NL2019171B1 - Method and system for production of natural polyelectrolytes such as microbial extracellular polymeric substances - Google Patents

Abstract

The present invention relates to a method and system for the production of natural, biodegradable polymeric flocculants from a fluid, such as a waste fluid, such flocculants and their use. The method comprising the steps of: — providing a reactor comprising at least one reactor vessel, one fluid inlet, one fluid outlet, one flocculant outlet, and at least one membrane provided in the reactor vessel between the fluid inlet and the fluid outlet; — inoculation of the reactor; — providing feed to the at least one fluid inlet; — forming the flocculants; — separating the flocculants using the membrane; and — providing the flocculants at the flocculant outlet.

Description

Netherlands Patent Office © 2019171 (2?) Application number: 2019171 © Application filed: July 4, 2017 © B1 OCTROOI

Int. CL:

C02F 1/52 (2017.01) C02F 1/56 (2017.01) C02F 11/14 (2017.01) C02F 1/38 (2017.01) C02F 1/42 (2017.01) C02F 1/469 (2017.01) C02F 3/12 (2017.01)

0 Application registered: © Patent holder (s): January 14, 2019 Wetsus Foundation, European Center or Excellence for Sustainable Water Technology © Request published: in LEEUWARDEN. © Patent granted: © Inventor (s): January 14, 2019 Bernard Gerhard Temmink in LEEUWARDEN. Victor Olusola Ajao in LEEUWARDEN. © Patent issued: May 8, 2019 © Authorized representative: ir. P.J. Hylarides et al. In The Hague.

(54) METHOD AND SYSTEM FOR PRODUCTION OF NATURAL POLYELECTROLYTES SUCH AS MICROBIAL EXTRACELLULAR POLYMERIC SUBSTANCES use. The method including the steps of:

- providing a reactor comprising at least one reactor vessel, one fluid inlet, one fluid outlet, one flocculent outlet, and at least one membrane provided in the reactor vessel between the fluid inlet and the fluid outlet;

- inoculation of the reactor;

- providing feed to the least one fluid inlet;

- forming the flocculants;

- separating the flocculants using the membrane; and

- providing the flocculants at the flocculant outlet.

NL B1 2019171

This patent has been granted regardless of the attached result of the research into the state of the art and written opinion. The patent corresponds to the documents originally submitted.

METHOD AND SYSTEM FOR PRODUCTION OR NATURAE POLYELECTROLYTES

SUCH AS MICROBIAL EXTRACELLULAR POLYMERIC SUBSTANCES

The invention relates to a method for the production of natural, biodegradable polymeric flocculants from a fluid, for example a waste fluid. For example, the method discloses the manufacturing of microbial Extracellular Polymeric Substances (EPS) that can be applied as flocculants for waste fluid treatment or other fluids containing (colloidal) particles.

It is known from practice to use carboxyl cellulose flocculants and (biodegradable) flocculants. Conventional production methods for these flocculants include EPS production strategies involving identification and isolation of EPS producing microbial strains with single organic substrate feeding. Conventional EPS production uses pure cultures which need to be fed with expensive and unsustainable carbon sources as well as with other valuable nutrients.

From practice it is also known to use inorganic coagulants that are cheap and easy to use. However, inorganic coagulants do not flocculate efficiently at low dosages, are non-specific, leave residual metal pieces in treated water, and produce toxic sludge (metal hydroxide). This makes disposal of this sludge difficult, expensive and non-reusable, for example in agriculture and, therefore, the associated food chain. Synthetic organic polyelectrolytes (Pes) / flocculants, have higher flocculating efficiency, lower dosage requirements, ability to water more effectively, and can form strong and dense flocs. Nonetheless, they suffer non-negligible drawbacks or slow biodegradability and generation of toxic degradation products / monomer residues that may enter the food chain and cause severe neurotoxic or carcinogenic effects. Besides, unreacted chemicals used to synthesize lite monomer units, such as formaldehyde, epichlorohydrin and dimethylamine, are toxic and have been found as sources of contaminants in "treated" water. Hence, the use of synthetic flocculants can hardly be considered a sustainable water treatment approach, especially in open systems such as dredging and mining applications.

