Carrier element for wastewater treatment and carrier element modification method
11541418 · 2023-01-03
Assignee
Inventors
- Selda Murat Hocaoglu (Gebze-Kocaeli, TR)
- Pamir Talazan (Gebze-Kocaeli, TR)
- Recep Partal (Gebze-Kocaeli, TR)
- Irfan Basturk (Gebze-Koceali, TR)
Cpc classification
B01J19/30
PERFORMING OPERATIONS; TRANSPORTING
C02F3/2806
CHEMISTRY; METALLURGY
C02F2305/06
CHEMISTRY; METALLURGY
Y02W10/10
GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
International classification
Abstract
The invention relates to the development of a carrier material providing high surface area for biofilm formation in wastewater treatment plants and a carrier material surface modification method for accelerating and enriching biofilm formation.
Claims
1. A surface modification method of a carrier element developed for use of microorganisms growing on biofilm, for wastewater treatment and pollutant removal, characterized by comprising the following steps of: Washing a carrier element to free it from contaminants, Liquefaction of a paraffin wax containing trace elements, Immersion of the carrier element into the paraffin wax bath for 3-5 seconds, Allowing the excess paraffin remaining on the carrier element surface to flow away and harden for 3-5 seconds, Allowing the material to dry at room temperature for 5-10 seconds.
2. A surface modification method according to claim 1, characterized in that paraffin-modified surface of the carrier element is impregnated with nutrients and trace elements.
3. A surface modification method according to claim 2, characterized in that the impregnation with the nutrients comprises immersion of the paraffin-modified surface of the carrier element into a nutrient solution and keeping it there for 24 hours.
4. A surface modification method according to claim 3, characterized in that the nutrient solution is a solution containing 20-30% peptone by weight.
5. A surface modification method according to claim 1, wherein the carrier element is selected from the group consisting of a cubic form carrier element (1), a cylindrical form carrier element (2) and, a second-stage plate-type carrier element (3), wherein wherein the cubic form carrier element (1) comprises: a central support section (8) three-way single biofilm growth chambers (5), three-way three biofilm growth chambers (6) and four-way two biofilm growth chambers (7), wherein the cylindrical form carrier element (2) comprises: a central support section (8) two-way biofilm growth chambers (9), three-way four biofilm growth chambers (10), a circular outer surface (11), and fins (12) of the same length as the outer surface height, wherein second-stage plate-type carrier element (3) comprises: a central support section (8), three-way three biofilm growth chambers (6), two-way biofilm growth chamber (9), four-way two biofilm growth chambers (7) and a circular outer surface (11).
6. A surface modification method according to claim 1, further comprising adding trace elements in powder form into the melted paraffin wax or immersing the carrier element coated with paraffin wax into a solution of trace elements.
Description
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING(S)
(1)
(2)
(3)
(4)
(5)
(6)
(7)
DESCRIPTIONS OF THE REFERENCES IN THE FIGURES
(8) 1: Cubic configuration of the carrier element 2: Cylindrical configuration of the carrier element 3: Second-stage plate-type cylindrical configuration of the carrier element 4: Surface modification process 5: Three-way single-channel biofilm growth chamber 5.1: Channel 6: Interlocking three-way three-channel biofilm growth chamber 7: Interlocking four-way two-channel biofilm growth chamber 8: Central support section 9: Two-way biofilm growth chamber 10: Interlocking three-way four-channel biofilm growth chamber 11: Circular outer surface 12: Fin A: Paraffin wax B: Paraffin liquefaction step C: Carrier element D: Step of immersing the carrier element into paraffin E: Step of removing excess paraffin F: Drying step G: Step of immersing into peptone solution
DETAILED DESCRIPTION
(9) The invention relates to (i) the development of a carrier element providing high surface area for biofilm formation in wastewater treatment plants and (ii) a carrier element surface modification method for accelerating and enriching biofilm formation.
(10) Within the scope of the invention, carrier elements—with a large effective specific surface area and with a high ratio of this area to total specific surface area—have been developed. Depending on the designs of these carrier elements, the representation of the biofilm growth chamber is shown in (9). When the carrier element is placed in a reactor with circulating wastewater, a biofilm is formed in this chamber (9) by microorganisms. The geometric form of the biofilm growth chamber (9) may vary depending on the carrier element design. Since the liquid flow in this biofilm growth chamber (9) is through the upper and lower clearances, this design (9) is called two-way biofilm growth chamber. Three-way single-channel biofilm growth chambers (5) allow liquid flow in three directions, which are through the upper and lower clearances and the channel (5.1). Interlocking three-way three-channel biofilm growth chamber (6) includes three combined three-way three-channel biofilm growth chambers (5). The interior parts of these chambers (5) allow liquid transfer among each other. The four-way two-channel biofilm growth chamber (7) allows interlocking liquid transfer in four directions, which are through the upper and lower clearances and the two channels (5.1). Interlocking three-way four-channel biofilm growth chamber (10) has four channels (5.1) and four three-way single-channel biofilm growth chambers (5).
