Clean technology, or alsoknown as Cleantech, is used to define a set of technologies that can reduces orimproves the use of natural resources, while at the same time reducing the harmfuleffect of technology has on the earth and its ecosystems (Pirolini, 2015). Pirolini(2015) also stated that, cleantech also used to describe products, processes orservices that reduce waste and require as few non-renewable resources aspossible for example, clean coal technology.
Examples above explains how cleantechnology is a part of the solutions and have a positive advantage in relationto climate change and sustainable development. The investment community takesclean technology as solutions to be economically practical and have thepotential to be profitable. On the other hand, the environmental groups andgovernments focuses on the beneficial impacts of clean technology has on theenvironment solutions and feels that it is more important than currentprofitability calculations. Solid waste management Theproblems related to the wide consumption and depletion of natural resources andthe increasing output of wide-ranging types of waste are becoming more seriousnowadays. This can be caused by the economic development, industrialization andincreasing population (Ministryof the Environment Japan, 2012). Therefore, the management of solidwaste has to be efficient enough to solve this problem other than limiting theconsumption of natural resources.
Ministry of the Environment Japan hasinvented some of leading Japanese waste disposal and recycling technologieswhich is a cleantech to overcome this problem. The cleantech is used for thesolid waste management from the collection and transportation of waste to the disposal in landfills. Underthe collection and transport of waste, the Ministry of the Environment Japanset up waste transfer stations to transfer from small or medium sized garbagetrucks to larger trucks. The transfer station method commonly adopted in Japanis the compactor container transfer station. The compactor container able tocompress three of 2 ton trucks into only one container. The improvement in theefficiency of collection and transport can directly reduce the cost whilemaintaining or improving services to residents. Therefore, according to Ministryof the Environment Japan (2012), transfer of waste to larger trucks attransport stations improves transport efficiency, reduces cost, reduces fuelconsumption, and reduce CO2 emissions which contribute to the prevention ofglobal warming. Anothercleantech used in Japan’s solid waste management is by incinerating garbage.
Itis well known that incinerate municipal waste can generate SOx, HC1, NOx, smokeand dioxin. Therefore, Ministryof the Environment Japan has taken measures to prevent and reducedioxin generation by increasing furnace temperature when starting operation,and maintain high temperature at the end of operation to completely burn waste.Moreover, exhaust cooling is also installedto prevent the re-synthesis of dioxin, application of bag filters installed toeliminate dioxin contained in smoke systematically, and the activated coal isdeveloped, to adsorbs and eliminates dioxin in exhaust fumes and a catalystthat decomposes dioxin (Ministryof the Environment Japan, 2012). Next,in Japan, they use sanitary disposal technology with high-environmentpreservation capability to dispose medical wastes.
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The risk of contaminated waste beingmixed with general waste increase the possibility of the spread ofcontamination and a simple incineration of medical waste may generate hydrogenchloride and dioxin. Thus, the Ministry of the Environment Japan set upincinerator specifically for medical waste are to reduce dioxin content in thegas emissions. In the incinerator, waste is broken down and fully disinfectedso that contagious pathogens cannot spread through the air. Next, gastemperature in the incinerator is maintained at 800°C or higher, and when thetreatment capacity of the incinerator is less than 2t/hour, dioxin should be5ng-TEQ/m3 or lower (Ministryof the Environment Japan, 2012). Thecollected bottles are cleaned, and caps and labels taken off to improve theirquality.
The bottles are then compressed, bound and passed on to reproductioncontractors. Under the 3R policy (Reduce,Reuse, Recycle), Japan has been collecting PET bottles, food trays, and cansseparately for reuse as recycle resources in the manufacturing of new products.Relatively high-grade PET bottles are collected and remade into PET bottles orother products with the high technology possessed by Japan. The collectedbottles are cleaned, and caps and labels taken off to improve their quality.The bottles are then compressed, bound and passed on to reproductioncontractors to make recycle products such as shirts, carpets, bottles fordetergents, cosmetic containers, paper packs, containers and etc. To make newPET bottles, collected bottles are washed, dissolved under high temperature andfiltered to reproduce high quality plastic resin.
New PET bottles are madeusing 50% recycled resin produced through the material recycle method and 50%recycled resin produced through the chemical recycle method, for 100% recycled PETbottles for beverages. Ministryof the Environment Japan (2012) reported that this reproduction led toan approximately 90% reduction in the use of petroleum-derived resources and a60% reduction in CO2 emission. Lastly, the last resort forsolid waste management is by disposal in landfill. Japan has invented a landfilldisposal technology that enables the stabilization of waste in a short timeusing a semi-aerobic landfill which is sanitary and has no environmentalproblem.
