SK5662Y1 - Composite sorbent - Google Patents

Abstract

Technical solution to the sorbent to reduce high concentrations of phosphorus in surface waters, as a composite material consisting of a main component sorption Al (OH) 3, side components semi fire dolomite and stabilization components fine perlite and bentonite, that are fixated created sorbent product. After preparing all the technological components of homogenized in a weight ratio aluminum hydroxide in an amount of 35 to 55% by weight; semi fire dolomite 10 to 35% by weight; bentonite 18% by weight and fine perlite 16% by weight.

Description

The technical solution relates to the production of a composite sorbent for reducing high phosphorus concentrations in surface waters, which in most cases are the primary cause of the eutrophication process in water reservoirs, such as recreational water bodies and ponds.

BACKGROUND OF THE INVENTION

Reducing the concentration of increased phosphorus concentrations in surface waters is one way to eliminate the eutrophication process. Eutrophication is caused by increased concentrations of nitrogen (N) and phosphorus (P) macro elements. If the N: P weight ratio is greater than 7, the key element of eutrophication is P. Several solutions have been used to reduce high P contents in surface waters, which mostly did not give satisfactory results.

Among these, an attempt may be made to reduce the P content in the lake using an aluminum salt sorption material. The experiment was successful in the first year, but in the following years the effects achieved were negated by the acidification process initiated by the formation of HCl as a by-product. The attempt in 2004 on the Kuchajda Lake in Bratislava, part of the New Town, ended without significant success, when Aquasystem used enzymes to reduce the number of sinia and algae. Better results were achieved in the Czech Republic on Machovo Lake, where they used chemical spraying, but they did not manage to seal them into the hygiene standard. In the Czech Republic, experiments were carried out with the preparation PAX, which is essentially a polyaluminium hydroxide chloride of the general formula Al (OH) _x (Cl) _y , where x + y = 3. Algae were first destroyed, but after 2-3 weeks they reappeared. This was due to poor binding of P to the sorption complex of PAX, which could serve as a source of nutrients for algae. Another experiment with coagulant PAX-18 was carried out in 2005 in Bila Lhota near Olomouc in order to restore the europhized pond (Lelkova, E., Rulik, M., Hekera, P., Dobias, P., Dolejs, P., Borovickova, M. & Poulíčková A. 2008. The influence of PAX1 coagulant on Planktothrix agardhii bloom in a shallow eutrophic fishpond (Fottea 8, 2, pp. 147-154). The main aim of the work aimed at the elimination of cyanobacteria was fulfilled, but the long-term effect has not been confirmed.

1) At the Technical University in Zvolen - Faculty of Forestry, Department of Natural Environment - several experiments were carried out with a composite sorbent, which originally contained iron oxide. In 2004 it was its first modification used in an experiment in two 500 liter containers (Vass, D. Machava, J. 2006. Tirjakova, E. and Belina, P .: Decontamination of stagnant waters by mobilization of phosphorus. European Science Week at PF KU in 163-170 p.), In which the conditions were identical except for the application of the sorbent, which was used only in the model container. The sorbent used reduced the P concentration by 7-fold. The highest values in the control and model vessels were recorded in August 2004 (the concentration of 1200 pg.l ^-1 was reduced to 162 pg.l ^-1 ). High concentrations were caused by high temperatures in experimental vessels not incorporated in the soil. It was noteworthy that the content in the model vessel greatly exceeded the eutrophication limit value, and even under given conditions the content of ciliates, flagellins and crustaceans was reduced. This points to the potentially toxic effects of the sorbent used. In 2007, in another experiment, reported even greater reduction in the concentration of P 300 pg.l ¹ to 20 pg.l ^'1, but at the end of the experiment was to release P into the water. The sorbent's ability to bind P was based on the sorption properties of silicate components and iron oxide. In the composite sorbent applied in the current project under the title "Avoiding the process of eutrophication in water reservoirs using a composite sorbent", iron oxide was replaced by aluminum hydroxide due to possible toxic effects.

