Kemira Oyj/Kemira M&I ABSTRACT Vesa Kettunen ... - Svenskt Vatten

Kemira Oyj/Kemira M&I ABSTRACT 

Vesa Kettunen 17th Jan 2013 

Author: Vesa Kettunen 

Application Manager 

Kemira Oyj / Municipal&Industrial 

vesa.kettunen@kemira.com 

This abstract is meant for platform presentation. Presentation language is 

English. 

CHEMICAL METHODS IN THE CONTROLLING OF 

CORROSION AND ODOURS IN MUNICIPAL SEWERS 

Due to the new wastewater purification demands and cost optimisation, the 

number of municipal wastewater treatment plants is decreasing. This means 

that longer sewer systems need to be constructed. Today even 10-20km 

long sewers are not rare any more. 

In the long sewers there is more time for microbiological activity and this 

may cause problems. The most common problems in sewers are odour 

formation and corrosion. Hydrogen sulphide(H2S) formation in the sewer 

systems is the main reason for problems. 

H2S gas is toxic to humans in high concentrations and causes unpleasant 

odours even at very low concentrations. These odours may be released to 

air in sewer pumping stations causing odour problems. 

In the existing sewer network concrete is widely used construction material. 

H2S gas may cause severe corrosion to concrete, because in contact with air 

and moisture, H2S gas will react and form sulphuric acid. 

H2S formation in municipal sewer systems can be controlled in several 

ways. Aeration and the use of oxidative chemicals provide the oxygen to 

the water and will prevent H2S formation. However, many times the 

problem with these methods is very short effect. Microbiological activity 

consumes oxygen fast and then H2S formation starts again. 

The addition of iron is efficient in H2S control, because iron can chemically 

bind sulphide and this way prevent H2S release and sulphuric acid 

formation. Iron also gives clearly longer lasting effect compared to oxygen. 

The efficiency of iron can be further improved by combining it with nitrate. 

Nitrate will function like oxygen, will release oxygen and this way prevent 

H2S formation. 

H2S Guard is Kemiras concept for corrosion and odour control is sewers. It 

provides continuous H2S measurement from sewer. Iron (and nitrate) 

containing chemicals can be dosed to the sewer in order to decrease H2S to 

the target level.

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Wastewater Overflow Reduction Project in Vantaa River Catchment Area 

Aninka Urho, project coordinator, Helsinki Region Environmental Services 

Authority 

Aninka.urho@hsy.fi, Platform presentation in English 

Vantaa River catchment area is located in the most densely populated area of Finland. Wastewater overflows 

into the river have been a matter of great public interest of great interest recently. The current method of 

leading untreated wastewater into the nearest watercourse when there is a fault or overload in the sewer 

system has faced strong resistance among environmentalists. 

There are 9 participating organisations in this project: 

Helsinki Region Environmental Services Authority, Project coordination 

Municipal utilities from Riihimäki, Hyvinkää, Nurmijärvi, Kerava, Tuusula and Järvenpää 

Keski-Uusimaa Joint Municipal Board for Water Pollution Control (KUVES) 

The Water Protection Association of the River Vantaa and Helsinki Region 

This cooperation project is financed by Regional Development Fund of Uusimaa (national allowance) and 

Water Utilities Development Fund. Project duration is 2 years (2012-2013) and total budget 170 000 €. 

The aim of the project is to decrease wastewater overflows by various means: 

1. The project was started by defining a Vision, a Strategy and an Action Plan for stopping 

wastewater discharges into the Vantaa River. The vision is: “No untreated wastewater spills into 

waters”. Significant investments and an attitude change within the utilities are demanded to reach 

this challenging vision. 

The Strategy and Action programme is divided into three themes: a) Reliable pumping stations, b) 

adequate condition and correct sizing of wastewater networks c) I/I control management. The cost 

impacts of the Action Plan will be assessed by consultant. 

2. Reliable pumping stations are the key aspect when fighting against sewer overflows. In this project 

the pumping specialists from the utilities defined together the best practices concerning a) pumping 

station equipment and b) operation and maintenance procedures. 

3. The performance of utilities can be enhanced by developing staff training, interest group 

cooperation and customer guidance. Small pilot projects related to these topics are to be launched 

during 2013. 

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Distribueret temperatur måling til opsporing af 

fejlkoblinger i spildevandsledninger 

Mads Uggerby 1 , Anne Laustsen 2 , Bo Snediker Jacobsen 2 , Peter Hjortdal 2 , Jes Vollertsen 3 , Carsten Jensen 4 , 

Rémy Schilperoort 5 , Jeroen Langeveld 6 

1 EnviDan A/S; 2 Aarhus Vand A/S; 3 Aalborg Universitet; 4 Per Aarslef A/S; 5 Royal HaskoningDHV; 6 Delft 

University of Technology 

E-mail of presenting author, Mads Uggerby: mau@envidan.dk 

Platform presentation 

Danish language 

Fejlkobling af spildevand og regnvand er et hyppigt forekommende problem i separatkloakerede oplande. 

Undersøgelser udført af Aarhus Vand viser, at en fejlkoblingsgrad på 5-10% ikke er ualmindelig, hvilket 

betyder hydraulisk overbelastning af spildevandsledninger, såvel som uønsket miljøbelastning via 

regnvandsledninger. Specielt førstnævnte er et væsentligt problem for forsyningen, idet folk i 

separatkloakerede oplande oplever kælderoversvømmelser via spildevansledningen. 

Fejlkoblet regnvand kan spores på en række måder, hvor den hyppigst anvendte er at hælde vand i nedløb 

og riste samtidigt med, at spildevandsstik inspiceres med tv. Metoden kræver, at den udførende 

entreprenør får adgang til privat grund, samt at alle nedløb og riste er tilgængelige. Metoden er derfor ikke 

uproblematisk, og man har derfor været på udkik efter alternativer hertil. 

Ny forskning udført i især Holland har vist, at distribueret temperatur måling (Distributet Temperature 

Sensor, DTS) – som det kendes fra en række applikationer indenfor fx olie- og gasindvinding – også kan 

anvendes til at opspore fejlkoblinger i afløbssystemer. En DTS måling foretages med et fiberoptisk kabel, 

der installeres på bunden af en regnvands- eller spildevandsledning. Kablet forbindes med et instrument, 

der sender laserimpulser ind i kablet, og analyserer på det signal, der reflekteres af glassets amorfe 

struktur. Mønsteret med hvilken signalet reflekteres bestemmes bl.a. af kablets temperatur, og kablet 

fungerer herved som én lang temperaturføler, hvor temperaturen kan registreres kontinuert i hele kablets 

længde. Der anvendes et specialbygget instrument, der integrerer laser, dataopsamling og computer i én 

enhed. I praksis er det computerens ydeevne, der sætter grænsen for den nøjagtighed med hvilken 

temperaturen kan måles, og den opløsning, der kan opnås i tid og sted. Typiske nøjagtigheder er en 

temperaturopløsning på 0,1°C, en stedslig opløsning på 1-2 meter og en tidslig opløsning på 15-60 

sekunder. Typiske maksimale kabelængder er i praksis knap 2 km. 

EnviDan A/S, Aarhus Vand A/S, Aalborg Universitet og Per Aarslef A/S har, i samarbejde med Royal 

HaskoningDHV iHolland, og støttet af Vandteknologiudviklingsfonden (VTUF), igangsat et forsknings- og 

udviklingsprojekt hvor vi videreudvikler DTS teknologien og implementerer den i et forsøgsopland i Aarhus 

kommune. Vi udvikler teknologien til danske forhold, og anvender den i et antal separate 

spildevandssystemer, hvor vi benytter temperaturmålingen til at identificere lokaliteter, hvor

uvedkommende regnvand er koblet på spildevansledningen. En sådan tilledning vil ses som en pludselig 

temperaturstigning eller –fald når regnvand når ned i ledningen. Endvidere vil vi kunne se hvor der sker 

anden sporadisk tilledning af uvedkommende vand, så som overlækning og omfangsdræn. 