An objective objective of the present invention is to provide a method for the production of natural, biodegradable polymeric flocculants from a waste fluid that obviates or at least reduces the aforementioned problems and / or is more efficient as compared to conventional methods.

The objective is achieved with the method for the production of natural, biodegradable polymeric flocculants from a fluid, such as a waste fluid, according to the invention, the method including the steps of:

- providing a reactor including:

- at least one reactor vessel:

- at least one fluid inlet;

- at least one fluid outlet:

- least one flocculant outlet; and

- at least one membrane provided in the reactor vessel between the fluid inlet and the fluid outlet;

- inoculation of the reactor;

- providing feed to the least one fluid inlet;

- forming the flocculants:

- separating the flocculants using the membrane: and

- providing the flocculants at the flocculant outlet.

Production of natural, biodegradable polymeric flocculants from a fluid, such as a waste fluid enabling cost, effective manufacturing. This is achieved by the use of readily available raw material for the manufacturing process. The flocculants can be used for waste fluid treatment and / or treatment or other fluids containing (colloidal) particles. This use of the flocculants will therefore be effective and cheap to use. In presently preferred fluid related to fluids such as a waste fluid.

In the context of the present invention waste fluids include fresh and saline waste fluids, for example. The waste fluid could be obtained as domestic waste fluid and / or industrial waste fluids. Examples of industrial waste fluids are waste fluids from chemical industry, agriculture industry, food processing industry, pharmaceutical industry and health care industry.

In the context of the present invention EPS relates to Extracellular Polymeric Substances and includes organic matter such as flocculants.

Microbial Extracellular Polymeric Substances (EPS) applied as flocculants are generally considered as biopolymers excreted by micro-organisms. These microbial EPS are products of biochemical secretion and / or cell lysis.

The production of flocculants is performed in a reactor vessel. Preferably, the reactor vessel comprises a volume such that the hydraulic retention time is below 6 hours, more preferably below 4 hours and most preferably below 2 hours. The solids retention time is significantly below 3 days, preferably below 2 days and more preferably below 1 day. The reactor vessel involves at least one fluid inlet including a pipe, a tube, a valve, for example. The reactor vessel also includes a fluid outlet and / or flocculent outlet. These outlets may involve a pipe, a tube, an overspill, a container, a valve, for example.

According to the method of the invention the reactor vessel is inoculated. Preferably, inoculation involves micro-organisms that preferably originate from a biological waste water treatment plant. This allows to recover valuable resources, for example poly electrolytes. These micro-organisms are readily available and can be used in a non-sterile environment. As compared to conventional sterile pure microorganism cultures that need to be fed with non-sustainable carbon sources as well as with other valuable nutrients, the present invention allow the use of non-sterile microorganisms that are less demanding in nutrients source and cheaper as compared to sterile micro-organisms. This renders the manufacturing method or the in vention more cost effective and more sustainable.

After inoculation the flocculants are formed including organic microbial EPS. The EPS is separated by a membrane and collected at the flocculant outlet. The flocculants are preferably formed in the reactor vessel volume. It will be understood that according to the invention another separation technique can also be applied in addition to or as an alternative to the membrane separation.

The method of the invention uses waste fluid, such as a waste water, as feedstock. Such feedstock typically involves biodegradable and preferably water-soluble organic pollutants. In one of the invention of the waste water flows comprises fresh and saline waste water conditions containing ethanol and glycerol, for example. This allows an effective manufacturing process.

As a further effect of forming of the flocculants in accordance with the method of the invention less exploited natural flocculants including organic microbial EPS are provided. These flocculants are products of biochemical secretions and / or cell lysis, and can make up as much as 50-90% of the organic matter content or microbial aggregates. These microbial EPS include high molecular weight substances, for example polysaccharides, proteins, lipids, and combinations. Examples of combinations are liposaccharides, glycoproteins and lipoproteins.

Flocculants produced by the method of the invention can show comparable or better flocculation properties as compared to conventional flocculants. For example, the natural flocculants produced according to the method of the invention appear to be less shear sensitive as compared to conventional flocculants from synthetic polymers achieving a larger operation window, specifically a wider range of shear conditions.

