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Report

Teaser, summary, work performed and final results

Periodic Reporting for period 1 - AFTERLIFE (Advanced Filtration TEchnologies for the Recovery and Later conversIon of relevant Fractions from wastEwater)

Teaser

Summary

Human activities generate a high volume of wastewater that should be treated before being discharged with the finality to remove organic matter and nutrients that can cause environmental damage. Despite the interesting potential of many of these compounds (proteins, sugars, lipids ...) as raw materials fro bio-based industry, their valorisation is currently limited, with the best technologies on stream, to the production of bioenergy.

Within this context, the main objective of AFTERLIFE is to demonstrate at TRL-5 a promising innovative wastewater treatment with the simultaneous recovery of compounds of interest and the conversion of the rest of the organic matter into a high-volume added value biopolymer. The concept includes the use of a promising technology for the treatment of industrial and municipal wastewater, the filtration of membranes of different pore size. AFTERLIFE process is embedded in a circular economy approach through the reuse of the outlet water and the valorisation of the organic matter by the recovery and purification of high value added compounds, the conversion into value-added products and the generation of energy and clean water to be used within the process

Work performed

At this stage of the project, the selected wastewaters have been sampled, characterised and various pretreatment, recovery and conversion methodologies have been developed. The model of the process has been developed as basis for its optimisation and the first iteration of LCA-based environmental assessment and techno-economic assessment activities is on-going.

The advances in the design and testing of the pretreatment and filtration steps, have allowed the definition of filtration processes adapted to the considered wastewaters, recovering the soluble solids and providing pure water for its reuse. The performed characterisation has allowed the detection of value-added compounds in the wastewater. To recover and valorise such compounds, a comprehensive screening of recovery and purification methods has been developed and tested with the concentrates from filtration step. The most adequate techniques have been identified and an initial flowchart has been proposed. The organic matter in the wastewater has been successfully fermented to produce volatile fatty acid (VFA). Besides, bacterial processes for the conversion of VFA into polyhydroxyalkanoates (PHA) are already being optimised using as substrate VFA produced from real wastewater. The organic matter not valorised as PHA will go into a valorisation step to produce methane as source of energy. A holistic mathematical model of the process, first stage for the multidisciplinary design optimization (MDO) of the process, has been developed. The MDO strategy has also been defined and initial sets of optimised design parameters have been already produced. The demonstration activities will start in the month M30 for the most promising flowcharts. First hot spot analysis of economic and environmental impacts of the AFTERLIFE process are ongoing and will be provided in M22. The exploitation activities have started. The exploitation and communication plan have been updated once in this first period

Final results

Although membrane technologies for valuables recovery are commercially available, the developed concepts reported here are novel. Wastewaters and whey are so complex feeds to membrane filtration that even for production of pure water developed pretreatment concepts are required to control fouling of the membranes. At this stage, the concepts were designed for valuables recovery from original wastewaters and whey. In the future, after suspended solids recovery the developed concepts are tested for the feeds which are first fermented for PHA production. Examples of such activities cannot be found in literature.

The challenge in the recovered of valued added compounds from filtration concentrates lied on the diversity of polarity of the targeted metabolites and on the interactions that these targets have with the suspended solids. The screened techniques were green-oriented and cost-effective. The recovered fractions have potential antioxidant properties for food application or could also be used as food additive. Combination of these technique could also be considered. Interactions with the partners in charge of demonstration and process assessment will define more precisely the flowchart of the process including up-scaling feasibility and techno-economic preference.

The viscosity of the liquid decreases after the fermentation process for the production of VFA, which resultes also in an increase of the dewaterability capacity. Specifically, the viscosity and the Capillary Suction Time decrease, which could favour and make more feasible the application of filtration steps useful to enhance the degree of purity and concentration of the VFAs. Currently, samples of fermentation liquid are being collected to test the treatment through membranes for filtration.

For single culture process, a bacterium strain has been selected for the production of PHA by single cultures. The strain was able to grow in the presence of VFAs from real wastewater even under the highest concentration tested. Regarding mixed culture process, the results showed that a good selection of PHA accumulating bacteria is possible with the VFA stream supplied. The maximum capacity of the selected culture to accumulate PHA will be used to produce PHA in batch tests. The obtained biomass, rich in PHA, will be sent for extraction tests.

Through the application of MDO on the process, the sizing of the main equipment of the process will be improved. The MDO problem have been defined and integrated with the model of the process. The results will be verified by the experiments carried out by the experimental and technic partners. The final objective is to improve the overall performance, and the optimised AFTERLIFE process will be more energy and environmentally efficient than the original one.

The evaluation of environmental impacts and of economics will focus on the AFTERLIFE process with the PHA polymer as the main product. A survey for key stakeholder will be prepared and handed out to the participants of the stakeholder workshop (due date: M36) to gather information for the social and socio-economic assessment as well as the consumer acceptance study.

Dissemination and exploitation activities are contributing to enhance the impact of every single project result. Partners have participated in several conferences and events where they have disseminated AFTERLIFE activities. Discussion about Key Exploitable Results are planned within the consortium during the next months. The final objective is to enhance the possibility for a result to be brought to the market, making the potential impact real. The solutions developed in AFTERLIFE will contribute to mitigate risks for health (food, water and soil contamination) associated to the pollution of traditional plastics and wastewater.