SIST EN 12255-14:2004
(Main)Wastewater treatment plants - Part 14: Disinfection
Wastewater treatment plants - Part 14: Disinfection
This European Standard specifies performance requirements for the disinfection of effluents from wastewater treatment plants.
The primary application is for wastewater treatment plants designed for the treatment of domestic and municipal wastewater for over 50 PT.
Differences in wastewater treatment throughout Europe have led to a variety of systems being developed. This standard gives fundamental information about the systems, this standard has not attempted to specify all available systems.
Detailed information additional to that contained in this standard can be obtained by referring to the bibliography.
Kläranlagen - Teil 14: Desinfektion
Diese Europäischen Norm legt Leistungsanforderungen für die Desinfektion von Kläranlagenabläufen fest.
In erster Linie gilt diese Europäische Norm für Kläranlagen, die für die Behandlung von häuslichem und kommunalem Abwasser von mehr als 50 EW ausgelegt sind.
Die Unterschiede in Planung und Bau von Kläranlagen in Europa haben zu einer Vielzahl von Anlagen-ausführungen geführt. Diese Europäische Norm enthält grundsätzliche Angaben zu den Anlagenausführungen; sie beschreibt jedoch nicht alle Einzelheiten jeder Ausführungsart.
Die in den Literaturhinweisen aufgeführten Unterlagen enthalten Einzelheiten und Hinweise, die im Rahmen dieser Norm verwendet werden können.
Stations d'épuration - Partie 14: Désinfection
La présente Norme Européenne spécifie les exigences de performance pour la désinfection des effluents des stations d'épuration.
Elle s'applique, avant tout, aux stations d'épuration des eaux usées de plus de 50 EH, conçues pour traiter des eaux usées municipales et domestiques.
Les différences qui caractérisent le traitement des eaux usées dans toute l'Europe ont conduit a la mise au point d'un éventail de systemes. La présente Norme fournit des informations fondamentales sur ces systemes.
La présente norme ne vise pas a spécifier tous ceux qui existent.
Des informations détaillées peuvent etre obtenues en se référant a la bibliographie, en complément de celles contenues dans la présente Norme.
Čistilne naprave za odpadno vodo - 14. del: Dezinfekcija
General Information
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Standards Content (Sample)
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.Kläranlagen - Teil 14: DesinfektionStations d'épuration - Partie 14: DésinfectionWastewater treatment plants - Part 14: Disinfection13.060.30Odpadna vodaSewage waterICS:Ta slovenski standard je istoveten z:EN 12255-14:2003SIST EN 12255-14:2004en01-maj-2004SIST EN 12255-14:2004SLOVENSKI
STANDARD
SIST EN 12255-14:2004
EUROPEAN STANDARDNORME EUROPÉENNEEUROPÄISCHE NORMEN 12255-14December 2003ICS 13.060.30English versionWastewater treatment plants - Part 14: DisinfectionStations d'épuration - Partie 14: DésinfectionKläranlagen - Teil 14: DesinfektionThis European Standard was approved by CEN on 11 September 2003.CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this EuropeanStandard the status of a national standard without any alteration. Up-to-date lists and bibliographical references concerning such nationalstandards may be obtained on application to the Central Secretariat or to any CEN member.This European Standard exists in three official versions (English, French, German). A version in any other language made by translationunder the responsibility of a CEN member into its own language and notified to the Central Secretariat has the same status as the officialversions.CEN members are the national standards bodies of Austria, Belgium, Czech Republic, Denmark, Finland, France, Germany, Greece,Hungary, Iceland, Ireland, Italy, Luxembourg, Malta, Netherlands, Norway, Portugal, Slovakia, Spain, Sweden, Switzerland and UnitedKingdom.EUROPEAN COMMITTEE FOR STANDARDIZATIONCOMITÉ EUROPÉEN DE NORMALISATIONEUROPÄISCHES KOMITEE FÜR NORMUNGManagement Centre: rue de Stassart, 36
B-1050 Brussels© 2003 CENAll rights of exploitation in any form and by any means reservedworldwide for CEN national Members.Ref. No. EN 12255-14:2003: ESIST EN 12255-14:2004
EN 12255-14:2003 (E)2ContentspageForeword.31Scope.42Normative references.43Terms and definitions.44Design.65Requirements.13Bibliography.15SIST EN 12255-14:2004
EN 12255-14:2003 (E)3ForewordThis document (EN 12255-14:2003) has been prepared by Technical Committee CEN/TC 165 “Wastewaterengineering”, the secretariat of which is held by DIN.This European Standard shall be given the status of a national standard, either by publication of an identical text orby endorsement, at the latest by June 2004, and conflicting national standards shall be withdrawn at the latest byJune 2004.This is the fourteenth Part prepared by the Working Groups CEN/TC 165/WG 42 and WG 43 relating to the generalrequirements and processes for treatment plants for a total number of inhabitants and population equivalents (PT)over 50. EN 12255 with the generic title “Wastewater treatment plants” consists of the following Parts:¾ Part 1: General construction principles¾ Part 3: