PNNS asociācijas aktivitāte amonija biodegradācijas procesā, izmantojot dažādas modeļu sistēmas
Date
2009
Authors
Mihailova, Alīna
Journal Title
Journal ISSN
Volume Title
Publisher
Latvijas Universitāte
Abstract
Amonjaks ir toksiska un reaktīva gāze, kas izdalās organisko atkritumu pārstrādes vietās un daudzos rūpnieciskos uzņēmumos. Noteikumi par amonjaka emisijām kļūst aizvien stingrāki, un tas dod stimulu atrast efektīvākas un rentablas kontroles tehnoloģijas.
Biofiltrācija ir salīdzinoši jauna tehnoloģija, kas jau ir atzīta par efektīvu un piemērotu amonjaka piesārņojuma likvidēšanai. Biofiltrācijas gaitā amonjaks iziet cauri nesējmateriālam, uz kura ir imobilizēta mikroorganismu biomasa. Amonjaks labi šķīst ūdenī, un biofiltrā tā lielākā daļa pāriet amonija formā. Bioloģiskā amonija degradācija norit nitrifikācijas procesā, kur amonijs oksidējas līdz nitrītiem un nitrātiem, kas savukārt var tālāk reducēties līdz brīvajam slāpeklim denitrifikācijas procesā.
Amonija biofiltrācijas procesā galvenā lomā ir autotrofām nitrificējošām baktērijām. Mūsu pētījumā ir izmantota amonjaku degradējoša baktēriju asociācija PNNS, kas iepriekš ir izolēta no zivju pārstrādes rūpnīcas notekūdeņu dūņām.
Darba gaitā ir izstrādātas kombinētā dziļuma-cietfāzes fermentācijas un cietfāzes triklinga modeļu sistēmas, lai pārbaudītu PNNS asociācijas augšanu un amonija degradācijas aktivitāti. Pārbaudīta un salīdzināta dažādu oglekļa avotu ietekme uz PNNS asociācijas augšanu un I fāzes nitrifikācijas procesu, novērtēti dažādi substrāti kā potenciālie nesējmateriāli PNNS asociācijas imobilizēšanai, kā arī noskaidrota izvēlētā nesējmateriāla pirmsapstrādes ietekme uz PNNS asociācijas imobilizācijas procesu.
Organiskās piedevas tādas, kā: melase, KLE un fruktoze atstāj stimulējošu efektu uz PNNS asociācijas augšanu un I fāzes nitrifikācijas procesu eksperimentālajās modeļu sistēmās. 0,45% fruktozes pievienošana barības videi būtiski palielina amonija degradāciju diapazonā no 0,53-1,59 g/l N-NH4+. Vispiemērotākais nesējmateriāls amonjaka biofiltrācijai no pārbaudītajiem materiāliem ir keramzīta granulas. Uz tām imobilizētās biomasas enzīmātiskā (FDA hidrolīzes) aktivitāte, pārrēķinot uz nesējmateriāla svara vienību un salīdzinot ar citiem nesējmateriāliem, ir būtiski augstāka (p<0,001). Keramzīta granulu pirmsapstrāde ar dažādām organiskām vielām būtiski neietekmē PNNS asociācijas imobilizēšanas procesu, taču imobilizētās biomasas amonija degradācijas aktivitāte (kombinētajā dziļuma-cietfāzes fernmentācijas sistēmā) vidē bez fruktozes ir būtiski augstāka (p<0,05) tajos variantos, kur keramzīta granulu pirmsapstrādē tās apstrādātas ar melasi. Iegūtos rezultātus plānots izmantot turpmākajos lielāka mēroga biofiltrācijas sistēmas eksperimentos.
Atslēgvārdi: amonjaks, amonijs, biofiltrācija, nitrifikācija, PNNS asociācija.
