Rumah sakit adalah tempat yang unik. di dalamnya terdapat orang-orang yang menginap layaknya hotel, ada orang yang bekerja layaknya di kantor, ada juga restoran dan dapur yang melayani orang yang menginap dan bekerja tadi. Lebih rumit lagi, rumah sakit ada alat-alat besar yang mendukung operasionalnya seperti genset, boiler, clarifier (pemasok air panas) dan alat-alat kesehatan seperti mesin haemodialysa, alat penguji darah dan sejumlah peralatan lain.
Karena kondisi yang unik tersebut, maka desain kebutuhan air untuk rumah sakit tidak dapat disamakan dengan desain kebutuhan air untuk hotel, hunian/residential, mal atau bangunan komersial lainnya. Desain kebutuhan air untuk rumah sakit harus dibuat unik pula berdasarkan pelbagai aktivitas rumah sakit dan orang-orang di dalamnya yang meliputi, pegawai, pasien, pengunjung dan mesin-mesin di dalamnya.
Contoh yang ekstrim untuk ini misalnya kebutuhan air untuk pasien di unit haemodialysa (cuci darah) yang membutuhkan air reverse osmosis dan steril, para pengunjung membutuhkan air bersih untuk aktivitas mereka di MCK, sementara para unit instalasi gizi membutuhkan tingkat kualitas air minum baik untuk supply pegawai atau para pasien rawat inap.
Jika didetailkan lebih jauh, maka kebutuhan air untuk rumah sakit dapat digolongkan sebagai berikut :
1. Air bersih (Permenkes 416 tentang standard air bersih) untuk MCK dan kebutuhan umum
2. Air lunak / soft water --> heat exchanger, mesin sterilisasi di CSSD, clarifier / air panas)
3. Air Reverse Osmosis yang diaplikasikan untuk :
- Air minum --> untuk instalasi gizi dan kantin / cafetaria
- Unit Haemodialysa
- steam generator di boiler dan alat CSSD
- laboratorium, biasanya ditambahkan lagi deionizer untuk lebih memurnikannya
Kenyataannya, pendirian rumah sakit tidak didasarkan atas kebutuhan tersebut. Rumah sakit baru yang didirikan biasanya hanya menggunakan filter pasir dan karbon aktif saja. Rumah sakit kemudian akan membuat instalasi air bersih parsial di unit-unit yang membutuhkan tingkat kualitas air lebih tinggi. Hal ini menyebabkan biaya lebih tinggi dan tidak efisiennya ruangan yang digunakan karena pengelola harus menyediakan tempat untuk instalasi air parsial tersebut. Belum lagi masalah estetika, karena rumah sakit modern dirancang lebih nyaman bagi para pasien dan pengunjungnya.
Untuk mendapatkan desain kebutuhan air yang efektif dan efisien baik secara budget dan luasan tempat yang dipakai sebaiknya menyarankan kepada arsitek, konsultan ME bekerja sama dengan specialis water treatment yang faham dengan kebutuhan air rumah sakit. Salah satunya bisa kontak di telpon 0856 888 1197 dengan pemilik blog ini :-)
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Selasa, 29 Desember 2009
Minggu, 28 Juni 2009
Ultraviolet light for water treatment
Drinking water is essential for life, but is a valuable and scarce commodity. Lessthan 0.01% of the planet‘s 1.4 billion cubic kilometers of water is easily accessiblefreshwater. Several global mega-trends, like population growth, urbanization andclimate change, are driving water scarcity and public concerns on water quality.According to the World Health Organization (WHO), more than two million people –many of them children – die each year of diarrhoeal diseases that are caused bywater borne pathogens. Access to safe water is one of the big challenges of ourtimes and ultraviolet light for water treatment has become an essential technologyto meet it.
Drinking water is essential for life, but is a valuable and scarce commodity. Lessthan 0.01% of the planet‘s 1.4 billion cubic kilometers of water is easily accessiblefreshwater. Several global mega-trends, like population growth, urbanization andclimate change, are driving water scarcity and public concerns on water quality.According to the World Health Organization (WHO), more than two million people –many of them children – die each year of diarrhoeal diseases that are caused bywater borne pathogens. Access to safe water is one of the big challenges of ourtimes and ultraviolet light for water treatment has become an essential technologyto meet it.
UV Water Disinfection – a Safe Method and Economic AlternativeThe first UV water decontamination was installed in Paris, France as early as 1910.Quartz glass lamps – a development that goes back to the chief developer at Heraeus,Richard Küch (1860 – 1915) - are still used today, but modern high-tech UV lampsand their early predecessors are worlds apart. Today’s UV disinfection is a wellestablishedtechnology. The method is very safe and based on profound scientificknowledge. The real challenge today is to further increase the efficiency and servicelife of the lamps.
