Turnkey solution for water and waste waterCreating difference in the similarities
6/27/2013 2Topics covered underneath Bioaugmentation ETP designing brief Screens design Primary clarifier Biological process Sedimentation tank Practical issues faced by Paper industry How bioaugmentation helps Cost saving measures
With Bioaugmentation…….. Reduction of BOD, COD of effluent. Lesser retention time as compared to normal microbes• Increased rate of decomposition - breaks down proteins,carbohydrates, fats, oils, for effective waste digestion and odorreduction.• Same plant treat more amount of influent with conventional design. Effective at : pH range(5.5 to 9.5) Low D.O. (0.8) Temperature Range (5-45 degree centigrade) And very importantly F/M ratio is kept balance
Bonus Benefits……… Odour Reduction upto 95%, Significant Energy Saving, Substantial Chemical Saving, Reduced Sludge Formation, Less Operation and Maintenance Cost, Upto 90-95% Water Recycling
Roebic TechnologyActive bacteriaIn Active bacteriaIsolated Activebacterial strain andcultured inR & D labCultured bacteriapacked in in activeform.Inoculation of activebacteria by utilizingroebic Technology toincrease MLVSSPercentage ofMLVSS increaseso treatmentlevel also
Figure Definition sketch for types of screens used in wastewater treatment
Design ConsiderationVelocity The velocity of flow ahead of and through the screenvaries and affects its operation. The lower the velocity through the screen, the greateris the amount of screenings that would be removedfrom effluent. However, the lower the velocity, the greater would bethe amount of solids deposited in the channel.
Hence, the design velocity should be such as topermit 100% removal of material of certain sizewithout undue depositions. Velocities of 0.6 to 1.2 mps through the open area forthe peak flows have been used satisfactorily. Further, the velocity at low flows in the approachchannel should not be less than 0.3 mps to avoiddeposition of solids.
Head loss Head loss varies with the quantity and nature ofscreenings allowed to accumulate between cleanings. Head loss through screens mainly depends on: Size and amount of solids in waste water Clear openings between bar Method of cleaning and its frequency Velocity of flow through the screens
The head loss through clean flat bar screens iscalculated from the following formula:h = 0.0729 (V2 - v2)where, h = head loss in mV = velocity through the screen in mpsv = velocity before the screen in mps
Another formula often used to determine the head lossthrough a bar rack is Kirschmers equation:where h = head loss, mb = bar shape factor (2.42 for sharp edge rectangular bar, 1.83for rectangular bar with semicircle upstream, 1.79 forcircular bar and 1.67 for rectangular bar with both u/s andd/s face as semicircular).W = maximum width of bar u/s of flow, mb = minimum clear spacing between bars, mhv = velocity head of flow approaching rack, m = v2/2gq = angle of inclination of rack with horizontalh = b (W/b)4/3 hv sin q
The head loss through fine screen is given bywhere, h = head loss, mQ = discharge, m3/sC = coefficient of discharge (typical value 0.6)A = effective submerged open area, m2h = (1/2g) (Q/CA)
Oil & Grease Trap Grease traps (also known as grease interceptors, greaserecovery devices and grease converters) are plumbing devicesdesigned to intercept most greases and solids before they enter awastewater disposal system.6/27/2013 21
Primary Clarifier Purpose: to remove settleable organics and floatingscum (grease and oils). Efficiencies: Suspended solids 50 – 65% BOD 30 – 35% Primary clarifiers are either circular or rectangular. Theyare very similar to sedimentation basins used in watertreatment except that scum removal is always providedin addition to sludge collection.
The most common suspended growth processused for municipal wastewater treatment is theactivated sludge process.
Activated sludge plant involves:1.wastewater aeration in the presence of amicrobial suspension,2.solid-liquid separation following aeration,3.discharge of clarified effluent,4.wasting of excess biomass, and5.return of remaining biomass to the aerationtank.
Process The process involves air or oxygen being introduced into a mixture ofprimary treated or screened sewage or industrial wastewatercombined with organisms to develop a biological floc which reducesthe organic content of the sewage. The combination of wastewater and biological mass is commonlyknown as mixed liquor. In all activated sludge plants, once the wastewater has receivedsufficient treatment, excess mixed liquor is discharged into settlingtanks and the treated supernatant is run off to undergo furthertreatment before discharge.