DTS giver en meget stor datamængde, der efterfølgende kræver systematisk behandling. Således vil en 

enkelt målekampagne let føre til i størrelsesorden 100 millioner individuelle temperaturregistreringer. I 

projektet udvikler vi et GIS baseret værktøj, der automatisk analyserer disse datamængder og fortæller 

brugeren hvor der sker tilledning af uvedkommende vand, samt tilledningens natur. 

I nærværende præsentation viser vi resultaterne af den første målekampagne udført på cirka 1½ km 

spildevandsledning i en mindre by nord for Aarhus. Vi viser hvordan metoden kan benyttes til at 

identificere forskellig former for uvedkommende vand, og viser detaljer af værktøjet til dataanalyse. På 

samme opland identificere vi endvidere uvedkommende vand på traditionel vis – altså ved at hælde vand i 

nedløb og riste under samtidig visuel inspektion med kloak-tv. Vi sammenligner herpå de to metoder og 

diskuterer praktisk og økonomisk fordele og ulemper ved DTS.

Inlägg 13:e Nordiska Avloppskonferensen, Malmö 8-10 oktober 2013 

Annika Malm, kretslopp och vatten 

David Jacobsson, kretslopp och vatten 

Karin Thörnqvist, kretslopp och vatten* 

*karin.thornqvist@kretsloppochvatten.goteborg.se 

KRITISKA LEDNINGSNÄTET I GÖTEBORG 

Bakgrund 

Riskanalyser är en tillgång inom förebyggande arbete, och genom att använda riskanalyser 

kan man hitta svaga punkter i avloppsledningsnätet innan något akut inträffar. Kretslopp och 

vatten bedömer att ett effektivt förebyggande arbete inte innebär att utföra riskanalyser för 

hela ledningsnätet, utan att riktade insatser inom vissa strategiska områden är mer effektivt. 

De riktade insatserna skall göras för de ledningar som, vid problem, ger stor påverkan på 

samhälle, verksamhet och brukare. Dessa ledningar, som kallas kritiska ledningar, skall 

inspekteras i förebyggande syfte, med målsättningen att samtliga kritiska ledningar skall 

inspekteras under en tioårsperiod med start 2010. Övriga ledningar inspekteras inte i 

förebyggande syfte, utan åtgärdas efter driftstörningar. 

Metodik 

Ledningar, där sannolikheten att något allvarligt kommer att ske är hög, kallas 

sannolikhetsledningar, och kan exempelvis vara ledningar där många stopp inträffar eller 

ledningar där problem med svavelväte förekommer. Sannolikhetsledningar har tagits fram på 

erfarenhetsbasis. Utfallet är lågt då många av dessa ledningar åtgärdats när väl problemen 

upptäckts. Det är i många fall inte effektivt att ta fram alla sannolikhetsledningar på förhand, 

utan bättre att lösa problemen när de väl uppstår. 

Exempel på sannolikhetsledningar: 

• Ledningar med mycket stopp 

• Träledningar 

• Lergodsledningar med större dimension än 300 mm 

Ledningar, som vid driftavbrott ger stora konsekvenser, t.ex. ledningar i hårt trafikerade gator 

eller ledningar som vid driftavbrott drabbar många brukare, kallas konsekvensledningar. Ju 

större konsekvens desto mer kostar det. Konsekvensledningarna har tagits fram ur GISdatabasen 

samt kompletterats med erfarenheter från både kretslopp och vatten och Göteborg 

Energi. 

Exempel på konsekvensledningar: 

• Dagvattenledningar med större dimension än 1 500 mm 

• Kombinerade ledningar med större dimension än 1000 mm 

• Spillvattenledningar med dimension som är större eller lika med 500 mm 

• Ledningar under järnväg, spårväg, motorväg, vattendrag och byggnader 

• Ledningar som vid störning ger konsekvenser för råvattnet 

En risk definieras som en konsekvens sammanvägt med sannolikhet. Stor konsekvens och hög 

sannolikhet innebär en hög risk. Kritiska ledningar kan vara antingen sannolikhetsledningar,

konsekvensledningar eller både och. Detta kan redovisas i en riskmatris, se figur, där de 

kritiska ledningarna hamnar inom rött område. 

Resultat 

Kretslopp och vatten har totalt 2 500 km avloppsledningar, av vilka kritiska ledningsnätet 

utgör 265 km, dvs. omkring 10 %. För att uppfylla målsättningen skall drygt 25 km av dessa 

inspekteras varje år. De kritiska ledningarna finns redovisade i kretslopp och vattens GISdatabas. 

Prioritering av vilka ledningar som skall inspekteras när, görs på följande kriterier: 

• Kritiska ledningar med störst konsekvens 

• Driftstörningar i det kritiska ledningsnätet 

• Kommunens beläggningsprogram 

• Planerade spårvägsavstängningar 

• Remisser 

• Detaljplaner och bygglov 

• Kritiska ledningar i investeringsprojekt eller planerat underhåll 

• Planlagda inspektioner av ledningar som skall inspekteras för andra gången 

Ledningarna inspekteras med hjälp av filmkamera eller okulärt, genom att en person går i 

ledningen. Okulär besiktning är dock enbart möjligt i stora ledningar som ej står dämda. När 

en ledning inspekteras bedöms status, om åtgärder krävs samt när nästa inspektion skall göras. 

Resultaten dokumenteras väl och skall följas upp. Grundtanken är att samtliga kritiska 

ledningar skall besiktas vart tionde år, men detta bedöms från fall till fall. 

Kretslopp och vatten anser att detta arbetssätt ger en bra uppfattning om ledningsnätets status. 

Det anses inte motiverat att regelbundet inspektera hela ledningsnätet, utan det är fullt 

tillräckligt att besiktiga de kritiska ledningarna. Man har möjlighet att hitta problem och hinna 

åtgärda ledningar innan något händer, och slipper på så sätt de stora konsekvenser för 

samhället som en driftstörning hos en kritisk ledning skulle innebära.

Pres_Agertved_Samstyring_ Reneseanlæg og afløbssystem_regnprogose.docx 

13 th Nordic Wastewater Conference, 2013 

Abstract til mundtlig præsentation under temaet: 

“Integrated wastewater systems – a holistic approach” 

Sprog -Dansk 

Titel 

”Intelligent Spildevandshåndtering – regnprognose og integreret styring af afløbssystem og renseanlæg” 

Forfattere 

Jeanette Agertved 1* , Henrik Sønderup 2 , Henrik Dehn 3 , Lorenzo Benedetti 4 , Carsten Thirsing 5 og Kim 

Rindel 5 

1 EnviDan A/S, Fuglebækvej 1A, 2770 Kastrup, Danmark * e-mail adresse: jam@envidan.dk 

2 Rambøll, Hannemanns Alle 53, 2300 København, Danmark 

3 HOFOR A/S, Ørestads Boulevard 35, 2300 København S, Danmark 

4 WATERWAYS srl Via del Ferrone 88 50023 Impruneta (FI) Italy 

5 Lynettefælleskabet, Refshalevej 250, 1432 København K 

Stikord 

MIKE URBAN, WEST, Integrering af matematiske modeller, styring og regulering, reduktion af bypass, 

regnprognose, forvarsling, tilbageholdelse i afløbssystem, driftsomkostninger 

Abstract 

Modelberegninger viser, at tilbageholdelse af spildevandvand i afløbssystemet på Amager ved styring 

af pumpestationer kombineret med anvendelse af radarbaseret prognose for indløbsflow til 

Renseanlæg Lynetten samlet set kan halverer aflastningerne fra anlægget, hvormed den stofmæssige 

belastning af recipienten reduceres betragteligt. 