(11) Based on the cubic configuration (1) that allows increased oxygen transfer and multi-directional substance transfer on biofilm surface and that has in its central support section (8) three-way single-channel biofilm growth chambers (5), interlocking three-way three-channel biofilm growth chambers (6) and interlocking four-way two-channel biofilm growth chambers (7), a cylindrical configuration (2) has been developed to contribute to the increase of biofilm thickness and to allow a protected and inhibition-resistant biofilm growth, with a central support section (8) surrounded by three-way single-channel biofilm growth chambers (5), two-way biofilm growth chambers (9) and interlocking three-way four-channel biofilm growth chambers (10), having a circular outer surface (11) and fins (12) with the same height as the circular outer surface (11). Carrier elements can be made of polyethylene (PE), high density polyethylene (HDPE), polypropylene (PP), polyvinylchloride (PVC) and/or composite plastic materials. The specific gravity of the material is preferably in the range between 0.94 and 1.05 g/cm.sup.3. The carrier elements can be made from pure raw material and/or preferably, owing to environment-friendly nature, from duly recycled material that is not contaminated with micro-pollutants and/or toxic substances. While the protected cylindrical carrier element configuration (2) with increased biofilm thickness compared to the cubic configuration (1) allows more biomass retention, the cubic configuration (1), on the other hand, allows material transfer into the biofilm to take place from three or four directions owing to water movements, as well as allowing relatively thinner biofilm formation due to shear forces and supporting more oxygen and substance transfer into the biofilm compared to the cylindrical configuration (2).
(12) The effective specific surface area in the invention is in a range of 490-960 m.sup.2/m.sup.3 in the cubic configuration (1), 430-850 m.sup.2/m.sup.3 in the cylindrical configuration (2) and 410-680 m.sup.2/m.sup.3 in the second-stage plate-type cylindrical configuration (3). The ratio of effective specific surface area to total specific surface area is averagely 97% in the cubic configuration (1), 76% in the cylindrical configuration (2) and 71% in the second-stage plate-type cylindrical configuration (3).
(13) The cubic configuration (1) of the carrier element to be used for biofilm development as a part of the present invention is shown in
(14) The cylindrical configuration (2) of the carrier element to be used for biofilm development as a part of the present invention is shown in
(15) The second-stage plate-type cylindrical configuration (3) of the carrier element to be used for biofilm development as a part of the present invention is shown in
(16) The carrier elements can preferably be produced by extrusion and/or injection molding methods.
(17) The carrier element surface modification method (4), which is another subject matter of the invention, is related to the acceleration of biofilm attachment to the surface and the reduction of biofilm fragility. In many studies, it is reported that microorganism attachment to a surface is directly related to the hydrophobicity of the surface and that the hydrophobicity supports the microorganism attachment to the surface (Donlan et al., 2002; Cerca et al., 2005; Mazumder et al., 2010; Pagedar et al., 2010).
(18) Accordingly, the invention relates to increasing the hydrophobicity of the carrier element surface used in wastewater treatment plants by coating it with paraffin wax, consequently, shortening the biofilm formation time, and also reducing the biofilm fragility and preventing peeling-type complete biofilm ruptures, owing to the achievement of a more stable and durable structure in the attached biofilm. In the surface modification method (4) developed within the scope of the invention, the carrier element surface is washed with water, freed from particles like dust, burr, etc., dried at room temperature and made ready for surface treatment. Paraffin wax (A) in solid state at room temperature containing 25-50 carbon atoms per molecule is switched to liquid state (B) at a temperature of 70-80° C. by using hot water bath, oven, etc. The carrier element (C) is immersed into the bath containing hot paraffin wax in liquid state (D); after a period of time (preferably a few seconds), the material is removed from the bath, and the excess paraffin remaining on the surface is allowed to flow away and harden (E). Finally, the material is allowed to dry at room temperature (F). Drying process is preferably realized by keeping the material at room temperature for 5-10 seconds.
(19) The carrier element surface modification method (4) of the invention also includes the impregnation of a nutrient solution on the carrier element surface covered with paraffin wax as a second stage surface treatment in order to support the acceleration of biofilm formation in nutrient-poor wastewater. For this purpose, the carrier element coated with paraffin is immersed in the nutrient solution (G) and after an average of 24 hours, it is removed from the solution and allowed to dry at room temperature (F). In an embodiment of the invention, it is possible to use peptone solution as the nutrient. For this purpose, the carrier element coated with paraffin is immersed into a solution preferably containing 20-30% peptone by weight, and the described process is performed.
(20) Surface treatment can be applied either completely on the all carrier elements added to the reactor, or partially.
(21) In wastewaters with quite variable characteristics, especially in industrial wastewaters, trace elements (such as zinc, copper, cobalt, molybdenum) required for biological reactions may be insufficient. In wastewaters without sufficient trace elements, the needed elements can be determined by analyzing the wastewater, and can be applied to the carrier material surface preferably by adding an appropriate amount of relevant trace elements in powder form into the melted paraffin (B) or by immersing into a solution of trace elements.
INDUSTRIAL APPLICATION OF THE INVENTION
(22) The carrier material developed, can be produced by plants processing plastic materials by injection and/or extrusion method.
(23) The carrier material surface modification method developed, can be applied by enterprises having infrastructures for coating by immersion method.
REFERENCES
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