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Greywater reuse proposal for duke university campus
 

Greywater reuse proposal for duke university campus

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A team proposal (with Liwei Zhang, Changheng Yang) analyzing the potential of reusing water on Duke University campus.

A team proposal (with Liwei Zhang, Changheng Yang) analyzing the potential of reusing water on Duke University campus.

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  • The drought plaguing much of the Southeast has dried up these boat docks on Georgia's Lake Lanier.
  • Yellow color mean the most important
  • 匡大一點
  • Consider physical treatment for the treatment because it will be cheaper and easier to maintain than chemical treatment.
  • Prefer mechanical, less human maintenance
  • Why this as opposed to other membranes?
  • Based on earlier characteristics, the top line uses E. Coli to represent fecal coliform reduction for our purposes. “The UV dosage, a product of UV intensity and exposure time, is measured in microwatt second per square centimeter (μw s/cm2). The UV dosage required to achieve 3 Log reduction of E. coli suspension is 7000 μw s/cm2 for traditional low-pressure mercury vapor lamps verified by researchers.”

Greywater reuse proposal for duke university campus Greywater reuse proposal for duke university campus Presentation Transcript

  • Greywater Reuse on Duke’s Campus Natalya Polishchuk Liwei Zhang Changheng Yang 1 1
  • OutlineIntroductionSourcesTreatmentUse PlanConclusion 1 1
  • IntroductionWhat is greywater? Urban wastewater that includes  Baths, showers,  Hand basins, washing machines,  Dishwashers and kitchen sinks,  But excludes streams from toilets 1 1 http://green.harvard.edu/theresource/new-construction/design-element/water-efficiency/images/greywater-system_000.gif
  • IntroductionUN: Good grade water should not be used for purposes that can be served with a lower grade unless there is a surplusWater is becoming more scarceSerious drought in the Southeast in 2007 1 1 http://ndn3.newsweek.com/media/62/071219_NewDrought_wide-horizontal.jpg
  • Introduction Duke used 566.4 million gallons in 2007  Residential housing (11%)  Reused water (estimate: 40 % of residential housing)  68,300 gpd or 47 gpmDuke University, (April 25, 2008). Sustainability: What is Duke doing to conserve water?. Retrieved April 12,2009, from Duke Sustainability Web site: 1 1http://www.duke.edu/web/ESC/campus_initiatives/water/conservation.html
  • SourcesResidential Housing at Duke: Sinks Showers (hair collectors added) Washing machines (lint filters installed) 1 1
  • Sources Characteristics of the grey water Particle Total BOD COD TOC TSS size coliforms Mean 20 86 49 29 286 5.26 Standard deviation 6 23 13 34 142 0.80Unit: BOD, COD, TOC and TSS (mg L−1), Particle size (μm), Total coliforms ((log10CFU100 mL−1))(Winward et al. 2008) 1 1
  • North Carolina Regulations5 mg/L TSS Storage: 5 daymonthly, 10 mg/L detention pond plusTSS daily irrigation pond forMax fecal coliform overflow1/100 mL *Hydraulic loadingTreatment in <1.75”/weekduplicate 100’ vegetative bufferBack-up power to nearest dwellingsourceNo COD or BOD limit in North Carolina 1 1
  • TreatmentRaw grey waterBar screen Equalization tank Physical TreatmentDisinfection Reuse 1 1
  • TreatmentPhysical treatment methods and performances TSS Turbidity COD BOD Reference Processes In Out In Out In Out In Out Sand filter+ Ward (2000) Membrane+ - - 18 0 65 18 23 8 Disinfection Screening+ CMHC Sedimentation+ (2002) 67 21 82 26 - - - - Multi-media filter+Ozonation Gerba et al. Cartridge filter 19 8 21 7 - - - - (1995) UF membrane 35 18 - - 280 130 195 86 Sostar-Turk et al. (2005) NF membrane 28 1 0 30 1 226 15 - - 1
  • TreatmentMembrane filtration advantages: Easy to operate Moderate cost Removal rate meets regulationsNo biological treatment processes. No COD or BOD limit in North CarolinaThe disinfection process is needed To meet fecal coliform limit in North Carolina 1 1