EnviDan Øst, A/S • Fuglebækvej 1A • DK-2770 Kastrup • Tlf.: 32 50 79 44• www.envidan.dk


EnviDan Øst, A/S • Fuglebækvej 1A • DK-2770 Kastrup • Tlf.: 32 50 79 44• www.envidan.dk 

Side 2 af 4 

Projektet Intelligent Spildevandshåndtering blev i gangsat af Lynettefællesskabet I/S i samarbejde 

med de otte ejerkommuner og deres respektive Forsyningsselskaber i 2008. De otte kommuner afleder 

regn-og spildevand til to renseanlæg med en kapacitet på hhv. Renseanlæg Damhusåen (350.000 

PE) og Renseanlæg Lynetten (750.000 PEProjektet har haft til formål; 

At udvikle en optimal driftsmæssig styring af det samlede eksisterende spildevandssystem i 

Lynettefællesskabets opland 

At gøre Lynettefællesskabet og dets ejerkommuner som centrale udførende virksomheder 

indenfor udvikling af området 

Projektet er gennemført i 4 faser, og projektforløbet fremgår af nedenstående figur: 

Figur 1: Faseopdelt projektforløb 

Renseanlæg Lynetten aflaster forrenset spildevand efter primærtankene via et bypass til recipienten 

Øresund. Aflastningerne sker næsten hver gang det regner og udgør typisk 1-2 mio m 3 på årsbasis. 

Vandkvalitetsmålinger viser, at koncentrationerne af forureningsparameter i bypass er meget 

høje i betragtning af, at der er tale om fortyndet spildevand og at vandet har passeret primærtankene. 

Der er identificeret to årsager aflastningerne fra Lynetten: 

1. Den samlede kapacitet af de tre hovedpumpestationer, der pumper vand fra oplandet til 

renseanlægget, er væsentlig større end den biologiske kapacitet på Lynetten. Der er således 

tale om trykledninger, hvormed der ved en stigning i flowet indledningsvist aflastes ufortyndet 

spildevand. 

2. Omstilling til regnstyring på anlægget sker i dag, når indløbsflowet til anlægget overskrider 

den biologiske kapacitet. Herved øges den hydrauliske kapacitet fra 17.000 m 3 /h tl 23.000 

m 3 /h over to timer. En rettidig omstilling kan potentielt reducere aflastning via bypass. 

I projektet er det undersøgt to tiltag til reduktion af hyppigheden af bypass:



Side 3 af 4 

1. Øget tilbageholdelse af spildevand i store magasineringsvoluminer på Øst- og Vestamager 

gennem styring af pumpestationer, således at afledningen herfra begrænses, når tilløbshydrografen 

til Lynetten overskrider anlæggets biologiske kapacitet. 

2. Anvendelse af prognose for indløbsflow til Lynetten til omstilling til regnstyring. Der er regnet 

på forvarsling fra regnmålere samt forvarsling på basis af egentlig flowprognose, der 

forudsiger indløbet til Lynetten en eller to timer i forvejen. 

Vurderingen af tiltagene er gennemført ved at anvende modeller for hhv. renseanlægget (WEST) og 

for afløbssystemet (MIKE URBAN). 

Modelberegningerne viser et stort potentiale for en miljømæssig optimering af det samlede spildevandssystemet 

gennem bedre udnyttelse af magasineringsvolumner på Amager og forvarsling for 

omstilling til regnstyring på renseanlæget, se figur 2 og 3. 

Figur 2: Beregnet reduktion af aflastede stofmængder ved optimering af tilløbshydrografen til Renseanlæg 

Lynetten.



Side 4 af 4 

Figur 3: Beregnet reduktion af aflastede stofmængder til recipienten ved forvarsling til omstilling af 

regnstyring på renseanlæg Lynetten. 

Ved at optimere i forhold til vandmiljøet gennem reduktion af bypass mængden ledes en tilsvarende 

øget mængde spildevand til renseanlægget. Dette resulterer i ekstra driftsomkostninger samt en 

øget statsafgift for afledning af forureningsparameterne (BOD, Total-N og Total-P). 

Ud over disse resultaterne er der i projektgruppen foregået en løbende erfaringsudveksling og dermed 

en bedre forståelse for funktionen af det samlede spildevandssystem og hvilke potentialer der 

eksistere for optimering af spildevandssystemet. 

De beregningsmodeller, der er opstillet i projektet Intelligent Spildevandshåndtering, er sideløbende 

blevet anvendt til projektering og planlægning hos flere af forsyningsselskaberne til andre projekter, 

bl.a. til klimatilpasningsplan for Københavns Kommune, projekter for reduktion af aflastninger 

til Damhusåen, spildevandsplanlægning i Gentofte og Gladsaxe, projekter på DTU og til udviklingsprojekterne 

METSAM og SWI.

Presentation på svenska 

Rubrik: ”Är bräddning från avloppsledningsnät ett hot mot miljökvalitetsnormer och 

dricksvattenförsörjning?” 

Författare: Åsa Bengtsson Sjörs, Daniel Larson, Lena Thyberg och Sofia Billvik 

Föredragshållare: Åsa Bengtsson Sjörs och Daniel Larsson 

Organisation: WSP Samhällsbyggnad 

Epost: asa.bengtsson.sjors@wspgroup.se daniel.larson@wspgroup.se 

Nyckelord: Bräddning miljöpåverkan avloppsledningsnät 

WSP utför under våren 2013 en förstudie inom bräddningars påverkan på recipienter med 

avseende på övergödning och hygieniska risker. Metoden som vi vill presentera på 

NORDIWA 2013 kommer att användas vid en huvudstudie där den nationella problembilden 

av bräddning ska kartläggas. 

Abstract 

Bräddning från avloppsledningsnät leder till utsläpp av näringsämnen och smittoämnen som 

kan bidra till både övergödning och att försämra vattenkvaliteten i dricksvattentäkter. Det 

finns ingen rikstäckande kvantifiering av bräddproblemets omfattning och riskerna med 

bräddning från avloppsledningsnäten är oftast inte kartlagda. Samtidigt finns en fara att 

klimatförändringar kommer att innebära en ökning av mängden avloppsvatten som bräddas. 

Det finns idag inga utarbetade riktlinjer om hur kvantifiering av bräddning från ledningsnät 

ska utföras. Många VA-huvudmän har bräddregistrering eller utför någon form av 

bräddberäkning idag, men man använder många olika metoder och det finns ingen säkerhet 

för hur tillförlitliga metoderna är. För att få ett samlat grepp har en tillämpbar metodik 

arbetats fram. 

Svenskt Vatten har med hjälp av WSP arbetat fram en metodik för kartläggning och 

kvantifiering av bräddningars påverkan. I metodiken ingår att kartlägga bräddningens 

omfattning samt att koppla omfattningen till påverkan på recipient och 

dricksvattenförsörjning. För påverkan på recipient utgår metoden från bedömningssystemet 

för miljökvalitetsnormer i ytvatten. 

Inom tillsyn och prövning har miljökvalitetsnormer för vatten fått ett allt större fokus. Målet 

är att samtliga ytvatten ska uppvisa en god ekologisk status. Ett av de miljöproblem som 

särskilt uppmärksammats är övergödning, där avloppsförsörjning pekats ut som en viktig 

källa. Eftersom bräddning kan utgöra en betydande, men ofta okänd del, av 

näringsämnesbelastningen från avloppsförsörjningsanläggningar så är det troligt att krav på 

utredningar och åtgärder som avser bräddning kommer att öka. Det är också av intresse att få 

fram underlag som kan användas i kommunernas arbete med lokala åtgärdsprogram som en 

del i vattenförvaltningsarbetet. 

Den brädddata som nu kommer att tas fram i Sveriges kommuner kan analyseras på många 

sätt. Exempel på detta är en bedömning av vilken utsträckning som bräddning i ledningsnät 

orsakas av påkopplade takavlopp, brister på privata fastigheter eller otäta självfallsledningar. 