Preliminary treatment¾ Part 4: Primary settlement¾ Part 5: Lagooning processes¾ Part 6: Activated sludge processes¾ Part 7: Biological fixed-film reactors¾ Part 8: Sludge treatment and storage¾ Part 9: Odour control and ventilation¾ Part 10: Safety principles¾ Part 11: General data required¾ Part 12: Control and automation¾ Part 13: Chemical treatment — Treatment of wastewater by precipitation/flocculation¾ Part 14: Disinfection¾ Part 15: Measurement of the oxygen transfer in clean water in aeration tanks of activated sludge plants¾ Part 16: Physical (mechanical) filtrationNOTEFor requirements on pumping installations at wastewater treatment plants, provided initially as Part 2: Pumpinginstallations for wastewater treatment plants, see EN 752-6 Drain and sewer systems outside buildings — Part 6: Pumpinginstallations.EN 12255-1, EN 12255-3 to EN 12255-8 and EN 12255-10 and EN 12255-11 were implemented together as aEuropean package (Resolution BT 152/1998).According to the CEN/CENELEC Internal Regulations, the national standards organizations of the followingcountries are bound to implement this European Standard: Austria, Belgium, Czech Republic, Denmark, Finland,France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Luxembourg, Malta, Netherlands, Norway, Portugal,Slovakia, Spain, Sweden, Switzerland and the United Kingdom.SIST EN 12255-14:2004
EN 12255-14:2003 (E)41 ScopeThis European Standard specifies performance requirements for the disinfection of effluents from wastewatertreatment plants.The primary application is for wastewater treatment plants designed for the treatment of domestic and municipalwastewater for over 50 PT.Differences in wastewater treatment throughout Europe have led to a variety of systems being developed. Thisstandard gives fundamental information about the systems, this standard has not attempted to specify all availablesystems.Detailed information additional to that contained in this standard can be obtained by referring to the bibliography.2 Normative referencesThis European Standard incorporates by dated or undated reference, provisions from other publications. Thesenormative references are cited at the appropriate places in the text, and the publications are listed hereafter. Fordated references, subsequent amendments to or revisions of any of these publications apply to this EuropeanStandard only when incorporated in it by amendment or revision. For undated references the latest edition of thepublication referred to applies (including amendments).EN 1085:1997, Wastewater treatment — Vocabulary.EN 12255-1, Wastewater treatment plants — Part 1: General construction principles.EN 12255-5, Wastewater treatment plants — Part 5: Lagooning processes.EN 12255-10, Wastewater treatment plants — Part 10: Safety principles.EN 12255-12, Wastewater treatment plants — Part 12: Control and automation.3 Terms and definitionsFor the purposes of this European Standard, terms and definitions given in EN 1085:1997 and the following apply.3.1residual concentrationconcentration of a disinfectant in the
final effluent of the wastewater treatment plant3.2UV radiation (UV dose)the received UV-dose over the duration of the UV irradiation along the pathway of an infinitesimal small watervolume expressed in J/m²3.3UV intensityquotient of the energy flux of the UV radiation received on the surface of an infinitesimal small area divided by thesize of the area. The unit of UV intensity is W/m²3.4UV-reactora closed vessel reactor or an open channel section with an assembly of UV-lamps irradiating the water passingthrough the UV-reactorSIST EN 12255-14:2004
EN 12255-14:2003 (E)53.5bioassaymethod to determine the effective UV radiation of an UV system using a calibrated test organism. Calibration of testorganisms is done in a laboratory device with an UV radiation of a homogeneous and measured intensity (see [15],[20])3.6ozone demandamount of ozone required to attain a certain residual ozone concentration in the effluent of a treatment stage. Theozone demand includes the ozone consumption due to the decay of the ozone and due to reactions of ozone withany of the pollutants in the water3.7chlorinatorequipment for dosing chlorine gas into water3.8contact basintank for providing the required detention time for certain reactions to take place3.9membranesemipermeable material used as filter media in membrane filtration processes. Membranes normally are flatsheets, tubes or hollow fibres composed of a thin semipermeable layer on a structural material3.10moduleunit containing an assembly of membranes and systems for distributing the raw water inflow, and systems forcollecting permeate and the concentrate3.11permeatefluids passing through the membrane in membrane filtration processes3.12concentratefluids enriched with substances not passing the membranes in membrane filtration processes3.13fluxmembrane surface area specific rate of fluids passing through the membrane in membrane filtration processesnormally indicated in l/(m²h). The flux is mainly determined by the wastewater quality, the type of membrane used,the mode of filtration and the transmembrane pressure3.14transmembrane pressurepressure difference between concentrate and permeate side of the membrane3.15cross flow filtrationfiltration with a significant flow parallel to the membrane surface, which is intended to prevent substances fromaccumulating on the surface of the membrane3.16dead end filtrationfiltration without a significant flow parallel to the membrane surface3.17perpendicular mixingmixing vertical to floating directionSIST EN 12255-14:2004
