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ERT 417/4 WASTE TREATMENT IN BIOPROCESS INDUSTRY SEM 1 (2009/2010)

ERT 417/4 WASTE TREATMENT IN BIOPROCESS INDUSTRY SEM 1 (2009/2010). ‘Biological Treatment’. By; Mrs Hafiza Binti Shukor. OBJECTIVES OF BIOLOGICAL TREATMENT. To transform ( eg . Oxidize) dissolved and particulate biodegradable constituents into acceptable end products

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ERT 417/4 WASTE TREATMENT IN BIOPROCESS INDUSTRY SEM 1 (2009/2010)

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  1. ERT 417/4WASTE TREATMENT INBIOPROCESS INDUSTRY SEM 1 (2009/2010) • ‘Biological Treatment’ By; MrsHafizaBintiShukor

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

  3. 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 N2 and P in ww treatment process • Oxidizing NH3 (nitrification) to nitrite and nitrate • Reduce the oxidized nitrogen to gaseous nitrogen. • Biomass (S.G > H2O) can be removed from the treated • liquid by gravity settling. ERT 417/4WASTE TREATMENT IN BIOPROCESS INDUSTRY SEM 1 (2009/2010)

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

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

  6. Activated sludge? • 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. ERT 417/4WASTE TREATMENT IN BIOPROCESS INDUSTRY SEM 1 (2009/2010)

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

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

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

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

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

  12. CLASSIFICATION OF MICROORGANISM • NOTE; • Autotrophic- organism that derive cell carbon from CO2 • Heterothrophic – organism use organic carbon for formation new biomass ERT 417/4WASTE TREATMENT IN BIOPROCESS INDUSTRY SEM 1 (2009/2010)

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

  14. 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”. ERT 417/4WASTE TREATMENT IN BIOPROCESS INDUSTRY SEM 1 (2009/2010)

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

  16. Max specific substrate utilization rate, g substrate/g microb .day RATE OF UTILIZATION OF SOLUBLE SUBSTRATE Biomass (microorganism) conc, g/m3 Growth-limiting substrate conc in solution, g/m3 Rate of substrate conc change due to utilization (g/m3.day) - 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. ERT 417/4WASTE TREATMENT IN BIOPROCESS INDUSTRY SEM 1 (2009/2010)

  17. Rate of change of substrate utilization vs biodegradable soluble COD conc based on saturation type model. max 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. Substrate utilization rate, -rsu - ks Substrate concentration, mg bsCOD/L ERT 417/4WASTE TREATMENT IN BIOPROCESS INDUSTRY SEM 1 (2009/2010)

  18. 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 True yield coefficient, g/g - max specific substrate utilization rate, g/g.day ERT 417/4WASTE TREATMENT IN BIOPROCESS INDUSTRY SEM 1 (2009/2010)

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

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

  21. SUSPENDED GROWTH PROCESS Schematic of activated sludge unit Complete-mix aeration tank influent clarifier Q, So, Xo S, X,V effluent (Q-Qw), S, Xe System boundry Qr, S, XR Return activated sludge 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) sludge Qw, S, Xw ERT 417/4WASTE TREATMENT IN BIOPROCESS INDUSTRY SEM 1 (2009/2010)

  22. 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 = - + ERT 417/4WASTE TREATMENT IN BIOPROCESS INDUSTRY SEM 1 (2009/2010)

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

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

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

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

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

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

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

  30. 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 MLVSS conc in aeration tank, gVSS/m3 Total solid waste daily (gVSS/d) Volume of reactor (m3) ERT 417/4WASTE TREATMENT IN BIOPROCESS INDUSTRY SEM 1 (2009/2010)

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

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

  33. Design of Activated Sludge 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 ERT 417/4WASTE TREATMENT IN BIOPROCESS INDUSTRY SEM 1 (2009/2010)

  34. 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 wwflowrate, 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 ERT 417/4WASTE TREATMENT IN BIOPROCESS INDUSTRY SEM 1 (2009/2010)

  35. 1-L mL Sludge Volume Index (SVI) Sludge settleability is determined by sludge volume index (SVI) Final settling tank sludge V x 1000 SVI (ml/g) = ___________ MLSS where V is volume of settled sludge after 30 min ERT 417/4WASTE TREATMENT IN BIOPROCESS INDUSTRY SEM 1 (2009/2010)

  36. EXAMPLE ; ACTIVATED SLUDGE PROCESS • An activated sludge plant is setat 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/m3. The solid loss in secondry rectifier is neglegible. ERT 417/4WASTE TREATMENT IN BIOPROCESS INDUSTRY SEM 1 (2009/2010)

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

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