Att identifiera de olika skälen för bräddning ger en uppfattning om hur kostnaden för att 

åtgärda problemet kan räknas fram. Tidpunkt på året då bräddningen sker kan ge en hint om 

lämplig åtgärd, och kan också ställas i relation till hur känslig en recipient är för orenat 

avloppsvatten vid denna tidpunkt.

Disinfection of Combined Sewer Overflow with Micro-Screening 

Combined with Ozone or Chlorine Dioxide 

F. Nilsson A , J. Väänänen B , S. Haghighatafshar C , M. Hagman D , G. Hey E & K. Jönsson F 

A: Corresponding Author, Ind. Ph.D student, Water & Env. Eng. at Dep. Chem. Eng. Lund University and 

Primozone Production AB, Terminalvägen 2, SE-24642, Löddeköpinge, Sweden, filip.nilsson@primozone.com 

B: Ind. Ph.D student, Water & Env. Eng. at Dep. Chem. Eng. Lund University and Hydrotech AB 

C: Project Assistant, Water & Env. Eng. at Dep. Chem. Eng. Lund University 

D: Ph.D, NSVA (municipal company operating Öresundsverket WWTP) 

E: Ph.D student, Water & Env. Eng. at Dep. Chem. Eng. Lund University 

F: Associate professor, Water & Env. Eng. at Dep. Chem. Eng, Lund University 

Abstract 

During wet weather flow (WWF) the capacity of a wastewater treatment plant (WWTP) can 

be exceeded, leading to a portion of the flow being discharged into the recipient either untreated 

or only partially treated . This flow, combined sewer overflow (CSO), can be a major 

contributor of pathogens found in receiving waters. It is possible to disinfect CSO with a 

number of methods including UV, ozone, hydrogen peroxide, chlorine, chlorine dioxide etc. 

But due to the fickle nature of the appearance of CSO, high chemical oxygen demand (COD) 

and particle content, it can be difficult and costly to implement [1]. In 2006, the EU issued a 

new bathing water directive which specifies that for sufficient quality coastal bathing water, 

Escherichia Coli and intestinal Enterococci levels cannot exceed 500 and 185 cfu/100 ml, 

respectively [2]. The aim of this study is to evaluate the efficiency of ozone and chlorine 

dioxide for reducing Escherichia Coli, intestinal Enterococci and total coliform bacteria in 

CSO to comply with the EU directive. 

A pilot plant was set up in order to treat the incoming wastewater at Öresundsverket WWTP 

in southern Sweden. The wastewater passed through screens and aerated grit chambers before 

being pumped into the pilot plant. The pilot plant consisted of chemical phosphorus 

precipitation (coagulation/flocculation) and 100 µm screening as a primary treatment 

followed by ozone injection for disinfection. In parallel to the ozone treatment, the screened 

water was treated in lab-scale with chlorine dioxide. Since the CSO had been treated by 

micro-screening prior to addition of disinfection agent it was hypothesised that the dose 

needed would be in a range of 3-12 g O3/m 3 for ozone and 5-15 g ClO2/m 3 for chlorine 

dioxide, with 8 minutes hydraulic retention times for both disinfection agents. Along with 

microbiological analysis of the three target organisms, the pilot plant was evaluated for 

phosphorus-, SS-, COD-, BOD- and turbidity reductions.

The trial experiments showed that lab-scale chlorine dioxide addition to chemically 

precipitated and screened wastewater was the most effective disinfectant, achieving a 

reduction of all three target organisms down to

Jukka Yli-Kuivila, project manager, investments for water services 

Helsinki Region Environmental Services Authority HSY 

jukka.yli-kuivila@hsy.fi 

NORDIWA 2013 13th Nordic Wastewater Conference, platform presentation, English 

No prolonged maintenance breaks in a sewer rocktunnel 

A general plan for a new 150 000 m 3 /d wastewater treatment plant in Espoo, Finland was completed in 

October 2011. Purified wastewater should be transferred 8,5 km via a rocktunnel to the outlet tunnel of the 

present WWTP. The tunnel would be below a river at -20 m depth and further below a metro at -60 m. If 

water could not pass through the tunnel, a six months period was estimated to be needed for fixing it. 

Meanwhile the water would be discharged to the crossing river. This was estimated to happen once within a 

hundred years. 

The river leads to the Gulf of Espoo (Baltic Sea), where lives a population of Macroplea pubipennis– very 

rare water insect, protected by a national law and Natura-2000 program. Regional environmental authorities 

wrote in November 2012, that no major risk for that insect population could be allowed. This meant a delay 

risk for the whole 286 million euros WWTP project, and possible 20 million euros extra investment costs for 

an emergency outlet tunnel. Therefore the outlet tunnel plans are updated as follows and extra costs limited 

to about 2 million euros. 

The part of the outlet tunnel from the new WWTP to the river will be blasted above the sea level. This part 

can be reached by men and vehicles whenever needed. Most inspection and maintenance can take place, 

while the WWTP and the outlet tunnel are operated normally. If those duties can’t be completed when water 

is flowing on the bottom of the tunnel, treated wastewater can be turned back to the inlet tunnel to avoid a 

total break in the WWTP. The storage capacity of the inlet tunnel enables one to two days break for the 

WWTP use, or running it with diluted wastewater. Excellent purification results are easier to maintain, if the 

exception period doesn’t last longer than 8 h/d. That enables repeatedly one working shift for tunnel 

maintenance and two shifts for emptying the inlet tunnel storage. The fixing of the tunnel bottom can be 

done part by part while the flow is isolated from the part under construction. Therefore no prolonged 

maintenance breaks are needed for this part of the tunnel. 

Before the tunnel would cross the river, a 20 m vertical shaft is needed to remain the tunnel in a solid rock. 

After that the slope of the tunnel is towards the seashore, where another vertical shaft is needed from -60 m 

to the present outlet tunnel. Normally this 7,5 km part of the tunnel is full of water. A pumping station will 

be built beside the tunnel before it dives deed because of the metro. This pumping station can raise water 

about 30 m, from tunnel bottom level to sea level behind a pressure wall in the tunnel. If the tunnel from the 

pumping station to the present outlet tunnel should be emptied, water would be pumped via another pipe to 

the street level above and from there further to a nearby ditch and seashore. When inspections or 

maintenance is needed, water level could be kept low in the tunnel and vehicles driven in. 

The normal outlet tunnel discharge is 7.5 km to deeper sea and a discharge to seashore should also be 

avoided. Therefore the last tunnel part will be inspected by a diving robot and kept empty only during 

essential maintenances. 

Another benefit of the pumping station is the adaptation to climate change. The WWTP can be built to lower 

position and booster pumps used only, when the sea level or water flow is too high for gravity discharge.

Wastewater pipes in Oslo: from condition monitoring to 

rehabilitation planning 

Ugarelli R.M. 1 , I. Selseth 1 , Y. Le Gat 2 , J. Rostum 1 and A. H. Krogh 3 

1 SINTEF Building and infrastructure, contact detail: Dr. Rita Maria Ugarelli, SINTEF Building 

and Infrastructure, Pb. 124 Blindern, NO-0314 Oslo, Norway, rita.ugarelli@sintef.no 

2 Irstea Bordeaux – REBX, 50 avenue de Verdun, 33 612 Cestas 

3 Vann- og avløpsetaten, Oslo kommune 

Abstract Strategic use of condition monitoring to support rehabilitation planning of the Oslo 

wastewater network is the topic presented. The full paper will describe the process followed 

from investigating the quality of the data, overcoming limitations of the Nordic standard for 

condition assessment, selecting the final dataset for models calibration and finally modelling 

the prediction of the deterioration process under selected rehabilitation strategies. The model 

applied for the analysis is termed GompitZ and it based on the probabilistic theory of Markov 

chains; it defines the relationship between the current state and the expected service time of 

sewer pipes using Close Circuit TV inspections (CCTV) as classification input. 

