Integration of the Anammox process to the rejection water and main stream lines of WWTPs
Introduction
Up to now the main goal of wastewater treatment plants (WWTPs) was to remove pollutants content in order to protect downstream users. Most efforts have been traditionally focused on achieving the disposal requirements in terms of solids, organic matter and nutrients content (Benedetti et al., 2006). Recently, new challenges are under consideration, oriented to assure the sustainability of WWTPs in terms of their technical reliability, economic feasibility and environmental impact. Energy consumption, sludge production, and greenhouse gases emissions are among the aspects that should become key-factors concerning the overall performance of the WWTPs (Mo and Zhang, 2013, Yerushalmi et al., 2013).
It is known that the potential energy available in the raw wastewater, as organic compounds, exceeds significantly the electricity requirements of the applied treatments (Garrido et al., 2013). However, part of this organic matter is wasted when the nitrification and denitrification processes are used to remove nitrogen and organic matter simultaneously. In reality an effective use of the contained COD is only performed in the case of primary and secondary sludge which are normally anaerobically digested and energy is recovered through methane production (Wett et al., 2007a). Nevertheless, in these conditions only about 35–45% of the solids are converted into CH4 during anaerobic digestion. This limitation increases the interest in implementing sludge disintegration units prior to the anaerobic digesters to maximize the recovery of energy from sludge (and also to reduce sludge production) (Carrère et al., 2010).
In order to improve the recovery of energy from the raw wastewater, the application of Anammox based processes, which take place in autotrophic conditions, to the main stream in the WWTPs is one of the most interesting options (van Loosdrecht et al., 2004, Wett et al., 2013). According to this strategy both organic matter and nitrogen are removed in separated processes. In this case the energy contained in the organic matter can be saved and recovered by means of the application of an anaerobic psychrophilic digester (Alvarez et al., 2008) or an aerobic stage operated at a low solids retention time (Wett, 2007b; Ge et al., 2013) followed by an anaerobic digestion of the generated sludge. Thus oxygen requirements are minimized while methane production is maximized.
Anammox based processes are already applied at full scale to treat the supernatants of anaerobic sludge digesters (Lackner et al., 2014). This application allowed reducing the total electrical consumption of the WWTPs by 40–50% (Siegrist et al., 2008). If Anammox based processes are applied in the main line the energy savings could be increased and the WWTPs could generate 24 W h per person equivalent per day (W h pe−1 d−1), compared to a consumption of 44 W h pe−1 d−1 in conventional treatment (Kartal et al., 2010).
These data indicate the potential benefits of the implementation of Anammox based processes in the WWTPs main line. Nevertheless, there is still scarce information about the procedure how to apply such processes at low temperature and/or low ammonia concentrations at full scale. Therefore, prior to their application, an appropriated understanding of the effects of the operational conditions (nitrogen and biomass concentrations, dissolved oxygen concentrations…) on the process efficiency and also on the effluent quality is required (Fig. 1). For this reason, the aim of this work was to carry out an overall evaluation of the application of Anammox based processes on the WWTPs, to identify the possible bottlenecks and to propose strategies to avoid them.
Section snippets
Impacts of Anammox based processes applications on the WWTPs preformance
The effects of the Anammox based processes implementation on the WWTP performance have been evaluated from an energetic point of view taken into account the increase of methane production and the costs reduction associated with aeration (Siegrist et al., 2008, Kartal et al., 2010). However, the implementation of these processes also affects to the sludge and N2O production. Then, in order to quantify all these effects on the WWTPs performance, the possible implementation of the Anammox based
Anammox based processes operated at low temperature and/or low ammonia concentrations
The Anammox based processes have mainly been applied at full scale, operated at temperatures in the process optimum range values between 30 and 40 °C and treating high ammonia concentration streams. Early Anammox based processes implementations used two stage reactor configuration (van der Star et al., 2007, Abma et al., 2007). This configuration was chosen in order: (a) to avoid possible negative effects of toxic or organic biodegradable compounds, present in the influent, on the stability of
Process start-up
Up to date most of the experiences with Anammox based processes units started up at full scale were carried out at the optimal temperature values and treating concentrated streams coming from anaerobic digesters (Abma et al., 2007, Joss et al., 2009). The fact that the biomass growth rate decreases with the decrease of temperature and that the large flowrate of the water line induces the biomass washout slows down the process start up.