In a preferred embodiment of the in vention the feedstock has a chemical oxygen demand to nitrogen ratio above 5, preferably above 8, and most preferably above 10 and / or a chemical oxygen demand to phosphorous ratio above 10, preferably above 15, and most preferably above 20.

Experiments have shown that the method of the invention effectively provides the desired flocculants.

In a presently preferred embodiment of the forming and / or separating of the flocculants from the fluid preferably comprising the step of aerating.

Performing an aerating step contributes to the amount of dissolving oxygen in the reactor vessel. Therefore, aerating improves the activity of the micro-organisms that are present in the reactor. Under these conditions tests show a mixed-culture or micro-organisms develop and mineralize a small fraction of the organic pollutants to carbon dioxide and water (typically less than 30%) and produces EPS, These may be used for the flocculants.

In a preferred embodiment of the invention a dissolved oxygen level of at least 0.5 mg O ₂ / L, preferably at least 0.75 mg CE / L, and most preferably at least 1 mg O? / L is maintained to obtain further improvement or the yield of the flocculants formation.

Providing and maintaining the oxygen level in the ranges mentioned has a stimulating effect on the productivity of the micro-organisms, and thus on the manufacturing process of the flocculants.

In a further preferred embodiment of the invention the formation of the flocculants provides extracellular polymeric substances or polymers or proteins or a mixture of polymers and proteins.

Flocculants involving extracellular polymeric substances or polymers or proteins or a mixture of polymers and proteins provide an effective and efficient product. Preferably, the polymer fractions are polysaccharides and the charge density is 0.2 - 7 meq / g, preferably 0.35 - 6 meq / g, and most preferably 0.5 - 5 meq / g.

The waste fluid comprises one or more of fresh and saline waste water including feedstock for the production of microbial EPS.

In experiments the saline and fresh water originating polymers gift a flocculation activity of 80% or above. This activity could be improved by the addition of free calcium ions in a concentration below 200 mg / L, preferably below 150 mg / L, more preferably below 100 mg / L. and most preferably below 50 mg / L. The addition of calcium results in the increase of the flocculation activity.

In a preferred embodiment of the invention flocculant production is combined with biological waste water treatment, preferably including treatment and production under fresh water and / or saline conditions.

The use of these condition results in an effective combination of purification of waste water and the recovery of valuable recourses. This provides efficient and cost-effective purification and recovery in a single operation.

The invention also relates to a system for the production of environmentally safe, biodegradable, organic microbial extracellular polymeric substances from a waste fluid, the system being capable of performing the method in one or more of the method according to the invention, including the system including:

- at least one reactor vessel;

- at least one fluid inlet;

- at least one fluid outlet;

- at least one flocculants outlet; and

- at least one membrane provided in the reactor vessel between the fluid inlet and the fluid outlet.

The system provides the same effects and advantages as those described for the method.

More specifically, the system allows efficient and effective water treatment and flocculants production involving at least one reactor, at least one fluid inlet, at least one fluid outlet, at least one flocculant outlet and at least one membrane provided in the reactor vessel between the fluid inlet and the fluid outlet.

The system could be extended with different sensors, for example a pH sensor, a temperature sensor, an oxygen level sensor, and / or a level control sensor. It will be understood that further or alternative sensors may also be applied in accordance with the present invention. Preferably, the sensors are connected to a controller / processor that allows monitoring and / or control of the production process. For example, this may involve maintaining the manufacturing within specific boundaries, such as dissolved oxygen level.

The invention also relates to flocculants that are produced by a method according to one of the many of the invention.

The flocculants provide the same effects and advantages as those described for the method and / or system.

In a presently preferred embodiment of the flocculants produced by the method in the disclosed system, including the EPS including a molecular weight, ranging between 2 kDa and 10000 kDa, preferably ranging between 3 kDa and 8000 kDa, more preferably ranging between 5 kDa and 6000 kDa , and most preferably ranging between 10 kDa and 2000 kDa,

An effect of (maintaining) the EPS in these range (s) is the effective recovery and regaining of valuable recourses, preferably in combination with the cost effective treatment of waste fluid.

