Nitrogen and residual organic matter removal from anaerobic reactor effluentin a fixed-bed reactor with biogas for denitrification

Abstract

BACKGROUND This paper describes an evaluation of a fixed‐bed aerobic/anoxic reactor (AAFBR) for the post‐treatment of effluent from an up‐flow anaerobic sludge blanket (UASB) reactor treating domestic sewage. This is a new reactor configuration comprising an upper aerobic nitrification chamber fed with effluent from the UASB reactor. The nitrified effluent flows downwards to an anoxic chamber that is fed synthetic biogas (CH4, CO2 and H2S) from the bottom for denitrification. RESULTS The AAFBR removed organic matter at efficiencies higher than 90% for hydraulic detention times (HDT) of 7.5 and 5.0 h. The average nitrogen removal efficiencies were higher than 70% under conditions of excess H2S in the synthetic biogas. At an HDT of 5.0 h and with synthetic biogas of a similar composition to that in UASB reactors treating domestic sewage, the average N removal was approximately 50%. Under these conditions, the reactor achieved hydrogen sulfide and methane removal efficiencies of 100% and 60%, respectively. CONCLUSIONS The results obtained for the denitrifying activity indicated the coexistence of both autotrophic and heterotrophic denitrification in the anoxic chamber. The AAFBR exhibited additional ability as a gas cleanup system. The results demonstrate the potential of AAFBR as an alternative for the tertiary treatment of domestic wastewater. © 2014 Society of Chemical Industry

Dynamics of the nitrification and sulfide‐driven autotrophic denitrification processes in a single reactor using oxidation–reduction potential as an indicator of the process effectiveness

“…Anaerobic technologies have been widely used to treat high‐strength wastewater, mainly in tropical and subtropical regions . Anaerobic processes are characterized by the production of energetic compounds (methane and hydrogen) and the presence, in the final effluent, of phosphate, nitrogen and reduced sulfur compounds, which can be recovered by implementing post‐treatment systems . In the case of conventional nitrogen removal systems, a lack of electron donors for heterotrophic denitrification can occur due to the fast consumption by aerobic heterotrophic bacteria in the aerated tank.…”

“…Biogas from anaerobic reactors contains methane (CH 4 ), nitrogen gas (N 2 ), carbon dioxide (CO 2 ) and traces of other gases such as hydrogen sulfide (H 2 S). The H 2 S present in biogas and in the liquid medium causes harmful effects to the equipment due to corrosion, and to the environment due to toxicity to the organisms, demanding mitigation of its effects . The post‐treatment of anaerobic waste by sulfide‐driven autotrophic denitrification is a suitable approach for the concomitant removal of nitrogen and sulfur .…”

Remoção de nitrogênio de efluente de reator anaeróbio via processo NDS utilizando sulfeto como doador de elétrons na desnitrificação autotrófica

“…O efluente gasoso de reatores anaeróbios utilizados no tratamento de esgoto sanitário contém sulfeto (H2S), metano (CH4), gás nitrogênio (N2), dióxido de carbono (CO2) e traços de outros gases. O H2S presente no biogás causa efeitos deletérios aos equipamentos devido à corrosão, ao ambiente devido à toxicidade aos organismos, demandando mitigação de seus efeitos (MANCONI et al, 2007;PANTOJA FILHO et al, 2014). O pós-tratamento de efluentes de sistemas anaeróbios a partir da desnitrificação autotrófica utilizando sulfeto como doador de elétrons mostra-se como uma solução viável para a remoção de nitrogênio e enxofre (GUERRERO; ZAIAT, 2018;MAHMOOD et al, 2007;MORAES;ORRÚ;FORESTI, 2013;PANTOJA FILHO et al, 2014;PELAZ et al, 2017).…”

“…Estudos visando a integração entre os ciclos biogeoquímicos do nitrogênio e enxofre são realizados, geralmente, em biorreatores contendo diferentes câmaras, nas quais o tanque anóxico recebe uma mistura de efluente anaeróbio (rico em compostos reduzidos de enxofre) com efluente nitrificado (LU et al, 2012;PANTOJA FILHO et al, 2014;SAIA et al, 2016).…”

“…Os primeiros estudos na temática da integração entre os ciclos do nitrogênio e enxofre foram realizados utilizando reatores verticais contendo diferentes câmaras, nas quais o tanque anóxico recebe uma mistura de efluente anaeróbio (rico em compostos reduzidos de enxofre dissolvidos) com efluente nitrificado (PANTOJA FILHO et al, 2014;PELAZ et al, 2017;SAIA et al, 2016). Sistemas horizontais diretamente conectando câmaras aeróbias e anóxicas também tem sido implementados, como o reator horizontal aeróbio-anóxico e com leito fixo (MAAFBR) (GUERRERO; ZAIAT, 2018).…”