EN 12255-14:2003 (E)64 Design4.1 GeneralDisinfection processes are used to improve the microbiological quality of effluents, if required, e.g. because of sensitiveuses of the receiving waters downstream. A disinfection of effluents from wastewater treatment plants can berequired to contribute to public health to prevent a contamination by human pathogens of:¾ waters used for bathing and other recreational activities involving immersion;¾ shellfisheries;¾ treated wastewater to be reused for unrestricted irrigation or as process water or grey water;¾ sources used for potable water supply.A disinfection of effluents from wastewater treatment can be attained by two possible mechanisms:¾ inactivation of micro-organisms rendering micro-organisms incapable of reproduction;¾ removing the micro-organisms from an effluent (e.g. by filtration) but not necessarily inactivating them.Processes most commonly used for disinfecting wastewater by removing inactivating micro-organisms are:¾ Ultraviolet (UV)-radiation;¾ Chlorination;¾ Ozonation.Processes most commonly used for disinfecting wastewater by removing respectively reducing micro-organismsare:¾ membrane filtration;¾ effluent maturation ponds;¾ soil filtration.4.2 Planning4.2.1 GeneralDisinfection, if required, should be the last stage in the wastewater treatment process. Poor performance byupstream processes will affect the performance of the disinfection process. If an effluent has to be stored prior todischarge – e.g. in case of discharge to tidal water or irrigation – it should be preferably disinfected after storagedirectly prior to discharge in order to limit regrowth hazards.When planning disinfection systems consideration shall be given to:a) level of disinfection required;b) stability and efficiency of disinfection process;c) technological level of disinfection process;d) operational requirements;e) safety hazards;SIST EN 12255-14:2004
EN 12255-14:2003 (E)7f) environmental impacts, e.g.:¾ effects on the quality of the effluents (reduction of BOD5,COD, SS, Ptot);¾ deleterious effects of residual disinfectants;¾ production of toxic or bioaccumulating by-products;g) power requirements.4.2.2 Level of disinfectionDisinfection processes shall reduce or inactivate human pathogens to a level that the risk of the disinfectedwastewater being a source of infections is minimised. Disinfection processes are not intended to remove all micro-organisms, or even remove all human pathogens.The level of disinfection is specified by national and local authorities.The specification of the level of disinfection shall include procedures for sampling, analysis and evaluation.Statistical criteria for complying with the level of disinfection required shall be named explicitly e.g. for dry weatherand storm water conditions.4.3 Process Design4.3.1 GeneralA disinfection system has to be designed and sized to ensure that¾ the required treatment (minimum disinfectant dose) is applied to all wastewater;¾ the required level of disinfection is maintained at the maximum effluent flow rate and disinfectant demand(worst case condition).With respect to the high required reduction rate no short circuiting, by-passing, or incomplete treatment ispermitted. The required treatment has to be applied to all wastewater because the microbiological quality ofdisinfected wastewater reacts very sensitively to any wastewater not being disinfected properly.NOTEThis is due to the fact that the required reduction of indicator organisms is usually in the magnitude of 99,9 % to99,99 %. A leakage or short circuiting of 0,01 % to 0,1 % of the wastewater or a reduced reduction rate of only 99 % in 1 % to10 % of the wastewater due to incomplete treatment can cause germ counts that already exceed the effluent standards.4.3.2 UV radiationUV disinfection is the application of UV radiation artificially generated in UV lamps in UV reactors to the wastewaterto be disinfected. An appropriate dose of UV radiation will cause an irreversible inactivation of micro-organisms withno other significant effects on the wastewater.NOTEThe disinfection by UV radiation is due to a photochemical effect. UV radiation of germicidal wavelength causes theformation of dimers of neighbouring thymine bases in nucleic acids. These dimers disturb the replication of the nucleic acids andcause an irreversible inactivation of the micro-organisms, if due to the UV dose the formation of dimers is too numerous to berepaired by the cells repair mechanisms.UV radiation systems for wastewater disinfection can be classified as follows:¾ type of UV reactor (open channel gravity flow systems, closed vessel systems);¾ type of UV-lamps (low pressure or medium pressure mercury discharge lamps);¾ configuration of UV-lamps (in wastewater immersed lamps housed in quartz glass sleeves, non-contactsystems).SIST EN 12255-14:2004
