EA007088B1 - Filters biomass carrier for biological treatment of sewage water - Google Patents

Abstract

The invention relates to biological treatment of industrial and residential waste waters using aerobic biofilters with solid fixed load - carrier of microorganisms.The filters biomass carrier for biological treatment of sewage water is embodied as fibro-porous nonwoven fabric made from synthetic fibers are joined therebetween by cohesive bonds in contact zones with cubic density 0.2-0.3 g/cm, wherein polymer fibers are produced by pneumomatic extrusion method, the melt flow index being at least 25g/10min, diameter of said fibers is 50-80 mkm.The carrier is embodied as a hollow cylindrical element, the wall is 5-10mm thick, the inner diameter is 45-55mm and porosity is 65-80%. The average pore size of the fibro-porous nonwoven fabric is 50-70 mkm. The carrier is produced by directing gas-polymer stream to being cooled forming support.The inventive carrier can be used in systems of biologic treatment of sewage waters.

Description

The invention relates to the technique of biological treatment of industrial and domestic wastewater using aerobic biofilters with a solid fixed loading - carrier of microorganisms.

High-quality wastewater treatment from toxic pollution is one of the important problems solved in the field of filtration technology and industrial ecology. The ingress of toxic substances into the soil and water bodies (for example, aromatic and halogenated hydrocarbons, ethers, ketones) sharply worsens the ecological situation, upsets the natural balance in the environment and creates a danger to human health. Due to the specificity of chemical properties, many organic compounds are practically not utilized by natural means and are not caught by traditional adsorbent filters. A promising way to purify water from organic matter is biodegradation of the latter using biomass. The destructor microorganisms contained in it carry out the biotransformation of organic pollutants along a chain of specific biochemical transformations. Among such microorganisms, the most famous are the bacteria of the families Rkeibotopak, Aegotopak and some others. An important problem remains the choice of an optimal and inexpensive carrier of biomass.

The most important criteria for selecting a carrier are: developed surface, porosity, satisfactory mechanical strength and chemical resistance, maximum affinity for biomass and biotransformable substrates (i.e., high sorption characteristics), biocompatibility, ability to ensure sustainability of microbial associations and the absence of toxic action on them ( Yakovlev, SV, Voronov, Yu.V., Biological Filters, Moscow: Stroyizdat, 1975, 135 p.

When choosing a carrier for the industrial process of bioremediation usually use the most accessible technical materials. However, the known inorganic (sand, gravel, gravel, glass, brick, slag, coke, expanded clay, zeolite, activated carbon, etc.), organic natural (chips, bark, sawdust, peat), as well as artificial and synthetic polymeric (cellulose acetate , PE, PP, PPU, PVC, PS, PVA, etc.) carriers, as a rule, are not optimal for a number of operational criteria. The most common forms of polymer carriers (smooth and corrugated films, tapes, rods, ruffs, rings, tubes, discs, saddles, honeycomb structures made of polymer sheets, etc.) have an undeveloped surface (from 50 to 300 m ² / m ³ ). The layer of foam polymer granules is poorly permeable and clogs with time. Fine-grained polymeric carriers (including gel-forming) can work effectively only in the fluidization mode (Berne F., Cordonier J. Water treatment. Refining wastewater treatment. Preparing water cooling systems / Transl. Fr. - M .: Chemistry, 1997, 288 with).

Optimal is a carrier that combines flexibility and durability. This can be achieved using the beneficial properties of polymer-based fibers. A porous carrier with a two- or three-dimensional arrangement of communicating pores is known [Japanese Application 1055917, C 02P 3/28, 3/00, 3/10, publ. 1989], which is formed from a fibrous material with a plurality of through holes with a diameter of 100 μm. The substrate for the fixation of microorganisms used for the purification and treatment of water (French application 2639342, C 02P 3/06, 3/12, 3/28, publ. 1990) is obtained from synthetic fibers, tangled into irregular tangles to form a three-dimensional element, free the volume of which reaches 85-99.5%.

However, these types of woven and non-woven fibrous-porous materials that are acceptable according to sorption and other service characteristics do not have dimensional stability. To give them structural certainty, they are reinforced with frames, which complicates the manufacture and operation of the carrier, creates additional mechanical loads on the bioreactor.

