1. ERT 417/4 WASTE TREATMENT IN BIOPROCESS INDUSTRY SEM 1 (2009/2010) ‘Biological Treatment’ By; Mrs Hafiza Binti Shukor

2. ERT 417/4 WASTE TREATMENT IN BIOPROCESS INDUSTRY SEM 1 (2009/2010) OBJECTIVES OF BIOLOGICAL TREATMENT To transform (eg. Oxidize) dissolved and particulate biodegradable constituents into acceptable end products Capture and incorporate suspended and nonsettleable colloidal solids into a biological floc or biofilm Transform or remove nutrients such as nitrogen and phosphorus. Remove specific trace organic constituents and compounds.

3. ERT 417/4 WASTE TREATMENT IN BIOPROCESS INDUSTRY SEM 1 (2009/2010) ROLE OF MICROORGANISMS IN WW TREATMENT To remove dissolved and particulate carbonaceous BOD and the stabilization of organic matter found in ww. microorganisms are used to; oxidize (convert) the dissolved and particulate carbonaceous organic matter into simple end products and additional biomass. Remove N 2 and P in ww treatment process Oxidizing NH 3 (nitrification) to nitrite and nitrate Reduce the oxidized nitrogen to gaseous nitrogen. Biomass (S.G > H 2 O) can be removed from the treated liquid by gravity settling.

4. ERT 417/4 WASTE TREATMENT IN BIOPROCESS INDUSTRY SEM 1 (2009/2010) TYPES OF BIOLOGICAL PROCESS FOR WW TREATMENT A)Suspended Growth Process B) Attached Growth Process A) Suspended Growth Process  Biological treatment processes in which microorganism responsible for the conversion of the organic matter or other constituent to gases or cell tissue.  The microorganism responsible for treatment are maintained in liquid suspension by appropriate mixing methods.  Operated with a +ve DO conc but applications exist where suspended growth anaerobic reactors are used such as for high organic conc industrial ww and organic sludges.  Most common suspended growth process used is activated sludge process and aerated lagoon

5. ERT 417/4 WASTE TREATMENT IN BIOPROCESS INDUSTRY SEM 1 (2009/2010) influent effluent sludge Return activated sludge air Plug flow aeration tank clarifier influent effluent sludge Return activated sludge Complete-mix aeration tank clarifier Plug Flow Activated Sludge Process Complete-Mix Activated Sludge Process

6. ERT 417/4 WASTE TREATMENT IN BIOPROCESS INDUSTRY SEM 1 (2009/2010)  activated sludge: microbial aggregates (flocs) in the aeration tank.  Flocs stay in suspension with mixing by aeration.  Recycle of the activated sludge is crucial to maintaining a high concentration of cells. Activated sludge?

7. ERT 417/4 WASTE TREATMENT IN BIOPROCESS INDUSTRY SEM 1 (2009/2010) Bar rack Grit Chamber Secondary clarifier Disinfection Aeration Tanks Primary Clarifier screeningsgritsludge Waste sludge (optional) effluent sludge Return activated sludge Waste sludge (optional) Activated Sludge Process influent Bar rack Settling Pond Disinfection Aerated Lagoon screenings Waste sludge (optional) effluent sludge Aerated Lagoon influent

8. ERT 417/4 WASTE TREATMENT IN BIOPROCESS INDUSTRY SEM 1 (2009/2010) B) Attach Growth Process  The microorganisms responsible for the conversion of organic material or nutrients are attached to an inert packing material.  The organic material and nutrients are removed from the wastewater flowing past the attached growth also known as biofilm.  Packing materials used include;  Rock  Gravel  Sand  Wide range of plastic  Other synthetic materials.  Can be operated as aerobic as aerobic or anaerobic processes.

