7/31/2019 Singapore Water Action: The Lean, Mean, Green Wastewater Machine
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Country water actions are stories that showcase water reforms undertaken by individuals,
communities, organizations, and governments in Asia-Pacific countries and elsewhere.
Coun t ry Wat e r Act ions
Singapore : The Lean , Mean , Green Was tew a te r Mach ineA u g u s t 2 0 1 1
By Cezar T ign oWeb Writer
After the success of NEWater, water technology hubSingapore now turns to technological innovations inwastewater management with the help of private sectorpartners.
New Was tew a te r T echno l ogy
Singapore is fastbecoming theleader in waterand wastewatertechnologies.Since the successof NEWater,Singapore’s ownbrand of reclaimed orrecycled water, asa major source of water supply, the country’s scientists have been busy withdeveloping and innovating technologies.
Together with Siemens, Singapore has been cooking upsomething to make wastewater management more efficient,less costly, and more environment-friendly. Called “TheGreen Machine,” it is an innovative process of wastewatertreatment that can be easily adopted, with a little upgradingand expansion, by existing wastewater treatment plants. Itis meant to replace conventional wastewater treatment thatconsumes a lot of energy, generates a lot of sludge, andreleases carbon dioxide, contributing to the globalgreenhouse effect.
The Green Machine has comparable COD removal efficiencyas the conventional process. However, it consumes lessenergy, and more importantly helps generate more energyin the form of biogas. It combines contact stabilization withanaerobic digestion to create the hybrid process thatproduces about 50% less sludge than conventionaltreatment.
Wate r T echno logy Hub
Global city Singapore is home to about 4.5 million peoplethat consume some 300 million gallons of water per day,not counting the tourists that arrive by the tens of thousands daily. Lack of water in this small, multi-culturalcountry could have serious repercussions, but as early asthe 1970s, Singapore has foreseen its freshwater sourcesproblem.
Singapore’s Public Utilities Board (PUB) built a pilot waterreclamation plant in 1974, but implementation plans wereshelved because of huge costs and unreliable technology. Itwasn’t until 1998 that the project was revived through a joint initiative between PUB and the Ministry of Environmentand Water Resources.
The 1998 Singapore Water Reclamation Study (or NEWaterStudy) clinched the deal on NEWater as a raw waterresource to supplement the country’s water supply. NEWateris a product of stringent purification and treatmentprocesses capable of making sewage water clean, clear, andsparkling.
PUB started adding NEWater into its reservoirs at about 1%of total daily consumption following an evaluation by anExpert Panel from the National University of Singapore that
gave the go-signal for indirect potable use. PUB plans toincrease this to about 2.5% of total daily consumption by2011.
The Green Machine Project was financially supported by theEconomic Development Board, Environment & WaterIndustry Development Council
The Green Machine
In essence, the Green Machine is a combination of twoprocesses:
B ioso rp t i on , a physiochemical process that occursnaturally in certain biomass, which allows it topassively concentrate and bind contaminants onto its
cellular structure. It provides an economicalalternative for removing toxic heavy metals fromindustrial wastewater and aid in environmentalremediation.Anaerob ic d iges t ion , a series of processes in whichmicroorganisms break down biodegradable material inthe absence of oxygen, used for industrial ordomestic purposes to manage waste and/or torelease energy.
In this hybridprocess, organicmatter isabsorbed into themicrobial flocsurface duringcontact
stabilization andretention time iscontrolled beforemicrobes havetime to degradethe organics. Microbes carry the adsorbed organics into theanaerobic digestor where biogas is generated. The GreenMachine offers:
7/31/2019 Singapore Water Action: The Lean, Mean, Green Wastewater Machine
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Lower Energy Consumption: Less aerobic degradation / less aerationEasy for Retrofit: Upgrade existing wastewatertreatment plants with minimum structure changeLow Sludge Yield: Combined bio-sorption & anaerobicdigestion lead to low sludge productionWaste to Energy: Recover more energy fromwastewaterReliable Process: Activated sludge process andanaerobic digestion are accepted and proven
Design Flexibility: Operate with or without primaryclarifiers
P il o t i ng and Re tu rn o f I nves tm en t
Ruediger Knauf, Vice President of Siemens Global R & D inSingapore, said, “This treatment process consumes lowerenergy and at the same time is energy-neutral since itharvests energy.”
“Large plants can be retrofitted with this process, and wherethe cost of energy and availability of land are critical, thisprocess has great relevance,” Knauf added.
Pilot testing of the Green Machine began in October 2010 inSingapore, the Philippines, and the United States.
Upgrading and expansion of the existing wastewatertreatment plants gives a ROI of 5 years for US, 3 years forSingapore, and 4 years for Philippines. It is expected to becommercially introduced into the market in 2012.
References
Singh, Sahana. “Singapore: Setting the Stage for NewTechnologies.” In Asian Water, April 2011, Vol. 27, No. 03.
Bobby, Ding Hong-Bo, Xiao Lan, Rohan Wikramanayake andShouvik Chanda. “Green Machine-A Hybrid ProcessCombining Bio-Sorption and Anaerobic Digestion.” Presentation at the session on “Technology Options ForDifferent Settings: Making Sanitation Effective”at the 2ndADB and Partners Sanitation Dialogue: Making Sanitation aSustainable Business, 23-25 May 2011; Manila, Philippines.
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*This article was first published online at ADB's Water for All website in August 2011: http://www.adb.org/water/actions/sin/Green-Wastewater-
Machine.asp.
The Country Water Action series was developed to showcase reforms and good practices in the water sector undertaken by ADB’s member countries. It
offers a mix of experience and insights from projects funded by ADB and those undertaken directly by civil society, local governments, the private
sector, media, and the academe. The Country Water Actions are regularly featured in ADB’s Water for All News, which covers water sector developments
in the Asia and Pacific region.
