Bài giảng công nghệ môi trường_29 ppt

1 SPECIALIZED ENGLISH-SEMESTER 5 VAN LANG UNIVERSITY DEPARTMENT OF ENVIRONMENTAL TECHNOLOGY AND MANAGEMENT Chapter 29Chapter 29 FUNDAMENTALS OF BIOLOGICAL FUNDAMENTALS OF BIOLOGICAL Dr. Tran Thi My Dieu Sep. 2011 VAN LANG UNIVERSITY DENTEMA WASTEWATER TREATMENTWASTEWATER TREATMENT Biological denitrificationBiological denitrification CONTENTSCONTENTS Process descriptionProcess description MicrobiologyMicrobiology VAN LANG UNIVERSITY DENTEMA Stoichiometry of biological nitrificationStoichiometry of biological nitrification Environmental factorsEnvironmental factors PROCESS DESCRIPTIONPROCESS DESCRIPTION Nitrogen transformations in biological treatment processes VAN LANG UNIVERSITY DENTEMA PROCESS DESCRIPTIONPROCESS DESCRIPTION VAN LANG UNIVERSITY DENTEMA (a) substrate driven (preanoxic denitrification) Substrate denitrification Most common process used BOD inf provide electron donor PROCESS DESCRIPTIONPROCESS DESCRIPTION VAN LANG UNIVERSITY DENTEMA (b) endogenous driven (postanoxic denitrification) Electron donor is from endogenous decay Postanoxic denitrification Much slower rate than preanoxic process Add exogenous carbon source: CH 3 OH MOCROBIOLOGYMOCROBIOLOGY Heterotrophic bacteria Achromobacter, Acinetobacter, Agrobacterium, Alcaligenes, Arthrobacter, Bacillus, Chromobacterium, Corynebacterium, Fl b t i H i bi M ll VAN LANG UNIVERSITY DENTEMA Fl avo b ac t er i um, Hyp om i cro bi um, M oraxe ll a, Neisseria, Paracoccus, Propionibacterium, Pseudomonas, Rhizobium,Rhodopseudomonas, Spirillum, and Vibrio Autotrophic bacteria Nitrosomonas europaea 2 MOCROBIOLOGYMOCROBIOLOGY VAN LANG UNIVERSITY DENTEMA Pseudomonas Pseudomonas MOCROBIOLOGYMOCROBIOLOGY VAN LANG UNIVERSITY DENTEMA Agrobacterium MOCROBIOLOGYMOCROBIOLOGY VAN LANG UNIVERSITY DENTEMA Rhizobium STOICHIOMETRY OF BIOLOGICAL STOICHIOMETRY OF BIOLOGICAL DENITRIFICATIONDENITRIFICATION NONO 33 NONO 22  NO NO  NN 22 O O  NN 22 Several steps in nitrate reduction reactions VAN LANG UNIVERSITY DENTEMA Clarifier Electron donor bsCOD inf bsCOD decay methanol or acetate STOICHIOMETRY OF BIOLOGICAL STOICHIOMETRY OF BIOLOGICAL DENITRIFICATIONDENITRIFICATION C 10 H 19 O 3 N + 10NO 3 -  5N 2 + 10CO 2 + 3H 2 O + NH 3 + 10O H Organic materials  VAN LANG UNIVERSITY DENTEMA Clarifier 5CH 3 OH + 6 NO 3 -  3N 2 + 5 CO 2 + 7 H 2 O + 6 OH - 5CH 3 COOH + 8NO 3 -  4N 2 + 10CO 2 + 6H 2 O + 8OH - Metanol Acetate GROWTH KINETICSGROWTH KINETICS dn n nm n k NK N               n = specific growth rate of nitrifying bacteria, g new cells/g cells.d VAN LANG UNIVERSITY DENTEMA Clarifier  nm = maximum specific growth rate of nitrifying bacteria, g new cells/g cells.d N = nitrogen concentration, g/m 3 k n = half-velocity constant, substrate concentration at one-half the maximum specific substrate utilization rate, g/m 3 k dn = endogenous decay coefficient for nitrifying organisms, g VSS/g VSS.d 3 GROWTH KINETICSGROWTH KINETICS SK kXS r S su    VAN LANG UNIVERSITY DENTEMA = fraction of denitrif y in g bacteria in the biomass, g VSS/gVSS  = 0.20 to 0.80 for preanoxic denitrification GROWTH KINETICSGROWTH KINETICS                               DOK K NOK NO SK kXS r o o NOSS su ' ' 3, 3 3 Effect of DOEffect of DO VAN LANG UNIVERSITY DENTEMA   3 K o ’ = DO inhibition coefficient for nitrate reduction, mg/L K S,NO3 = half velocity coefficient for nitrate limited reaction, mg/L ENVIRONMENTAL FACTORSENVIRONMENTAL FACTORS Less concern about pH influence pH opt = 7.0-8.0 VAN LANG UNIVERSITY DENTEMA pH decrease from 7.0 to 6.0  decrease rate VAN LANG UNIVERSITY DENTEMA Fluid mechanism in Fluidized Bed Reactor Fluidized Bed Reactorn used for denitrification RBCs for denitrification is similar to that for aerobic processes except the medium is totally submerged to avoid oxygenating the liquid VAN LANG UNIVERSITY DENTEMA . ENGLISH-SEMESTER 5 VAN LANG UNIVERSITY DEPARTMENT OF ENVIRONMENTAL TECHNOLOGY AND MANAGEMENT Chapter 29Chapter 29 FUNDAMENTALS OF BIOLOGICAL FUNDAMENTALS OF BIOLOGICAL Dr. Tran Thi My Dieu Sep. 2011 VAN