  • TreatmentBar screen Coarse particles, Body hairs and Large-size items  Vegetable leaves  Eggshell pieces, etc) http://www.chishun.com.tw/image/barscreen.jpg 1 1
  • TreatmentTypical design parameters: (Tchobanoglous et al, 2002) 1 1
  • TreatmentMicrofiltration membrane Stainless metal membrane is used.Basic characteristics are in the following table: Metal membrane characteristics summary (Kim et al, 2007) Parameters Values Nominal pore 0.5μm radius (ri) Filter 0.222m length (L) Membrane 0.32m2 area (Am) Membrane 1.04×1010 m–1 resistance (Rm) 1 1
  • TreatmentImpact of fouling on the permeate fluxFollowing expression is applied to calculate the permeateflux when fouling is considered (Wiesner and Bottero,2007): ∆P J= (1) µ[ Rm (t ) + Rc × c (t )] δAssume the resistance of the membrane (Rm(t)) does not change withtime, thenRm(t)=const=1.04×1010 1/m. dp=286×10-6m△P=operation pressure=100kPa εc=0.4μ=viscosity of water=10-3kg.m/s 180(1 − ε c ) 2 Rc = = 1.238 × 1010 m −2Rc=resistance of the cake, d pε c3 2 1 1
  • TreatmentAssume δc(t) = J × C × t/ρ, J is the permeate flux (m3/(m2.s)) C is the mass concentration of particles (29×10-3kg/m3), ρ is the density of particles (1.01×103 kg/m3).  Put all values of parameters into expression (1), we have: 105 Pa J= kg −3 −1 −2 29 × 10−3 kg ×m −3 (2) 10 [1.04 ×10 m + 1.238 × 10 m ×J × 10 10 −3 ×] t m ×s 1.01× 10 kg ×m 3 Final expression: 0.00704 × (−2.08 ×106 + 2383.28 × 761690 + t ) J= (3) t 1 1
  • TreatmentThe curve of permeate flux vs. time: Critical Point:(1688 hours , 4.81×10-3 m3/m2s) 1 1
  • TreatmentParticle removal efficiency of the membraneRemoval Efficiency, % 100 90 80 70 60 50 40 30 20 10 0 d≥ 15μm 13μm 10μm 8μm 5μm 2μm Particle size 1 (Kim et al, 2007) 1
  • Treatment Characteristics of the grey water: D mean=286μm, D 10=13μm Removal amount of particles (C be the concentration of TSS in influent ) (D>13μm) is C×90%×95%=0.855C (D<13μm) is C×10%×35%=0.035C(worst case: assume the removal efficiency of particles withDp=2μm can represent the overall removal efficiency of particles(D<13μm) ). Total Removal Efficiency = 0.855C + 0.035C = 89% C Meet North Carolina ∵TSS in influent=29mg/L, regulations (5 mg/L TSS monthly, 10 mg/L TSS daily) ∴TSS in effluent=3.19 mg/L 1 1
  • TreatmentComparison: Microfiltration membrane vs. Traditional sand filterKey Design Parameters: Parameters Value Flow rate (m3/s) 2.99×10-3 Bulk velocity (m/s) 6.67×10-3 Filter plan area (m2) 0.45 Depth of filter media (m) 0.762 Sand grain diameter (mm) 0.6 Porosity of filter bed 0.4 1 1
  • TreatmentThe particle removal rate of the filter be calculated as(Wiesner M. 2009): Final result:  3α ηT  removal rate=1-n/n0= 1 − exp  − 2 ×(1 − ε ) ×d ×L ÷ , where  c α is the affinity of the adsorbed particles to the filter media, εisthe porosity of the media, ηTis the collector efficiency, 1 1 dc is the diameter of the collector and L is the media depth.
  • TreatmentCollector efficiency (ηT) can beevaluated with the use of theexpression developedby Rajagopalan and Tien (1976): 1 1
  • TreatmentParticle removal efficiency of the membrane andthe sand filter: removal Removal rate Removal rate particle rate (membrane) (sand filter) diameter D=286μm (Dmean) >97% 100% D=13μm (D10) 95% 99.8% D=2μm 35% 46.4% The table shows that the particle removal efficiency of the sand filter is a little higher than the microfiltration membrane. Therefore, the sand filter can also work well in the filtration process. 1 1
  • Treatment Microfiltration cost Estimated between $400-800 (Keystone Filter Division) Sand filtration cost Estimated between $400-600 (Doheny’s water ware house)http://www.thomasnet.com/catalognavigator.html?cov=NA&what=microfiltration+membrane+price&heading=51 1 1170967&cid=141076&CNID=&cnurl=http%3A%2F http://www.waterwarehouse.com/Pool-Filters.html?gclid=%2Fkyfltr.thomasnet.com%2FCategory%2Ffine-sediment-