The semi-aerobic landfill technology able to stabilize landfill sites rapidlyafter the land has completed its role as landfill, allowing it to be used for otherfunction such as parks and open space for sports. In the semi-aerobic landfill, Ministryof the Environment Japan (2012) stated that leachate collecting pipe isarranged at the bottom of the landfill to remove leachate from the landfill, sothat leachate will not remain where waste is deposited and natural air isbrought in from the open pit of the leachate collecting pipe to the landfilllayer, which promotes aerobic decomposition of waste. This technologies caneffectively prevent global warming by enables early stabilization of waste,prevents the generation of methane and also greenhouse gases. Soil & ground water remediation Accordingto EPA (2017), one of the method to clean up or remediate contaminated soil andwater is by using nanotechnology. Nanotechnology can be defined as theunderstanding and control of matter at dimensions between approximately 1 and100 nanometers, where unique occurrences allow different applications (Otto et al., 2008). Nano-sized particles have largesurface areas relative to their volumes and may have enhanced chemical and biologicalreactivity. Nanotechnology holds promise in remediating sites cost effectivelyand addressing challenging site conditions, such as the presence of dense nona-aqueousphase liquids (DNAPL).
Therefore, nanomaterials have been used to remediatecontaminated groundwater and subsurface source areas of contamination athazardous waste sites. Metallicsubstances is used due to its properties such as elemental iron to degradechlorinated solvent plumes in groundwater and one of the example of an in situtreatment tools for chlorinated solvent plumes is, the installation of a trenchfilled with macroscale zero-valent iron to form a permeable reactive barrier(PRB) (ITRC, 2005). Studies have found that, nanoscale zero- valent iron (nZVI)may prove more effective and less costly than macroscale ZVI because it can degradetrichloroethene (TCE), a common contaminant at Superfund sites, more rapidlyand completely than larger ZVI particles. Also, nZVI can be injected directlyinto a contaminated aquifer, eliminating the need to dig a trench and install aPRB. Research indicates that injecting nZVI particles into areas withinaquifers that are sources of chlorinated hydrocarbon contamination may resultin faster, more effective groundwater cleanups than traditional pump-and-treatmethods or PRBs (Otto et al., 2008).
Nanoscaleiron particles can be altered to include catalysts such as palladium (Pd),coatings such as polyelectrolyte or triblock polymers or can be encased inemulsified vegetable oil droplets (Otto et al., 2008). Otto et al. (2008) further stated that to remediate the contaminationsin soil and groundwater, bi-metallic nanoscale particles (BBNPs) have been usedand it contain particles of elemental iron or other metals in conjunction witha metal catalyst, such as platinum (Pt), gold (Au), nickel (Ni), and palladium.The combination of metals in the BBNPs cause the increase of kinetics of theoxidation-reduction (redox) reaction, thus catalyzing the reaction. One of the example ofproject that used nanotechnology and showed positive results at full scale is aformer fill area in Hamilton Township, New Jersey, which was treated with ananoiron water slurry.
The groundwater at the site was contaminated with TCEand associated daughter products, with an initial maximum volatile organiccompound (VOC) concentration of 1,600 micrograms per liter (?g/L). The nZVI wasthen injected in two phases over a total of 30 days. The project reported thatpost injection monitoring indicated a decrease in the concentration ofchlorinated contaminants of up to 90 percent. Currently the site is in themonitoring phase (Varadhi, 2005). Otto et al.
(2008) also reported that previous research hasfound that nanoparticles such as nZVI, emulsified zero-valent iron (EZVI) and bi-metallicnanoscale particles (BNPs) may effectively reduce contaminants such as perchloroethylene(PCE), TCE, cis- 1, 2-dichloroethylene (c-DCE), vinyl chloride (VC), and1-1-1-tetrachloroethane (TCA), and also polychlorinated biphenyls (PCBs),halogenated aromatics, nitroaromatics, and metals such as arsenic or chromium. Nanoparticlescan be highly reactive due to their large surface area to volume ratio and thepresence of a greater number of reactive sites. This allows for increased contactwith contaminants, thus resulting in rapid reduction of contaminantconcentrations.
CONCLUSION Cleantech is a new technology and related business models thusoffering competitive returns for investors and customers while also providing resolutionsto worldwide challenges. Cleantech is focussed by market economics thereforeoffering greater financial upside and sustainability. The concept of cleantechembraces a diverse range of products, services, and processes across industrythat are designed to deliver superior performance at lower costs, reduce oreliminate negative environmental impact, improve the productive and responsibleuse of natural resources.