The GompitZ deterioration modeling tool has been delivered by IRSTEA (Le Gat, 2008) within 

the framework of the CARE-S FP5 project (Sægrov, 2005). The model has been further 

developed in the last years also thanks to the testing and validation done in Oslo. 

Besides a model parameter calibration module, the GompitZ tool contains a module devoted 

to long term simulation of rehabilitation programmes. Four rehabilitation strategies can be 

performed and therefore compared: i) a "do-nothing" option that simulates the "natural" 

evolution of the pipes in the absence of rehabilitation, ii-iii) a "length-driven" and a "budgetdriven" 

option that simulates the annual rehabilitation of the most deteriorated pipes up to a 

total length/budget fixed by the user for each year belonging to the simulation period, and iv) 

an "optimization" option that estimates the optimal mean annual rehabilitation length of most 

deteriorated pipes to be implemented in order to bring the network just below a given global 

deterioration condition at a user-given time horizon. 

By comparing different strategies is possible to see (and calculate) the benefit in terms of 

improvement of the network conditions obtained by applying a given rehabilitation strategy, 

instead of “doing nothing”. Costs versus benefits can therefore be balanced in order to choose 

the winning and more feasible solution. 

The research also highlighted a major issue: the need to review the Norwegian standard 

(NorskVann, 2007) used to classify pipes from visual inspection. The problem consists on the 

standard being too pessimistic in the pipe classification leading to a much more negative 

figure of the overall network need for rehabilitation that it is in reality. By classifying the pipes 

as much more close to collapse than thy actually are, brings also to a too high estimation of 

the investment needs for rehabilitation plans. 

1

The research is currently focused on further developing the GompitZ tool by introducing the 

concept of “risk” in the ranking of segments for prioritizing rehabilitations in long term 

simulations. The choice of the strategy to undertake would be then based on a trade-off 

between costs, conditions and risk. 

Reference 

Le Gat, Y. 2008. Modelling the deterioration process of drainage pipelines. Urban Water 

Journal, 5, 10. 

NORSKVANN 150/2007: Dataflyt - Klassifisering av avløpsledninger (Dataflow. Classification of 

sewer pipes. 

Sægrov S, 2005. CARE-S Computer Aided Rehabilitation of Sewer and storm water networks, 

IWA publication 2005, ISBN 1843391155. 

Information 

The abstract is meant as a platform presentation and the language of the platform 

presentation is English. 

2

Prioritering av flomforebyggende tiltak i norske avløpssystemer 

G. Torgersen*, J. Bjerkholt** 

*geir.torgersen@hiof.no Høgskolen i Østfold / Universitetet for miljø og biovitenskap, Norge 

** Universitetet for miljø og biovitenskap, Norge 

Abstract 

I denne artikkelen presenteres det en studie av 22 store norske byers forhold til metoder for 

bærekraftig overvannshåndtering og flomforebyggende tiltak. Studien omfatter også noen 

svenske og danske byer. Målet med studien har vært å finne ut hvordan kommunene 

prioriterer dette i praksis ved utbedring av eksisterende avløpssystem. 

Klimaendringer fører til mer intens nedbør i mange deler av verden, også i Norge. Det gir 

blant annet store utfordringer i forhold til å håndtere vannet i byer. Ledningene i byene er 

dimensjonert for lavere nedbørsintensiteter enn det som forventes i framtiden, og allerede i 

dag merkes endringene i klima. Disse utfordringer kommer i tillegg til lav utskiftingstakt på 

avløpssystemet og økt urbanisering. 

I Norge har det ennå ikke vært oversvømmelser i den størrelsesorden som man har sett i 

København de siste årene. Fra 1992-2007 ble det utbetalt 5 milliarder kroner fra 

forsikringsselskapene knyttet til vannskader i kjellere, naturskader ikke medregnet. I det 

nasjonale vannskaderegisteret har det vært en økning i antall kjelleroversvømmelser fra ca. 

2000 i 2008 til ca. 3000 i 2012. Forsikringsbransjen regner med at utbetalingene for skader vil 

øke med 40 % de neste 10 årene. Det har de siste årene vært flere rettsaker som følge av at 

forsikringsselskaper har krevd at kommunene holdes ansvarlige for skader på grunn av 

manglende kapasitet på det offentlige avløpsnettet. 

Internasjonal forskning konkluderer med at lokal overvannshåndtering med minst mulig bruk 

av ledningsnett, er den beste og mest fleksible måten å møte framtidens overvannsutfordringer 

på. Et skifte fra tradisjonell metode der overvannet føres i ledninger, til en mer bærekraftig 

metode, er som prinsipp en så fundamental endring at det betegnes som et «regimeskifte». En 

slik overgang forventes å tvinge seg fram som følge av bl.a. klimaendringer. 

I spørreundersøkelsen til Norges største kommuner framkom det at byene i dag har store 

utfordringer i forhold til personellsituasjonen, og aktiviteten ikke uten videre kan økes fra 

dagens nivå. Undersøkelsen viste at større satsing på flomforebyggende tiltak må skje 

gjennom strengere prioritering innenfor dagens økonomiske rammer. For å undersøke 

satsingen på bærekraftige løsninger og flomforebyggende tiltak, var det derfor relevant å finne 

ut hva som i praksis prioriteres når avløpssystemet skal utbedres. Undersøkelse ble gjort i 2 

steg: 

Steg 1 var en undersøkelse av hva som var utløsende årsaker og hvilke metoder som ble 

benyttet ved utbedring av avløpssystemene. Det for å gi et bilde på hvor kommunen står i dag 

på overgangen mot et nytt «regime».

Steg 2 var en gruppering og vurdering av drivere som ble antatt å påvirke utviklingen. Det er 

bl.a.: dagens tilstand, virkemidler, hendelser, myndighetskrav, press fra opinionen. Ved 

intervjuer / litteratursøk ble kvantitative data vurdert i forhold til hvor mye/lite de betyr for 

overgangen til et mer bærekraftig regime. 

Resultatene fra undersøkelsen viste at i Norge står tradisjonelle metoder som åpen grøft og 

separering veldig sterkt i de undersøkte byene. I 2010 ble 75 % av eksisterende 

avløpssystemet utbedret ved åpen grøft og separering. Utløsende årsak oppgis å være 

flomreduksjon i 23 % av tilfellene. De forespurte kommunene i Sverige og Danmark syntes å 

ha kommet lenger i bruk av bærekraftige løsninger for overvannshåndtering. Sentrale 

myndighetskrav etterfulgt av økonomiske incentiver i forhold til rapporterte resultater, kan 

være viktig for svenske og danske kommuners prioriteringer. Norge har i praksis ingen slike 

økonomiske incentivordninger. Dagens innrapporteringssystem oppfordrer kommunene til å 

være aktivitetsorienterte, bl.a. gjennom fokus på investeringsbeløp og antall meter utskiftet 

ledning. Et rapporteringssystem bør heller sette krav til å måle effekten av et tiltak, f.eks. 

redusert vannføring. Det kan føre til mer innovasjon, bærekraftige løsninger og gi større fokus 

på flomforebyggende tiltak.

Abstract - presentation January 31, 2013 

WANDER Nordic Water and Materials Institute 1 

Sinkokatu 11, FI-26100 Rauma, Finland 

Title: Developing the renovation of the sewerage and the drainage standards, quality and 

harmonization process chains in Finland 

Authors: Pelto-Huikko, A.* and Kaunisto, T.* 

* WANDER Nordic Water and Materials Institute / Prizztech Ltd., Sinkokatu 11, FI-26100 Rauma, 

Finland. 

Contact person: Aino Pelto-Huikko, email: aino.pelto-huikko@wander.fi 

Presentation in English. 

In Finland, the rehabilitation of sewerage and drainage can be done with many techniques. These include 

total repair, replacement and renovation. The renovation techniques have been used for several years in 

sewerage (>DN 150) but drainage have had a minor role until recent years. However, there are still many 

questions concerning for example selection of the right technique. 