  • TreatmentHowever, compared with the membrane, a sand filterrequires a higher frequency of backflushing.Typical backflushing frequency of sand filters whentreating surface water:Rapid sand filter (widely used in potable water supplyfacilities; pressure-driven filtration process)—48-72hours (Salvato et al, 2003) (1688 hrs- MF at Duke)Therefore, microfiltration membrane is still a betterchoice. 1 1
  • DisinfectionThe advantage of UV Cheaper than chlorine according to the EPA. Does not create harmful chlorinated hydrocarbons Salt concentration is higher in recycled water, which can damage plants, especially in sprinkler irrigation. 1 1
  • Disinfection 1 1Lu, G., C. Li, et al. (2008).
  • Option: ROThe membrane has good total ion removal rate(>80%) (Yoon and Lueptow. 2005)However, the cost will be definitely high, due to alarge membrane area (344m2) is needed.Commercial price of RO membrane: $30.92/m 2 (FILMTEC Membranes product information,2009). Therefore, total price of the RO membraneis $10,636. 1 1
  • Use PlanNorth Carolina grey water reuse regulation:  Allowed  Not Allowed: Golf courses Parks, Toilets Cemeteries Residences, Fountains Highway medians Construction Sites http://www.dataflowsys.com/services/images/scada- http://www.roadstothefuture.com/Western_Freeway.jpg applications/golf-course-irrigation.jpg 1 1
  • Use Plan Duke uses reclaimed water from North Durham Water Reclamation Facility to water select plants  Advantages of grey water: Available water during droughts, when more reclaimed water must be sent to the lake Less energy use Less trucking water Learning opportunity for students Good publicityDuke University, (April 25, 2008). Sustainability: What is Duke doing to conserve water?. Retrieved April 12, 2009, f Duke Sustainability Web site: http://www.duke.edu/web/ESC/campus_initiatives/water/conservation.html 1 1
  • ConclusionsSource: on-campus residencesTreatment: Bar screen microfiltration membrane UV disinfectionUses: golf course irrigation street median irrigation 1 1
  • Thank YouQuestions? 1 1
  • ReferencesLi F., Wichmann K., Otterpohl R., 2009. Review of the technological approaches for grey water treatment and reuses. Science of the Total Environment, 407: 3439–3449Ward M., 2000. Treatment of domestic greywater using biological and membrane separation techniques. MPhil thesis, Cranfield University, UK.CMHC (Canada Mortgage and Housing Corporation), 2002. Final assessment of conservation Co-op’s greywater system. Technocal series 02–100, CHMC, Ottawa, Canada.Gerba C., Straub T., Rose J., et al, 1995. Water quality study of greywater treatment systems. Water Resour J., 18:78–84.Sostar-Turk S., Petrinic I., Simonic M., 2005. Laundry wastewater treatment using coagulation and membrane filatration. Resour.Conserv. Recycl., 44 (2):185–96.Tchobanoglous G., Burton F., Stensel D, et al, 2002. Wastewater Engineering: Treatment and Reuse. McGraw-Hill Professional, 1 1 USA
  • ReferencesDuke University, (April 25, 2008). Sustainability: What isDuke doing to conserve water?. Retrieved April 12,2009, from Duke Sustainability Web site:http://www.duke.edu/web/ESC/campus_initiatives/water/conservation.htmlLu, G., C. Li, et al. (2008). "A novel fiber optical devicefor ultraviolet disinfection of water." Journal ofPhotochemistry and Photobiology B: Biology 92(1): 42-46.US EPA, (1992). Manual, Guidelines for Water Reuse.Washington, DC: US Agency for InternationalDevelopment. 1 1
  • ReferencesKim R., Lee S., Jeong J., et al, 2007. Reuse of greywater and rainwater using fiber filter media and metal membrane. Desalination, 202: 326–332Wiesner M., Bottero J., et al, 2007. Environmental Nanotechnology: Applications and Impacts of Nanomaterials. McGraw-Hill Professional, USAWiesner M. 2009. Class note of course: physical and chemical processes in Environmental Engineering.Rajagopalan R. and Tien C., 1976. Trajectory analysis of deep-bed filtration with the sphere-in-a-cell porous media model. AIChE J. 2(3): 523-533Winward. P.G. , Avery M. L., , Stephenson T, and Bruce Jefferson,2008. Chlorine disinfection of grey water for reuse: Effect of organics andparticles. Water Res. 42: 483–491. 1 1