WO2019029755A1

WO2019029755A1 - Process and device for the treatment of domestic wastwater using multiple filters with bioadsorbent material and microalgae

Info

Publication number: WO2019029755A1
Application number: PCT/CO2018/000019
Authority: WO
Inventors: Ruben Dario CANETRO RODELO; RAMIREZ Margarita del Pilar CASTILLO; FUENTES Eduardo Antonio ESPINOZA; Euler GALLEGO CARTAGENA; Nubia Mireya GARZON BARRERO; Andrea Liliana MORENO RIOS
Original assignee: Corporacion Universidad De La Costa Cuc
Priority date: 2017-08-11
Filing date: 2018-08-13
Publication date: 2019-02-14
Also published as: CO2017008145A1

Abstract

The present invention relates to a treatment process which removes nutrients from domestic wastewater through the combined use of pretreatment units together with filtration based on oyster shells, other bioadsorbent materials and microalgae. The process according to the present invention involves a group of reactors having a central tube divided into segments by chambers inserted therein, said chambers containing bioadsorbent particulate matter from shells of molluscs of the genera Crassostrea sp and/or Polymesoda sp. and/or Coquina-type coral rocks having different particle sizes, in which process the bioreactor contains living microalgae of the genus Chlorella sp. The domestic wastewater treatment process of the present application consists in connecting two or more bioreactors in series, and conveying water through the chamber-segmented central tube of the first bioreactor, the wastewater passing through the mixture of bioadsorbent material contained in the chambers and leaving the central tube and entering the bioreactor through perforations provided in the lower portion of the central tube. Subsequently, the water passes through the space between the central tube and the inner wall of the bioreactor, where the wastewater comes into contact with the microalgae. The water leaves the first reactor through the upper portion and enters the next reactor through the upper portion of the central tube, where the process is repeated.

Description

PROCESS AND APPARATUS FOR THE TREATMENT OF WASTEWATER

HOUSING THROUGH THE IMPLEMENTATION OF MULTIPLE FILTERS

WITH BIOADSORBENT MATERIAL AND MICROALGES TECHNICAL FIELD

The present invention relates to a treatment process that removes nutrients from domestic wastewater, through the combined use of pretreatment units with filtration based on oyster shells, other bioadsorbent materials and microalgae.

The design of the filtration system and operation of the same has a multifunctional mechanism in series and sustained, because in the reactors physicochemical processes are integrated as the adsorption of the bioadsorbent based on shells other bioadsorbent materials and the biological absorption of the microalga what contributes to a significant removal of phosphate in domestic wastewater.

BACKGROUND OF THE INVENTION It has been found that among the effects of municipal effluents is eutrophication. This problem began in the 1940s and took on greater visibility in the 1960s. Due to the impact of its effects, since in recent decades the trophic conditions of many of the continental waters have increased rapidly. Eutrophication has become one of the most widespread and serious anthropogenic disturbances in aquatic ecosystems. In the publication of the A US Environmental Protection Agency Perspective. Journal of Environmental Quality, 27 (2), 258-261, 1998, Parry, R., refers to the fact that in freshwater bodies the nutrient that most affects eutrophication is the phosphorus, while in saltwater, the highest incidence is nitrogen. Likewise, in 2001, Aertebjerg and others at the European Environment Agency affirmed that phosphorus is an important nutrient in the reproductive growth of plants and in the formation of ATP; it is generally found in its oxidized state, as inorganic orthophosphate ions or in organic compounds. Specifically, it is found in higher concentrations in the sediment than in the water column, in the bond with the sediment is released, although, the equilibrium of phosphorus concentrations between the sediment and water is controlled by many factors, such as pH and dissolved oxygen.

