Nutrient recovery technologies are rapidly expanding due to the need for the appropriate recycling of key elements from waste resources in order to move towards a truly sustainable modern society based on the Circular Economy.Nutrient recycling is a promising strategy for reducing the depletion of non-renewable resources and the environmental impact linked to their extraction and manufacture. However, nutrient recovery technologies are not yet fully mature, as further research is needed to optimize process efficiency and enhance their commercial applicability. This paper reviews state-of-the-art of nutrient recovery, focusing on frontier technological advances and economic and environmental innovation perspectives. The potentials and limitations of different technologies are discussed, covering systems based on membranes, photosynthesis, crystallization and other physical and biological nutrient recovery systems (e.g. incineration, composting, stripping and absorption and enhanced biological phosphorus recovery).

IWA PublishingBarat Baviera, R.; Serralta Sevilla, J.; Ruano García, MV.; Jiménez Douglas, E.; Ribes Bertomeu, J.; Seco Torrecillas, A.; Ferrer, J. (2013) INTRODUCTIONWhole wastewater treatment plant modelling is one of the most important topics for the scientific community. This issue has been tackled by two philosophical approaches: using separated models (which were developed for the different process units) that are connected to simulate the whole plant, or using one unique and general model for the whole plant. In 2004, the CALAGUA research group published the Biological Nutrient Removal Model Nº 1 (BNRM1, Seco et al., 2004) including different physical, chemical and biological processes taking place in a WWTP. The physical processes included were: settling and clarification processes (flocculated settling, hindered settling and thickening), volatile fatty acids elutriation and gas-liquid transfer. The chemical interactions considered were acid-base processes, where equilibrium conditions are assumed. The biological processes included were: organic matter, nitrogen and phosphorus removal; acidogenesis, acetogenesis and methanogenesis. This model has been successfully applied for the design and optimization of numerous WWTPs (Ruano et al., 2010). However, these applications showed that nitrogen removal via nitrite and chemical precipitation processes should be considered to properly simulate WWTPs.

No abstract

No abstract

Ammonia oxidizing bacteria (AOB) are very sensitive to environmental conditions and WWTP operational parameters. One of the most important factors that affect their activity is the pH. Its effect is associated to: NH 3 /NH 4 + and HNO 2 /NO 2 -chemical equilibriums and biological reactions rate. The aim of this study was to quantify and model the effect of pH and free nitrous acid concentration on the activity of the AOB present in a lab-scale partial nitritation reactor. For this purpose, two sets of batch experiments were carried out using biomass from this reactor. FISH analysis disclosed that Nitrosomona eutropha and Nitrosomona europaea species were dominant in the partial nitritation reactor (>94%). The experimental results showed that free nitrous acid inhibits the AOB activity. This inhibition was properly modeled by the non-competitive inhibition function and the half inhibition constant value was determined as 1.32 mg HNO 2 -N L -1 . The optimal pH for these AOB was found to be in the range 7.4-7.8. The pH inhibitory effect was stronger at high pH values than at low pH values. Therefore, an asymmetric inhibition function was proposed to represent the pH effect on these bacteria. A combination of two sigmoidal functions was able to reproduce the experimental results obtained.