9. ERT 417/4 WASTE TREATMENT IN BIOPROCESS INDUSTRY SEM 1 (2009/2010) Attach Growth Process (continue….)  The packaging can be submerged completely in liquid or not submerged with air or gas space above the biofilm liquid layer.  The most common aerobic attach growth process used is trickling filter and rotating biological contactors

10. ERT 417/4 WASTE TREATMENT IN BIOPROCESS INDUSTRY SEM 1 (2009/2010) Trickling Filter Process Rotating Biological Contactors Bar rack Grit Chamber Secondary clarifier Disinfection Trickling Filters Primary Clarifier screeningsgritsludge Waste sludge (optional) effluent sludge recycle influent Bar rack Grit Chamber Secondary clarifier Disinfection RBS units Primary Clarifier screeningsgritsludge effluent sludge influent

11. ERT 417/4 WASTE TREATMENT IN BIOPROCESS INDUSTRY SEM 1 (2009/2010) Trickling Filter with Rock Packing Tower Trickling Filter with Plastic Packing influent effluent sludge Recycle (optional) Trickling Filter with Rock Packing clarifier influent effluent sludge Recycle (optional) Trickling Filter with Plastic Packing clarifier

13. ERT 417/4 WASTE TREATMENT IN BIOPROCESS INDUSTRY SEM 1 (2009/2010) CLASSIFICATION OF MICROORGANISM AUTOTROPHICHETEROTHROPHICCHEMOHETROTHROPHIC Photoautotrophic  Energy source – light  Carbon source – CO 2 Photoheterotropic  Energy source – onorganic redox reaction  Carbon source – CO 2 Aerobic  oxygen as final electron acceptor Chemoautotrophic  Energy source – inorganic redox reaction  Carbon source – CO 2 Chemoheterotropic  Energy source – light  Carbon source – organic Anaerobic  NO 3 -, SO 4 2-, and CO 2 as electron acceptor NOTE;  Autotrophic- organism that derive cell carbon from CO 2  Heterothrophic – organism use organic carbon for formation new biomass

14. ERT 417/4 WASTE TREATMENT IN BIOPROCESS INDUSTRY SEM 1 (2009/2010) MICROORGANISM IN WW  Bacteria: major component  Fungi: low pH, toxicity, N deficient waste  Protozoa: gazing on bacteria  Rotifers: multicellular organism (help to floc formation)  Algae: supply oxygen to ww.  Organic/ inorganic particle

15. ERT 417/4 WASTE TREATMENT IN BIOPROCESS INDUSTRY SEM 1 (2009/2010)  Aerobic heterotrophic bacteria are main “activated”organisms. → Microbial community is highly diverse and competative.  Floc formation is really key –individual bacteria do not settle fast enough to be captured in the settling tank. Cells not in flocs are washed out.  The suspended flocs particles are called “activated”.

16. ERT 417/4 WASTE TREATMENT IN BIOPROCESS INDUSTRY SEM 1 (2009/2010) - BACTERIAL GROWTH & BIOMASS YIELD BIOMASS GROWTH  Mostly organic materials  An increase of biomass can be measured by VSS, particulate COD or TSS  Other parameter to indicate biomass growth are DNA, protein content and ATP.  VSS used as an apparent indicator of biomass production (measure of reactor solid in general) BIOMASS YIELD

17. ERT 417/4 WASTE TREATMENT IN BIOPROCESS INDUSTRY SEM 1 (2009/2010) - RATE OF UTILIZATION OF SOLUBLE SUBSTRATE Rate of substrate conc change due to utilization (g/m3.day) Max specific substrate utilization rate, g substrate/g microb.day Biomass (microorganism) conc, g/m3 Growth-limiting substrate conc in solution, g/m3 Half velocity constant (substrate conc at one-half the max specific substrate utilization rate, g/m3) Substrate= the term used to denote the organic matter or nutrients that are converted during biological treatment or that may be limiting in biological treatment. Eg. Carbonaceous organic matter is ww is referred as the substrate that is converted during biological treatment.