Among the technological alternatives that have been implemented for the treatment of wastewater (AR) from both the domestic, industrial and agricultural sectors, are artificial methods based on engineering systems for the removal of nutrients from these. Teixeira and others in the Faculty of Engineering Magazine of the University of Antioquia, volume 67, pages 172-182, 2003., mention the implementation of fluidized bed reactors with internal circulation (RALFCI) based on the use of active biomass with large capacity of removing excess organic matter and nitrogen in RA. Likewise, as alternatives for the elimination of phosphorus and nitrogen in AR, there are stabilization ponds, systems for controlled disposal in the soil; activated sludge and aerobic reactors with biofilm, as well as the removal by physical-chemical processes or the combination of some of the above. In this sense, another alternative technology for the removal of phosphorus from AR naturally has been the implementation of microalgae, which are photosynthetic microorganisms that use the sun's energy to grow, in addition to consuming inorganic compounds and CO2, their use for the AR treatment was first proposed by CaldweII (1940), who reported the initial studies, on the use of microalgae as AR purifiers due to the use of inorganic nutrients contained in the water. Then, Oswald and Gotaas in 1957, published an article entitled "Photosynthesis in sewage treatment" in American Civil Society Enginering, 122, 73-105, in which they exposed the possibility of making the use of microalgae both for the removal of contaminants, as for the production of vegetable biomass, which can be considered as recovery of wastewater.

In this way, microalgae have been widely used for domestic and industrial wastewater treatment, becoming a low-cost technology. He and others, in Bioresource technology, 146, 562-568, 2013, make reference to the fact that microalgae allow the recycling of nutrients such as phosphorus and nitrogen, which are incorporated into the biomass and lead to the generation of oxygen. According to Komolafe and others in Bioresource technology, 154, 297-304, 201., These can in turn reduce BOD, Coliforms and heavy metals in AR. Likewise, Ruiz et al., In Bioresource tecnhnology, 126, 247-253, 2012., found that the percentages of nutrient removal were satisfactory when using microalgae and allow the combination of AR treatment with biomass production. In addition to the above, N. Abdel-Raouf et al., In the Saudi Journal of Biological Sciences 19, 257-275, 2012, point out that the use of microalgae offers a tertiary biotreatment of the RA, also allowing the removal of heavy metals and coliform inhibition.

He and others (2013), make reference in their research that among the species most studied in removal of contaminants, is Chlorella sp, which is a species of rapid growth and short generation time, with the capacity to tolerate rigorous environmental conditions. as those found in wastewater, efficiently assimilating the Nitrogen and Phosphorus of the AR; this species It has a high nutrient removal capacity (approximately 80%) in primary treatments, as well as secondary and in certain conditions it can completely remove ammoniacal nitrogen, nitrate, nitrogen and total phosphorus. Tubular-type photobioreactors are among the reactors most used for the growth of the Chlorella sp species. Basically, these reactors are a closed system consisting of a transparent tube inside which the algae grow, using the AR as a source of nutrients for their growth. One of the first publications on this subject was made by Davis and others, from the Laboratory fo Pilot Plant. Ccarnegie Institution I heard Washington D. C in 1953.

In patent US20160272524 of 2015 refers a procedure for the treatment AR by means of photosynthetically active algae that form a sediment in a state of rest, comprising the following stages: a) supply of wastewater to the algae and formation of the sediment in state at rest, b) transport of the wastewater supplied to the algae against gravity from a lower level to a higher level, while simultaneously exposing the wastewater mixed with the RA to the light; c) introduction of the ARs supplied to the algae from the upper level to the upper region of a sedimentation tank; d) allow the algae to sediment in the sedimentation tank and e) eliminate the wastewater released from the algae by sedimentation as treated AR.

On the other hand, new research points to the use of waste materials as BADs bioadsorbents. Ucun et al., In Journal of Hazardous Materials, 161 (2), 1040-1045, 2009 studied the removal of heavy metals with BADs; Panda et al., In Journal of Hazardous Materials, 164 (1), 374- 379, the removal of dyes in RA, promulgating the use of waste of agricultural, industrial or municipal waste origin, as described by Cardona et al., in Revista Ingenierías 1 (1), 1 -9, and Chao et al., in Interciencia Magazine 26 (10), 774 - 778. With the use of such materials, appropriate materials would be available for the removal of contaminants at a low cost and with a lower environmental impact.

