Pilot-scale continuous flow granular reactor for the treatment of extremely low-strength recirculating aquaculture system wastewater

To avoid toxic ammonium and nitrite concentrations in aquaculture systems is crucial to maintain the fish production. When recirculating aquaculture systems (RAS) operate in freshwater farms during the dry seasons, the concentrations of these pollutants increase. The objective of the present study is the evaluation of a Continuous Flow Granular Reactor (CFGR) for the treatment of freshwater RAS stream at pilot-scale during two consecutive dry seasons. The CFGR was fed with a extremely low-strength recirculation stream of a trout farm (0.12–1.84 mg NH4+-N/L and 2.2–8.14 mg C/L). Two different configurations were evaluated. The first configuration consisted on a CFGR fed from the bottom, being the up-flow velocity the only shear force to mix the biomass. The second configuration incorporated a mechanical stirrer and a sieve to improve the biomass mixing and retention. The CFGR was operated at short hydraulic retention times (HRT) which ranged from 11 to 68 min. The configuration with a mechanical stirrer and sieve was optimal in terms of biomass retention and nitrogen removal performance. Despite the low nitrogen and organic matter concentrations, granulation was achieved in 55 days, with an average granule diameter up to 0.47 mm. Ammonium and nitrite removal percentages up to 81% and 100% were achieved, respectively. The ammonium and nitrite production rate in the trout farm were lower than the removal achieved by the CFGR, which makes the implementation of this system appropriated to maintain the concentration of these compounds below toxic levels for rainbow trout.info:eu-repo/semantics/publishedVersio

Evaluation of two different granular sludge reactor configurations for the treatment of freshwater aquaculture streams

Two aerobic distinct granular sludge reactors were operated to treat freshwater aquaculture streams at laboratory-scale: An Expanded Granular Sludge Bed(EGSB)reactor operated in continuous mode and an Aerobic Granular Sludge -Sequencing Batch Reactor(AGS-SBR) operated as a sequencing batch reactor. Both units were fed with low ammonium concentrations (2.5 mg N/L). Granular biomass accumulated in both reactors. With the imposed operational conditions, nitrogen removal was of 10 -20 % and 80 % for the EGSB and AGS-SBR, respectively.info:eu-repo/semantics/publishedVersio

Short and long term orange dye effects over AOB and anammox activities

"This is the pre-peer reviewed version of the following article: Val del Río, A., Stachurski, A., Méndez, R., Campos, J. L., Surmacz-Górska, J., & Mosquera-Corral, A. (2017). Short- and long-term orange dye effects on ammonium oxidizing and anammox bacteria activities. Water Science and Technology, 76(1), 79-86, which has been published in final form at [http://dx.doi.org/10.2166/wst.2017.186. This article may be used for non-commercial purposes in accordance with IWA Publishing."In this research work the effects of orange azo dye over ammonia oxidizing bacteria (AOB) and anammox bacteria activities were tested. Adsorption onto the biomass was detected with both types of biomass however no biological decolourization occurred. Performed batch tests indicated that concentrations lower than 650 mgorange/L stimulated AOB activity while anammox bacteria activity was inhibited at concentrations higher than 25 mgorange/L. Long-term performance of both processes was tested in the presence of 50 mgorange/L. In the case of the partial nitritation process both the biomass concentration and the specific AOB activity increased after 50 days of orange azo dye addition. Regarding the anammox process, specific activity decreased down to 58% after 12 days of operation; however, initial values were restored 54 days after stopping the dye additionThis work was funded by the European Union through the Cost Action (ES-10755) and by the Spanish Government through FISHPOL (CTQ2014-55021-R) and GRANDSEA (CTM2014-55397-JIN) projects co-funded by FEDER. The authors from the USC belong to CRETUS (AGRUP2015/02) and the Galician Competitive Research Group (GRC 2013-032), programs co-funded by FEDERNO

2012 ACCF/AHA/ACP/AATS/PCNA/SCAI/STS guideline for the diagnosis and management of patients with stable ischemic heart disease

The recommendations listed in this document are, whenever possible, evidence based. An extensive evidence review was conducted as the document was compiled through December 2008. Repeated literature searches were performed by the guideline development staff and writing committee members as new issues were considered. New clinical trials published in peer-reviewed journals and articles through December 2011 were also reviewed and incorporated when relevant. Furthermore, because of the extended development time period for this guideline, peer review comments indicated that the sections focused on imaging technologies required additional updating, which occurred during 2011. Therefore, the evidence review for the imaging sections includes published literature through December 2011

Stability of the ANAMMOX process in a gas-lift reactor and a SBR

In the last years, the ANAerobic AMMonium OXidation (ANAMMOX) process has been put forward as a promising alternative to treat ammonium rich wastewaters. An ANAMMOX gas-lift reactor and a sequential batch reactor (SBR) were operated during around 200 days in this study, reaching nitrogen loading rates (NLRs) of 2.0 and 0.75 g l(-1) per day, respectively. The efficiency in the nitrite (limiting substrate) removal was 99%. The ammonium and nitrite influent concentrations were increased stepwise until biomass in the reactors started to float. These flotation events coincided with periods when the NLR exceeded the maximum specific ANAMMOX activity (MSAA) of the sludge. The MSAA, determined in batch experiments, was 0.9 and 0.44 g g(-1) per day for biomasses from the gas-lift reactor and the SBR, respectively. Flotation of the biomass occurred most likely due to a granule density decrease caused by dinitrogen gas accumulation inside the granules and an apparent breakage of the granules. Further research is needed to understand this phenomenon and to optimise the corresponding strategies to counteract the location. (C) 2004 Elsevier B.V. All rights reserved

Kinetics of denitrification using sulphur compounds: Effects of S/N ratio, endogenous and exogenous compounds

The influence of different sulphur to nitrogen (S/N) ratios on the specific autotrophic denitrification activity was studied in batch experiments using thiosulphate and nitrate as substrates. Transitory accumulations of nitrite were observed for assays with S/N ratios of 3.70 and 6.67 g/g, probably due to the higher specific reduction rate of nitrate compared to that of nitrite. Nitrite was the main end product when S/N ratios of 1.16 and 2.44 g/g were tested. The effects of endogenous and exogenous compounds (acetate and NaCl) on the specific denitrifying activity of the sludge were tested. Nitrite and sulphate did exert clear inhibitory effects over the process while thiosulphate, acetate and NaCl did not have strong effects at the concentrations tested. Similar experiments also showed that sulphur was not a suitable electron donor for these microorganisms, but sulphide was used successfully.This work was funded by the Spanish CICYT through the BIOGRAMEN project (Ref: CTQ2005-04935/PPQ) and the Xunta de Galicia which funded this research through the project (PGIDIT03PXIC 20906 PN).Peer reviewe