Recently, polymeric fibrous materials made by pneumatic extrusion technology have been used. They possess the necessary for the carrier complex of properties, including dimensional stability and high sorption capacity. To increase the last parameter, the technology of carrier formation is sometimes combined with methods of giving physical activity to the fibrous material. This is due to the role of physical fields in the vital activity of microorganisms (Goldad, V.A., Makarevich, A.V., Pinchuk, LS, etc. Polymer Fibrous Te11-Yo / Pack Materials. - Gomel: IMMS NANB, 2000, 260 s).

Known carrier material of active biomass, made in the form of non-woven material bonded together synthetic fibers. These fibers have a linear density in the range from 0.9 to 6.8 dtex and are bonded to each other by needling or thermally (RF Patent No. 2226181, MPK7 C 02P 3/10, publ. 2004).

The disadvantage of the carrier material is the low mechanical stiffness of the woven elements, which are easily deformed under load, increasing the hydrodynamic resistance of the filter layer. The instability of the free volume in which microorganisms are settled reduces their viability under critical operating conditions of biofilters (salvo emissions of effluents, temperature changes, etc.)

The prototype of the claimed invention is a biomass carrier (Patent of RB No. 2753, MPK7 C 02P 3/00, C 02P 3/10, publ. 1999) made of non-woven fibrous-porous synthetic material with a fiber diameter of 10-200 microns, which are interconnected cohesive spikes at the points of contact, and has a bulk density of 0.2-0.3 g / cm ³ . The carrier has the form of rings with a wall thickness of 4-5 mm, an internal diameter of 40 mm and a height of 30 mm.

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The main disadvantage of the prototype is the non-optimality of its structural characteristics, as well as its low sorption capacity for biomass. The establishment of such a wide range of fiber diameters (10-200 μm) is hardly justified, since the material, indeed having a significant variation in fiber thickness, will be extremely non-uniform, which does not allow predicting its properties as a carrier of biomass. In addition, the process of immobilization of microorganisms is quite long, and therefore it is reasonable to expect the growth of biofilm to a much greater depth than the thickness of the walls of the prototype carrier. It is known that some microorganisms destructors, in the absence of organic food sources, use amorphous sites of the polymer as theirs (L.8. Rsseyik, Α.ν. Makags \ '1c11. 6.M. U1a5ot. A..6. Κτανΐδον, ν.Α. 81ιαρονα1ον Essss (gs (111sgsha1 apalu155 Yu YA55S55 sudbytayop vy ov sobrutek zakrozek // 1p1sgp. Vyube1yuga1yuppe Vybegydgab1yup, 2004, no. 54, p. 13-18.). Considering this consideration, the thin-walled design seems to be underage, 2004, no. 54, p. 13-18.). and collapse. Of thin-walled elements and biomass will be washed away much easier. All this reduces the efficiency of the support, technical resources and the reliability of the biofilter.

The objective of the invention is the creation of a biomass carrier having a high homogeneity of the fibrous porous layer, high sorption capacity for biomass, stability of functional properties and stable modes of bio-cleaning.

The problem is solved in that the carrier of biomass of filters for biological wastewater treatment is made in the form of a fibrous-porous nonwoven material made of synthetic fibers interconnected by cohesive spikes at the points of contact with a bulk density of 0.2-0.3 g / cm ³ , while as synthetic fibers it contains polymer fibers obtained by the method of pneumatic extrusion with a melt flow index of the polymer of at least 25 g / 10 min, and these fibers have a diameter of 50-80 microns.

The carrier is made in the form of a hollow cylindrical element with a wall thickness of 5-10 mm, an internal diameter of 45-55 mm and a porosity of 65-80%. The average pore size of a fibrous-porous nonwoven fabric is 50-70 microns. The carrier is obtained by directing the gas-polymer flow to a cooled forming substrate.