Some types of ADBs are broad spectrum, that is, they are not selective for a particular type of pollutant, while others may be specific for certain types of contaminants. Bioadsorption is a process that has been studied by many researchers, proving to be an alternative technique to conventional methods for the treatment of different industrial effluents contaminated with heavy metals and dyes. This is why the use of materials of biological origin has intensified, such as: algae (Cuizano et al., 2010), fungi (Acosta et al., 2007), bacteria (Monge-Amaya et al., 2008), remains of shellfish (Moreno, 2013), agricultural remains (Tapia and others., 2011), metallic sludge (Yang et al., 2006) which are in great abundance and are easily transformable to bioadsorbents. Rafatullah et al., In Journal of hazardous materials, 166 (2), 1050-1059, 2010., made an allusion that one of the advantages of the use of biomaterials as adsorbents is that they are abundant in nature and are available to a very low cost.

In recent years have increased the studies on the use of biadsorbentes materials, however, there are few devices or systems developed based on the utility they offer. When searching in various databases of patents and / or scientific articles, little information was found on the use of bio-sorbent based on oysters. Wanielista et al., In the patented US007927484B2 (201 1) proposed a filtration system or bioretention of compounds with nitrogen and phosphorus in water waste, using a mixture of recycled materials such as crushed tires, sawdust, orange and coconut shells, compost leaves, oyster shell, orange peels and other materials of natural origin including sand, zeolites and clay.

For its part, Fengming and Xiangjun in the patent CN103585995A (2014), disclosed a new material consisting of a mixture of various materials such as white titanium, quartz sand, kaolin and oyster shell, among others. In this study, only the material was patented, but a device or technology for its use is not presented. Other similar materials consisting of mixtures of different bioabsorbent material and inert materials have also been patented (Ferngming and Xiangjun (2014- CN103585966A), (Quoquiang 2014 - CN104176805A), (Quoquiang 2014 - CN104176806A), (Zhen 2015 - CN104326546A), (Wang Lu and Xu Jing 2015- CN104445448) Additionally, it has been found that bioadsorbents have also been applied for the treatment of industrial wastewater contaminated with dyes from the textile industry, as described in patent WO0242228 (2002).

There are also patents in which methodologies are mentioned for the treatment of RA only with the use of microalgae. Among them is the patent KR101444643 (B1) of 2016, which refers to an apparatus for the treatment of wastewater with microalgae, consisting of a biofilm filtration tank at the front end of a tank of photosynthesis / nitrification , for the elimination of floating material and reduction of turbidity, thus minimizing the reduction of light transmittance due to heterotrophic bacteria, and while allowing the nitrification microorganisms, to adhere to a floating support, to grow on it, and use the oxygen generated by photosynthesis of microorganisms in the tank photosynthesis / nitrification with microalgae. As a result, the authors mention that the competition of substrates between microorganisms can be avoided to improve the efficiency of treatment of organic matter, nitrogen and phosphorus with microalgae. In the following figure the scheme presented in said patent is shown.

The patent CN102336498 (B) of 2012 refers to another procedure for the treatment of RA, which includes the following stages: elimination of impurities and sediments from RA with high concentrations of nitrogen and phosphorus, then treatment of RA using active sludge in a sequential sequencing reactor, then the decanting of the supernatant of the sequencing lot is carried out, adding the supernatant in a membrane bioreactor for further aerobic treatment. Subsequently, it is filtered by ultrafltration membrane in the bioreactor to eliminate micro-suspensions and bacteria. The ultrafiltration supernatant generated is added to a photobioreactor, disinfected by ozone and algae filaments are added, carbon dioxide is added to perform the cultivation of the microalgae and then these are taken to a sedimentation pool to be separated. Patent CN103043851 (A) of 2013 describes a similar procedure for the treatment of RA with microalgae cultures, flocculation, clarification and filtration processes connected in series.