Design Consideration The quality or characteristics of raw waste water to be treated. The desired quality or characteristics of effluent or treatedwaste water. The type of reactor that will be used. Volumetric and organic loading that will be applied to thereactor.
Amount of O2 required and the aeration system willprovide to supply O2 and to support mixing. The quantity of sludge that will be generated andwasted for its further management. Besides these nutrient requirements of microbes,environmental conditions under which plantoperated.
Design steps The design computations require thedetermination of: Volume or dimensions of the aeration tank Flow of the influent. Amount of O2 required and power needed foraeration Quantity of sludge that will produced for particularwaste and treatment conditions Volume and dimensions of sec. settling tank
Design criteria No of aeration tanks, N= min. 2 (small plants)= 4 or more (large plants) Depth of waste water in tank= 3-4.5 m (usually)= 4.5-7.5 m (diffuse aeration)= 1-6 m (surface aeration) Freeboard= 0.3-6 m (diffuse aeration)= 1-1.5 m (surface aeration) Rectangular aeration tank L:B= 5:1 and B:D=3:1 to 4:1(depends on the aeration system)
Diffused aeration Providing maximum water surface per unit volume ofair. Air bubbles brought with water in a mixing or contactchamber. A common way to aerate water is via diffused air. Air is pumped through some sort of diffuser togenerate small bubbles.
Usually gas is injected into the bottom of the aerationtank and is allowed to rise to the surface in an opentank. The rising bubbles transfer oxygen to the water, aswell as transport bottom water to the surface. The bubbles raising through water create turbulence. Untreated water is allowed to enter the tank from topand exit from bottom.
Efficiency of diffused aeration can be improved: Fine bubbles (0.2 cm dia) as compared to coarsebubble (2.5 cm dia) By increasing water depth (9-15 ft) By improving the basin geometry (width to depthratio not exceed 2) By increasing the retention time (10-30 min)
There are a large variety of diffuser types. For example ceramicplates
These plates are arranged on manifolds at the bottom ofaeration tanks as shown here.
Other types of diffusers include coarse aerators
Again, these diffusers would be arranged by a manifoldon the bottom of an aeration tank.
To determine the oxygen transfer rate in these diffused aerationsystems, first define the pressure difference from top to bottomof the tank.14.7(1 0.032 AlPsurfac t)e Alt = altitude in thousands feet above sea levelPsurface has units of psiAt the surface:
62.4 HP P (psi)bottom surface 144 H = depth of tank (depth of discharge point) in feet.
Mechanical AerationBasically there are two types of mechanical aeration.Turbine Aeration: In this system coarse bubbles are injected into thebottom of the tank and then a turbine shears thebubbles for better oxygen transfer. Efficiency of turbine aerators is generally higher thandiffused aeration.
Surface Aeration: In this case a mixing device is used to agitate thesurface so that there is increased interfacial areabetween liquid and air. There are many different proprietary types ofsurface aerators .
Design consideration for mechanical aerators is usuallybased on Eckenfelder and Ford equation. T 20C Cw lN N (1.02)0 9.17 Notice that there is no depth consideration formechanical aeration.