Contaminated water can be treated with high energy UV radiation which inactivatesviruses or micro-organisms such as bacteria, yeasts, fungi or even parasites. UV watertreatment has several benefits over other disinfection processes, notably chemicalssuch as chlorine and ozone, or filtration. It does not use chemicals, which makesit environmentally friendly.
The method is not pH-dependent and does not affectthe water’s qualities, like taste, odor or color. Disinfection byproducts (DBPs) withcarcinogenic or toxic effects are not formed. An all-important advantage is the fact,that pathogens cannot build any resistance to UV light. Thus, UV inactivates evenGiardia and the chlorine-resistant Cryptosporidia. UV disinfection has low overallcapital and operating costs, and is easy to maintain and operate.
Removal of Harmful Chemicals – Advanced Oxidation with UV Micropollutants, which include such chemicals as endocrine disrupting compounds,pharmaceuticals and personal-care-products have come into public focus in recentyears and are a serious threat for drinking water quality. In order to decompose thegenerally complex structures (e.g. of steroids or antibiotics) UV radiation is combinedwith powerful chemical oxidants such as ozone or hydrogen peroxide. A processknown as advanced oxidation process (AOP).
Fertilizers, herbicides and pesticidesfrom agriculture are other examples of micropollutants that can be successfullytreated with this method, as is shown in Andijk at Holland’s largest drinking waterreservoir Ijsselmeer.
Spectrum
Sketch of a typical low
pressure lamp
Drinking water is essential for life, but is a valuable and scarce commodity. Lessthan 0.01% of the planet‘s 1.4 billion cubic kilometers of water is easily accessiblefreshwater. Several global mega-trends, like population growth, urbanization andclimate change, are driving water scarcity and public concerns on water quality.According to the World Health Organization (WHO), more than two million people –many of them children – die each year of diarrhoeal diseases that are caused bywater borne pathogens. Access to safe water is one of the big challenges of ourtimes and ultraviolet light for water treatment has become an essential technologyto meet it.
UV Water Disinfection – a Safe Method and Economic AlternativeThe first UV water decontamination was installed in Paris, France as early as 1910.Quartz glass lamps – a development that goes back to the chief developer at Heraeus,Richard Küch (1860 – 1915) - are still used today, but modern high-tech UV lampsand their early predecessors are worlds apart. Today’s UV disinfection is a wellestablishedtechnology. The method is very safe and based on profound scientificknowledge. The real challenge today is to further increase the efficiency and servicelife of the lamps.
Contaminated water can be treated with high energy UV radiation which inactivatesviruses or micro-organisms such as bacteria, yeasts, fungi or even parasites. UV watertreatment has several benefits over other disinfection processes, notably chemicalssuch as chlorine and ozone, or filtration. It does not use chemicals, which makesit environmentally friendly.
The method is not pH-dependent and does not affectthe water’s qualities, like taste, odor or color. Disinfection byproducts (DBPs) withcarcinogenic or toxic effects are not formed. An all-important advantage is the fact,that pathogens cannot build any resistance to UV light. Thus, UV inactivates evenGiardia and the chlorine-resistant Cryptosporidia. UV disinfection has low overallcapital and operating costs, and is easy to maintain and operate.
Removal of Harmful Chemicals – Advanced Oxidation with UV Micropollutants, which include such chemicals as endocrine disrupting compounds,pharmaceuticals and personal-care-products have come into public focus in recentyears and are a serious threat for drinking water quality. In order to decompose thegenerally complex structures (e.g. of steroids or antibiotics) UV radiation is combinedwith powerful chemical oxidants such as ozone or hydrogen peroxide. A processknown as advanced oxidation process (AOP).
Fertilizers, herbicides and pesticidesfrom agriculture are other examples of micropollutants that can be successfullytreated with this method, as is shown in Andijk at Holland’s largest drinking waterreservoir Ijsselmeer.
Spectrum
Ultraviolet radiation covers the wavelength range from 100 to 380 nanometers.The disinfection process uses wavelengths in the UVC range from 240 to 280nanometers, while the oxidation process uses the wavelengths down into the VUVrange below 200 nanometers.
UVC light for technical applications is usually generated by mercury lamps becauseof their high efficiency in terms of electrical energy conversion into UVC light.Commonly, there are two types of mercury lamps used: low pressure and mediumpressure lamps.