Based on the findings in the different patents and scientific articles, it can be affirmed that, although inventions have been developed around the use of microalgae for the treatment of RA, as well as developments of new materials that include the oyster shell , each of them presents different types of combinations in terms of material and does not reveal a device or system that allows its application in conventional wastewater treatment plants. Therefore, the proposed procedure will allow the development potential of an invention that allows the removal of compounds such as nitrogen and phosphorus and in turn leads to the generation of an added value through the use of the biomass generated in the simultaneous process of the combined filtration system bioabsorbent-microalgae.

SUMMARY OF THE INVENTION

The present invention is directed to a process for the treatment of residential wastewater. The design of the process consists of the combined use of units of pretreatment with filtration based on bioadsorbent material of mollusc shells of the genera Crassostrea sp. and / or Polymesoda sp., Coquina type coral rocks and / or microalgae culture. Its operation involves a multifunctional mechanism in series and sustained, because in the reactors physicochemical processes are integrated such as the adsorption of the material based on shells and the biological absorption of part of the microaiga which contributes in a significant removal of phosphate in waters domestic residuals. The process for the treatment of domestic wastewater according to the present application consists in connecting two or more bioreactors in series, passing the waste water through a central segmented tube integrated with interspersed chambers with or without bioadsorbents and leaving the central tube at bioreactor through perforations in the base of said central tube. Then, the water passes to the area located between the central tube and the body wall of the bioreactor where the wastewater comes into contact with the microalgae, from there it is passed to the next bioreactor. The water leaves the first reactor at the top and enters the next reactor through the upper part of the central tube, where the process is repeated.

BRIEF DESCRIPTION OF THE FIGURES The present invention is understood more clearly from the following figures which show the components and results associated with this process and apparatus, as well as the novel elements with respect to the state of the art, where, the figures are not intended to limit the scope of the invention, which is only given by the appended claims, wherein:

Figure 1 corresponds to a view of a bioreactor according to the present application. Figure 2 corresponds to a detailed front view of one of the interleaved chambers forming part of the segmented central tube of the bioreactor, as shown in Figure 1.

Figure 3 corresponds to a cross-sectional view of a cylinder of plastic meshes with bio-absorbent material located inside the central tube in Figure 2.

Figure 4 corresponds to a set of bioreactors for the treatment of domestic wastewater according to the present application.

Figure 5 corresponds to a flow diagram of the process of the present invention.

DETAILED DESCRIPTION OF THE INVENTION The present invention is directed to a process for the treatment of domestic wastewater. The process consists of two or more bioreactors connected in series or in parallel, which take the domestic waste water and treat it to be discharged. Figure 1 shows a view of a bioreactor according to an embodiment of the present invention. The bioreactor comprises a domestic wastewater inlet (1) connected by a universal connection (2) to the feed tube (4) of the bioreactor, which comprises a valve (5) joined by a T-tube (3) to the tube feed (4). In one embodiment according to the present invention, the central tube has approximately the same length as the body of the bioreactor. The feeding tube (4) is connected to the bioreactor by means of an inlet of the bioreactor, which is located in the upper part of the bioreactor, has a larger diameter than the feeding tube (4) and is secured to the bioreactor by means of a flange (6). ). The entrance to the bioreactor is coupled to an internal tube of the bioreactor (9) by means of a coupling (7); said inner tube of the bioreactor (9), consists of a central tube segmented by intercalated chambers (9a), with or without bioadsobent material connected by couplings (10) which, in one embodiment of the present invention, two or more segments of the tube central contain plastic mesh cylinders with an opening diameter between 1.0 to 3.0 mm, which in turn contain particulate material of different sizes of mollusc shells of the genera Crassostrea sp. and / or Polymesoda sp. and / or Coquina coralline rocks ranging from 0.45 to 3.5 mm in polyethylene plastic mesh wrappers with an aperture diameter between 0.3 to 1.8 mm.