The renovation techniques include many technical solutions including linings with different materials and 

slip linings. The technique can crack the old pipe or not. The structure of the new pipe can be a part of the 

old pipe or it can be self-supporting. 

The standardization of the methods is done mostly in European level or in some cases in international 

level. The content of the standards have to be evaluated. Because the European product acceptance 

system for these products is still under preparation, national regulation is needed to set the requirements. 

Besides the composition of the material, also the work performance affects the quality of renovation 

significantly. Corporate or personal certificates, internal and external quality control and documentation 

of work performance are all factors to be examined. These issues need to be decided and implemented 

nationally. For sewerage, there is no authority which would be responsible for what material is placed, 

and how the renovations are done. For the drainage, the local authority evaluates whether the building 

license is needed. 

The aim of the project is to evaluate the renovation situation, the standardization, quality, harmonization 

schemes, assistance to the workmanship and the evaluation of the work quality. 

The report will be published in December 2013 (in Finnish). 

WANDER 

www.wander.fi 

first.last@wander.fi

Title: Demand Driven Distribution 

Author Jim Rise 

Company Grundfos AS 

Email jimrise@grundfos.com 

Type Platform presentation 

Language Can do it in English as well as Scandinavian 

Reduce water loss with flow-dependant pressure management 

Leakages can cost water companies much more than the water lost from the distribution 

system. Demand-driven distribution solutions can help reduce and control leakage by 

compensating for surplus pressure in the pipes system and by reducing water hammer which 

causes new holes. 

The solution in both these cases is the control system, and in particular proportional pressure control 

– a unique solution that automatically optimises energy consumption and minimises water loss by 

15%. 

Reduce leakage 

Water companies continue to dedicate significant resources to resolve issues related to non-revenue 

water (NRW). NRW is water that has been produced and is “lost” before it reaches the customer, 

thereby costing water companies’ money. 

Reducing leakage and water loss requires initiatives such as increasing the speed of leakage 

detection, optimising asset management and not least by designing a pressure management strategy. 

Pressure management is now well recognised as being essential to effective leakage management. 

The benefits of reducing and controlling NRW and leakage reduction in particular include financial 

gains from the increased amount of water reaching the customer, effectively meaning a reduction in 

water production. This includes the possible delay of costly capacity expansion, the increased 

knowledge about the distribution system gained in the process, and the reduced risk of damage and 

contamination. 

Water hammer a major issue 

An important contributing factor behind new leaks is water hammer. Caused by sudden momentum 

changes in a pipe system, this phenomenon can be reduced or eliminated by lowering fluid 

velocities, gradual pump ramp-up/ramp-down or reducing pump size, for example. Software 

analysis packages exist today; these vary in complexity, dependent on the processes modelled. 

For example, a big pump has a big water hammer effect; this is a factor of the pump’s inertia. 

Smaller pumps reduce the risk of water hammer and involve cost savings from lower operating 

costs, reduced energy consumption and less leakage loss. 

Compensating for friction loss

The central challenges for any water distribution system are to secure a stable water supply, manage 

what may be scarce water resources, locate and remedy pipe breaks, reduce leakages, and keep 

operating costs as low as possible. 

Traditionally, a water distribution system would consist of one duty pump supplying demand at 

constant pressure maintained by valves or variable frequency drives (VFD). In addition, an identical 

pump and VFD would be installed as a backup, in case of failure. 

With a demand-driven distribution solution.. The system is designed to supply precisely the flow 

needed at the pressure required, with a number of parallel-coupled pumps running at best efficiency 

point, instead of one big pump. Surplus pressure in the pipes system is considerably reduced, and 

the risk of water hammer causing new leakages is substantially lessened. For the consumer there is 

no change in tap pressure, but leakage is reduced significantly. 

Reduce leaks with a pressure management strategy 

Proportional pressure control automatically optimises energy consumption and minimises water by 

automatically adapting the set point to the actual flow. 

If the pressure loss in the pipe system is 2 bar during high flow periods, the pump discharge 

pressure must be set to 6 bar in order to deliver a tap pressure of 4 bar. 

However, in a low-flow situation, the pressure loss in the pipe system may only be 1 bar. If the set 

point remains fixed at 6 bar, this would increase tap pressure to 5 bar. The surplus 1 bar in the 

system increases leakage loss and represents excess energy consumption, hitting your cost level in 

two ways.

c:\users\icnmsm\desktop\pres_clementson_inlackage_atgardsforslag_helhetssyn.doc 

Abstract 

Beställare NORDIWA 2013 

Från Ingemar Clementson/ Viveka Lidström 

Till nordiwa2013@svensktvatten.se 

Tillskottsvatten i ledningsnät - en ansvarsfråga 

Att ha ett klart definierat verksamhetsområde för VA är viktigt. Detta ger en 

tydlighet i ansvarsfördelningen för de olika vattenslag som hanteras både vad gäller 

skyldigheter och rättigheter. Ett fall då oklarheter i ansvarsfrågan och 

åtgärdshanteringen råder är t.ex. då flödet ökar i spillvattennätet vid nederbörd i ett 

område där det inte är samma huvudman för spillvattenhantering och 

dagvattenhantering. För att ta reda på vem som har juridiskt och tekniskt ansvar 

behöver kommunen ha en god översikt över vilka ledningar som finns i marken 

och vilka flöden och avrinningsområden som gäller. 

Ramböll Sverige har för Staffanstorps kommun genomfört en större utredning 

kring problematiken med ökat flöde i spillvattennätet i samband med nederbörd. 

Det ökade flödet i spillvattennätet har lett till flera översvämningar inne på 

fastigheter, ökat slitage på pumpstationer, oönskad breddning samt svårigheter i att 

optimera reningsprocessen i reningsverk. 

Inom uppdraget har olika källor till inläckage lokaliserats för att ge ledningsägare 

möjlighet att göra kostnadseffektiva åtgärder. I fält har ca 650 fastigheter, ett flertal 

ledningssträckor samt andra möjliga källor till inläckage undersökts med röktest, 

färgning av vatten samt flödesmätningar. Källorna till inläckage har varierat 

beroende på vilket område som undersökts. I tätorter har felkopplingar varit den 

största enskilda källan, i rurala områden är det främst dräneringsledningar och i 

vissa områden har läckande ledningar stått för en stor del av inläckaget. 

Genom att känna till de felkällor för tillskottsvatten som finns kan konstruktiva 

åtgärder genomföras i samarbete med fastighetsägare inom ett område där 

dagvatten ej ingår i kommunens verksamhetsområde. 

Datum 2013-01-30 

Ramböll Sverige AB 

Skeppsgatan 5 

211 11 Malmö 

T: +46-10-615 60 00 

www.ramboll.se 

Ramböll Sverige AB 

Org nr 556133-0506 

1(2)

c:\users\icnmsm\desktop\pres_clementson_inlackage_atgardsforslag_helhetssyn.doc 

Resultatet av projektet har givit en helhetsbild av flödessituationen i aktuellt 

område. Denna har redovisats i en GIS-modell där anteckningar, beräkningar, 

fotodokumentation samt klassificeringsstatus visas på ett sätt som är kompatibelt 

med kommunens nuvarande och framtida digitala VA-system. Modellen är också 

gjord för att kunna anpassas till VA-banken samt ligga till underlag för 

översvämnings/ledningsmodeller såsom Mike Urban/ Mike She. 

Helhetsgreppet som tagits har bidragit till att skapa ett underlag för kommunen att 

på ett systematiskt sätt räta ut frågetecken om ansvarsfördelningen i 

dagvattenhanteringen. 

Vidare har hanteringen av information gjorts på ett sätt som förbereder kommunen 

för en möjlig utvidgning av verksamhetsområdet som inkluderar även 

dagvattenhantering. 

