Tui, Spain
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Vazquez-Padin J.R.,Aqualia FCC Group | Morales N.,Aqualia FCC Group | Gutierrez R.,Aqualia FCC Group | Fernandez R.,Aqualia FCC Group | And 5 more authors.
Water Science and Technology | Year: 2014

The feasibility of treating the supernatant of a municipal sludge digester supplemented with co-substrates by means of an anammox-based process (ELAN®) was tested in Guillarei (NW of Spain). Ammonia concentration measured in the supernatant of the sludge digester varied in the range 800-1,500 g N/m 3 due to the fact that the sludge produced in the plant was co-digested with wastes coming from surrounding food industries. Treating this supernatant in the ELAN® reactor, nitrogen removal rates up to 1.1 kg N/(m3 d) were reached in experiments run in a pilot plant reactor operated in batch mode. No nitrite oxidation was registered after several months of operation despite the average dissolved oxygen (DO) concentrations being 1.5 g O2/m3 and the temperature reaching values as low as 18°C. By keeping the DO set point at 1-2 g O2/m3 and tuning the hydraulic retention time, the stability of the process was guaranteed and the presence of co-substrates in the anaerobic digester did not affect negatively the operation of the autotrophic nitrogen removal process. Due to the success of the pilot plant experiment, an upscale of the process to full scale is proposed. Mass balances applied to Guillarei wastewater treatment plant revealed that in the main stream line the average denitrification rate calculated with the data of year 2011 was 226 kg N/d. Since the nitrogen removal efficiency is limited by the amount of readily biodegradable organic matter available to carry out denitrification in the water line, the implementation of an anammox-based process to treat the supernatant seems the best option to improve the effluent quality in terms of nitrogen content. The nitrogen removal rate in the sludge line would be 30 times higher than the one in the water line. The implementation of the process would improve the energetic balance and the nitrogen removal performance of the plant. © IWA Publishing 2014.

Iglesias-Obelleiro A.,University of Santiago de Compostela | Fernandez-Gonzalez R.,Aqualia FCC Group | Garrido-Fernandez J.M.,University of Santiago de Compostela
Desalination and Water Treatment | Year: 2012

Membrane bioreactors (MBRs) technology shows many advantages that convert it into an attractive solution for upgrading existent wastewater treatment plants (WWTP). The aim of this study was to investigate the feasibility of applying an MBR for treating primary settled wastewater in large WWTPs. In the 400,000 inhabitants equivalent WWTP of Vigo (NW Spain), 174,000 m3 d-1 of wastewater receives primary treatment, whereas only 130,000 m3 d-1 receives secondary treatment. In this facility, land scarcity is an issue, thus, the conventional activated sludge system (CAS) used may be replaced by MBR to retrofit this WWTP. This study was carried out in an MBR pilot plant of 3.97 m3 effective volume using a modified University of Cape Town (UCT) process with a Zenon ZW500d membrane module operating at low HRT (4-7 h). During the experimental stage, permeability values ranged from 90 to 125 l h-1 m-2 bar-1, with fluxes between 20-23 l m-2 h-1. Only three maintenance cleanings were applied during the 286 experimental days. Total COD values of the used wastewater were 50-350 mg l-1. Good performance in COD and BOD5 removal was achieved, being 15 ± 7 mg l-1 and 5 ± 3 mg l-1, respectively. Nitrogen removal efficiency was limited (40-60%), due to the low COD/N ratio in the influent. Primary settling protects MBR against membrane clogging and gives robustness to this technology. © 2012 Desalination Publications. All rights reserved.

Alvarino T.,University of Santiago de Compostela | Suarez S.,University of Santiago de Compostela | Katsou E.,Brunel University | Vazquez-Padin J.,Aqualia FCC Group | And 2 more authors.
Water Research | Year: 2015

Pharmaceutical and personal care products (PPCPs) are extensively used and can therefore find their way into surface, groundwater and municipal and industrial effluents. In this work, the occurrence, fate and removal mechanisms of 19 selected PPCPs was investigated in an 'ELiminación Autótrofa de Nitrógeno' (ELAN®) reactor of 200L. In this configuration, ammonium oxidation to nitrite and the anoxic ammonium oxidation (anammox)processes occur simultaneously in a single-stage reactor under oxygen limited conditions. The ELANS® process achieved high removal (>80%) of the studied hormones, naproxen, ibuprofen, bisphenol A and celestolide, while it was not effective in the removal of carbamazepine (<7%), diazepam (<7%) and fluoxetine (<30%). Biodegradation was the dominant removal mechanism, while sorption was only observed for musk fragrances, fluoxetine and triclosan. The sorption was strongly dependent on the granule size, with smaller granules facilitating the sorption of the target compounds. Increased hydraulic retention time enhanced the intramolecular diffusion of the PPCPs into the granules, and thus increased the solid phase concentration. The increase of nitritation rate favored the removal of ibuprofen, bisphenol A and triclosan, while the removal of erythromycin was strongly correlated to the anammox reaction rate. © 2014 Elsevier Ltd.

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