Impact of phytoremediation and bioaugmentation on the microbial community in oil shale chemical industry solid waste
Kuupäev
2010-05-21T12:18:11Z
Autorid
Ajakirja pealkiri
Ajakirja ISSN
Köite pealkiri
Kirjastaja
Abstrakt
Poolkoks on põlevkivikeemiatööstuses põlevkiviõli tootmise (utmine) käigus tekkiv tahke jääde, mis põhjustab Eestis suuri keskkonnaprobleeme. Värske poolkoks on väga aluseline ja sisaldab suurtes kogustes sulfiide, Ca2+ ja Mg2+ ioone ning orgaanilist süsinikku. Poolkoksi on ladustatud 85 aasta vältel suurte mägedena maapinnale, kattes käesolevaks ajaks ligikaudu 200 ha suuruse maa-ala ja sisaldades umbes 100 miljonit tonni poolkoksi. Poolkoksiprügilad senisel kujul on avatud erinevatele keskkonnamõjudele, sealhulgas on suurimaks probleemiks poolkoksimägedelt pärit nõrgvesi, mis saastab põhjavett ja ümberkaudseid veekogusid. EL regulatsioonidest tulenevalt tuleb need prügilad 2013 aastaks sulgeda. Käesoleva doktoritöö üldiseks eesmärgiks oli välikatse käigus hinnata alternatiivse võimalusena taimede (fütoremediatsioon) ja spetsiifiliste omadustega bakteritüvede (bioaugmentatsioon) kasutamise sobivust poolkoksiprügila remediatsioonil. Konkreetsemalt on töö keskendunud fütoremediatsiooni ja bioaugmentatsiooni mõjule saasteainete kontsentratsioonidele, mikroorganismide metaboolsele aktiivsusele ja bakterikoosluse struktuuris toimuvatele muutustele, aga ka poolkoksi viidud bakteritüvede ellujäämisele. Töö tulemused näitasid, et taimestiku ja bakteritüvede mõjul suurenes poolkoksis mikroorganismide metaboolne aktiivsus ning kiirenes saasteainete biodegradatsioon, kusjuures need näitajad olid eriti kõrged taimede juurte vahetus läheduses (risosfääris). Bakterikoosluse struktuur taimede risosfääris oli ajas suhteliselt stabiilsem võrreldes juurevaba poolkoksiga. Bioaugmentatsioonikatses kasutatud Pseudomonas perekonna bakterid ja neile omased kataboolsete radade geenid tuvastati poolkoksis taimede risosfääris veel ka mitmeid kuid pärast tüvede sisseviimist. Kokkuvõtteks võib öelda, et taimestik ja sisseviidud bakteritüved kiirendasid poolkoksis funktsionaalse ja stabiilse, saasteained efektiivsemalt lagundada suutva mikroobikoosluse tekkimist.
Semi-coke is oil shale chemical industry solid waste that causes severe environmental problems in Estonia. Fresh semi-coke is characterised by a high initial pH value, a high concentration of sulphides, Ca2+ and Mg2+ ions and high amount of organic carbon. During 85 years of oil shale chemical industry semi-coke has been deposited into mounds, which nowadays contain up to 100 million tons of semi-coke and cover an area about 200 ha in the north-eastern part of Estonia. Open deposition of semi-coke causes diffusion of pollutants to the groundwater and underlying aquifers by leaching. In addition, according to the EU regulations semi-coke landfills must be closed by 2013. General aim of this thesis is to assess the feasibility of combination of phytoremediation (utilization of plants) and bioaugmentation (utilization of microorganisms with specific catabolic properties) as an alternative option for the remediation of semi-coke landfills. Impact of vegetation and bacterial strains on the concentration of pollutants, metabolic activity of microbial community and dynamics in microbial community composition in semi-coke, as well as survival and catabolic performance of introduced bacteria was studied. Study revealed that vegetation was the key factor for the acceleration of pollutants degradation. The rate of biodegradation of pollutants and microbial potential metabolic activity were exceptionally high in rhizosphere of plants. Major shift in bacterial community composition were obtained in the year of bioaugmentation application. Bacterial community composition in rhizosphere was relatively stable over time. Used Pseudomonas sp. strains both survived and their metabolic traits persisted at the contaminated site for long period of time due to the vegetation. It could be concluded that vegetation and added bacterial strains facilitated the development of a functional and stable microbial community with an elevated capacity for the degradation of pollutants in semi-coke.
Semi-coke is oil shale chemical industry solid waste that causes severe environmental problems in Estonia. Fresh semi-coke is characterised by a high initial pH value, a high concentration of sulphides, Ca2+ and Mg2+ ions and high amount of organic carbon. During 85 years of oil shale chemical industry semi-coke has been deposited into mounds, which nowadays contain up to 100 million tons of semi-coke and cover an area about 200 ha in the north-eastern part of Estonia. Open deposition of semi-coke causes diffusion of pollutants to the groundwater and underlying aquifers by leaching. In addition, according to the EU regulations semi-coke landfills must be closed by 2013. General aim of this thesis is to assess the feasibility of combination of phytoremediation (utilization of plants) and bioaugmentation (utilization of microorganisms with specific catabolic properties) as an alternative option for the remediation of semi-coke landfills. Impact of vegetation and bacterial strains on the concentration of pollutants, metabolic activity of microbial community and dynamics in microbial community composition in semi-coke, as well as survival and catabolic performance of introduced bacteria was studied. Study revealed that vegetation was the key factor for the acceleration of pollutants degradation. The rate of biodegradation of pollutants and microbial potential metabolic activity were exceptionally high in rhizosphere of plants. Major shift in bacterial community composition were obtained in the year of bioaugmentation application. Bacterial community composition in rhizosphere was relatively stable over time. Used Pseudomonas sp. strains both survived and their metabolic traits persisted at the contaminated site for long period of time due to the vegetation. It could be concluded that vegetation and added bacterial strains facilitated the development of a functional and stable microbial community with an elevated capacity for the degradation of pollutants in semi-coke.
Kirjeldus
Väitekirja elektroonilisest versioonist puuduvad publikatsioonid.