The invention further also relates to a use of the environmentally safe, biodegradable, organic microbial extracellular polymeric substances from a waste fluid for the production of flocculants.

The use provides the same effects and advantages as those described for the method, the system and / or the flocculants.

In a presently preferred embodiment the use of the flocculants is cheap and cost effective.

Further advantages, features and details of the invention are elucidated on the basis or preferred otherwise, where reference is made to the accompanying drawings, in which:

Figure 1 shows a schematic overview of the method according to the present invention: and

- Figure 2 shows an embodiment of the system capable of performing the method described in the description.

Method 2 (Figure 1) for the production of environmentally safe, biodegradable, organic microbial extracellular polymeric substances, preferably from a waste fluid, follow's a sequence of different steps.

In the illustrated embodiment this starts with providing 4 a reactor and a feedstock. The reactor is inoculated in inoculation step 6 and supplied 8 with microorganisms if these are not already present in the feedstock. As a next step, after inoculation 6, forming 12 or flocculants occurring from the waste fluid. The flocculants are separated from the remaining fluid in separation step 14, preferably using a membrane such as an ultrafiltration membrane. Flocculants are collected in collecting slept8 resulting in a valuable product and treated waste water. The left over fluid could be recycled in recycling step 16 and returned to the reactor and mixed with the waste and / or recycle fluid.

In an illustrated embodiment of the invention, system 102 (Figure 2) produces environmentally safe, biodegradable, organic microbial extracellular polymeric substances from a waste fluid involving method steps of method 2.

System 102 comprises a feed tank 104 that can be filled with waste fluid 106. System 102 has outlet 108 connecting tank 104 to inlet pump 110. Pump 110 provides feedstock to inlet 112, In the illustrated embodiment inlet 112 is part of a so-called submerged membrane bioreactor 114, It will be understood that other reactor types and / or parts could also be in accordance with the invention.

In the illustrated system, in use, fluid 116 is present in reactor 114. In fluid 116 flocculants 118 are formed, specifically in compartment / reactor part 120. In compartment / reactor part 122 comprising (ultrafiltration) membrane 124 flocculants 118 are separated from fluid 116. Alternatively, a separation is achieved by centrifugation or by a sodium-based cation-exchange resin, all followed by dialysis to remove low molecular weight compounds (<3 kDa).

Reactor 114 is provided with permeate outlet 126 that is connected to permeate pump 128 for further transport or permeate 130. Aeration base 132 allows aerating fluid 116. Waste outlet 134 is connected to waste pump 13 for further transport or waste 138. Sensors 140 enable monitoring and / or control of the production process.

Experiments have been performed wdth system 102. In the experiments parameters as mentioned in tables 1 and 2 are applied.

In the experiments, in the fresh water application the reactor was inoculated with aerobic sludge from a municipal waste water treatment plant and in the saline application the reactor was inoculated with aerobic sludge from a saline water treatment plant for chemical industries. The polymers were produced from a mimicked industrial waste water, mainly containing ethanol and glycerol, both under fresh and saline waste water conditions. The membrane sheet in the experiments had a nominal pore size of 0.2 µm. After extraction using an ultrafiltration membrane, followed by dialysis to remove low molecular weight compounds (<3 kDa) and freeze-drying, solutions of these polymers were prepared and used to flocculate kaolin clay suspensions under fresh and saline water conditions and in the absence and presence of calcium ions. Kaolin clay was used to mimic usually negatively charged surface water and waste water particles.

