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Author Pedrouso, A.; del Rio, A.V.; Morales, N.; Vazquez-Padin, J.R.; Campos, J.L.; Mendez, R.; Mosquera-Corral, A. pdf  doi
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  Title Nitrite oxidizing bacteria suppression based on in-situ free nitrous acid production at mainstream conditions Type
  Year 2017 Publication Separation And Purification Technology Abbreviated Journal Sep. Purif. Technol.  
  Volume 186 Issue Pages 55-62  
  Keywords Ammonium oxidizing bacteria; Flocculent sludge; Free nitrous acid; Mainstream; Nitrite oxidizing bacteria; Partial nitritation  
  Abstract The application of autotrophic nitrogen removal processes in the main line of wastewater treatment plants will contribute to achieve its self-energy-sufficiency. However, the effective suppression of nitrite oxidizing bacteria (NOB) activity at the conditions of low temperature and low ammonium concentration (mainstream conditions) was identified as one of the main bottlenecks. In this study, stable partial nitritation at 16 degrees C and 50 mg NH4+-N/L was achieved maintaining inside the reactor free nitrous acid (FNA) concentrations inhibitory for NOB (>0.02 mg HNO2-N/L), without dissolved oxygen concentration control, The FNA inhibitory concentration was generated by the partial nitritation process, and its stimulation was studied with two different inhibitors: sodium azide and nitrite. The microbiological analysis revealed that, throughout the operational period with inhibitory FNA levels, the NOB populations (dominated by Nitrospira) were effectively washed out from the reactor. This is an advantage that allowed maintaining a good stability of the process, even when the FNA concentration was not enough to inhibit the NOB, taking about 40 days to develop significant activity. The observed delay on the NOB development is expected to enable the establishment of corrective actions to avoid the partial nitritation destabilization. The use of the FNA to achieve a stable partial nitritation process is recommended to profit from the natural pH decrease associated to the nitritation process and from its favoured accumulation at low temperatures as those from the mainstream. In this research study an analysis about the influence of ammonium and alkalinity concentrations was also performed to know in which scenarios the FNA inhibitory concentration can be achieved. (C) 2017 Elsevier B.V. All rights reserved.  
  Address [Pedrouso, Alba; del Rio, Angeles Val; Mendez, Ramon; Mosquera-Corral, Anuska] Univ Santiago de Compostela, Sch Engn, Dept Chem Engn, E-15705 Santiago De Compostela, Spain, Email: alba.pedrouso@usc.es;  
  Corporate Author Thesis  
  Publisher Elsevier Science Bv Place of Publication Editor  
  Language English Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 1383-5866 ISBN Medium  
  Area Expedition Conference  
  Notes WOS:000406730700007 Approved  
  Call Number UAI @ eduardo.moreno @ Serial 755  
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Author Valenzuela-Heredia, D.; Panatt, C:, Belmonte, M.; Franchi, O.; Crutchik, D.; Dumais, J.; Vazquez-Padin, J.R.; Lesty, Y.; Pedrouso, A.; del Rio, A.V.; Mosquera-Corral, A.; Campos, J.L. doi  openurl
  Title Performance of a two-stage partial nitritation-anammox system treating the supernatant of a sludge anaerobic digester pretreated by a thermal hydrolysis process Type
  Year 2022 Publication Chemical Engineering Journal Abbreviated Journal Chem. Eng. J.  
  Volume 429 Issue Pages 131301  
  Keywords Ammonium oxidizing bacteria; Autotrophic nitrogen removal; Inhibition; NOB suppression; Operational stability; THP  
  Abstract A two-stage system (partial nitritation (PN) and anammox processes) was used to remove nitrogen from the dewatering liquor originating from the thermal hydrolysis/anaerobic digestion (THP/AD) of municipal WWTP sludge. Two strategies were tested to start up the PN reactor: 1) maintaining a fixed hydraulic retention time (HRT) and increasing the ammonium loading rate (ALR) by decreasing the feeding dilution ratio and 2) feeding undiluted dewatering liquor and gradually decreasing the HRT. With diluted feeding, the reactor performance had destabilization episodes that were statistically correlated with the application of high specific ammonium (> 0.6 g NH4+-N/(g TSS.d)) and organic (> 0.7 g COD/(g TSS.d)) loading rates. The second strategy allowed stable PN reactor operation while treating ALR up to 4.8 g NH4+-N/(L.d) and demonstrating that dilution of THP/AD effluents is not required. The operating conditions promoted the presence of free nitrous acid levels (> 0.14 mg HNO2-N/L) inside the PN reactor that inhibited the proliferation of nitrite oxidizing bacteria.

Batch activity tests showed that the inhibitory effects of organic compounds present in the THP/AD dewatering liquor on the ammonia oxidizing bacteria activity can be removed in the PN reactor. Thus, aerobic pretreatment would not be necessary when two-stage systems are used. The PN reactor effluent was successfully treated by an anammox reactor.

An economic analysis showed that using two-stage systems is advantageous for treating THP/AD dewatering liquor. The implementation of an aerobic pre-treatment unit is recommended for WWTPs capacities higher than 5.10(5) inhabitants equivalent when one-stage systems are used.
 
  Address  
  Corporate Author Thesis  
  Publisher Place of Publication Editor  
  Language Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 1385-8947 ISBN Medium  
  Area Expedition Conference  
  Notes WOS:000722469100005 Approved  
  Call Number UAI @ alexi.delcanto @ Serial 1507  
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