The essence of the technical solution

Better results in decreasing P concentrations in water were obtained with the present utility model. Its essence lies in the production of a composite sorbent to reduce high phosphorus concentrations in surface waters, which in most cases are the primary condition for eutrophication.

Ingredients:

- The main active sorption component of the composite sorbent is hydrargilite γ-Α1 (ΟΗ) 3, which binds with phosphorus to insoluble A1PO ₄ . The sorption capacity of the sorbent is enhanced by dolomite activated at 600 ° C, referred to as semi-burnt dolomite.

The cementitious constituents of the composite sorbent are bentonite (with a montmorillonite content> 50% by weight) and crude treated fine-perlite (with a SiO ₂ content of 70-75% by weight), which is an industrial waste.

The components of the composite sorbent according to their origin are divided into 2 groups:

- by-product of the process:

SK 5662 Υ1

- γ hydrargirit Α1 (ΟΗ) ₃ , which represents up to 94 wt. % dry matter. Insoluble phosphate is formed by reaction with P:

A1 (OH) ₃ + PO? ' = AIPO4 + 3 OH '

- crude treated fine perlite which is essentially dried volcanic glass (70-75% by weight). Of this, 75 wt. % is amorphous SiO ₂ and the remaining 25 wt. % represents the cryptocrystalline form,

the other component is an aluminosilicate, structurally similar to illite, hence designated as pseudoilitic -18-20 wt.

%.

the carbonate-oxide component is Ca and Mg - about 8 wt. % and Fe - about 5 wt. %.

Fine perlite has a large active surface that binds not only the ions released during PO ₄ ³ 'formation, but also binds the entire A1PO ₄ molecules.

- Slovak silicate raw material product:

- bentonite with a montmorillonite content exceeding 50% by weight, which binds cations released from phosphates (mainly Na ⁺ and K ⁺ ). Ca ²⁺ released from montmorillonite also binds to PO ₄ ³ '.

- semi-fired dolomite contains sorption components activated at 600 ° C - CaO and CaCO ₃ and MgO. The reaction with P takes place on the surface of the particles: 3 Ca ² '+ 2 PO? = Ca ₃ (PO ₄ ) ₂ Its stability is determined by pH conditions.

The composite sorbent consists of components of a silicate raw material base and waste during the technological process. Therefore, the raw material costs for producing the composite sorbent are not high. A1 (OH) ₃ and semi-fired dolomite must first be dried to dryness and then ground to the necessary size fraction:

- A1 (OH) ₃ <0.2 - 0.5 mm, - PVD <0.5 mm Bentonite and fine perlite need no treatment. Finally, all 4 components of the composite sorbebent are homogenized in a weight ratio:

SI: 46% Al (OH) _3> 20% PVD, 18% bentonite and 16% fine perlite. (1)

The composition of the composite sorbent was refined after several experiments as described in the following section. The proportion of individual components is given by their sorption ability.

EXAMPLES

I) First, the composite sorbent, composed of 5 components, was tested under laboratory conditions. This composite sorbent also contained CaO and this amount was lower in Al (OH) ₃ (wt%):

S2: 45% Al (OH) ₃ , 5% CaO, 20% semi-baked dolomite, 16% bentonite and 14% fine perlite. (2J

The prepared sorbent was used at 0.2, 0.4, 0.6 and 0.8 g per 1 liter of the solution to increase the initial concentration of 800 pg Ρ.Γ ^first With application of the composite sorbent in amounts of 0.6 and 0.8 g per liter of solution after 132 hours, the P concentrations have already fallen below 20 pg.l ^-1 , which is the limiting content of the eutrophication process in surface waters. Since this was a solution of orthophosphate H ₂ PO ₄ 'in distilled water, under natural conditions, however, the amount of composite sorbent applied must be greater.