Between the inner tube of the bioreactor (9) and the body wall of the bioreactor (8) a space (11) is formed where live microalgae are inoculated. In one embodiment of the present invention, the internal diameter of the bioreactor is approximately four times the internal diameter of the central tube. In one embodiment of the present invention, the microalgae used are of the genus Chlorella sp. The central tube of the bioactor (9) comprises, in its lower part, a coupling (12) that connects the inner tube of the bioreactor (9) to a lid with multiple perforations in the outlet area (14). In the lower part of the bioreactor there is an aeration inlet (13), which feeds air into the space (11) where the microalgae are. The flange (6) also houses the outlet pipe of the bioreactor (16), which also comprises a valve (15) coupled by means of a T-tube (18) to the outlet pipe. Said outlet tube is connected to an inlet pipe of another bioreactor or to an outlet pipe of the system by means of a universal union (17).

Figure 4 shows a view of the apparatus for the treatment of wastewater, according to an embodiment of the present application. Said apparatus comprises four bioreactors (201, 202, 203, 204) connected in series. In this embodiment, each of the central tubes is segmented by interspersed chambers, with or without bioadsobent material connected by couplings, in which the segments contain particles of bioadsorbent material from shells of the genera Crassostrea sp. and / or Polymesoda sp. and / or Coquina coralline rocks of different particle sizes coated in plastic meshes of different opening diameters, where the segmented central tube of the bioreactor (201) contains a coarse particle size, while the segmented central tube of the bioreactor (202) has an average particle size, and the segmented center tubes of the bioreactors (203, 204) contain a fine particle size.

In an alternative embodiment, the central tube segmented by intercalated chambers of the first (201) of the bioreactors has a distribution of segments in the upper part with bioadsorbent material with a coarse particle size, up to a height equal to half the length of the same, and a second distribution of segments with bioadsorbent material in the lower part with a size of medium particle; the central tube of the second bioreactor (202) has a segment distribution at the top with bioadsorbent material with a coarse particle size and a second segment distribution with the bioadsorbent material at the bottom with an average particle size; and the center tubes segmented by intercalated chambers of the remaining bioreactors (203, 204) contain the bioadsorbent material with a fine particle size distributed in the interspersed chambers. In one embodiment of the present invention, the bioadsorbent material has a particle size between 0.45 mm and 3.5 mm. In one embodiment of the present invention, the bioreactor is made of a transparent plastic material such as, for example, acrylic and the central tube segmented by intercalated chambers is made of an opaque plastic material such as, for example, PVC. The person skilled in the art will appreciate that it is possible to vary the distribution and composition of the chambers containing the bio-absorbent material within the central tubes of each of the bioreactors without departing from the spirit and scope of the present application. Likewise, the technician with skill in the subject will appreciate that it is possible to increase or reduce the number of bioreactors used per process, the way in which they are connected, that is, whether they are serial or parallel, and the dimensions of the without departing from the spirit of the present invention.

The present invention also teaches a method for treating domestic wastewater, which comprises connecting two or more bioreactors according to the present application, to form an apparatus (set of reactors); connect the first of said reactors to a domestic wastewater outlet pipe; open the valve to allow the flow of said waste water, so that they descend through the central tube coming into contact with the bioadsorbent material contained in the intercalated chambers and then ascend through the internal space of the bioreactor to come into contact with the microalgae. The water treated in the first bioreactor comes out of the upper part of it, enters the second reactor through the upper part of it and repeats the cycle in each of the bioreactors included in the set of reactors, until they exit through the last bioreactor of the set and are properly discharged. Although up to now a description has been made of one or more embodiments of the present invention, it is not limiting and the expert with skill in the art will appreciate that it is possible to develop versions with some modifications but without departing from the spirit and the scope of the invention, as set forth in the claim chapter below.

