COAGULATION-FLOCULATION PROPERTIES OF DISPERSIONS FORMED BY ALUMINUM-CONTAINING COAGULANTS AND COMPOSITIONS BASED ON THEIR BASED IN THE PROCESSES OF PURIFICATION OF WASTE WATER OF SERICULTURE

ABSTRACT

One of the important issues in the modern world is the study of the targeted synthesis of various promising substances and the creation of active preparations, on the basis of which effective wastewater treatment is carried out. In particular, the development of the composition of new components using finely dispersed inorganic chemical methods and on the basis of which wastewater treatment is actively developing at industrial enterprises. Among the substances obtained, great importance is attached to the creation of coagulants, adsorbents and flocculants with highly effective properties.

One of the most common methods of purification of waste water from textile enterprises is their purification using coagulants. In the practice of wastewater treatment, the following mineral coagulants are used: aluminum sulfate Al₂ (SO₄)₃ ∙ 18H₂O, ferrous sulfate – FeSO₄ ∙ 7H₂O, ferric chloride – FeCl₃ ∙ 6H₂O.

The main process of coagulation treatment of industrial wastewater is heterocoagulation - the interaction of colloidal and fine particles of wastewater with aggregates, which is formed when coagulants are introduced into the wastewater.

AННОТАЦИЯ

Одним из важных вопросов в современном мире является изучение направленного синтеза различных перспективных веществ и создание активных препаратов, на основе которых осуществляется эффективная очистка сточных вод. В частности, разработка состава новых компонентов методами тонкодисперсной неорганической химии, на основе которых на промышленных предприятиях активно развивается очистка сточных вод. Среди получаемых веществ большое значение придается созданию коагулянтов, адсорбентов и флокулянтов с высокоэффективными свойствами.

Одним из наиболее распространенных способов очистки сточных вод текстильных предприятий является их очистка с использованием коагулянтов. В практике очистки сточных вод применяют следующие минеральные коагулянты: сульфат алюминия Al₂(SO₄)₃∙18H₂O, сульфат железа – FeSO₄∙7H₂O, хлорид железа – FeCl₃∙6H₂O.

Основным процессом коагуляционной очистки промышленных сточных вод является гетерокоагуляция - взаимодействие коллоидных и мелкодисперсных частиц сточных вод с агрегатами, образующимися при введении в сточные воды коагулянтов.

Keywords: adsorbent-bentonite, kaolin, efficiency, suspended solids, active substance surface-(ASS), polyacrylamide-(PAA), coagulyant-aluminum sulfate-(Al₂(SO₄)₃), sodium hydrosulfite-(NaHSO₃), purification by intensity, сhemical oxygen demand-(COD), ferrous sulfate (FeSO₄∙7H₂O), ferric chloride-(FeCl₃∙6H₂O).

Ключевые слова: адсорбент-бентонит, каолин, эффективность, взвешенные вещества, поверхность активного вещества-(ПАВ), полиакриламид-(ПАА), коагулянт-сульфат алюминия- Al₂(SO₄)₃, гидросульфит натрия-(NaHSO₃), очистка по интенсивности, химическое потребление кислорода-(ХПК), сульфат железа (FeSO₄∙7H₂O), хлорид железа-(FeCl₃∙6H₂O).

Within the framework of this study, an increased characteristic of the purified water was provided with a parallel simplification and reduction in the cost of its purification process. Due to the indication of the dependencies of these coagulation aggregates on the conditions of their formation, the chemical composition of the coagulant and the origin of the components of the dispersed phase, the developers made it possible to intentionally produce newly made compositions of coagulants, optimize the situation of their introduction and achieve the maximum level of productivity of the water purification flow.

In the process of studying the efficiency of wastewater treatment in dyeing and finishing production, depending on the doses of mineral coagulants, it was determined that the optimal doses for aluminum sulfate are 0.75-1.0 g / l and for sodium bisulfite - 0.375-0.75 g / l (counting on the anhydrous salt product), while the purification efficiency in terms of COD reaches 38-65%, in terms of color intensity - 82-95% [1,p.12-15;3,p.29-33;4,p.44].