II) Acute toxicity test with composite sorbent S (2) on aquatic organisms and tests of growth inhibition of algae and higher crops were performed in the accredited geological laboratories of SGU DS in Spišská Nová Ves on three organisms:

- test for inhibition of Scenedesmus quadricauda green algae,

- acute toxicity test on fish Poecilia reticulata,

- acute toxicity test on Daphnia magna,

The Ecotoxicity test was performed under the following conditions: T = 25 ± 2 ° C, amount of test solution - 50 ml, illumination - minimum intensity 5000 lux, initial algal culture concentration - 25 000 cells per ml. Growth of the algal culture of Scenedesmus quadricauda was evaluated during the test. Two samples were followed and incubated for 6 days, one stirred and the other not. Inhibitory effect of sorbent on algae growth in nutrient solution prepared according to STN 83 8303 was observed on day 1, 3 and 6. In the other two modifications, the composition of the composite sorbent was modified as follows (wt%):

S4: 55% A1 (OH) ₃ , 15% semi-baked dolomite, 16% bentonite and 14% fine perlite, (3)

S5: 50% Al (OH) ₃ , 10% semi-calcined dolomite, 10% CaCl ₂ , 16% bentonite and 14% fine perlite. (4)

The sorbent testing was carried out as follows. During the first day, it was not yet possible to notice any apparent differences between the control sample and the sorbent sample as the algae began to grow from the beginning

Test after inoculation with algae suspension. By day 3, differences between the mixed and unmixed control in the number of subjects per ml were already noted: 310,000 and 172,500 (Table 1). The sorbent treatment reduced the content of P in the nutrient solution, which was reflected in the number of individuals. In the unmixed sample and the mixed sample, the numbers were 67,500 and 80,000 subjects per ml, while in the controls the numbers were 3-4 times higher. According to STN 83 8303, the result of the Scenedesmus quadricauda green algae growth inhibition test is positive if the algal culture growth inhibition is> 30% compared to the control.

Table 1. Scenedesmus quadricauda algae growth inhibition test result (Source: Annex 2)

mark The beginning First day Third day Sixth day Area below inhibition samples Number of cells per ml N, n ₂ n ₃ a growth curve (%) Kl 25 000 15 000 172 500 252 500 251 250 0 WITH N 25 000 22 500 67 500 217 500 136 250 45.8 S4 25 000 5 000 77 500 195 000 117 500 53.2 S5 25 000 5 000 85 000 136 250 106 250 57.7 K2 25 000 42 500 310 000 325 000 452 50 0 WITH P 25 000 42 500 80 000 192 500 192 500 57.5 S4 25 000 50 000 80 000 166 250 166 250 63.3 S5 25 000 50 000 92 500 182 500 182 500 59.7

Legend: - N - mixed nutrient, P - mixed nutrient,

Results taken from accredited Geological Laboratories of ŠGU DS in Spišská Nová Ves.

After 6 days of testing in the Stirring Control (K2), the seaweed breeding process no longer occurs because P was already consumed. This is also confirmed by a low concentration of P <3 pg.l ^-1 . In the non-shuffling control (K1), the number of algae cells increased but reproduction was slowed. Sorbents showed an increase in algal cell counts from day 3 of the assay, but the quality and staining of Scenedesmus quadricauda algae cells was impaired. The algae were agglomerated and their color was lighter (yellow to green).

The measured concentration of P in the nutrient solution at the start of the assay was 303 pg.l- ¹ and after completion of the test in the test solutions and control was <3 pg.l- ¹ . When comparing the modifications of the composite sorbent in mixing, the S4 modification was most effective because there was the highest content of Al (OH) ₃ . Inhibition after 6 days was 63.3% and 10% higher than that of S modification. With no mixing, it was the S5 modification because Cl 2 is present, which has toxic effects on algae. The resulting composition of the 4-component composite sorbent (1) was adjusted according to the results obtained.

The acute toxicity test on fish Poecilia reticulata was negative because none of the 30 fish deployed died during the test. Similarly, the result of acute toxicity on Daphnia magna was negative, as 4% of the 180 birds were killed in the validation test. If the mortality is less than 10%, the test result is considered negative and no further testing is performed.