Claims

An apparatus for the treatment of wastewater, characterized in that it comprises two to four bioreactors each of which consists of:

• a wastewater inlet (1);

• a sewage feed pipe (4) connected to the inlet (1) by a universal joint (2), said pipe (4) comprises a valve (5) joined by a T-tube (3);

• a body of the bioreactor (8) in which microalgae are placed;

• an inner tube (9) coupled by a coupling (7), said inner tube of the bioreactor (9), consists of a central tube segmented by intercalated chambers (9a), with or without bioadsobent material connected by couplings (10);

• a space (11) formed between the internal tube (9) and the body wall of the bioreactor (8), where said space corresponds to inoculation of live microalgae;

• a lid with perforations in the outlet area (14) coupled to the lower part of the inner tube (9) by means of a coupling (12); Y

• an aeration inlet (13) connected to the space (11) of the microalgae;

• an outlet tube (16) connected to the flange (6) for connection to the supply pipe (4) in the upper part of the bioreactor, said outlet pipe (16) comprises a valve (15) coupled by means of a T-tube ( 18) to the outlet tube,

wherein the bioadsorbent material is a material derived from mollusc shells of the genera Crassostrea sp. and / or Polymesoda sp. and / or coquina type coralline rocks; and where the microalgae correspond to the genus Chiorella sp.

The apparatus according to claim 1, characterized in that the central tube (9) has the same body length of the bioreactor (8).

The apparatus according to claim 1, characterized in that two or more segments of the central tube (9) contain plastic mesh cylinders with an opening diameter between 1.0 to 3.0 mm, which in turn contain the bioadsorbent material with particle sizes. between 0.45 and 3.5 mm in polyethylene plastic mesh wrappers with an opening diameter between 0.3 to 1.8 mm.

The apparatus according to any of the preceding claims, characterized in that it comprises four bioreactors connected in series.

The apparatus according to claim 4, characterized in that the bioadsorbent material is distributed in the central tubes in the following manner:

• The central tube of the first bioreactor (201) contains a bed of bioadsorbent material with a coarse particle size;

• The central tube of the second bioreactor (202) contains a bed of bioadsorbent material with a medium particle size; Y

• The central tube of the third and fourth bioreactors (203, 204) contain a bed of bioadsorbent material of fine particle size.

The apparatus according to any of the preceding claims, characterized in that the diameter of the body of the bioreactor (8) is twice the diameter of the central tube (9).

Process for the removal of phosphates from domestic wastewater CHARACTERIZED because it includes the steps of: making the domestic wastewater interact with a bio-absorbent material based on mollusc shells of the genera Crassostrea sp. and / or Polymesoda sp. and / or Coquina-type coral rocks with particle sizes between 0.3 μπι and 3.5 mm; circulate water to adsorb phosphate concentrations; and circulate the water with the microalgae of the genus Chorella sp. to remove the remaining phosphates not removed in the previous step.

Process according to claim 7, characterized in that the preparation of the bioadsorbent material used for the removal of phosphates includes the following steps:

a) wash with water to remove the remains;

b) remove impurities and organic matter, by submerging each quantity in 100 ml of 10% HCL solution for 24 hours and doing a rewind in hot water;

c) subjecting the material to grinding in a mill to reduce the size; and d) sorting by sieving (No. 16, 10 and 8, ASTM E-1 1/95 Standard), with particle sizes between> 1.00 to 3.35 mm.

9. Process according to claim 7, characterized in that the size of the initial inoculum of the culture with microalgae is greater than 0.85 x 106 cells / ml of Chorella sp obtained during the exponential phase of a stock culture, previously maintained under culture conditions. in vitro in medium with filtered domestic residual water.

10. Process for removal of phosphates in domestic wastewater, characterized in that it comprises the steps of entering the domestic wastewater with phosphate concentrations to a reactor (1) the wastewater comes into contact in a descending manner with the bioadsorbent material (ADB) contained in it. a vertical central pipe that allows mixing between the material bioadsorbent, wastewater and microalgae (2) the water leaves the lower part of the tube generating a change of direction upwards towards the outer chamber that contains microalgae (3) the residual water treated with an initial percentage of phosphate removal leaves the reactor through a pipe to the reactors 2, 3 and 4 located in series repeating the aforementioned removal cycle.