Wastewater Treatment

Sequencing batch reactors (SBRs) are advocated as one of the best available techniques for slaughterhouse wastewater treatment. Its flexibility, easy operation, potential to remove nutrients (N and P) at high rates and the possibility to optimise energy consumption make this technology the best solution for slaughterhouses. SBR will be designed with a daily capacity of 50 m3 and will be preceded by a fine screen (rotary fine screen) and fats removal unit. Fats will feed the fermentation unit. The effluent obtained in the biological process (with high content on soluble NO3) will be treated by BIOAZUL obtaining an extract of soluble salts, mainly nitrates (SMR1).

Fermentation unit

The processing of obtained sludge by fermentation with Bacillus licheniformis has a dual purpose. In first place, sanitization of the sludge is achieved, since pretreatment necessary to perform this stage eliminates most of pathogenic microorganisms present. Secondly, these fermented sludges have a hydrolysed organic matter of high bioavailability, which may be used in other biological processes such as methanization, where significant increases in production yields are achieved. Furthermore, the B. licheniformis composed product can be formulated and marketed as a biostimulant for agronomic use (SMR2).

Fermentation unit will consist of two subunits thus by, pretreatment subunit and fermentation subunit, basically composed by a bioreactor. Both will be arranged in form of portable modules which may be transported to facilities where they will be used, either in Matadero del Sur, or other slaughterhouses.

Biogas valorisation

The anaerobic digestion of the hydrolysed sludge obtained in the fermentation unit, has multiple purposes: produce electricity by co-generation and High Temperature PEM Fuel Cell; obtain biogas from liquid hydrolysed sludge, and produce a liquid fraction with high amount of nutrients (such as NH4+ and PO43-), which represent source of nutrients for growth of microalgae.

The highly polluted hydrolysed sludge will be treated by anaerobic digestion, where the organic compounds will decompose into CH4, CO2 and other gaseous impurities, named biogas. Part of this biogas stream will pass through a CHP unit, while the other part will be fed to a biogas valorisation unit, where the CH4 will react with O2, at high temperature in a catalytic bed, to produce H2. After the main reactor, the hydrogen stream will pass through a series of processes to envision its refinement. The hydrogen rich stream will be sent to a fuel cell to generate electric energy.

Algal treatment plant

Algae treatment will be used to recover the remaining nitrogen and phosphorus in anaerobic digestate and subsequently act as the bio-stimulants and bio-fertilisers in agricultural production (SMR3). To utilize the algal ponds also as CO2-sinks, the AlgaBioGas (ABG) technology, has been validated in the frame of Eco-innovation pilot and market replication project.

ABG system consists of algal ponds (inoculation pond and main pond) with the fully automated control system measuring input and output parameters of water. Additionally, an innovative CO2 diffuser will be employed to optimise CO2 diffusion to the algal ponds, leading to mitigation of the GHG emission during treatment. The technology will be designed as a module in a large-scale demonstrator in Matadero del Sur, making it applicable also as a part of other treatment systems

Agronomic valorisation

We will generate 3 main Secondary Raw Materials (SRMs) with agricultural value. SMR-1, a soluble nitrogen source, that will be recovered from the wastewater treatment. SMR-2, a bacterial-based biostimulant, coming from the fermentation unit. Finally, a microalgae-based biostimulant (SMR-3) collected from the algal treatment.

SRMs will be characterized, formulated and tested to generate 3 different agronomic products. Chemical, physicochemical and biological tests will be run for a proper characterization. Product formulation will be carried out in order to improve product stability and performance. Agricultural tests will be performed (greenhouse and field tests), with different crops (garden cress, wheat, maize, tomato, lettuce, cherry, etc.) and 4 different geographical localization (Spain, Lithuania, Rumania and Slovenia), covering different European soil and climate conditions.