Project Results

Smart valorization of biomass coming from saline wastewater from food & beverage industry.

Biomass from microalgae treatment of wastewater from F&B industry contains valuable compounds that can be used for several applications, such as, animal feed, coating and resins, and biopolymers. Three species of microalgae biomass coming from the SaltGae Demo sites have been valorized: Spirulina, Nannochloropsis sp and Tetraselmis sp. In contrast to the classical use of biomass for energy where those valuable fractions are spent into gas or heat, valorization of the different fraction of the SaltGae provides an important income to the process in such a way that can cover the treatment cost and even generate a surplus.

Tetrasemis sp produces antimicrobial reduction; thus, a 3% of Tetraselmis avoids the preventive use of Neomicine. Spirulina in-vivo trials allows to replace at least the 50% of fishmeal in the diet. Edible coatings. Spirulina protein concentrate (70%) has been able to replace the protein content of edible coatings formulations with good performance. It was validated at semi-industrial scale treating 1 Tons of pears stored in a cold room for five months. Varnishes and adhesives. Lipids from Nannochloropsis sp can be valorized as varnishes and adhesives. Three different families: acrylates, polyurethanes with isocyanate and polyurethanes without isocyanate, which can be applied as water-base dispersions or as mass product. Polyurethanes without isocyanate opens the door to produce a less harmful consumer product using materials from bio-source. Biocomposites. Microalgal biomass can be added to materials derived from gluten, increasing stiffness, strength and the resistance to mechanical solicitations. The biomass was also included in ceramic pastes for 3D-printing to produce complex structures in clay, cement or other similar materials. Radical innovation breakthrough: Wastewater nutrient recovery.

Salt-tolerant anaerobic bacterial treatment.

The biological treatment of saline wastewaters is considered a challenge due to the salt inhibition. The two-phase anaerobic digestion system (acidogenic and methanogenic stages), using granular sludge, presents a potentially more economical and feasible process to treat saline wastewater, producing biogas rich in methane (up to 85%), that can be used as energy source. The acidogenic stage allowed to treat saline wastewaters with salinity up to 58 gNa+ /L while the methanogenic stage allowed to produce up to 0.5 LCH4/d with a productivity up to 0.23 LCH4/(L.d) and a salinity up to 14 gNa+ /L. So high salinities in acidogenic stage, to our knowledge, where never reported in anaerobic granular reactors. The process can be applied in pickling industries facilities, or similar, allowing the wastewater treatment and achieve bioenergy recovery.

Optimization of the acidogenic phase showed that anaerobic granules used were capable of converting the organic matter present in the pickling wastewater to fermented product even at sodium concentrations as high as 58 gNa+ /L. At pH 6.5, an acidification degree up to 80.7±19.2% was reached at an organic loading rate of 1.24 gCOD/L.d. Regarding to the methanogenic reactor, the start-up with feeding the fermented wastewater with high sodium (30 gNa+ /L), was unsuccessful since no biogas was produced and the fermentation products were not consumed, even after 60 days of operation. This result showed that, the microbial community was not able to start their activity under high salinity content. However, the second strategy imposed, i.e., adapting the microbial culture to increasing amounts of sodium proved to be successful. Using this strategy, the microbial community was capable to withstand with sodium concentration up to 14 gNa+ /L, producing 0.50 LCH4/d with a productivity of 0.23 LCH4/(L.d)) and no apparent destruction of the anaerobic granules. Overall, the obtained results have demonstrated the feasibility of using anaerobic granules for the treatment of high salinity wastewater.

Improved high pressure pump for a more energy-efficient Reverse Osmosis.

The SALTAGE project equips the RO process with a newly developed pumping system. About 90% of the total energy expenditure for RO is imputable to pumps. The pumps deployed in desalination plants are mainly of the rotary type with efficiencies between 50% and 75%. An improvement in the energy efficiency of the pumping solutions would greatly reduce the energy consumption of this process. At the same time, the only improvements introduced nowadays include better process designs such as the use of larger centrifugal pumps with inherently greater efficiencies and variable frequency drives. Additionally, feed booster pumps have been used to improve high pressure pump efficiency but has an energy cost.

The newly developed continuous flow volumetric pump design merges the benefits of the rotary pumps (i.e. no pulsations) commonly used in RO, with the benefits of positive displacement (piston) pumps, i.e. higher energy efficiency volumetric behaviour, ability to work at much higher pressures. At the same time, it eliminates the negative aspects of the two families of pumps, that is: lower efficiency (~60%) and load-dependence of the rotary pumps; spurious and uncontrolled pulsatility of common piston pumps. The continuous flow of the new pump is generated by a new mechanism which guarantees very low pulsatility of the fluid flow both at the inlet and the outlet by forcing the proper motion profile of the pistons and the proper design of related components (valves and shaft). Energy efficiency measured at nominal working conditions according to ANSI Standards was 88%. However, this value is about 91% when couplings are taken into account. This represents a significative advance in energy saving. A key feature is also its ability to self-prime at low inlet pressure removing the need for a booster pumps, but still with some limitations in this respect needs to be solved prior to its commercialization.

Integration and demo testing of SaltGae algal-bacterial treatment for wastewater from F&B industry.

Being SaltGae a modular wastewater treatment technology, smart integration of the different innovations around the algal-bacterial treatment is of crucial importance at time of increasing performance and saving resources. The SaltGae technology have been scaled-up and integrated in three demo sites available at different locations Israel (Arava), Italy (Camporosso) and Slovenia (Ljubljana). They present different climatic conditions and origins for the wastewater to be treated: water from the milk industry (Spirulina or Tetraselmis, 20 kg/day), water from hide warehouse as representative of tannery wastewater (mixed algae, 1 kg/day), and water from the fish farming to grow Spirulina (alga used for food, 5 kg/day). Processes in each of these demo sites are as diverse as they will be in the real industrial sites and modules are adapted to the quality of the substrate. They allow to proof the feasibility of modular SaltGae technology under different scenarios.

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