Where as: N = actual transfer rate (lb-O2/hr) N0 = manufacturer specified transfer rate ( lb/hr)for clean water, 20oC, zero DO. Cw = saturation value for oxygen for wastewaterunder operating conditions. 9.17 = saturation DO for clean water, 20oC. Cl = the design oxygen concentration in theaeration basin. T = Temp. α = oxygen transfer correction factor for wastewater
Anaerobic Process Untreated wastewater is mixed withrecycled sludge solids and then digestedin a sealed reactor The mixture is separated in a clarifier The supernatant is discharged aseffluent, and settled sludge is recycled
Advantages/DisadvantagesAdvantages Methane recovery Small area required Volatile solidsdestructionDisadvantages Heat required Effluent in reducedchemical form requiresfurther treatment Requires skilledoperation Sludge to be disposedoff is minimal
Upflow Anaerobic Sludge Blanket Wastewater flows upwardthrough a sludge blanketcomposed of biologicalgranules that decomposeorganic matter Some of the generated gasattaches to granules that riseand strike degassing bafflesreleasing the gas Free gas is collected byspecial domes The effluent passes into asettling chamber
Advantages/DisadvantagesAdvantages Low energy demand Low land requirement Low sludge production Less expensive thanother anaerobicprocesses High organic removaleficiencyDisadvantages Long start-up period Requires sufficientamount of granularseed sludge for fasterstart-up Significant wash out ofsludge during initialphase of process Lower gas yield thanother anaerobicprocesses
Solid liquid separation process in which asuspension is separated into two phases – Clarified supernatant leaving the top of thesedimentation tank (overflow). Concentrated sludge leaving the bottom of thesedimentation tank (underflow).Secondary Clarifier
Purpose of Settling To remove coarse dispersed phase. To remove coagulated and flocculated impurities. To remove precipitated impurities after chemicaltreatment. To settle the sludge (biomass) after activatedsludge process / tricking filters.
Principle of Settling Suspended solids present in water having specificgravity greater than that of water tend to settle downby gravity as soon as the turbulence is retarded byoffering storage. Basin in which the flow is retarded is called settlingtank. Theoretical average time for which the water isdetained in the settling tank is called the detentionperiod.
Types of Settling Type I settling (free settling) Type II settling (settling of flocculatedparticles) Type III settling (zone or hinderedsettling) Type IV settling (compression settling)
Design Details Detention period: for plain sedimentation: 3 to 4h, and for coagulated sedimentation: 2 to 2.5 h. Velocity of flow: Not greater than 30 cm/min(horizontal flow). Tank dimensions: L:B = 3 to 5:1. Generally L= 30m (common) maximum 100 m. Breadth= 6 m to10 m. Circular: Diameter not greater than 60 m.generally 20 to 40 m.
Depth 2.5 to 5.0 m (3 m). Surface Overflow Rate: For plain sedimentation12000 to 18000 L/d/m2 tank area; forthoroughly flocculated water 24000 to 30000L/d/m2 tank area. Slopes: Rectangular 1% towards inlet andcircular 8%.
1. Inadequate ETP in terms of its sizing.2. Inadequacy of the Electro mechanical equipment.3. Manpower issues1. Less educated2. Proper monitoring or guidance not done.4. Laboratory facility not available to monitor the plant.5. Lack of knowledge on the waste water treatmentprocess have let them use various techniques on asingle unit.6. Water consumption very high on per ton paperresulting to high flow.PRESENT CONSTRAINTS TOINDUTRY ETP
Action plan System feasibility check knowledge and nature check of employees at ETP(Client side). Design modification if required Desilting of all tanks Commissioing startup Regular laboratory check like OUR, DO, MLVSS After 500ppm Mlss shock dosage of bioaugmentationstart. After 1500ppm MLSS controlled flow taken in thesystem. After 2500ppm complete focus towards the quality ofthe water
Common Plant faults Recirculation from aeration to secondary clarifiermissing. Flocculating well missing in clarifier. Relative velocity water at the surface is not zero. Bioculture missing. Surface aerators installed at height 3m which need to beideally at 2.25mt. Irregular sludge drainage. No any Lab facility. If plants are at6/27/2013 68
Bioaugmentation support incost optimization Aeration hour saving (powerconsumption). Sludge handling cost reduction. Chemical saving. Environmental friendly process6/27/2013 70
Cost reduction by optimization ofDissolved OxygenAfter inoculation the running of all aerators ismust to avoid the anoxic condition in theaeration system.With inoculation the oxygen demand of thesystem will reduce so we can run the aeratorson rotational basis diagonally as per the oxygenuptake.Scheme of aerators inaeration tank (TopView)Sectional View
6/27/2013 72Dosing of Nutrient Urea: Source of Nitrogen DAP: Di-Ammonium Phosphate,Source of phosphate as well asnitrogen in a less quantity. Jaggery: Source of carbon.Ratio to be maintainedAeration Tank: 100:5:1Anaerobic tank: 250:5:1
6/27/2013 73Thank YouWe wish to provide completeknowledge, quality and economicalsolutions to paper and pulp industry.We look forward for your support….