The essence of the invention is that in its implementation a slight increase in the wetting time of the culture liquid of thicker structures and the time of the biofilter to a stationary mode of operation will be compensated by several factors. Firstly, while maintaining the high porosity of the fibrous layer, the biofilm can be fixed not only on the easily deformable and washable surface layer, but to grow deep into the material. Secondly, using amorphous polymer sites as an additional power source, biomass will be able to prolong the period of productive functioning to a greater degree. Third, the risk of rapid separation and destruction of the carrier will be reduced. Fourth, a narrower range of fiber diameters will cause greater uniformity of the material without loss of strength and predictability of its properties. The use of a polymer with a melt flow index of at least 25 g / 10 min will enhance the processability of the carrier formation process.

Let us give an example of the implementation of the invention.

The carrier was obtained by the method of pneumatic extrusion - aerodynamic spraying of a polymer melt by an air stream. The starting material is garnished polypropylene of the Kaplen brand (GOST 2699686) with a melt flow index of not less than 25 g / 10 min, the plasticizer is dioctyl phthalate in an amount of 2 wt.%. The polypropylene melt was processed in a single-screw extruder with three-zone heating (temperatures in zones, ^о С: I - 210, II - 270, III - 360, spray head - 370) and squeezed through a spinneret, after which he was fascinated by the air flow under pressure of 1.5 atm. and went to the rotating cylindrical forming device on which the web was formed. The pore size of the material was 50-70 microns. After cooling the fibrous-porous mass to room temperature, it was removed from the forming device and cut into cylindrical elements with an inner diameter of 50 mm. The porosity of the elements was 65-80%.

By varying the temperature-dynamic modes of spraying melts, elements of various shapes and structures can be made. Fibrous carriers in the form of hollow cylindrical elements were made of polymeric materials: low-pressure polyethylene, HDPE, polypropylene, NO, polyamide PA. Variable parameters - the wall thickness of the elements, fiber diameter, density are given in Table. one.

Studies of the structural mechanical properties of nonwoven fibrous-porous material were carried out according to the following procedure.

The inner diameter of the cylindrical element of the carrier was determined using a ruler, the wall thickness - using a micrometer. To determine the average diameter of the fibers, individual fibers were isolated from each sample and their diameter was determined using a microscope MPSU. Bulk density, porosity was assessed by the results of measurement and weighing of samples according to GOST 15902.2, mechanical properties were characterized by breaking stress under tension and critical load during compression of cylindrical elements. Destructive tensile stress was determined according to GOST

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17370 on a tensile testing machine 2038 P-0.05, the critical load during compression of ring elements was evaluated by the magnitude of the load, causing a complete deformation of the cylindrical element.

Table 1

No. of samples Carrier material Mm inner diameter Controlled media parameters Wall thickness mm The diameter of the fibers, microns Density, g / cm ³ Destructive stress at stretching MPa Critical load in compression, N one PP 50 five 5O ± 5 203-211 2.1 90.0 2 HDPE Ί 65 ± 5 211-218 2.1 90.0 3 PA ten 80 ± 5 214-232 2.3 90.0 4 prototype PP four 20 ± 5 192-200 1.8 40.0

These tables confirm the opinion of the inexpediency of reducing the fiber diameter and carrier density. Sample No. 4 has unsatisfactory parameters of the critical load of carrier crease and tensile strength, while the samples according to the proposed technical solution significantly exceed the prototype.

Carriers were also tested according to the criterion of biomass immobilization, which was carried out in the culture fluid containing the daily culture of the microbial association BassSegeseus, Legoshopaz sp, Rzeiioshopaz sp. Temperature - 27-28 ° С, pH 6.5–7.5, immobilization time 72 hours. The values of specific (i.e. per unit mass of carrier) sorption of biomass were calculated by the gravimetric method.

The efficiency of carriers in the biological treatment of liquids was evaluated by reducing the chemical oxygen consumption index (COD) at the output of a pilot biofilter with a volume of 5.3 liters. Waste water from a chemical plant containing pollutants in concentrations, mg / l: ethyl hexanol (2550), chloroethylhexyl (1840), acetone (900), isopropanol (770), methyl isobutyl ketone (200), dimethyl phthalate (200), mesityl oxide (100) , toluene (50), etc. The limiting air consumption was 1 l / l of drainage an hour, the total pollution of wastewaters on the COD index was 14.1 g / l. Test data are given in table. 2

table 2

No. of samples Specific sorption, mg / g Wetting time, min Specific consumption of wastewater, l / l load in 24 hours COD at the outlet of the biofilter, g / l Cleaning efficiency % 0.10 0.1 99.5 one 11.8 321 0.25 0.2 98.6 0.50 0.2 98.6 0.10 0.2 98.6 2 11.6 310 0.25 0.2 98.6 0.50 0.3 97.6 0.10 0.2 98.6 3 11.2 302 0.25 0.3 97.6 0.50 0.4 97.2 0.10 1.2 91.5 4 (prototype) 9.2 82 0.25 0.7 95.2 0.50 1.2 91.5