Table 1 MBRs set-up and operation parameters

Parameter Saline and freshwater MBRs Reactor type Submerged membrane bioreactor Effective volume (L) 3.3 Temperature (° C) 20 + 1 pH 7.5 ± 0.1 Solids retention time, SRT (d) 15 Hydraulic retention lime, HRT (h) 2 Dissolved oxygen concentration (mg / L) 4.0 ± 1.0 Operation time (d) 50 Inlet COD ^a (mg 1..0 500 ± 40 mg / L Inlet TN ^b (mg / L) 32 + 2 mg / L Carbon / nitrogen ratio (g COD / g TN) 16 ± 1

¹¹ COD: Chemical oxygen demand. "TN: Total nitrogen - sum of all _r NH N, NOA-N, NO ₂ -N, organic N

Table 2 Composition of synthetic waste water in both reactors

Compound Concentration (mg / L) Nutrient solution Concentration (mg / L) Glycerol 205 FeCl ₃ .6H ₂ O 1500 Ethanol 120 ilbo. 150 M1, ·, Cl 100 CoCl ₂ .6H ₂ O 150 Yeast extract 60 ZnSo ..; 7H ₃ O. 120 K ₂ HPO ₄ 7.5 MnCk ₂ H ₂ O 120 ΡΟ ΡΟ; 12.5 After ₂ MoO ₄ .2H ₂ O 60 MgCl ₂ .6H ₂ O 100 CuSO ₄ .5H ₂ O 60 CaCl.-2H.-O 150 AI 30 NaCT ' 30000 Nutrient solution 2mL / L

* NaCl was fed only to the saline MBR

Flocculation tests show the applicability of the method according to the invention to produce flocculants, Furthermore, the results show an EPS yield after extraction, purification and lyophilisation as given in table 3.

Table 3 EPS yield after extraction, purification and lyophilisation.

EPS fraction Mg EPS / g VSS Mg EPS / g COD. _{ertlinv (J} Mg EPS / g COD _II % (gEPS / g COD _renwYt . _d ) FW SEES 123.5 + 1.7 83.7 + 1.1 79.3 ± 1.1 2.9 + 0.1 FW B-EPS 173.5 + 3.1 117.6 + 2.1 111.4 + 2.0 7.1 + 0.2 Sal S-EPS 142.5 + 3.3 66.2 + 1.5 61.7 + 1.5 4.4 + 0.1 Sal B-EPS 250.7 + 3.0 116.5 + 1.4 108.5 + 1.3 6.7 + 0.1

Data is expressed as standard ± standard deviation or duplicate extraction (VSS: volatile suspended solids; COD _inler : Chemical Oxygen Demand or inlet waste water; COD _brake over _e , Chemical Oxygen Demand removed during waste water treatment).

Tests and experiments performed with system 102 and parameters as mentioned in table and 2 in a mixture of polymers or variable molecular weight ranging between 10 kDa and 2000 kDa.

The present invention is by no means limited to the above and preferred by others. The rights sought are defined by the following claims within the scope of 15 which many modifications can be envisaged.

Claims (15)