18. ERT 417/4 WASTE TREATMENT IN BIOPROCESS INDUSTRY SEM 1 (2009/2010) - Substrate utilization rate, -r su Substrate concentration, mg bsCOD/L ksks max Rate of change of substrate utilization vs biodegradable soluble COD conc based on saturation type model. From figure, max substrate utilization rate occurs at high substrate conc. In practice, biological treatment systems are designed to produce an effluent with extremely low substrate value. When the substrate is being used at its max rate, the bacteria are also growing at their max rate.

19. ERT 417/4 WASTE TREATMENT IN BIOPROCESS INDUSTRY SEM 1 (2009/2010) - The max specific growth rate of bacteria is related to the max specific substrate utilization rate as follow; max specific bacterial growth rate, g new cells/g cells.day max specific substrate utilization rate, g/g.day True yield coefficient, g/g

20. ERT 417/4 WASTE TREATMENT IN BIOPROCESS INDUSTRY SEM 1 (2009/2010) - RATE OF BIOMASS GROWTH WITH SOLUBLE SUBSTRATE Relation between the rate growth & rate of substrate utilization is applicable in both batch and continuous culture systems. Endogenous decay; Net biomass production rate Endogenous decay coefficient, gVSS/gVSS.day

21. ERT 417/4 WASTE TREATMENT IN BIOPROCESS INDUSTRY SEM 1 (2009/2010) - Net Biomass Growth;

22. System boundry influent effluent sludge Return activated sludge Complete-mix aeration tank clarifier Q, S o, X o (Q-Q w ), S, X e Q w, S, X w Q r, S, X R S, X,V ERT 417/4 WASTE TREATMENT IN BIOPROCESS INDUSTRY SEM 1 (2009/2010) In the aeration tank, contact time is provided for mixing and aerating influent ww with the microbial suspension, generally referred to as the mixed liquor suspended solids (MLSS) or mixed liquor volatile suspended solids (MLVSS) SUSPENDED GROWTH PROCESS Schematic of activated sludge unit

23. ERT 417/4 WASTE TREATMENT IN BIOPROCESS INDUSTRY SEM 1 (2009/2010) Biomass Mass Balance - Rate of accumulation of microorganism within the system boundary Rate of flow microorganism into the system boundary Rate of flow accumulation of microorganism out of the system boundary Net growth of microorganism within the system boundary =+

24. ERT 417/4 WASTE TREATMENT IN BIOPROCESS INDUSTRY SEM 1 (2009/2010) - Where, = rate of change of biomass concentration in reactor measured as gVSS/m3.day = reactor volume (aeration tank)m3 = influent flowrate, m3/day =concentration fo biomass in influent, gVSS/m3 = waste sludge flowrate, m3/day = concentration of biomass in effluent, gVSS/m3 = concentration of biomass in return line from clarifier, gVSS/m3 = net rate of biomass production, gVSS/m3.day

25. ERT 417/4 WASTE TREATMENT IN BIOPROCESS INDUSTRY SEM 1 (2009/2010) Assumption;  Xo = 0 (neglected)  Steady state condition prevail (dx/dt)=0 Where, ÷VX

26. ERT 417/4 WASTE TREATMENT IN BIOPROCESS INDUSTRY SEM 1 (2009/2010) - Inverse above equation

27. ERT 417/4 WASTE TREATMENT IN BIOPROCESS INDUSTRY SEM 1 (2009/2010) - Sludge Retention Time (SRT)  Important design  Operating parameter for activated sludge process  Is average time the activated sludge solid are in the system  Is determine by dividing the mass of solid in the aeration tank by the solids removed daily via the effluent and by washing for process control

28. ERT 417/4 WASTE TREATMENT IN BIOPROCESS INDUSTRY SEM 1 (2009/2010) - Substrate Mass Balance Is a mass balance for substrate utilization in an AERATION TANK Accumulation InflowOutflow Generation = + Influent soluble substrate concentration, g/m3 Outflow soluble substrate concentration, g/m3 Assumption, At steady state, dS/dt=0

