Part 2 of this book“Milestones in Water Reuse: The Best Success Stories”presents a number of case studies showing how water managers have used recycled water to meet the urban water needs which do not require drinking water quality.
Systems have varied in scale from large centralised dual reticulation schemes down to decentralised schemes at a local housing subdivision scale or in some cases for a single large public building or residential building scale. The case studies of decentralised systems are presented in Part 3.
Chapter 7 presents a demonstration study of a semi-centralised (local) water recycling project in Knittlingen in Germany to supply recycled water in an urban subdivision of 105 houses. The main objective is to demonstrate the performance, feasibility and cost efficiency of a small-scale anaerobic membrane bioreactor for energy recovery and nutrient valorisation as fertilisers for agricultural irrigation.
Chapter 8 describes how recycled water is being used to meet the water needs of population growth in the autonomous communities of Madrid in Spain. Water reuse was included in the 2005 Master Plan “Madrid Dpura Plan” with the
Table1Highlightsandlessonslearnedfromtheselectedcasestudiesofurbanuseofrecycledwater. Project/ LocationStart-up/ CapacityTypeofusesKeyFiguresDriversand OpportunitiesBenefitsChallengesKeysto Success Demonstration project DEUS21, Knittlingen, Germany 2004 MBRfor175 inhabitants (semi-centralised systems) Evaluationof thequality/ costforuse inagricultural irrigation
Developmentarea with105plots MBRperformance: At12.8–26.5°C AverageCODin effluent:135mg/L with85%removal Volatilesuspended solids:20–25g/L Sustainableflux: 13–14L/m2 ·h Implement semi-centralized systemsthat operates economically andmore sustainablythan otherconcepts
Optimisationofthe anaerobic membrane bioreactorsat smallscaleandlow temperature. Potentialapplication inwarmclimate. Potentialbenefits fromenergy recovery(biogas) andnutrients (irrigation).
Combinationof anaerobicbiological treatmentand membranefiltration (AnMBR)atlow T°C. Start-upproblems duetolackof adequateinoculum. Re-contamination oftheeffluent.
Processchoiceofan AnaerobicMembrane Bioreactorwithpre-treatment byrotatingdiskfilter. Vacuumsewersystemreduces amountofwastewater. Rainwateriscollected separately,treatedandused in-door. Earlyinvolvementof stakeholders. Madrid, Spain2005 “DpuraPlan”10 existingplus20 newreclamation facilities Tertiarytreatment capacity: 267,000m3 /d
Totalvolumeof treatedwastewater: 563Mm3 /yr Totalvolumeof recycledwater2010: 6.82Mm3 /yr InvestmentsinMadrid DpuraPlan:€200 million Waterreuse standards(urban uses):,200 E.coli/100mL ,1helm.egg/10L ,10NTU Increaseinwater consumption. Climatechange withsevere droughts. Politicaland institutional commitment.
Environmental benefitssuchas increasingwater reservesinthe region’sreservoirs. Cheaperpricethan drinkingwater. Efficient communication andinvolvement ofstakeholders.
Supplyreclaimed waterto52 municipalitiesin theAutonomous Communityof Madrid. Constructionand operationofthe dualdistribution system.
Citizensandmunicipalities havebecomeawareofthe advantagesofusingrecycled water Awarenessandcommitmentof theregionalauthoritiesledto thedecisionsforthenecessary investments.Municipalitieshad notborneanycostforthe constructionofinfrastructures. Costefficiencyand environmentalbenefits. Honolulu, Hawaii2000 Treatment capacity:45,400 m3 /d
Totalannualvolume oftreated wastewater: 12.6Mm3 /yr Totalvolumeof recycledwater: 11Mm3 /yr Capitalandoperation costs:approximately $3.3million/year Waterreuse standards:,2.2 Fecal coliform/100mL Conservationof potable resources. Energy efficiency. Examiningnewer technologiesto increaseeffluent efficiency.
Useofrecycledto lowerdemandand pressureonwater resources. Loweroperating costs,beneficial toclientand customers. Increaseoverallflow efficiencyoffacility todelivermorereuse water.
Meetingdemandas growthofreuse waterincreases. Controlling operationalcosts withunpredictable energyprices. Capitalcostsand footprintrequiredfor newequipment.
Customizedlocalsolutionthat isdemand-basedtomatch customerneeds. Connectedtechnologyand designwithlocalindustrial, commercial,residential, environmentalandrecreational needs. Minimizesimpactsofperiodic droughts. Superiorqualityultra-pure processwaterforindustry.
