Removal of petroleum hydrocarbons from water and sediment by an integrated process of adsorption and microbial degradation

[M. Lukić]

131 str.

Hemija - Biohemija / Chemistry - Biochemistry

U ovoj disertaciji je predstavljen proces in situ bioremedijacije sedimenta i podzemne vode kontaminirane naftnim jedinjenjima na industrijskom nivou, kao i ispitivanje nove tehnološke procedure za uklanjanje rastvorne frakcije (WSF) dizela iz voda. In situ bioremedijacioni tretman se sastojao od biostimulacije, bioaugmentacije i recirkulacije podzemne vode u zatvorenom sistemu. Za bioaugmentaciju je korišćen zimogeni konzorcijum mikroorganizama izolovan iz kontaminiranog sedimenta. Nakon bioaugmentacije udeo naftnih degradera u ukupnom broju hemoorganoheterotrofnih bakterija je porastao više od 60 puta u sedimentu, a broj naftnih degradera u podzemnoj vodi je održavan između 105 i 108 CFU/mL. Nakon jednogodišnje bioremedijacije, GC analiza je pokazala smanjenje sadržaja naftnih ugljovodonika u sedimentu za 82%, a u podzemnoj vodi za gotovo 100%. GCxGC-MS analiza sedimenta je pokazala stepen degradacije različitih grupa naftnih ugljovodonika: sterana (99,58%), izoprenoida (98,39%), derivata benzena (98,35%), alkana (97,17%) i terpana (49,32%). Eksponencijalni model degradacije za sediment je pokazao da je najveći stepen degradacije bio na dubinama od 8 do 10 m, sa prosečnom konstantom degradacije od 0,227, nezavisno od početne koncentracije naftnih ugljovodonika. Ovi rezultati pokazuju da je primenjeni in situ bioremedijacioni tretman bio vrlo efikasan u uklanjanju naftnih ugljovodonika iz podzemne vode i sedimenta u kontaktu sa podzemnom vodom. U drugom delu disertacije je analizirana sposobnost prirodnog zeolita, čija je površina modifikovana pomoću kvaternarne amonijumove soli heksadeciltrimetilamonijum bromida (HDTMABr), za adsorpciju WSF dizela iz vode. Eksperimenti adsorpcije su izvedeni korišćenjem organozeolita u šaržnom sistemu sa početnim koncentracijama WSF dizela od 2,5 do 25 mg/L pri pH 6 i temperaturi od 20 °C. GC analiza je pokazala da je uklonjeno više od 90% WSF dizela, pri čemu je ravnoteža postignuta nakon 1 sata. Maksimalni kapacitet adsorpcije organozeolita za uklanjanje WSF dizela iz vode iznosio je 22,2 mg/g. Ravnotežni podaci su najbolje opisani linearnom izotermom, dok su se kinetički podaci dobro uklopili u model pseudo-drugog reda. Prirodni zeolit i organozeolit pre i posle adsorpcije WSF-a dizela okarakterisani su pomoću FTIR i SEM analize, kao i određivanjem zeta potencijala. Uspešnost adsorpcije WSF-a dizela potvrđena je i dodatnim testom ekotoksičnosti. Nakon adsorpcije je sproveden 15-dnevni eksperiment biodegradacije u šaržnim uslovima. Rezultati su pokazali da je ispitivani konzorcijum mikroorganizama, sastavljen od sojeva izolovanih i okarakterisanih u prvom delu disertacije, razgradio 80% adsorbovane zagađujuće supstance. Dodatne respirometrijske analize pokazale su da je, paralelno sa razgradnjom adsorbovane frakcije dizela, došlo i do razgradnje dugolančanih HDTMA jona na površini organozeolita, odnosno do regeneracije adsorbenta.

This dissertation presents an industrial-scale in situ bioremediation process of hydrocarboncontaminated sediment and groundwater, as well as the examination of a new technological procedure for the removal of the water-soluble fraction (WSF) of diesel from water. In situ bioremediation treatment consisted of biostimulation, bioaugmentation, and groundwater recirculation in a closed system. For bioaugmentation, a zymogenous microbial consortium, isolated from the contaminated sediment, was used. Following bioaugmentation, the proportion of hydrocarbondegrading bacteria in total chemoorganoheterotrophs increased by more than 60-fold in the sediment, while the number of hydrocarbon degraders in the groundwater was maintained between 10⁵ and 10⁸ CFU/mL. GC analysis showed an 82% reduction in the hydrocarbon content in the sediment and an almost 100% reduction in groundwater after one year of bioremediation. GC-GC-MS analysis of the sediment showed the order of degradation of various hydrocarbon groups: steranes (99.58%), isoprenoids (98.39%), benzene derivatives (98.35%), alkanes (97.17%), and terpenes (49.32%). The exponential decay model for sediment showed the greatest decomposition rate of hydrocarbons occurred at depths of 8-10 m, with an average decay constant of 0.227, independent of the initial concentration of hydrocarbons. The results obtained show in situ bioremediation very effectively removes petroleum pollutants from groundwater and its associated sediments. In the second part of the dissertation, the adsorption capacity of natural zeolite, modified with the quaternary ammonium salt hexadecyltrimethylammonium bromide (HDTMA-Br) on the surface, for the removal of the WSF of diesel from water was analyzed. The adsorption experiments, with initial WSF concentrations of 2.5–25 mg/L, at pH 6 and at 20 °C, were performed in a batch system using organozeolite. GC analysis showed that more than 90% of the WSF of diesel was removed, reaching equilibrium after 1 h. The maximum adsorbed capacity of organozeolite for the removal of the WSF of diesel fuel from water under the tested conditions was 22.2 mg/g. Equilibrium data were most accurately described by a linear isotherm, whereas kinetic data were well fitted by the pseudo-second-order model. The natural zeolite and organozeolite before and after adsorption of the WSF of diesel were characterizes by FTIR and SEM analysis, as well as zeta potential measurements. The efficiency of the adsorption was additionally confirmed by an ecotoxicity test. After the adsorption, a 15-day biodegradation experiment was carried out under batch conditions. The results showed that the examined microbial consortium, composed of strains isolated and characterized in the first part of the dissertation, degraded 80% of the adsorbed contaminant. Additional respirometric analyses showed that, in parallel with the degradation of the adsorbed diesel fraction, the degradation of the long-chain HDTMA ions at the surface of the organozeolite also occurred, i.e. the adsorbent was regenerated

in situ bioremedijacija, konzorcijum mikroorganizama, naftni ugljovodonici, frakcija dizela rastvorna u vodi, akvifer, organozeolit, adsorpcija, biodegradacija

in situ bioremediation, microbial consortium, petroleum hydrocarbons, water-soluble fraction of diesel, aquifer, organozeolite, adsorption, biodegradation

547.53:606:502(043.3)

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