A further experiment was performed with the composite sorbent S (2) - leaching 100 g in 1 liter of distilled water. Determined concentrations of water-released macro- and micronutrients as well as toxic elements are low, except for sulphates, whose concentration is relatively high (1937 mg.l- ¹ ), but does not present any risk when applied at 1 g.l- ¹ .

III) The efficacy of the 4-component composite sorbent (1) was monitored under field conditions in an 800 liter plastic tank. Composite sorbent (1) in an amount of ¹ µg was applied to water with an increased content of _Peaks (165 pg.l ^-1 ) in a 1.2 x 2 m and 0.32 m deep tank and the potential eutrophication process was monitored. At the same time, the natural course of eutrophication was monitored in a 12 liter bucket fixed in a tank to which no sorbent was added. Green algae appeared in the bucket within 10 days, only a hint of green algae appeared in the tank at a given concentration of composite sorbent. This result indicates the need to increase the amount of composite sorbent applied than 1.0 g.l ^-1 . The concentrations of the individual forms of P were determined at the beginning and end of the experiment.

Total content P _Cc | _k in the water used was 233 pg.l ^-1 . The reactive form P representing 70% (Table 1) far exceeded the limit of the eutrophication process. The N _Cdk ratio of 7P _Total = 30.4 clearly confirmed that the limiting element of algal reproduction is P. Using a composite sorbent, its content in water was reduced to a concentration that already limited the eutrophication process (Table 2).

SK 5662

Table 2 Concentrations of P _Rea k _t and Prozp ^{in the} source (well; 10.8.09), in the bucket and in the reservoir (23 September 2009)

Water ^ Reakt Prozp (Mg / L) source 164.66 ± 0.12 152.85 ± 0.35 heat 50.50 ± 0.64 26.05 ± 0.30 reservoir 12.41 ± 0.26 12.39 ± 0.36

Reactive, P _Ro7p - soluble

Concentrations of _Polv (STN EN 1189), P _Cclk and N _Ce , _k were determined on a DR 2800 spectrophotometer. The accuracy of the measurement was ensured according to the Instrument Instruction Manual.

Industrial usability

The use of a composite sorbent designed to reduce high concentrations of P in surface waters, which are mostly the primary cause of eutrophication in water reservoirs, will find application not only in Slovakia, but also worldwide.

The composite sorbent is designed to eliminate the eutrophication process in surface waters by reducing high phosphorus contents. Phosphorus is a key condition for eutrophication if the ratio of total N to P by weight is greater than 7. The formation of green algae as a product of eutrophication begins at the beginning of the growing season. By early application of the composite sorbent, the P content in surface waters is reduced and the formation of phytoplankton biomass is reduced or completely eliminated.

The composite sorbent is made as a fine grain material so that the active sorbent surface is as large as possible. The water tank is evenly distributed over the water surface. Its effect in water objects is applied in 2 phases.

Phase 1: Contact with surface water immediately decreases concentration of P.

The reduction of the P content in the surface water, as a result of the action of the sorption properties of the composite sorbent, results in the exhaustion of the P content or in the equilibrium state.

Phase 2: after the composite sorbent has settled, P is sealed in the bottom sediment - preventing vigorous eutrophication.

The composite sorbent should be applied at the beginning of the vegetation period when P reaches the highest concentration in surface water, but phytoplankton has not yet multiplied. Within 10 days, the sorbent will reduce the P content in the surface water to a value that is not sufficient to ensure the course of the eutrophication process.

PROTECTION REQUIREMENTS

Claims (2)

Composite sorbent for reducing high phosphorus concentrations in surface waters, characterized in that it consists of aluminum hydroxide in an amount of from 35 to 55% by weight, semi-fired dolomite in an amount of 10 to 35% by weight. and the remainder to 100 wt. bentonite and fine perlite. Composite sorbent according to claim 1, characterized in that it consists of 46% by weight aluminum hydroxide, 20% by weight semi-fired dolomite, 18% by weight bentonite and 16% fine pearlite. 1 drawing