Microbial and environmental factors affecting the nitrate removal efficiency from water in bioelectrochemical systems
Date
2023-07-07
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Abstract
Suur osa maapiirkondade veekogude ja põhjavee reostusest pärineb põllumajandusest. Üheks peamiseks probleemiks on üleväetamisest ja lämmastiku kadudest tingitud kõrge nitraadisisaldus vees, mis paljudes kohtades ületab EL kehtestatud piirnorme, tehes selle vee tarbimise tervisele ohtlikuks. Seetõttu on oluline leida viise selle ülemääraselt saastunud vee puhastamiseks. Tänu keerulisele tsüklile ja erinõuetele on nitraadi (NO3–) eemaldamine veest kallis ning energiamahukas. Seetõttu pakuvad bioelektrokeemilised süsteemid (BES) erilist huvi, kuna varasematest uuringutest on selgunud nende kõrge potentsiaal NO3– edukaks töötlemiseks ja veest täielikuks eemaldamiseks. BES efektiivsus NO3– eemaldamisel sõltub mikroobide aktiivsusest ja ehkki BES-i disaini on uuritud, on teadmised mikrobioomi rolli kohta endiselt piiratud. See uuring keskendus NO3– eemaldamise võimalustele ja analüüsis peamisi mikroobseid protsesse, mis vastutavad NO3– transformatsiooni eest kahte tüüpi BES-is – mikroobses elektrokeemilises snorkelsüsteemis (MES) ja ühekambrilises madala süsinikusisaldusega mikroobses elektrosünteesi reaktoris (MESR).
Käesolev uuring keskendus mikroobidele ja nendega seotud protsessidele, mis reguleerivad NO3– ärastamist veest. Analüüsiti ka keskkonnategurite ja süsteemi töörežiimide mõju leidmaks optimaalset disaini nitraadi eemaldamiseks BES-is.
Käesolev uuring kinnitab, et BES toetab mikroobseid protsesse, mis suudavad edukalt NO3– veest edukalt eemaldada, kasutamata seejuures tavaliselt NO3– eemaldamiseks vajalikku süsinikku. Uuringust selgus, et BES-i mikrobioomi struktuur on dünaamiline, nihkudes vastavalt NO3– kontsentratsioonidele ja muudele substraatidele BES-is. Olulise tulemusena võib esile tuua, et BES-i saab kasutada NO3 täielikuks eemaldamiseks ilma ohtliku kasvuhoonegaas ja stratosfääri osoonikihi hävitaja naerugaas (N2O) tekketa. BES aitab kaasa ka mikroobsetele protsessidele, mis võivad soodustada lämmastiku eemaldamist kõrgema saastekoormusega reoveest.
A large part of the pollution that resides in rural areas rely on groundwater for their water requirements, although this water remains unsafe to consume according to the standards set by EU. This is largely due to nitrate (NO3–), which contaminates water bodies and groundwater. Thus, it is essential to find ways to remediate this excessively contaminated water. NO3– is a difficult pollutant to eradicate due to its complex cycle and specific requirements essential for removal. Bioelectrochemical systems (BES) pose a special interest in removal of NO3 as they have displayed potential in treating NO3– successfully and completely remove it from the water. BES heavily rely on microbial activity in removal of NO3–, even though the BES design has been largely studied the knowledge on the role of microbiome remains limited. This study focused on NO3– removal capabilities and investigated the prevalent processes that are responsible for the NO3– transformation in two types of BES – a microbial electrochemical snorkel (MES) and a single-chambered carbon-deficient microbial electrosynthesis reactor (MESR). The current study focused on the microbes and related processes responsible for the NO3– removal. Likewise, the role of environmental factors and operational regimes has been analysed to suggest optimal design of BES for nitrate removal. This research states that BES support microbial process that can successfully eradicate NO3– removal and can also efficiently work by utilizing NO3– as fodder without relying on carbon. The BES microbiome structure shifts according to the NO3v concentrations and other substrates in the BES. It can be utilized for complete removal of NO3– with limited production of contaminants such as N2O, a potent greenhouse gas and stratospheric ozone depleter. The BES also aid microbial processes that can promote nitrogen removal from wastewater.
A large part of the pollution that resides in rural areas rely on groundwater for their water requirements, although this water remains unsafe to consume according to the standards set by EU. This is largely due to nitrate (NO3–), which contaminates water bodies and groundwater. Thus, it is essential to find ways to remediate this excessively contaminated water. NO3– is a difficult pollutant to eradicate due to its complex cycle and specific requirements essential for removal. Bioelectrochemical systems (BES) pose a special interest in removal of NO3 as they have displayed potential in treating NO3– successfully and completely remove it from the water. BES heavily rely on microbial activity in removal of NO3–, even though the BES design has been largely studied the knowledge on the role of microbiome remains limited. This study focused on NO3– removal capabilities and investigated the prevalent processes that are responsible for the NO3– transformation in two types of BES – a microbial electrochemical snorkel (MES) and a single-chambered carbon-deficient microbial electrosynthesis reactor (MESR). The current study focused on the microbes and related processes responsible for the NO3– removal. Likewise, the role of environmental factors and operational regimes has been analysed to suggest optimal design of BES for nitrate removal. This research states that BES support microbial process that can successfully eradicate NO3– removal and can also efficiently work by utilizing NO3– as fodder without relying on carbon. The BES microbiome structure shifts according to the NO3v concentrations and other substrates in the BES. It can be utilized for complete removal of NO3– with limited production of contaminants such as N2O, a potent greenhouse gas and stratospheric ozone depleter. The BES also aid microbial processes that can promote nitrogen removal from wastewater.
Description
Väitekirja elektrooniline versioon ei sisalda publikatsioone
Keywords
nitrates, water treatment, wastewater treatment, bioelectrochemistry, electrochemistry, electrosynthesis, environmental factors