29. ERT 417/4 WASTE TREATMENT IN BIOPROCESS INDUSTRY SEM 1 (2009/2010) - The reactor biomass conc is a function of SRT

30. ERT 417/4 WASTE TREATMENT IN BIOPROCESS INDUSTRY SEM 1 (2009/2010) -  If no return sludge flow where all sludge produce present in the effluent clarifier tank…….the SRT equation become; System boundry influent effluent sludge Complete-mix aeration tank clarifier Q, S o, X o (Q-Q w ), S, X e Q w, S, X w S, X,V

31. ERT 417/4 WASTE TREATMENT IN BIOPROCESS INDUSTRY SEM 1 (2009/2010) - Solid Production  Solid production from biological reactor represent the mass of material must be removed each day to maintain the process.  Solid production in terms of TS,VSS and biomass.  SRT provide expression to calculate total sludge produce daily from activated sludge process. Total solid waste daily (gVSS/d) Total MLVSS conc in aeration tank, gVSS/m3 Volume of reactor (m3)

32. ERT 417/4 WASTE TREATMENT IN BIOPROCESS INDUSTRY SEM 1 (2009/2010) - Biomass waste daily (gVSS/d) Niomass conc, gVSS/m3 Volume of reactor (m3) To find amount of biomass wastes perday (P x ), the biomass concentration, X can be used in place of X T in equation before;

33. ERT 417/4 WASTE TREATMENT IN BIOPROCESS INDUSTRY SEM 1 (2009/2010) Mixed Liquor Solid Concentration Total MLVSS in aeration tank Biomass conc nbVSS conc, xi = + Comprise of;  nbVSS in influent  nbVSS in waste  nbVSS produce from cell debris duty to decay ratio

34. ERT 417/4 WASTE TREATMENT IN BIOPROCESS INDUSTRY SEM 1 (2009/2010) loading Designed based on loading (the amount of organic matter added relative to the microorganisms available) Commonly called the food-to-microorganisms ratio, F/M F measured as BOD. M measured as volatile suspended solids concentration (VSS) F/M is the amount of BOD/day per amount of MLVSS in the aeration tank Design of Activated Sludge

35. ERT 417/4 WASTE TREATMENT IN BIOPROCESS INDUSTRY SEM 1 (2009/2010) Food to Microorganism (F/M) Ratio Defines as BOD @ COD applied perunit volume of mixed liquor Where; F/M = food to biomass ratio (g BOD or COD/g VSS.day) Q=influent ww flowrate, m3/day So=influent BOD @ COD conc, g/m3 V=aeration tank volume,m3. X=mixed liquor biomass conc in the aeration tank, g/m3 =hudraulic retention time of aeration tank, V/Q,day

36. ERT 417/4 WASTE TREATMENT IN BIOPROCESS INDUSTRY SEM 1 (2009/2010) Sludge Volume Index (SVI) where V is volume of settled sludge after 30 min Sludge settleability is determined by sludge volume index (SVI) SVI (ml/g) = ___________ MLSS V x 1000 Final settling tank sludge 1-L mL

37. ERT 417/4 WASTE TREATMENT IN BIOPROCESS INDUSTRY SEM 1 (2009/2010) EXAMPLE ; ACTIVATED SLUDGE PROCESS An activated sludge plant is set at SRT value of 10day. The reactor volume is 20 000m3 and MLSS conc is 400g/m3. Determine; a)The sludge production rate. b)The sludge washing flowrate when washing from reactor. c)The sludge washing flowrate when washing from recycle line. The concentration of suspended solid in recycle line is 10 000 g/m 3. The solid loss in secondry rectifier is neglegible.

38. ERT 417/4 WASTE TREATMENT IN BIOPROCESS INDUSTRY SEM 1 (2009/2010) THE END