2(2)

Title: Focusing of sewer network renovations 

Authors: Laakso, Tuija; Vahala, Riku, Aalto University 

E-mail addresses: tuija.laakso@aalto.fi, riku.vahal@aalto.fi 

Abstract for a platform presentation to be held in English. 

Abstract 

Getting accurate and up-to-date information on the renovation need of sewer assets is difficult; on 

the other hand, the sewer network needs to be renovated periodically. Traditionally, in Finland, the 

sewer network inspections and renovations have been made based on few sources of data (e.g., pipe 

age and material) and not necessarily using a systematic planning approach. In such a context, the 

EfeSus project aims at developing a systematic, comprehensive and a partly automated procedure 

for deciding which assets to renovate in the network and when. The main aim of this paper is to 

present the project and its objectives as an example on how the improvement of sewer network can 

be challenged in practice. 

Efesus, financed largely by the Finnish Funding Agency for Technology and Innovation (Tekes), 

focuses on the separate sewer network of the Finnish city Espoo (population of around 250 000) and 

analyzes in detail 20 representative network areas. The data utilized in the assessment include: 

GIS data from the utility’s network information system: 

o pipe locations and depths, pipe diameters, slopes, materials, installation years; 

o closed circuit television (CCTV) inspections; 

o occurred operational disturbances; 

o water consumption in different network areas (on annual level). 

Flow data from the utility’s telemetry system. 

Rainfall data. 

Environmental data concerning: 

o ecological status of groundwater areas; 

o ecological status of surface water areas; 

o road type classifications. 

In order to achieve efficient prioritization of the sewer renovations these data need to be collected, 

evaluated and analyzed. Efesus starts by gathering and combining from different sources data that 

are considered useful for renovation planning. Similar to the projects CARE-S (Saegrov 2005) and 

COST-S (Savic et al 2005), the approach in EfeSus is includes: 1) decision-making based on 

available data, and 2) automated data analysis and decision support by means of a software 

(prototype) created in the project. The software, using as inputs all the different data collected, 

assesses each pipe with respect to its estimated structural and operational condition, as well as to its 

importance in the network structure and the vulnerability of the surrounding environment. 

As a result of the analysis, an index will be assigned to each pipe indicating how often the pipe 

should be inspected and what its renovation need is. After this, so-called renovation entities are 

built up from a number of pipes that can be considered similar enough to be renovated at the same 

time. Based on this assessment, further on-site investigations such as CCTV inspections, smoke 

tests and manhole inspections as well as actual renovations can be targeted and scheduled much

more accurately than currently. As a result, both financial and human resources are expected to be 

allocated more efficiently than currently. 

References: 

Saegrov, S. (ed.) 2005. CARE-S. Computer-Aided Rehabilitation of Sewer Networks. International 

Water Association. 

Savic, D.A., Djordjevic, S., Dorini, G. 2005 COST-S: a new methodology and tools for sewerage 

asset management based on whole life costs. Water Asset Management International December 

2005, Vol. 20.

Title: A GIS based environmental risk assessment of wastewater pumping station overflows 

Name of author: Leena Sänkiaho, M.Sc(Eng.) 

Name of the institution: Pöyry Finland Oy, Jaakonkatu 3, 01621 Vantaa, Finland 

E-‐mail address to the author: leena.sankiaho@poyry.com 

Platform presentation 

Language of the platform presentation: English 

The Helsinki Region Environmental Services Authority (HSY) operates nearly 500 wastewater 

pumping stations around the Helsinki metropolitan area. As HSY is currently renewing its 

environmental permit, they are obliged by the environmental authority to conduct an environmental 

risk assessment, which reviews the wastewater pumping station overflows. Similar studies have not 

been conducted before, hence there are no common guidelines or previous examples of how the study 

should be carried out. 

To go through all 500 pumping stations individually would have been time consuming and inefficient. 

This led to the development of a new geographic information system (GIS) based method. The 

presentation will include a description of the method used and how the results can be utilized. 

In Finland the Finnish Environment Institute and The National Land Survey of Finland publish free GIS 

data. For instance all groundwater areas, lakes, rivers, sea shore and nature reserves are available in 

GIS formats. In addition the metropolitan area cities have conducted surveys that map the ecologically 

valuable small streams. Beaches can be mapped according to the address details available. HSY 

supplied the coordinates of the fresh water intakes. All these data was used as separate risk layers in 

the GIS analysis. The layers were rated according to the severity and consequence a sewer overflow 

may pose. The rating method has been modified from the rating method used in Water Safety Plans 

(WSP) (Bartramet al. 2009). 

HSY provided the pumping station coordinates and capacities. The GIS analysis is based on an overlay 

operation. If a pumping station overlaps a risk layer, the pumping station will be awarded with the risk 

rating. 

There are three ways to utilize the results: risk layers, risk sums or risk scores. 

Risk layers: 

This method detects the pumping stations which are located on certain risk layer. For instance 

pumping stations which are located less than 500 m from a beach can be listed and certain risk 

prevention methods can be applied to these stations or beaches. 

Risk sums: 

A risk sum is the aggregated risk rate for each pumping station. It is assumed that a pumping station 

will have a higher environmental risk if it is located on more than one risk layer. The values range 

from 0 to 6. For instance, the highest risk sum was allocated to a pumping station that is located on a 

groundwater area, it is also on the buffer zone of a groundwater well (< 500 m) and less than 100 m 

radius from an ecologically valuable small stream. 

Risk scores: 

It is assumed that the overall risk is also related to the pumping station capacity as the pumping 

station capacities vary from 3 l/s up to 2000 l/s. Therefore the risk sums were weighted by the

pumping capacities. Based on HSY’s experience several assumptions were made: For instance, it was 

assumed that the risk score of a mega sized (> 200 l/s) pumping station with a risk sum value 3 equals 

a small pumping station (< 10 l/s) with a risk sum value of 6. 

This analysis will help HSY to prioritize the pumping stations on which risk prevention actions should 

be taken. It will also give valuable information about which actions should be taken if an overflow 

occurs. 

References: 

Bartram, J. Corrales, L.; Davison, A.; Deere, D.; Drury, D.; Gordon, B.; Howard, G.; Rinehold, A.; Stevens, 

M. (2009) Water safety plan manual: step-‐by-‐step risk management for drinking-‐water suppliers. 

World Health Organization (WHO), Geneva

Methane formation in sewer systems 

Malin Isgren I *, Patrick Mårtensson I , Jes la Cour Jansen I , David J. I. Gustavsson II , Oriol Gutierrez III 

I 

Water and Environmental Engineering, Department of Chemical Engineering, Lund University, Box 124, 

SE-221 00 Lund, Sweden 

(E-mail:kt08mi2@student.lth.se, kt08pm4@student.lth.se, jes.la_cour_jansen@vateknik.lth.se) 

II 

VA SYD, Box 191, SE-201 21 Malmö, Sweden (E-mail: david.gustavsson@vasyd.se) 

III 

Catalan Institute for Water Research, ICRA. Scientific and Technological park of the UdG. Emili Grahit, 101 

17003 Girona, Spain (E-mail: ogutierrez@icra.cat) 

* Speaker We would like to present this paper as an oral presentation in English. 

INTRODUCTION 

Hydrogen sulphide in sewer systems is a well-known problem. However, formation of the potent 

greenhouse gas methane has not received as much attention. A few studies have been executed on 

rising mains (i.e. Guisasola et al., 2009) since these are theoretically the ones with the highest 

potential for methane formation. Gravity mains are the most common kinds of pipes but are still 

poorly investigated. Investigations of these are necessary if methane formation in sewer systems 

shall be fairly evaluated. Factors that affect methane formation are among other things the presence 

of organic carbon together with anaerobic conditions. The amount of methane formed per volume 

wastewater depends on the ratio between the inner surface wall area covered with biofilm and the 

volume of the pipe. This theory has been proved, not only in studies on rising mains but correlate 

also well with formation of hydrogen sulphide. The main aim of this work was to develop a 

sampling method for determination of dissolved methane in wastewater samples and to detect any 

methane content in gravity mains with the highest potential for methane production in Malmö, 

Sweden. 

