RU2044694C1 - Low turbid color water purification method - Google Patents

Abstract

FIELD: industrial and drinking water supply. SUBSTANCE: having 14,3 mg/dm³ of suspended substances natural water of 38 deg. chromaticity is specially polluted by salts of heavy metals and so increasing of commemoration of iron up to 0,9 mg/dm³, of copper 0,4 mg/dm³, of lead 0,2 mg/dm³. Then it is treated with coagulant sulfate of aluminum and with dust-shaped sorbent aluminosilicate. Flocculation is exercised in terms of continuous stirring of water with ejecting in it earlier formed flocs. After process of flocculation is finished water is clarified using mode of hindered precipitation. Due to introduction of dust-shaped sorbent in zone of stirring and ejecting flocs are in process of stirring are dispersing, time period, required for flocs precipitation, is decreased by 25 and simultaneously quality of purification is improved ( as compared with known method): by value of residual aluminum half the value, by value of residual iron 0.666 of previous value. EFFECT: improved quality of purification and decreased time of flocs precipitation. 2 cl, 1 tbl

Description

 The invention relates to methods for water purification and may find application in the field of domestic and drinking water supply.

A known method of purification of low turbid colored water, which consists in introducing a coagulant into it, flocculation and clarification in the mode of tight deposition [1]
The known method is ineffective, especially during periods of low temperature of the treated water, due to the sluggish flow of the process of flocculation and, accordingly, the forming flakes. As a result, the time required for clarifying water in the mode of constrained deposition substantially increases. In addition, the method practically does not have a barrier role with respect to the extraction of heavy metal ions and a number of organic compounds, as a rule, polluting natural waters.

A known method of purification of low turbid colored water, which consists in the sequential introduction of a dust-like sorbent and a coagulant into it, flocculation and clarification in the mode of tight deposition [2]
This method, compared with the above, has a slightly larger barrier role in relation to the extraction of heavy metal ions and a number of organic compounds from water. However, this method is also characterized by low efficiency due to the sluggish flow of the flocculation process.

The closest in technical essence and the achieved result is a method of purification of low turbid colored water, which consists in the sequential introduction of a dusty sorbent and a coagulant into it, flocculation, carried out by continuous mixing of water with previously formed flakes ejected into it, and clarification in the mode of constrained deposition [3]
The above method allows to intensify the process of flocculation and thereby to obtain flakes with greater hydraulic fineness. The latter circumstance provides an opportunity to slightly reduce the time required for clarification of water in the mode of constrained deposition.

 The specified method is characterized by an insufficient degree of water purification and a relatively large time spent on the process of cramped deposition.

 The purpose of the invention is to increase the efficiency of the method by reducing the deposition time and improving the quality of treatment.

 According to a method for purifying low-turbid colored water, a dusty sorbent is introduced into the mixing zone of the ejected flakes with the water to be purified, and the ejected flakes are dispersed during the mixing process.

 It is advisable to disperse the flakes by creating turbulence in the mixing zone.

PRI me R. Neva water with a color of 38 degrees, with a suspended matter content of 14.3 mg / dm ³ , an alkalinity of 0.5 mEq / dm ³ and a pH of 7.2 is artificially contaminated with heavy metal salts, increasing the iron concentration in it to 0.9 mg / dm ³ , for copper up to 0.4 mg / dm ³ , for lead 0.2 mg / dm ³ , and then mixed with a coagulant and a dusty sorbent and clarified in the mode of tight deposition carried out in the model of clarifier-recirculator [4] B of the indicated model, the process of flocculation was ensured by continuous mixing of water with previously formed flakes ejected into it E.

In all series of experiments, the dose of coagulant (aluminum sulfate) was 7.0 mg / dm ³ , the dose of pulverized sorbent (aluminosilicate) 20 mg / dm ³ .

Spend four series of experiments:
Series I (prototype), the coagulant and the dust-like sorbent are introduced into the purified water before it enters the model, i.e. before mixing the water with the previously formed flakes ejected into it;
Series II coagulant is introduced into the purified water before entering the model, and the dust-like sorbent directly into the mixing zone of water with ejected previously formed flakes, while ensuring such a mixing mode that the flakes do not disperse during ejection.

Series III (invention), the coagulant is introduced into the purified water before entering the model, and the dusty sorbent directly into the mixing zone of water with previously ejected flakes, while ensuring such a turbulence of the mixing mode so that the ejected flakes are dispersed;
Series IV coagulant is introduced into the purified water before entering the model, and a dusty sorbent 30 seconds after mixing water with ejected previously formed flakes, while ensuring turbulence of the mixing mode, similar to series III experiments.

The criteria for the effectiveness of water purification are: flow rate over a layer of suspended sediment, at which the amount of suspended solids in clarified water does not exceed 1.2 mg / dm ³ , as well as the content of residual aluminum, iron, copper, and lead in clarified water.

 The experimental results are summarized in table.

 The table shows that the best results in the quality of purification of low-turbid colored water and, if possible, the maximum flow rate over the layer of suspended sediment are achieved during the III experiment, when a dusty sorbent is introduced into the mixing zone of ejected flakes with purified water, and the ejected flakes are dispersed during mixing . It is under these conditions that the process of interaction and sticking together of dissimilar particles proceeds most intensively, i.e. a process called contact coagulation. A distinctive feature of this process is the increased rate of extraction of small substances from water by larger ones, i.e. intensification of flocculation.

 As a result, the density of the newly formed flakes increases, and, accordingly, their hydraulic fineness. There is also an increase in mass and volume concentration of the suspended sediment layer, which increases the surface area of sorption and adhesion. Thereby, the physicochemical conditions that have a direct impact on the water treatment process are improved, the time required for the deposition of particles is reduced, and the quality of treatment is improved.

 The invention allows, in comparison with the known method (under the conditions of purification of artificial polluted water of the Neva River), to increase the flow rate above the layer of suspended sediment, and accordingly, to reduce the time required for precipitation of flakes, to improve the quality of cleaning by 2 times the residual aluminum by 2% , iron 1.5 times.

Claims (2)

 1. METHOD FOR CLEANING LOW COLORFUL WATER, including the introduction of a coagulant and a dust-like sorbent into it, continuous mixing of the purified water with previously ejected flakes and subsequent clarification of the water in the mode of constrained deposition, characterized in that the dusty sorbent is introduced directly into the mixing zone with the sorbent flakes, and ejected flakes are dispersed during the mixing process.  2. The method according to claim 1, characterized in that the dispersion of the flakes is carried out by creating turbulence in the mixing zone.

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