Under these conditions if the inoculation of the reactor is
Conclusions
The application of Anammox based processes to the main stream of WWTPs will improve their performance from an energetic and environmental point of view. Saving costs can be as high as 28% while the amount of N2O produced can be 83% lower compared to a conventional WWTP.
All the recent Anammox based processes applications at relatively low temperatures and/or low ammonia concentrations were carried out in single-stage systems using biofilms, granular sludge or a mixture of flocculent nitrifying
Acknowledgements
This work was funded by the Galician government (Project: 10MDS265003PR) and the Spanish government through the Project Plasticwater (CTQ2011-22675). The authors belong to the Galician Competitive Research Group GRC 2013-032, programme co-funded by FEDER.
References (60)
- et al.
Anaerobic treatment of low-strength municipal wastewater by a two-stage pilot plant under psychrophilic conditions
Bioresour. Technol.
(2008) - et al.
Pretreatment methods to improve sludge anaerobic degradability: a review
J. Hazard. Mater.
(2010) - et al.
Performance of a completely autotrophic nitrogen removal over nitrite process for treating wastewater with different substrates at ambient temperature
J. Environ. Sci.
(2013) - et al.
Partial nitrification and anammox process: a method for high strength optoelectronic industrial wastewater treatment
Water Res.
(2013) - et al.
Short- and long-term effects of temperature on the Anammox process
J. Hazard. Mater.
(2008) - et al.
Operating aerobic wastewater treatment at very short sludge ages enables treatment and energy recovery through anaerobic sludge digestion
Water Res.
(2013) - et al.
Complete nitrogen removal from municipal wastewater via partial nitrification by appropriately alternating anoxic/aerobic conditions in a continuous plug-flow step feed process
Water Res.
(2014) - et al.
Short- and long-term effects of temperature on partial nitrification in a sequencing batch reactor treating domestic wastewater
J. Hazard. Mater.
(2010) - et al.
The Sharon process: an innovative method for nitrogen removal from ammonium-rich waste water
Water Sci. Technol.
(1998) - et al.
Autotrophic nitrogen removal from low strength waste water at low temperature
Water Res.
(2012)
Novel nitritation process using heat-shocked nitrifying bacteria entrapped in gel carriers
Process Biochem.
Enrichment of denitrifying methanotrophic bacteria from municipal wastewater sludge in a membrane bioreactor at 20 °C
J. Hazard. Mater.
Dynamics of nitric oxide and nitrous oxide emission during full-scale reject water treatment
Water Res.
Heterotrophic activity compromises autotrophic nitrogen removal in membrane aerated biofilms: results of a modeling study
Water Res.
Full-scale partial nitritation/anammox experiences: an application survey
Water Res.
Assessment of the positive effect of salinity on the nitrogen removal performance and microbial composition during the start-up of CANON process
Appl. Microbiol. Biotechnol.
Energy-nutrients-water nexus: integrated resource recovery in municipal wastewater treatment plants
J. Environ. Manage.
Factors affecting the growth rates of ammonium and nitrite oxidizing bacteria
Chemosphere
Modeling kinetics of ammonium oxidation and nitrite oxidation under simultaneous inhibition by free ammonia and free nitrous acid
Process Biochem.
A review of anaerobic membrane bioreactors for municipal wastewater treatment: Integration options, limitations and expectations
Sep. Purif. Technol.
Control of aeration, aerobic SRT and COD input for mainstream nitritation/denitritation
Water Res.
Pilot and full scale applications of sulfur-based autotrophic denitrification process for nitrate removal from activated sludge process effluent
Water Res.
Startup of reactors for anoxic ammonium oxidation: experiences from the first full-scale anammox reactor in Rotterdam
Water Res.
Applications of Anammox based processes to treat anaerobic digester supernatant at room temperature
Bioresour. Technol.
Treatment of anaerobic sludge digester effluents by the CANON process in an air pulsing SBR
J. Hazard. Mater.
Integration of anammox into the aerobic granular sludge process for main stream wastewater treatment at ambient temperatures
Water Res.
Evaluating the solid retention time of bacteria in flocculent and granular sludge
Water Res.
Selective inhibition of nitrite oxidation by chlorate dosing in aerobic granules
J. Hazard. Mater.
The enhancement of completely autotrophic nitrogen removal over nitrite (CANON) by N2H4 addition
Bioresour. Technol.
The advance of Anammox
Water
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