, W. Stark, Wasserwirtschaft-Wassertechnik 34 [1984].

In addition to the homopolymer poly-DMDAAC, copolymers of DMDAAC are also used as flocculants. For example, US Pat. Nos. 3,171,805,314,721 and GB-PS 1084540, 1228489 describe the use of copolymers of acrylamide with DMDAAC for water purification processes.

All previously mentioned copolymers of DMDAAC have a linear structure. In a publication by JE Morgan, MA Yorke and JE Boothe ("Ions in Polymers", Advances in Chemistry Ser. 187, pp. 235ff.), It is noted that copolymers of the branched-structure DMDAAC obtained by copolymerization at very low levels However, this effect is limited only to bijams (activated sludge from the aeration tanks of wastewater treatment plants), but no increase in dewatering rate has been observed for other sludges, eg the raw sludges from primary sedimentation tanks is reported in the same publication that there is a correlation between the dewatering rate of the biosludge and the proportion of cross-linking comonomer in the copolymer of the DMDAAC The rate of dewatering first increases with increasing comonomer content and achieves an optimum at comonomer contents <0.5%; For copolymers prepared by solution copolymerization of DMDAAC with methyl triallyl ammonium chloride, the optimum is 0.035 mole percent of the comonomer. Higher levels of crosslinking comonomer in the copolymer then lead to a significant decrease in the dewatering rate for the same amount of polymer used.

The said processes have the disadvantage that the flocculants are not universally applicable and the separation efficiency is generally insufficient. In addition, the amounts of flocculant, the cost of the separation process economically burden, are still too high.

Object of the invention

The object of the invention is to develop a process in which, in economically favorable catfish, a complete separation of solids suspended in water takes place.

Explanation of the nature of the invention

The object of the invention is to develop a Verfahron for the removal of suspended in water organic and / or inorganic solids by adding a suitable water-soluble organic polymer with which at low

Flocculant a high separation efficiency is achieved. The method should be applicable to suspensions with solids contents of 10 ~ ⁴ to 10'g / l.

According to the invention, the object is achieved by adding to the suspension a water-soluble, highly prevalent copolymer of DMDAAC and from 0.1 to 3.0 mol% of a crosslinking comonomer having a molecular weight of> 80,000 in amounts of from 0.05 to 2%, based on the solids content of the suspension, is added as a dilute aqueous solution.

Suitable crosslinking comonomers for the preparation of hyperbranched poly-DMDAAC are, for. As amine or ammonium salts with more than two Allylgruppon, u. a. Methyl triallyl ammonium chloride (MTAAC), retraallyl ammonium chloride (TAAC), N, N, N :, N'-tetraallylethylenediamine hydrochloride (TAEDC) and / or triallyl-amine hydrochloride (TAC) and methylene bisacryiamide (MBA). The preparation of the hyperbranched poly (DMDAAC) is carried out by copolymerization of DMDAAC with the crosslinking comonomer in aqueous solution with metered addition of the crosslinker, the addition being carried out during the ongoing homopolymerization or copolymerization of the DMDAAC after conversions of between 25 and 90%.

The method for the separation of the suspended solids is carried out so that the suspension, the desired amount of polymer, which also increases with increasing proportion of solids in the suspension added at temperatures between 278 K and 340K as a dilute aqueous solution and then with conventional technical Intensively mixed devices. Subsequently, sedimentation of the flocculated particles can be carried out without further intervention, with a constant transparency setting after some time or it is in a known manner weiterpeführt some time with reduced energy input and anschlioßond left the flocculated suspension for sedimentation. The solids can subsequently be separated off in a known manner.

As suspensions, all suspensions of inorganic and / or organic materials are suitable in water having a solids content between 10 ~ ⁴ and 10 ¹ g / l. In this case, the pH of the aqueous suspension may be arbitrary.

Surprisingly, it was found that when using the highly branched poly-DMDAAC a highly effective separation process begins, wherein the proportion of flocculant is kept low.

embodiments

example 1

100 ml of a suspension of kaolin in water with a solids content of 2 g / l was added at 293K1 mg / l of the polymer as a 0.1% aqueous solution and mixed for 4 min at 200U / min by means of a stirrer. Subsequently, the sedimentation velocity of the solids was measured. The results are summarized in Table 1.

Table 1:

No. Polymer sedimentation rate m / h

1 poly-DMDAAC 4.81 (homopolymer comparative example

2 Copolymer of DMDAAC and 0.035 mol% MTAAC Comparative Example 5.70

3 Copolymer of DMDAAC and O, 1 mole% MTAAC 6.70

4 Copolymer of DMDAAC and 0.5 mole% MTAAC 9.27

5 Copolymer of DMDAAC and 1.5 mol% MTAAC 12,10

6 Copolymer of DMDAAC and 3.0 mol% MTAAC 13.50

Example 2

100 ml of a suspension of kaolin in water with a solids content of 2 g / l was added at 293! ' 1 mg / l of the polymer was added as a 0.1% aqueous solution and mixed for 10 min at 200 U / min by means of a stirrer. Gt-nessen became the period of constant transparency and the value of transparency achieved. The results are shown in Table 2.

