ERT 417/4 WASTE TREATMENT IN BIOPROCESS INDUSTRY CH 7 – Fundamental of Biological Treatment

1. ERT 417/4 WASTE TREATMENT IN BIOPROCESS INDUSTRYCH 7 – Fundamental of Biological Treatment Prepared by: Pn. Hairul Nazirah Abdul Halim

2. Objectives of Biological Treatment • Transform dissolved & particulate biodegradable constituents into acceptable end products • Capture and incorporate suspended & nonsettleable colloidal solid into a biological floc or biofilm. • Remove nutrients such as nitrogen & phosphorus • Remove specific trace organic compounds

3. Schematic Flow Diagram For Biological Processes Flow diagram for biological process used for w/w treatment: a) Activated-sludge process

4. Flow diagram for biological process used for w/w treatment: b) Aerated lagoons

5. Flow diagram for biological process used for w/w treatment: c) Trickling Filters

6. Flow diagram for biological process used for w/w treatment: d) Rotating Biological Contactors.

7. Role of Microorganisms in W/w Treatment • To oxidize the dissolved and particulate carbonaceous organic matter into simple end products and additional biomass • Equation for aerobic biological oxidation of organic matter: • v1 (organic material) + v2 O2 + v3 NH3 + v4 PO43- v5 (new cells) + v6 CO2 + v7 H2O vi = stoichiometric coefficient. microorganisms

8. Types of Biological Processes for W/w Treatments • 2 categories: 1. Suspended growth process 2. Attached growth process

9. Biological Process Aerobic / Anaerobic Suspended Growth Process (SGP) • Activated Sludge Process • Aerated Lagoon • Aerobic/anaerobic Digestion Attached Growth Process (AGP) • Trickling Filters • Rotating Biological Contactors (RBC) • Packed Bed Reactors

10. Suspended Growth Process (SGP) • Microbs maintain in liquid suspension by mixing • Aerobic or anaerobic process • Most common SGP is the Activated Sludge Process.

11. Suspended growth biological treatment process (a-2) view of plug-flow activated-sludge process. (b-2) view of complete-mix activated-sludge process.

12. Attached Growth Process (AGP) • Microbs attach to an inert packing material • Packing material: rock, gravel, slag, sand, redwood, plastics & synthesis materials • Aerobic or anaerobic process • Most common AGP is the Trickling Filter.

13. Attached growth biological treatment process a-2) view of tricking filter with rock packing b-2) view of tower tricking filter with plastic packing The tower filter is 10 m high and 50 m in diameter.

14. Self Reading: • Composition & Classification of Microorganisms • Introduction to Microbial Metabolism

15. Bacterial Growth Bacterial Growth Patterns in a Batch Bioreactor Figure 7-10 Batch process biomass growth process with changes in substrate and biomass versus time

16. Lag phase – time required for organisms to acclimate to their new environment before significant cell division and biomass production occur. • Exponential growth phase – bacterial cells are multiplying at maximum rate • No substrate and nutrients limitation • Biomass increase exponentially • Temp. affects the growth

17. Stationary phase - biomass conc. remains relatively constant with time - No longer exponential growth - Offset by the death of cells • Death phase • Substrate has been depleted • No growth • Exponential decline in biomass conc.

18. Biomass yield, Yis the ratio of the amount of biomass produced to the amount of substrate consume (g biomass/ g substrate) Biomass yield, Y = g biomass produced g substrate utilized (i.e., consumed)

19. Microbial Growth Kinetics • The oxidation of substrate and the production of biomass which contributes to the total suspended solids (TSS) concentration in a biological reactor. • Performance of biological process for w/w treatment depends on the: i) dynamic of substrate utilization ii) microbial growth

20. Rate of utilization of soluble substrates • Where: rsu = rate of substrate conc. change due to utilization (g/m3.d) k = maximum specific substrate utilization rate (g substrate/ g microorganism.d) X = biomass (microb) conc. (g/m3) S = growth-limiting substrate conc. in solution (g/m3)

21. Where: µm =maximum specific bacterial growth rate (g new cells/g cells.d) k = maximum specific substrate utilization rate (g/g.d) Y = true yield coefficient (g/g)

22. Substrate Removal in Attached Growth Treatment Process • Biofilm consist of microbs, particulate material and extracellular polymers is attached and covers the support packing. • Support packing – plastic, rock, etc • Biofilm thickness: 100 um – 10 mm • Stagnant liquid layer separates the biofilm from bulk liquid • Substrates, oxygen & nutrients diffuse across stagnant liquid layer to biofilm • Product of biodegradation from the biofilm enter the bulk liquid after diffusion across the stagnant film

23. Figure 7-16 Schematic representation of the cross section of a biological slime in a trickling filter

24. Aerobic Biological Oxidation • Aerobic suspended growth or attached growth treatment processes. • Both required sufficient contact time between w/w and microbs, sufficient oxygen and nutrients.

25. bacteria bacteria Stoichiometry of Aerobic Biological Oxidation • Oxidation and synthesis: COHNS + O2 + nutrients CO2 + NH3 + C5H7NO2 + other end products • Endogenous respiration: C5H7NO2 + 5O2 5CO2 + 2H2O + NH3 + energy

26. Anaerobic Fermentation and Oxidation • Primarily for the treatment of waste sludge and high-strength organic waste. • Advantages: - lower biomass yield - produce energy (methane) - cost effective as compared to aerobic process with saving in energy, nutrient addition and reactor volume. • Process Description • Hydrolysis • Fermentation • Methanogenesis

27. 1. HYDROLYSIS • Particulate material is converted to soluble compound • soluble compound is hydrolyzed to simple monomers • Monomers are used by bacteria to perform fermentation

28. 2. FERMENTATION • Also refer to as asidogenesis • Amino acids, sugars and some fatty acids are degrade further as shown in Fig. 7-25. • Final products of fermentation: acetate, H2 & CO2 are precursors of methane formation (methanogenesis). 3. METHANOGENESIS • Carried out by a group of organisms – methanogens. • To produce methane.

29. Figure 7-25 Anaerobic process schematic of hydrolysis, fermentation and methanogenesis.

30. Figure 7-26 Carbon and hydrogen flow in anaerobic digestion process.

31. Stoichiometry of Anaerobic Fermentation & Oxidation