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BoraBora, French Polynesia 2005 300m3 /d,2008 500m3 /d
Landscape irrigationof hotels, stadium, sportfields, nursery,Boat washing, Fillingfire protection boats,Filling waterfallsand ponds, Cleaningand industrial uses Volumeofrecycled waterconsumption: ∼70,000m3 /yr O&Mcosts:0.68€/m3 (38%ofthe annualisedlifecost) Recycledwater charge:0.67to 2.51€/m3 plus fixedannualcharge dependingon volumes Waterquality standards: 0E.coli/100mL Waterstressand increasingwater demanddueto tourism development. Municipalpolicy ofsustainable development. Pollutionofthe lagoonwithrisk forthefragile ecosystem.
Savingofhigh qualityfreshwater waterforpotable watersupply(10% ofthedemand). Safeguardofthe lagoonandits biodiversity. Costsavingfor largeendusers. Preventionof revenuelossof buildingandtourist companiesduring droughts. Fastandeasier implementation thannew freshwatersupply.
Ensurehigh reliabilityof operationof membrane filtrationand efficientpreventive maintenance. Managereliable operationthrough floodconditions andrecycledwater supplywithout interruptions. Definethemost adequatepricing strategyofwater services. Overcomeaninitial poorperceptionof recycledwater byluxuryhotels.
Adequatechoiceofthe treatmenttechnologyandthe abilitytoprovidehigh-quality recycledwaterwithoutany interruption. Strongpoliticalengagement andcommitmentoftheelected officers. Implementationofanadequate publiccommunicationand educationprogram. Goodcollaborationwiththe localhealthauthoritiesto overcomenegativerisk perceptionofurbanspray irrigation. Public-privatepartnership. Economicviabilitywithabilityto coverO&Mcostsoftertiary treatmentanddistribution. AustraliaSince2001 Residential reusein250,000 houses by2030
Flushing toilets, Watering gardens, Washing cars,Clothes washing, Industrialuse
Projectedfuture volumeofresidential recycledwateruse: about37Mm3/yr by2030. Recycledwater tariffs:typically 80%ofdrinking waterprice. Waterreuse standards:fitfor purposebasedon riskassessment:,1 E.coli/100mLand virus-free Limitsonnew drinkingwater sources. Higherstandards fordischargesto theenvironment.
Annualdrinking waterusereduced by40%ormore. Peakdemandson drinkingwater systemsreduced by60%ormore.
Recycledwater qualitymonitoring. Qualitycontrolsto prevent cross-connections. Community education
Limitsonnewdrinkingwater sources. Developmentofclear guidelinesforurbanand residentialuse. Governmentsupportand Ministerialendorsement. Supportfromhealthauthorities basedonquantitativehealth riskassessment. AdaptionofU.S.experienceto localconditions. Urbanuseofrecycledwater
objective to use the recycled water produced by 10 existing plus 20 new reclamation facilities by means of a large dual distribution networks for urban and industrial uses.
Chapter 9. In Hawaii, an island surrounded by ocean but located in a drought-affected area, the Honolulu facility utilizes sophisticated technology, distinct process chains and cooperation between government and the private sector to produce adequate water products that meet the growing needs of industry, commerce and the public. The major specificity of this urban water recycling scheme is the distribution of two grades of recycled water, one for irrigation of landscaping, and a second higher grade for industrial processes.
Chapter 10 presents an outstanding example of a successful water reuse project in conditions of very restrictive water reuse regulations that had been overcome thanks to the strong political engagement of elected officers, trust of large end-users and support by local population. On the island of Bora Bora, a coral atoll in French Polynesia, fresh water supplies are distinctly finite. An urban reuse scheme has been developed to supply recycled water for landscape irrigation and other urban non potable uses with on-going projects for aquifer recharge. The reliable supply of high quality recycled water without interruptions and a suitable pricing of water services ensured the technical and economic viability of the project enabling to compensate for the water stress and to protect the lagoon, the most precious heritage of the Island.
Chapter 11. There has been widespread development of urban and residential reuse schemes in Australia. Recycled water is supplied for irrigation of household lawns and gardens, and connected indoors for toilet flushing. In some schemes, where recycled water quality is suitable, a recycled water tap is installed in the laundry to supply water for household clothes washing.
Keys to success
The common themes running through these case studies are that urban reuse has offset pressures from growing demands and water shortages due to drought and climate change by producing large savings in drinking water needs. There have been worthwhile economic and environmental benefits. Keys to success have included strong government and regulatory support, stakeholder involvement, development of community support through effective public education programs, effective treatment, careful monitoring and quality control, and recycled water priced lower than drinking water.
The major highlights and lessons learned from the selected case studies are summarised in Table 1.
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