EN 12255-14:2003 (E)8UV radiation systems can consist of one or more UV reactors. UV reactors can be in series or parallel. Designingand sizing a UV radiation system for wastewater disinfection, the following site specific parameters shall be takeninto consideration:¾ minimum UV dose;¾ peak flow;¾ minimal UV transmittance of effluent.The minimum UV-dose is the UV irradiation required to reduce the concentration of micro-organisms in an effluentto the requested level of disinfection. The minimum UV dose is independent of the UV radiation system used forthe disinfection. The minimum UV dose is only determined bya) the level of disinfection required specified in terms of¾ relevant indicator and/or pathogen organisms concentrations;¾ sampling and analysis procedures (photo-reactivation);¾ statistical criteria for approval.b) characteristics of the wastewater¾ suspended solids concentration;¾ concentrations of micro-organisms before disinfection.The required minimum UV-dose can be estimated on the basis of experimental data determined by collimatedbeam tests, pilot plant studies, or experience from other installations.On the basis of the minimum UV dose, peak flow, and minimum UV transmittance a UV radiation system can bedesigned and sized appropriate to deliver the required minimum UV dose to all wastewater to be disinfected.Design and sizing of UV radiation systems are system specific. Contractors should provide a verifiable UV dosecalculation based on a bioassay study or on an UV intensity distribution calculation combined with a detention timedistribution study (tracer study).For a safe disinfection and a good efficiency of a UV radiation system the hydraulic design and the efficiency of theUV-lamps are most important. For the UV-lamp-ballast-systems contractors should provide an expertise onefficiency and out-put drop over time from an independent source. The hydraulic design of UV radiation systemshould ensure that¾ no wastewater to be disinfected can by-pass the UV radiation system at any time;¾ all the cross sections of the UV reactors are irradiated (no shadowed areas);¾ hydraulic flow is as close to perfect plugflow as practicable;¾ hydraulic flow is as close to perfect perpendicular mixing as practicable.Efficiencies of UV radiation systems claimed by contractors can be verified by¾ bioassay studies (see [15], [24]);¾ pilot plant studies;¾ full scale experience.For systems with submerged UV-lamps a cleaning routine for the quartz glass sleeves of the UV-lamps has to beestablished. For systems with low pressure mercury discharge UV-lamps cleaning frequencies of less than onceSIST EN 12255-14:2004
EN 12255-14:2003 (E)9every two weeks can be expected. For systems using medium pressure mercury discharge UV-lamps cleaningmight be required much more frequently.UV-lamps should be replaced at intervals recommended by the manufacturers.4.3.3 OzonationAn ozonation system for wastewater disinfection includes:¾ ozone generator;¾ contactor;¾ reactor;¾ ozone destructor for waste gas. Ozone is an extremely reactive and unstable gas that can not be stored and has to be produced on site.Ozone is toxic. Ozonation can lead to the formation of other by products (chlorates, bromates and organic peroxides).In designing an ozonation plant all relevant safety regulations for generating and handling ozone have to berespected.Ozone is very corrosive. All parts that get in contact with ozone have to be ozone resistant. Especially all sealantshave to be ozone resistant.Of great importance for the efficiency of the ozonation process is the ozone transfer into the effluent. This is donein a contactor. The following types of contactors are commonly used:¾ diffused bubble (co-current and counter current);¾ positive pressure injection;¾ negative pressure injection (venturi);¾ mechanical agitation;¾ packed tower.The efficiency of the ozone transfer into the effluent can be improved by a multistage counter current contacting ofthe ozone and the effluent.The reactor should provide sufficient detention time for the disinfection reactions of the ozone to be completed.Flow conditions in the reactor should be as near to plug flow as is practicable. Short circuiting shall be avoided.Contactor and reactor can be integrated systems.With respect to its toxicity any residual ozone in the waste gas has to be destroyed. All ozone bearing parts of anozonation plant shall be a closed vessel system only vented through an ozone destructor. Ozone concentration inwaste gas has to be monitored and shall not exceed 0,02 mg/m³. In the case of an elevated ozone concentration(> 0,02 mg/m³) being detected the ozone generators shall shut down automatically. Systems used for ozonedestruction in the waste gas include¾ thermal destruction (T> 350 °C, tR > 2 s);¾ catalytic destruction (i.e. Palladium/CuO-MnO, T= 60 °C to 80 °C);¾ active carbon (active carbon is oxidised and consumed by the ozone destruct
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