Sketch of a typical lowpressure lamp
Sketch of a typical medium
pressure lamp
pressure lamp
Low Pressure Lamps
A low pressure lamp comprises of a quartz tube with pinched filaments, is filled withrare gas (some mbar) and mercury or amalgam. The filaments are coated with emitterpaste that facilitates escaping electrons from the filament. A voltage applied acrossthe lamp provides an electrical discharge. The power density of the discharge is low,therefore only a small portion of mercury is evaporated and enters the gas phase. Therare gas acts as a buffer gas and is necessary for maintaining the electrical discharge.Mercury atoms are ionized and excited in the discharge by electron impact. Excitedatoms emit very effectively photons with two wavelengths: 254 nm and 185 nm inthe UV range (often called spectral lines). 185 nm emission can be filtered out bychoosing quartz of suitable transmittance.
A low pressure lamp comprises of a quartz tube with pinched filaments, is filled withrare gas (some mbar) and mercury or amalgam. The filaments are coated with emitterpaste that facilitates escaping electrons from the filament. A voltage applied acrossthe lamp provides an electrical discharge. The power density of the discharge is low,therefore only a small portion of mercury is evaporated and enters the gas phase. Therare gas acts as a buffer gas and is necessary for maintaining the electrical discharge.Mercury atoms are ionized and excited in the discharge by electron impact. Excitedatoms emit very effectively photons with two wavelengths: 254 nm and 185 nm inthe UV range (often called spectral lines). 185 nm emission can be filtered out bychoosing quartz of suitable transmittance.
Disinfection process
The 254 nm emission is well absorbed by DNA ofall microorganisms and viruses. This absorptionleads to a destruction of the genetic structureof DNA and inhibits the transcription of itsinformation. The microorganisms and viruses arebiologically inactivated, thus 254 nm emission issuitable for disinfection purposes.
Drinking and Process Water Treatment
UV is applied in water treatment prior to consumption e.g. for drinking and processwater or afterwards in sewage plants to treat the waste water. Generally, watertreatment is performed in several stages. Usually UV water treatment is used in thesecond-to-last or last stage depending on the specific application (see chapter 3).Stages of water treatment depend on individual water quality and vary from case to case.
UV water treatment equipment can generally be classified into two groups:n closed systems for drinking and process water treatmentn open channel configuration for wastewater treatment in sewage plants.
Closed reactor systems are used for drinking and process water treatment, in order to avoid any recontamination. For drinking water, a fluence of 400 J/m² was established as a minimum requirement for effective disinfection. This minimum UVC fluence corresponds to DVGW, ÖNorm and NSF ANSI standard (class A UV system). Please refer to chapter 9 for further information.
UV water treatment is a simple, economic and reliable method, provided a good
water quality in terms of low content of organic compounds is given. Substances like iron and manganese, staining and clouding influence the water condition and the disinfection process. The absorption coefficient or transmittance of the water for UV is critical. To ensure an effective disinfection, the operating conditions must therefore be carefully monitored and controlled. Variations in the transmittance of the water can be compensated for by adjusting lamp power and/or flow rates accordingly. Thus, UV irradiance is monitored with at least one UV sensor at a representative position in the reactor to guarantee proper lamp operation.
Typically, the reactor consists in both cases of following components:
UV is applied in water treatment prior to consumption e.g. for drinking and processwater or afterwards in sewage plants to treat the waste water. Generally, watertreatment is performed in several stages. Usually UV water treatment is used in thesecond-to-last or last stage depending on the specific application (see chapter 3).Stages of water treatment depend on individual water quality and vary from case to case.
UV water treatment equipment can generally be classified into two groups:n closed systems for drinking and process water treatmentn open channel configuration for wastewater treatment in sewage plants.
Closed reactor systems are used for drinking and process water treatment, in order to avoid any recontamination. For drinking water, a fluence of 400 J/m² was established as a minimum requirement for effective disinfection. This minimum UVC fluence corresponds to DVGW, ÖNorm and NSF ANSI standard (class A UV system). Please refer to chapter 9 for further information.
UV water treatment is a simple, economic and reliable method, provided a good
water quality in terms of low content of organic compounds is given. Substances like iron and manganese, staining and clouding influence the water condition and the disinfection process. The absorption coefficient or transmittance of the water for UV is critical. To ensure an effective disinfection, the operating conditions must therefore be carefully monitored and controlled. Variations in the transmittance of the water can be compensated for by adjusting lamp power and/or flow rates accordingly. Thus, UV irradiance is monitored with at least one UV sensor at a representative position in the reactor to guarantee proper lamp operation.
Generally two different types are used:
- Longitudinal flow system
- Cross flow system
Typically, the reactor consists in both cases of following components:
- UV lamp
- quartz sleeve
- wiper for mechanical cleaning of quartz sleeves to protect against fouling
- UV sensor to control UV output
- power supply
Rabu, 10 Juni 2009
Extended Aeration System
The first stage in the treatment process is screening. Screening iscarried out using a static stainless steel retaining screen. Removal of solids isessential and results in higher treatment efficiencies for downstream biologicalsystem. Screening also ensures safety for transfer pumps which otherwisewould ultimately clog. The wastewater after screening enters an aeratedequalization tank.