From tab. 2 shows that the claimed carriers, despite the longer wetting time with the culture liquid, are better than the prototype according to the main criteria - specific sorption of microorganisms and purification efficiency, which is especially noticeable at low specific costs of wastewater. This confirms the expressed

- 3 007088 assumptions about additional factors that increase the performance of the claimed carrier. The material is homogeneous, by virtue of which it demonstrates good reproducibility of the main characteristics and linearity of their change. High cleaning efficiency is due to the presence in the permeable system of a large number of actively functioning microorganisms capable of biodegradation of pollution, in conjunction with the optimal structural characteristics of the carrier. Within 12 months of work as part of the pilot biofilter, the prototype carrier carrier MO (position No. 4, Table 1) almost completely collapsed, while the claimed carrier (position No. 1-3, Table 1) did not show any signs of destruction .

The inventive media can be used in systems of biological filtration of wastewater. By varying the structural and concentration parameters of fibrous polymeric carriers (fiber diameter, density and porosity in the volume of the element), it is possible to adapt them to different modes of bioremediation and biofilter loads. The proposed carriers have a low specific weight, which causes a decrease in the mechanical load on the biofilter and, consequently, its material intensity. The carriers can be simply regenerated by treatment with water vapor, during which the structural elements of the carrier do not lose their shape and stiffness.

Information sources

1. Yakovlev S.V., Voronov Yu.V. Biological filters.- M .: Stroyizdat, 1975, 135 p.

2. Berne F., Cordogne J. Water Treatment. Refining wastewater treatment. Preparation of water cooling systems / Trans. with fr. - M .: Chemistry, 1997, 288 p.

3. Application 1055917 Japan C02R3 / 28, 3/00, 3/10, publ. 1989.

4. Application 2639342 France, C02R3 / 06, 3/12, 3/28, publ. 1990

5. Goldade V.A., Makarevich A.V., Pinchuk L.S. and others. Polymeric fibrous te11-Ёo \ up materials. - Gomel: IMMS NANB, 2000, 260 p.

6. RF patent №2226181, MPK7 C 02 R 3/10, publ. 2004

7. Patent of the Republic of Belarus No. 2753, MPK7 C02P3 / 00, C02P3 / 10, publ. 1999 (prototype).

8. b.8. Rssyik, ш.ν. Makage1, O.M. Shakoua, A.O. Kgau1kou, ν.Α. 8yarouaou Е1ес! Г1-1йгта1па1у κίκ 1о acccque Jobedgabayoi about £ ro1yut sotrokyek // 1 and 1et. Würöberpörül & Vyubedgabuyuy, 2004, No. 54, R. 13-18.

Claims (5)

CLAIM 1. The carrier of the biomass of filters for biological wastewater treatment, made in the form of a fibrous-porous non-woven material from synthetic fibers interconnected by cohesive adhesions at the contact points, with a bulk density of 0.2-0.3 g / cm ³ , characterized in that as synthetic fibers it contains polymer fibers obtained by pneumatic extrusion with a melt flow index of the polymer of at least 25 g / 10 min, and these fibers have a diameter of 50-80 microns. 2. The carrier according to claim 1, characterized in that it is made in the form of a hollow cylindrical element with a wall thickness of 5-10 mm and an inner diameter of 50-55 mm. 3. The carrier according to claim 2, characterized in that the porosity of the cylindrical element is 6580%. 4. The carrier according to claim 1, characterized in that the average pore size of the fibrous-porous non-woven material is 50-70 microns. 5. The carrier according to claim 1, characterized in that it is obtained by directing a gas-polymer stream onto a cooled forming substrate. Eurasian Patent Organization, EAPO Russia, 109012, Moscow, Maly Cherkassky per., 2/6