           Table 1.

Efficiency of wastewater treatment of the first stream of the dyeing and finishing shop with optimal doses of mineral coagulants

The regularities of the efficiency of wastewater treatment in dyeing and finishing production depending on the dose of PAA have been studied, its optimal doses have been determined, which amounted to 0.25-0.5 g / l, while the value of the COD index of wastewater decreases by 43-51%, the color intensity by 90-95%. The optimal doses of both PAA and mineral coagulants (Al₂ (SO₄)₃: 0.75-1.0 g / l, NaHSO₃: 0.375-0.75 g / l) give practically the same cleaning effect in terms of color intensity and COD.

As a result of studying the kinetics of removing pollutants from wastewater, it was found that when using chemicals in optimal ratios, the highest degree of purification is achieved: by color intensity 93-95%, by suspended solids 80-84% [5,p.77;6,p.53;7,p.80-81;].

Thus, the use of the above reagents can provide a fairly high degree of purification in terms of color intensity, suspended solids and other main important indicators of wastewater pollution.

It is known from the literature that during adsorption, the concentration of molecules of the absorbed substance on the surface of the sorbent occurs under the action of the force field of the surface.

The force field of the surface is formed as a result of the presence of the boundary molecules of the solid phase, in contrast to the intra phase molecules, of greater free energy. As a result of this border molecules attract molecules from contacting phase.

Thus intermolecular interaction can be divided into three types:

1) interact interacting between sorbent molecules and water;

2) between the sorbent and the molecules recovered high -OPERATION;

3) between the molecules of the extractable substance and water.

The difference in the energies of these three processes is the energy with which the substance extracted from the solution is retained on the sorbent surface. Adsorption is a reversible process, i.e. sorbed substance move back from the adsorbent to the solution.

Table 2.

Changes in the efficiency of wastewater treatment of the second stream depending on the sorbent dose

In order to determine the optimal concentration of the sorbent during the purification process, we carried out studies at various ratios of kaolin and bentonite sorbent (tables 2 and 3). Since the developed composition has a complex composition, it is difficult to determine if the sorbent or coagulant more affects the degree of wastewater treatment in the presence of a joint presence.

Therefore, referring to the literature, when determining the concentration of the sorbent and the concentration of coagulants Al₂(SO₄)₃·18H₂O and FeCl₃·6H₂O, they were kept constant and equal to 0,5 and 0,75 mg/l, respectively [9-10,p.44-45].

Score growth sorption and desorption processes depend on the con centration substance on the adsorbent surface and in solution.

According to claim HALE pits wastewater second stream in table. 3 that the degree of removal of contaminants by this method is significantly higher than that of sedimentation of sediments of aluminum or iron oxyhydrates with adsorbed contaminants.

Table 3.

Efficiency of wastewater treatment of the second stream with optimal doses of mineral coagulants

Efficiency reduce the COD value of the indicator and the surfactant concentration in the effluent averaged 65% and 82%, the efficiency reduce these same parameters upon standing precipitation oxyhydrates constitute 48-54% and 54-61% respectively [11,p.25;12,p.149;13,p.104;14,p.8715,p.38].

The high degree of removal of surfactants and other organic contaminants from the wastewater of silk-winding production is explained by the fact that in the process, in addition to the sorption of these substances, on the surfaces of adsorbents, ions and molecules of dissolved substances are sorbed on the surfaces of air bubbles and carried out into the foam layer [16,p.4743;17,p.68;18,p.276].

The proposed technology facilitated wastewater filature enterprises from major contaminants-colorants, surfactants, sizing agents, etc [19,p.88-20,p.13]. The influence of the bentonite particle size on the degree of bleaching wastewater at different flow rates and the kinetics of removal of contaminants from wastewater has shown the principal possibility of joint use of kaolin and bentonite companion compositions.

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