The equalization tank is aerated by fine pore subsurface diffusers to preventsettling of solids and also to build up the dissolved oxygen level in thewastewater. Aeration ensures complete mixing of the wastewater and thesolids are maintained in suspension. Settling of solids could lead toaccumulation and stagnation, leading to anaerobic and septic conditions, theresult being strong odor problems. Aeration also aids in maintaining a residual dissolved oxygen level in the wastewater, which aids in treatmentefficiency.
Equalization pumps (one operating and one-100% standby) transferwastewater from the equalization tank to the extended aeration tank. Air-liftpumps are used for equalization pumps, up to a flow of 10,000gal/day. Theextended aeration process is a suspended growth biological treatmentprocess wherein the micro-organisms grow in the suspended form. A higherlevel of micro-biological population is maintained in the tank. The aerationtank is continuously aerated with fine pore subsurface AIRMAX diffusers. Theentire process is aerobic in nature.
Micro-organisms in their endogenous phase of respiration receive less food incomparison to the food available. This process is more popularly termed as“cannibalism”. Micro-organisms eventually consume themselves when notadequate food is available. The organic matter is consumed and biologicallydegraded to stable end products.
Extended aeration processes are very popular for sewage treatmentapplications. Waterworks has EA systems operating around the globe for thisapplication in remote camp sites, hotels, hospitals and resorts.Wastewater after extended aeration treatment flows by gravity to thesecondary clarifier. The biomass settles by gravity and the supernatantoverflows the weirs to the adjoining chlorine contact tank.
The settled biomassis air-lifted and recycled to the extended aeration tank to maintain thepopulation of biomass. The extended aeration tanks is operated at a MLSSlevel of 3000 to 3500 mg/L.
The food to micro-organism ratio is maintainedbetween 0.1 and 0.15 When the biomass concentration exceeds the required MLSS level in theextended aeration tank, sludge is wasted to the sludge holding tank.
Thesludge tank is an aerated tank where the waste biomass is held and aeratedcontinuously. In the absence of any organic matter entering the sludge tank,the biomass digests itself thereby concentrating and thickening itself.
The chlorine contact tank is a baffled tank to promote contact and mixing fordisinfection. The treated wastewater exits the chlorine contact tank.
The equalization tank is aerated by fine pore subsurface diffusers to preventsettling of solids and also to build up the dissolved oxygen level in thewastewater. Aeration ensures complete mixing of the wastewater and thesolids are maintained in suspension. Settling of solids could lead toaccumulation and stagnation, leading to anaerobic and septic conditions, theresult being strong odor problems. Aeration also aids in maintaining a residual dissolved oxygen level in the wastewater, which aids in treatmentefficiency.
Equalization pumps (one operating and one-100% standby) transferwastewater from the equalization tank to the extended aeration tank. Air-liftpumps are used for equalization pumps, up to a flow of 10,000gal/day. Theextended aeration process is a suspended growth biological treatmentprocess wherein the micro-organisms grow in the suspended form. A higherlevel of micro-biological population is maintained in the tank. The aerationtank is continuously aerated with fine pore subsurface AIRMAX diffusers. Theentire process is aerobic in nature.
Micro-organisms in their endogenous phase of respiration receive less food incomparison to the food available. This process is more popularly termed as“cannibalism”. Micro-organisms eventually consume themselves when notadequate food is available. The organic matter is consumed and biologicallydegraded to stable end products.
Extended aeration processes are very popular for sewage treatmentapplications. Waterworks has EA systems operating around the globe for thisapplication in remote camp sites, hotels, hospitals and resorts.Wastewater after extended aeration treatment flows by gravity to thesecondary clarifier. The biomass settles by gravity and the supernatantoverflows the weirs to the adjoining chlorine contact tank.
The settled biomassis air-lifted and recycled to the extended aeration tank to maintain thepopulation of biomass. The extended aeration tanks is operated at a MLSSlevel of 3000 to 3500 mg/L.
The food to micro-organism ratio is maintainedbetween 0.1 and 0.15 When the biomass concentration exceeds the required MLSS level in theextended aeration tank, sludge is wasted to the sludge holding tank.
Thesludge tank is an aerated tank where the waste biomass is held and aeratedcontinuously. In the absence of any organic matter entering the sludge tank,the biomass digests itself thereby concentrating and thickening itself.
The chlorine contact tank is a baffled tank to promote contact and mixing fordisinfection. The treated wastewater exits the chlorine contact tank.
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