Ammonia is toxic and reactive gas which is emitted in organic waste processing sites and many industrial plants. Regulations for ammonia emissions are becoming increasingly stringent, stimulating the search for more efficient and cost-effective control technologies. Biofiltration is a relatively new technology that has already been recognized as effective and suitable for elimination of ammonia pollution. In the process of biofiltration ammonia passes through carrier material with immobilized microbial biomass. Ammonia is highly water soluble, and in a biofilters is mostly converted to ammonium. Biological ammonium degradation occurs in the nitrification process, where ammonium is oxidized to nitrites and nitrates, which in turn can be further reduced to the free nitrogen via denitrification. In the process of ammonium biofiltration autotrophic nitrifying bacteria play the key role. In the present study we used ammonia degrading association (PNNS) which was previously isolated from the biological activated sludge of the fish factory wastewater treatment plant. Solid phase submerged system and solid phase trickling system have been developed for the evaluation of PNNS association growth and ammonium degrading activity. The study compared impact of different carbon sources on the growth of association and I phase nitrification, evaluated different substrates as potential carrier material for immobilization of PNNS, as well as determined impact of pre-treatment of selected material on the PNNS immobilization. Organic additives such as molasses, KLE and fructose have a stimulating effect on the growth of PNNS association and I phase nitrification process in the experimental systems. Addition of 0.45% fructose to the media significantly increases degradation of ammonium in the range of 0.53-1.59 g/l N-NH4+. Ceramic granules have been selected as the most appropriate material for ammonia biofiltration. Enzymatic (FDA hydrolysis) activity of the biomass immobilized on ceramic granules is significantly higher (p <0,001) compared to other materials if calculated for material dry weight. Pretreatment of ceramic granules with different organic substances does not impact significantly the process of PNNS immobilization, though ammonium degradation activity of the immobilized biomass (in the solid phase submerged system) in media without fructose has been significantly higher (p<0,05) in variants with molasses pre-treatment. Acquired results are planned to use in further bigger scale biofiltretion system experiments. Key words: ammonia, ammonium, biofiltration, nitrification, PNNS association.
Ammonia is toxic and reactive gas which is emitted in organic waste processing sites and many industrial plants. Regulations for ammonia emissions are becoming increasingly stringent, stimulating the search for more efficient and cost-effective control technologies. Biofiltration is a relatively new technology that has already been recognized as effective and suitable for elimination of ammonia pollution. In the process of biofiltration ammonia passes through carrier material with immobilized microbial biomass. Ammonia is highly water soluble, and in a biofilters is mostly converted to ammonium. Biological ammonium degradation occurs in the nitrification process, where ammonium is oxidized to nitrites and nitrates, which in turn can be further reduced to the free nitrogen via denitrification. In the process of ammonium biofiltration autotrophic nitrifying bacteria play the key role. In the present study we used ammonia degrading association (PNNS) which was previously isolated from the biological activated sludge of the fish factory wastewater treatment plant. Solid phase submerged system and solid phase trickling system have been developed for the evaluation of PNNS association growth and ammonium degrading activity. The study compared impact of different carbon sources on the growth of association and I phase nitrification, evaluated different substrates as potential carrier material for immobilization of PNNS, as well as determined impact of pre-treatment of selected material on the PNNS immobilization. Organic additives such as molasses, KLE and fructose have a stimulating effect on the growth of PNNS association and I phase nitrification process in the experimental systems. Addition of 0.45% fructose to the media significantly increases degradation of ammonium in the range of 0.53-1.59 g/l N-NH4+. Ceramic granules have been selected as the most appropriate material for ammonia biofiltration. Enzymatic (FDA hydrolysis) activity of the biomass immobilized on ceramic granules is significantly higher (p <0,001) compared to other materials if calculated for material dry weight. Pretreatment of ceramic granules with different organic substances does not impact significantly the process of PNNS immobilization, though ammonium degradation activity of the immobilized biomass (in the solid phase submerged system) in media without fructose has been significantly higher (p<0,05) in variants with molasses pre-treatment. Acquired results are planned to use in further bigger scale biofiltretion system experiments. Key words: ammonia, ammonium, biofiltration, nitrification, PNNS association.
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