CarboHydrate from Waste Water to ExoPolySaccharide : Waste and effluent Carbohydrate Valorization for the Production of Polysaccharides of commercial interest – CHWWEPS

CHWWEPS aims to directly reuse the EPS produced targeting applications in WWT processes, thus making this project a true example of a circular economy business model (in which supplier and end-user are the same).
CHWWEPS project focuses on the use of waste-based feedstocks aiming to surpass those challenges (heterogeneity of matrices, complexity of feedstock, diluted streams) which make them difficult to valorize by an innovative approach which consists in engineering open microbial consortiums by the imposition of appropriate selection pressures targeting function specialization, in this case EPS synthesis, rather than using specific bacterial cultures (as in pure culture processes, trying to condition the substrate in order to fit to the organism). In order to allow the imposition of an optimal selective pressure, the waste-based feedstocks are first hydrolyzed to produce hydrolysates containing a significant fraction of monomeric sugars. The EPS produced by the selected consortium will then be recovered and characterized to ensure that those EPS retained fulfill the specifications required for the polymers applied as coagulant/flocculant in the step of primary decantation of the processes of wastewater treatment. The compilation of the elements necessary for carrying out the techno-economic and environmental assessment of the process has been initiated.

For the waste-based feedstocks considered in the project, which have a content of sugars >50% of organic matter, a hydrolytic treatment based on the utilization of an adapted enzymatic cocktail allows to render nearly all the sugars available as monomers. These monomeric sugars are then used as substrate for selection and production of the EPS, allowing this way to maximize the valorization of the feedstocks.
The experiments carried out at lab-scale in a continuous reactor using a synthetic sugar substrate have allowed and the definition of operating conditions promoting the selection of microbial consortia producing EPS. These EPS present the functional properties of interest when evaluated utilizing wastewater. The experiments dealing with the recovery and quantification of EPS indicate that it is necessary to develop specific methods given the complex characteristics of the interactions between the EPS and other molecules of the biomass. The EPS raw (non-extracted) produced using the hydrolysates present functional properties comparable to polyacrylamide (PAM) when evaluated at pilot-scale utilizing municipal wastewater, which is positive from the performance and economic perspective.
Production of materials with high added-value: in parallel, a study addressing the feasibility of compounding alginate-like EPS has been carried out utilizing a commercial alginate. It was possible to obtain plasticized alginates by a conventional thermomechanical process, and this result is a world first in this field. The pprocessing conditions and optimal formulation were defined. Blends of alginate-chitosan were produced via thermomechanical mix, presenting intermediate mechanical properties between chitosan and alginate and antimicrobial properties.
The techno-economic and environmental evaluation of the process was done based on the pertinent elements gathered considering its integration on the context of wastewater treatment

The results obtained have allowed attaining the main objective of the project which is leading in the near future to the development of an application of the EPS produced by microbial consortia for utilization internally within the WWTP and this way promote a circular economy business model while reducing dependence on external supply of reagents. On the other hand, the work carried out has also put in evidence that this subject is innovative, and that:
• it is necessary to deepen the knowledge on the subject to fully understand the factors contributing for the functionality of the EPS produced. A more detailed characterization of the EPS produced is necessary for this to better control and produce sustainably these polymers (in view of an industrialization);
• other applications seem possible for some of the EPS produced and this clue is to be developed in additional projects.
Some aspects are being addressed through a complementary study of maturation.

The works of the project has resulted in ten communications done in conferences, at international level and one at national level. Two manuscripts have been published in international journals and several other scientific productions related to the production of EPS by a selected microbial consortium and its application within the treatment of WW are under preparation given the innovator character of CHWWEPS project. The collaborative work between INSA Toulouse and VERI has generated some IP, currently ongoing.

CHWWEPS project aims at developing a valorization route for wastes/effluents difficult to valorize, from industrial and municipal sources, to produce added-value polymers such as Alginate. Wastes/effluents containing heterogeneous mixtures of macromolecular carbohydrate substrates (such as cellulose or starch) together with other carbon substrates (proteins, lipids) as well as other organic and inorganic contaminants will be first hydrolyzed to produce hydrolysates containing a significant fraction of monomeric sugars. The obtained hydrolysates will be further used as carbon source for the microbial production of exopolyssaccharide polymers (EPS) of commercial interest.
The strain on fossil resources in our carbon based economy puts an increasing pressure on agricultural and biomass resources for both food and non-food applications (biofuels, bioenergy, chemicals and polymers). On the other hand, increasing human activity has led to production of significant amounts of wastes. A truly sustainable carbon based economy will require a zero waste discharge, that is, that all the intrinsic organic and inorganic value present in waste/effluent streams be recovered prior to rejection after treatment back into the natural environment.
Sustainable production processes based on renewable biobased feedstocks need to fully use this potential recyclability of the organic carbon derived from biological sources. In a circular biobased economy, we cannot simply replace fossil-based carbon sources by biobased carbon sources while keeping the same linear production processes (substrate to product to waste to CO2), but instead need to develop business models for our production chain in which carbon can be used in consecutive cycles before being finally oxidized to CO2 or converted to methane (energy). A key aspect of the project is the demonstration of this multi-cyclical approach to biogenic carbon use.
A large number of bacterial exopolyssaccharides (such as Alginate) have been identified to date, but only a few are used in industrial processes, all of which produced using pure microbial cultures from high cost carbon substrates. The rheological properties of such bacterial EPS are similar to those of exopolyssaccharides extracted from algae, which are currently used as thickeners and flocculants. EPS can thus be used to promote dehydration and control process rheology.
Wastewater (WW) treatment processes require coagulation and flocculation agents to remove suspended mater (clarification). Chemical coagulatants and flocculants are generally used (FeCl3 or polymeric materials, such as PAM). Veolia Water has a growing interest in the use biopolymers both in drinking water and in WW treatment processes as a means of reducing the dependence of its processes on chemicals, in order to improve their environmental sustainability. Furthermore, if such biopolymers can be produced from WWT by-products (thus closing the value chain), this would also reduce treatment cost dependence on external supply of reagents. Therefore, a significant in-house interest for the product targeted by CHWWEPS project is also at the center of this project (improve industrial competitiveness).
CHWWEPS aims to directly reuse the EPS produced targeting applications in WWT processes, thus making this project a true example of a circular economy business model (in which supplier and end-user are the same).
CHWWEPS project focuses on the use of waste-based feedstocks aiming to surpass those challenges (heterogeneity of matrices, complexity of feedstock, diluted streams) which make them difficult to valorize by an innovative approach which consists in:
Rather than using specific bacterial cultures (as in pure culture processes) trying to condition the substrate in order to fit to the organism, CHWWEPS aims at engineering open microbial consortiums by the imposition of appropriate selection pressures targeting function specialization, in this case EPS synthesis.