Report

Teaser, summary, work performed and final results

Periodic Reporting for period 2 - SALTGAE (Demonstration project to prove the techno-economic feasibility of using algae to treat saline wastewater from the food industry.)

Teaser

For any industry generating vast amounts of wastewater, management of their residues required to comply with the EU directives involves direct costs which can be very high. This issue is critical for many industrial sectors, such as food processing, leather industries and...

Summary

For any industry generating vast amounts of wastewater, management of their residues required to comply with the EU directives involves direct costs which can be very high. This issue is critical for many industrial sectors, such as food processing, leather industries and land-based aquaculture, which generate saline wastewater. This kind of wastewater, with high concentrations of biodegradable organic matter, suspended solids, nutrients (mainly nitrogen and phosphorus) and salt (concentrations up to 15%), is extremely difficult and expensive to treat by conventional means (e.g anaerobic bacterial treatment is inhibited), making this cost unaffordable for SMEs, who can decide not to comply with EU directives and discharge without prior treatment, causing severe damage to the environment.
The objective of the SALTGAE project is twice:
1) Develop a techno-economically viable solution for the treatment of saline wastewaters from the Food and Beverage (and related) industry and implement and demonstrate it at large scale.
2) Develop an innovative platform for the mobilization and networking of stakeholders from all the different sectors related to wastewater, and for the dissemination of results with the aim of promoting paradigm shift in perception from ‘wastewater treatment’ to ‘resource valorisation’

Work performed

The most important activities achieved during the project life are described next:

1. Selection and tests of the best performing algae-bacteria cultures for optimum BOD treatment efficiency suitable for different salinity and wastewater compositions.
2. Characterization of industrial wastewater and design of primary and pre-treatment processes. After testing, dimensioning and detailed design for implementation in the Demos sites.
3. Anaerobic digestion treatment applied on saline wastewater to reduce its BOD load. Bacterial adaptation to high saline waste water at continuous test at lab scale and scaled-up to Demo site.
4. Valorisation of effluents from algal treatment by assessment of best pre-treatment strategy for desalination (validated and optimized at pilot scale), electrodialysis for demineralisation of pre-treated effluents.
5. Creation of prototypes of a new pump for Reverse Osmosis and design of a device to recover the energy contained in the rejection stream
6. Biomass harvesting has been tested by combination of different techniques, including membrane technology and centrifugation with good results
6. The harvested biomass is refined with extraction of its different fractions. Both mechanical methods and chemical methods has been defined and extraction test performed for each of the type of algae.
7. Valorization of algal biomass fractions to produce new products: monomers for adhesives applications, water-based PU dispersions for coatings and adhesives, edible coatings, and high value material fillers & pastes.
8. Evaluation of the design and operational factors that influence high rate algae pond performance and cost efficiency, by mathematical models and CFD model
9. Sensorization, monitoring and control of the high rate algae ponds, including functionality of the control system
10. Integrated sustainability and businness viavility assesment
11. Testing of the three demo sites with different climatic conditions and algae strain integrating the innovations developed in previous fases of the project.

Final results

PROGRESS BEYOND THE STATE OF THE ART
a. Innovative use of algal-bacterial treatment that not only eliminates the energy requirement of aeration (algae produce oxygen), but also partially embodies the energy contained in the wastewater into the biomass which can then be used for other purposes or to recover energy into biogas. As result, the treatment is much cheaper due to the reduced costs of aeration, CO2 is recycled rather than contributing to the climate change, and biomass can be further utilized (and sold).
b. Obtain a salt-tolerant microbial consortium that treats wastewater with high salinity by means of anaerobic digestion. Archea are known to be salt sensitive and they cannot survive at elevated salinity levels. However, by means of the adaptation strategy and measures developed in the project this problem has overcome and biogas has been produced successfully in continuous under high salinity.
c. Eficient and economicaly affrodable algae harvesting by means of membrane process.
d. Valorisation of algae fractions (proteins, lipids an cell debris) in platform chemicals (adhesive and coatings) and high-value material fillers and pastes (geopolimers and rubber).
e. Design of a HP pressure pump with higher efficiency than the current ones that reduces the cost of the desalination process.

FINAL INTEGRATED RESULT
Saltgae Project has developed an innovative modular based technology platform for the efficient treatment of saline wastewaters containing organic load, enabling ease of operation, significant cost reductions, compliance with European Directives with minimal environmental impact, recycling of water for non-potable applications and valorisation of nutrient and energy resources, with the following performance:
• Efficiency of BOD, N and P removal (> 90%) and algae biomass growth (> 15 g/m2/day)
• Able to deal with different salinity levels (2 g/L to 60 g/L) and wastewater compositions.
• Cost reduction >40% with respect to current alternatives for saline wastewater with organic load.
• Able to valorise the algae biomass produced transforming the reject in revenue, with an increment of >15% profit margin earned per tonne of algae biomass produced.
• Techno-economically viable, implemented and tested at DEMO scale in order to operate and validate them under real environment conditions and scale.

POTENTIAL IMPACTS
a) Resource efficiency and environmental performance.
Saltgae is aimed to produce less energy consumption, energy extraction from the wastewater, less green-house gas emissions, better effluent quality, significantly reducing industrial salt emissions and resource savings by valorisation of biomass. It also reduced the ammonium content of wastewater, preventing euthrophication. In additon, it is helping process industries become less water dependent while ensuring efficient management of other resources.
b) Creation of new market opportunities.
The valorisation of biomass via creation of edible coatings, the generation of know-how linked to improved formulations for animal feed and adhesives, the innovations related to the generation of biogas, a more energy efficient Reverse Osmosis desalination process or a more sustainable cycle of water-fish production-crop irrigation will enable sustainable economic growth, business and job creation both in the water sector and beyond.
c) Contribution to the implementation of the EIP Water across a number of key areas
SALTAGE project contributes to the objectives of EIP water across a number of key areas: 1) Water and wastewater treatment, including recovery of resources (by reduction of dissolved nutrients and recover them as biomass with potential source of high value precursors); 2) Water Reuse and Recycling (almost complete elimination of salt from water stream with > 20% of expected water recycling rate). 3) Water Energy Nexus (recovery of energy from the wastewater by conversion of BOD to heat and electricity); 4) Cross cutting challenges (mobilizing

Website & more info

More info: http://www.saltgae.eu.