Table 2:

No, polymer constant transparency transparency

to

min%

1 poly-DMDAAC (homopolymer comparative example 12.4 78.6

2 Copolymer of DMDAAC and 0.035 mole% MTAAC Example 12.5 80.4

3 Copolymer of DMDAAC and 0.1 mol% MTAAC 12.2 81.4

4 · Copolymer of DMDAAC and 0.5 mol% MTAAC 12.0 82.1

5 Copolymer of DMDAAC and 1.5 mol% MTAAC 12.0 85.2

6 Copolymer of DMDAAC and 3.0 mol% MTAAC 12.0 87.1

Example 3

Following the procedure of Example 1, copolymers of DMDAAC prepared with 1.5 mole percent of a cross-linking comonomer were tested. The results are shown in Table 3.

Table 3:

No. Comonomer sedimentation rate

m / h

1 tetraallyl-ammonium chloride 12,70

2 triallyl-amine hydrochloride 11,50

3 Ν, Ν, Ν ', Ν'-Tetraallylethylenediarnine hydrochloride 12,20

4 methylenebisacrylamide 11.60

Example 4

A waste water from a food industry operation having an organic material solids content of 0.1 g / l was treated with 2 mg / l poly-DMDAAC (homopolymer) according to the procedure of Example 2. After 11.7 minutes, a constant transparency of 76.9% had set in. If, on the other hand, 2 mg / l of a copolymer of DMDAAC and 1.5 mol% of MTAAC is added, a constant transparency of 88.1% occurs after 9.8 min.

Example 5

A kaolin suspension in Wassor with a solids content of 10 g / l was tested at 278K according to Example 1. The results are shown in Table 4.

Table 4:

No additional sedimentation rate

Polymer amount

mg / lm / h

1 poly-DMDAAC (homopolymer) 10 4.95

2 Copolymer of DMDAAC and 0.025 mol% MTAAC 10 6.05

3 Copolymer of DMDAAC and 1.5 mol% MTAAC 5 12.70

Example 6

To an alkaline rinse water having a solids content of 1.1 g / l and a pH of 14 at 340 K, the following polymers were added as 0.1% aqueous solutions, the suspensions in a beaker by means of a stirrer 4min with 190U / The mixture is then stirred for 15 minutes and then stirred for 30 minutes and then, after a further 30 minutes, the remaining solids content FG of the aqueous phase is determined. The results are shown in Table 5.

Table 5:

No extra

Polymer amount FG

mg / l mg / l

1 poly-DMDAAC (homo-polymer) 10 121

2 Copolymer of DMDAAC and 0.035 mol% MTAAC 10 81

3 Copolymer of DMDAAC and 1.5 mol% DMDAAC 2 36

Example 7

An industrial wastewater having a solids content of 0.5 g / l and a pH of 1 was treated at 291K according to Example 6. The results are shown in Table 6.

Table 6:

No extra

Polymer amount FG

mg / l mg / l

1 poly-DMDAAC (homopolymer) 5 107

2 Copolymer of DMDAAC and 0.035 mol% MTAAC 4 94

3 Copolymer of DMDAAC and 1.5 mol% MTAAC 1 .31

Example 8

To an aqueous suspension of 10 ~ ⁴ g / l of iron hydroxide (iron hydroxide sol) was added 10 " ^e g / l of poly-DMDAAC (homopolymer), of the copolymer of DMDAAC and 0.035 mol% of MTAAC or of the copolymer of DMDAAC and 1.5 MTAAC was added according to Example 2 and the change in the transparency was investigated at 292 K. The first two additives did not change the transparency within 30 minutes, with the latter copolymer increasing the transparency from 20 to 91%.

Claims (4)

A process for the separation of suspended in water inorganic solids having solids contents of the suspension of 10 ~ ⁴ to 10 ¹ g / l using high molecular weight poly (dimethyl-diallyl-arnmoniumchlorid) (poly-DMDAAC), characterized in that the solids of the Suspension by addition of a water-soluble, highly branched, high molecular weight copolymers of dimethyl diallyl ammonium chloride and 0.1 to 3.0 mol% of a crosslinking comonomer in amounts of 0.05 to 2%, based on dr ";» ^p eststoffgehalt the suspension , flocculated and then separated in a known manner. 2. The method according to claim 1, characterized in that are used as crosslinking comonomers ammonium salts with more than two allyl groups. 3. The method according to claim 1 and 2, characterized in that are used as crosslinking comonomers methyl triallyl-ammonium chloride, tetraallyl-ammonium chloride, triallyl-amine hydrochloride, N, N, N ', N'-tetraallyl-ethylenediamine or methylene-bisacrylamide. 4. The method according to claim 1 to 3, characterized in that the flocculation is carried out at 278 to 340K.