CLAUSES 1. Method for production of natural, biodegradable polymeric flocculants from a fluid, such as a waste fluid, the method including the steps of: - providing a reactor including: - at least one reactor vessel; - at least one fluid inlet: - at least one fluid outlet; - at least one flocculant outlet: and - at least one membrane provided in the reactor vessel between the fluid inlet and the fluid outlet; - inoculation of the reactor; - providing feed to the least one fluid inlet: - forming the flocculants; - separating the flocculants using the membrane; and - providing the flocculants at the flocculant outlet. 2. Method according to clause 1, comprising the fluid comprises biodegradable and soluble organic pollutants. 3. Method according to clause 2, according to the pollutants comprises a chemical oxygen demand to nitrogen ratio above 5, preferably above 8, and most preferably above 10 and / or a chemical oxygen demand to phosphorous ratio above 10, preferably above 15, and most preferably above 20. 4. Method according to one or more of the foregoing clauses, inoculation of the reactor comprises inoculation with micro-organisms from a biological waste water treatment plant. 5. Method according to one or more of the foregoing clauses, separating and / or forming the flocculants comprising the step of aerating. 6. Method according to clause 5, forming and / or separating a dissolved oxygen level or at least 0.5 mg O? / L, preferably at least 0.75 mg O2ZL, and most preferably at least 1 mg O2 / L has been maintained. 7. Method by process according to one of the foregoing clauses, the formation of the flocculants provides extracellular polymeric substances or polymers or proteins or a mixture of polymers and proteins, 8. Method according to clause 7, where the polymer fractions are preferably polysaccharides, and the charge density is 0.2 - 7 meq / g, preferably 0.35 - 6 meq / g, and most preferably 0.5 - 5 meq / g . 9. Method by process according to one or more of the foregoing clauses, containing the waste fluid comprises one or more of fresh and / or saline waste water comprising microbial extracellular polymeric substances. 10. Method according to one or more of the foregoing clauses, further comprising the combined biological waste water treatment and flocculant production, including the treatment and production under fresh water and / or saline conditions. 11. System for the production of biodegradable, organic microbial extracellular polymeric substances, the system including: - at least one reactor vessel; - at least one fluid inlet; - at least one fluid outlet; - at least one flocculants outlet; and - at least one membrane provided in the reactor vessel between the fluid inlet and the fluid outlet. 12. System according to clause 11, further including two independent chambers. 13. Flocculants produced by the method and / or in the system of one or more of the foregoing clauses, including the flocculants including a flocculation activity of 80% or above, 14. Flocculants of clause 13, including the extracellular polymeric substances including a molecular weight, ranging between 2 kDa and 10000 kDa, preferably ranging between 3 kDa and 8000 kDa, more preferably ranging between 5 kDa and 6000 kDa, and most preferably ranging between 10 kDa and 2000 kDa. 15. Use of microbial extracellular polymeric substances for the production of flocculants from a waste fluid. CONCLUSIONS A method for producing natural, biodegradable polymeric flocculants from a liquid, such as a waste liquid, comprising the steps of: providing a reactor comprising: at least one reactor vessel; at least one fluid inlet: at least one fluid outlet; at least one flocculant outlet: and at least one membrane provided in the reaction vessel between the fluid inlet and the fluid outlet; seeding the reactor; providing a supply to the at least one fluid inlet; forming the flocculants; separating the flocculants using the membrane; and providing the flocculants at the flocculant outlet. The method of claim 1, wherein the liquid comprises biologically and soluble organic contaminants. A method according to claim 2, wherein the pollutants comprising a chemical oxygen demand to nitrogen ratio of above 5, preferably above 8, and most preferably above 10 and / or a chemical oxygen demand to phosphorus ratio of above 10, preferably above 15, and most preferably above 20. Method according to one or more of the preceding claims, wherein inoculation of the reactor comprises inoculation with a microorganism of a biological waste water treatment plant. Method according to one or more of the preceding claims, separation and / or wherein formation of the flocculants comprises the step of aerating. A method according to claim 5, wherein a dissolved oxygen level is maintained during formation and / or separation of at least 0.5 mg O ₂ / L, preferably at least 0.75 mg O ₂ / L, and most preferably at least 1 mg O ₂ / U. A method according to any one of the preceding claims, wherein the formation of flocculants provides extracellular polymeric substances with polymer or proteins or a mixture of polymers and proteins. A method according to claim 7, wherein the polymer fractions are preferably polysaccharides and the charge density is 0.2 - 7 meq / g, preferably 0.35 - 6 meq / g, and most preferably 0.5 meq / g. A method according to any one of the preceding claims, wherein the waste liquid comprises one or more waste water containing sweet and / or salt-containing microbial extracellular polymeric substances. Method according to one or more of the preceding claims, further comprising a combined biological waste water treatment and flocculant production, comprising treatment and production at salt water and / or salt water conditions. A system for the production of biodegradable, organic microbial extracellular polymeric substances, the system comprising: at least one reactor vessel: at least one fluid inlet; at least one fluid outlet; exhaust at least one flocculant; and at least one membrane provided in the. reaction vessel between the fluid inlet and the fluid outlet. The system of claim 11, further comprising two independent chambers. 13. Flocculants produced according to the method and / or in the system according to one or more of the preceding claims, wherein the flocculants comprising a flocculation activity of 80% or higher. The flocculants of claim 13, wherein the extracellular polymeric substances comprising a molecular weight, in a range between 2 kDa and 10000 kDa, preferably in a range between 3 kDa and 8000 kDa, more preferably in a range between 5 kDa and 6000 kDa, and most preferably between 10 kDa and 2000 kDa. Use of microbial extracellular polymeric substances for the production of flocculants from a waste liquid. 1/2 2/2 c-a m