title: Effect of metal ions and petrochemicals on bioremediation of chlorpyrifos in aerobic sequencing batch bioreactor (ASBR).
abstract: Application of chlorpyrifos (CP) has increased its environmental concentration. Increasing CP concentration has increased chances of adverse health effects. Its removal from environment has attained researcher's attention. CP degrading bacterial strains were isolated from wastewater and agricultural soil. Finally, selected five bacterial strains were identified using 16S rRNA nucleotide sequence analysis as Pseudomonas kilonensis SRK1, Serratia marcescens SRK2, Bacillus pumilus SRK4, Achromobacter xylosoxidans SRK5, and Klebsiella sp. T13. Interaction studies among bacterial strains demonstrated possibility for development of five membered bacterial consortium. Biodegradation potential of bacterial consortium was investigated in the presence of petrochemicals and trace metals. About 98 % CP removal was observed in sequencing batch reactors at inoculum level, 10 %; pH, 7; CP concentration, 400 mgL-1, and HRT, 48 h. Experimental data has shown an excellent fit to first order growth model. Among all petrochemicals only toluene (in low concentration) has stimulatory effect on biodegradation of CP. Addition of petrochemicals (benzene, toluene, and xylene) in high concentration (100 mg L-1) inhibited bacterial activity and decreased CP removal. At low concentration i.e., 1 mg L-1of inorganic contaminants (Cu, Hg, and Zn) >96 % degradation was observed. Addition of Cu(II) in low concentration has stimulated CP removal efficiency. Hg(II) in all concentrations has strongly inhibited biodegradation rate except at 1 mgL-1. In simulated pesticide, wastewater CP removal efficiency decreased to 77.5 %. Outcomes of study showed that both type and concentration of petrochemicals and trace metals influenced biodegradation of CP.
authors.affiliation: Institute of Environmental Sciences and Engineering, School of Civil and Environmental Engineering, National University of Sciences and Technology (NUST), H-12, Islamabad, 44000, Pakistan. saira@iese.nust.edu.pk.
authors.forename: Saira
authors.initials: S
authors.lastname: Khalid
authors.affiliation: Institute of Environmental Sciences and Engineering, School of Civil and Environmental Engineering, National University of Sciences and Technology (NUST), H-12, Islamabad, 44000, Pakistan.
authors.forename: Imran
authors.initials: I
authors.lastname: Hashmi
authors.affiliation: Institute of Environmental Sciences and Engineering, School of Civil and Environmental Engineering, National University of Sciences and Technology (NUST), H-12, Islamabad, 44000, Pakistan.
authors.forename: Sher
authors.initials: S
authors.lastname: Jamal Khan
authors.affiliation: Institute of Environmental Sciences and Engineering, School of Civil and Environmental Engineering, National University of Sciences and Technology (NUST), H-12, Islamabad, 44000, Pakistan.
authors.forename: Ishtiaq A
authors.initials: IA
authors.lastname: Qazi
authors.affiliation: School of Chemical and Material Engineering, National University of Sciences and Technology, Islamabad, 44000, Pakistan.
authors.forename: Habib
authors.initials: H
authors.lastname: Nasir
mesh_terms: D042441:Achromobacter denitrificans / Q000187:drug effects / Q000235:genetics / Q000378:metabolism; D000332:Aerobiosis; D000069979:Bacillus pumilus / Q000187:drug effects / Q000235:genetics / Q000378:metabolism; D061249:Batch Cell Culture Techniques; D001673:Biodegradation, Environmental; D019149:Bioreactors / Q000382:microbiology; D004390:Chlorpyrifos / Q000378:metabolism*; D003300:Copper / Q000494:pharmacology; D007709:Klebsiella / Q000187:drug effects / Q000235:genetics / Q000378:metabolism; D008628:Mercury / Q000494:pharmacology; D058889:Molecular Typing; D010575:Pesticides / Q000378:metabolism*; D011549:Pseudomonas / Q000187:drug effects / Q000235:genetics / Q000378:metabolism; D012329:RNA, Bacterial / Q000235:genetics; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D012706:Serratia marcescens / Q000187:drug effects / Q000235:genetics / Q000378:metabolism; D014050:Toluene / Q000378:metabolism / Q000494:pharmacology*; D014874:Water Pollutants, Chemical / Q000378:metabolism; D018508:Water Purification; D015032:Zinc / Q000494:pharmacology
chemical_list: D010575:Pesticides; D012329:RNA, Bacterial; D012336:RNA, Ribosomal, 16S; D014874:Water Pollutants, Chemical; D014050:Toluene; D003300:Copper; D008628:Mercury; D015032:Zinc; D004390:Chlorpyrifos
keywords: Biodegradation; Chlorpyrifos; Organophosphate pesticides; Petrochemicals; Trace metals