Descripció del projecte
Nitrogen compounds (organic and inorganic) are typical pollutants in sewage which need to be removed from wastewater to comply with discharge regulation according to the 91/271/EC Directive. At industrial-scale level in Europe, nitrogen is usually biologically oxidized to N2(g) which is emitted to the atmosphere in aerated reactors, contributing to 30 – 60% of the total wastewater treatment costs. Within the context of circular economy, new and innovative technologies to recover N from sewage instead of removing it are being developed.
The objective of this PhD thesis is the development and optimization of a technology for the production of nitrogen salts from ammonium-rich effluents at wastewater treatment plants (WWTP). The technology should be economically competitive with nitrogen removal technologies and conventional N fertilizer production methods based on the Haber-Bosch process. A treatment train combining adsorption materials and membrane technologies will be used for nitrogen recovery at a relevant pilot-scale level in a urban WWTP.
Specific sub-objectives of the PhD thesis would be the following:
· Understand N species concentration mechanisms in the adsorption unit; subjected to subsequent cycles of adsorption-desorption with different eluent agents. In-depth characterization of virgin and exhausted adsorbent materials
· Understand N species and water mass transfer at the membrane unit under different process conditions (membrane material and pore size, operating pH and temperature, G/L ratio, liquid phase composition, etc.) to maximize the concentration of the recovered salts and develop strategies to minimize inorganic scaling and organic fouling and biofouling. In-depth characterization of virgin and exhausted membranes
· Select and validate the most adequate pre-treatment unit to minimize impact of matrix macro-interferences (such as Chemical Oxygen Demand, suspended solids, phosphorus species, organic nitrogen, etc.) in the treatment train
· Assess the fate of micro-interferences (such as heavy and light metals, organic micro and nano-pollutants) in the treatment train and develop strategies to improve the quality of the recovered N salts
· Develop a suitable control system for N recovery in WWTP adapted to the developed treatment train
· Conduct technical, economic and environmental assessment of the developed technology and compare with other technologies used for the same application such as air/steam stripping systems; and N removal