METHOD 

Field samples were collected at the inlet, downstream a pressurized system at Sjölunda Wastewater 

Treatment Plant (WWTP) and in scattered selected manholes in the sewer system of Malmö, 

Sweden. The sampling technique enables sampling and at the same time avoids getting air into the 

sampling bottles. This was accomplished by keeping the collection vials under water, while putting 

the cap on (Alberto et al., 2000). Wastewater sampling at the WWTP was executed by lowering a 

sampling bottle close to the incoming pipe, the device is shown in Figure 1. The rubber stopper was 

released when the bottle reached the selected level. 

Figure 1. Device for wastewater collection at WWTP. 

Sampling in manholes was executed by climbing down and filling sampling bottles. From the 

sampling occasions all laboratory analysis were performed within 24 hours. The sampling analyses 

were done by filling half of a vacuum tube with wastewater and then allow equilibrium. The 

methane content was determined with a gas chromatograph and the amount of methane was

calculated with Henry´s law. 

RESULTS AND DISCUSSION 

The methane analysis of the samples taken from the manholes located in Malmö showed that 

methane exists. The concentration varied in every manhole and the highest and lowest encountered 

was 0.58 and 0.11 mg CH4/L respectively. Since none of the examined sewers were pressurised and 

only the wastewater was analysed, the emitted amount was probably higher than the encountered as 

most of the methane formed will be released to the air. The methane from the incoming pipe at 

Sjölunda WWTP was examined twice and the result is shown in Figure 2. 

Figure 2. Variation in amount of methane in the influent to Sjölunda WWTP. 

The methane amount varies during the day and the amount released is about 2 kg/h. The samples 

were taken in the middle of the winter (water temperature around 14°C) and as methane is favoured 

by increased temperature this value can be taken as minimum that enters the WWTP. 

The full paper will present all the measurements and evaluate research needs in order to be able to 

estimate the potential contribution of methane formation in the sewer system in Malmö to global 

warming. 

REFERENCES 

Alberto M.C.R., Arah J.R.M., Neue H.U., Wassmann R., Lantin R.S., Aduna J.B., Bronson K.F., 

2000. A sampling technique for the determination of dissolved methane in soil solution. Soil and 

Water Science Division, International Rice Research institute P.O Box 3127, MCPO 1271, Makati 

City, Philippines. Global Change Science 2 (2000) pp. 57-63. 

Guisasola A., de Haas D., Keller J., Yuan Z., 2008. Methane formation in sewer system, Advanced 

Water Management Center, The University of Queensland, St Lucia, 4067 Queensland, Australia. 

Water Research, 42 (6–7) (2008), pp. 1421–1430.

Abstract for: 

13 th Nordic Wastewater Conference 

To be considered in all categories 

Title: 

Laboratory and field investigation of Chemical disinfection of sewer overflow in 

Copenhagen Area 

Authors: 

Henrik R. Andersen, DTU Miljø, hran@env.dtu.dk 

Anitha K. Sharma , DTU Miljø 

Ravi K. Chhetri , DTU Miljø 

Jesper Berner, KEMIRA 

Robin Gramstad KEMIRA 

Öjstedt Ulrik KEMIRA 

Dines Thornberg, Udviklingssamarbejdet. 

Kasper Juel-Berg , HOFOR 

Annette Kolte-Olsen , Nordvand 

Jean De Dieu Otoa , Greve-Solrød forsyning 

Abstract 

Combined Sewer Overflow (CSO) has been a problem in every large city with old sewers resulting in 

deterioration of water quality of receiving waters around the city. . With the anticipated increased rain 

intensity due to climate change and increased loads on sewer system due to urbanisation the problem is 

expected to be magnified in the future. Copenhagen has many beaches and several public baths in the old 

harbour and to maintain the high water quality for bathing it is necessary to reduce the microbial pollution 

from the CSOs. 

Disinfection of CSOs reduces the load of microorganisms and the most common methods are UV-light or 

addition of different forms of chlorine. However, UV-disinfection of CSOs is not attractive due to high 

capital cost and non-predictive occurrence of CSOs. Disinfection with chlorine forms toxic by-products. In 

recent years, laboratory and full scale investigation of novel organoperoxide disinfectants, peracetic 

acid(PAA) and performic acid(PFA) have shown that these chemicals can be attractive disinfectants. We 

presents results from laboratory and field investigations on disinfection of CSOs using PFA and PAA. 

The laboratory part of the study aims to produce the relevant information in order to find the most suitable 

chemical disinfections agents for CSOs in different contexts: Concentration profiles, disinfection efficiency, 

byproducts and residual toxicity is investigated. Additionally a literature study is performed to describe the 

costs and handling of each chemical. The project, “DesiCSO”, partly funded by Vand-i-Byer and will be 

finished in March 2013. 

The field investigations will be performed at 3 different sites with the aim to investigate whether it is 

possible to obtain bathing water shortly after heavy rainstorms in full-scale. The project named FRODO,

which is partly funded by the Danish VTU-fond. The full-scale test will mainly take place in the spring and 

summer of 2013. 

The first field test is at a large pumping station north of Copenhagen (Skovshoved), where frequent CSOs 

occur and the CSOs are discharged 1,6 km out to the sea through a pipe. Performic Acid will be tested due 

to a short retention time in the pipes. 

Example of full scale dosing equipment from Kemira 

The second field test will investigate the combination of filtration and chemical disinfection with PFA and 

will be performed at an existing test site in Copenhagen, Scherfigsvej facility. This facility consists of two 

filtration units (100µ and 20µ) and in 2003-2006 investigations were performed in a LIFE project, where 

filtration in combination with UV-disinfection was tested for disinfection of CSOs with no success. 

The new beach at the effluent from Scherfigsvej is very popular in the summer

The third site is a series of overflow retention basins in Tune south of Copenhagen, where CSOs occur from 

the final basin to a small stream which merges in to the sea near the beach. PAA will be tested at this site 

since the CSOs occur very rarely like once a year with a long reaction time of 6 hours for the chemical 

disinfection in the basins.

Flood Risk Assessment Implementing GIS hydrological Computation and 1-D 

Hydraulic Model to Determine Service Level Capacity in Drainage Systems – A 

Case Study from Brøndby – Denmark 

Sabah Al-Shididi 1 & Joshkun Yolju 2 

1 MSc Environmental Eng., MSc Environmental Policy, BSc Building and Construction Eng., 

Project Manager/Modeller at Avedøre Wastewater Services (Spildevandscenter Avedøre), 

sas@spvand.dk, +45 3634 3854. 

2 BSc Environmental Eng., BSc Civil Eng., Drainage Engineer at Avedøre Wastewater Services 

(www.spildevandscenter.dk) for Brøndby Utility, jy@spvand.dk, +45 3634 3819. 

(Platform Presentation, English) Open for Poster. 

Abstract 

Climate change is already a challenge for water companies to optimize drainage systems capacity 

and it will continuously intensify. A need occurred to determine service level capacity and flood 

risk assessment in Brøndby – Denmark, 

which was exposed to the challenge of 

extensive flood in recent years and 

particularly during the monster rain event of 

July the 2 nd 5-year event 

2011. 

Potential flood 

This paper reviews a new method to 

combine GIS hydrological computation and 

1-D hydraulic model to determine flood and 

hydraulic capacity of the drainage system in 

Horsedammen in Brøndby, a catchment of 

78 ha. This new method has the ability to 

overcome the present hardware limitations 

regardless of size of the catchment and the 

resolution of the flood grid implemented in 

the model and still reaching accurate results. 

The results have saved a great deal of 

modelling and simulation time. Simulations 

of status scenario, solution scenario, future 

climate change solution scenario and 

monster rain event scenario have been 

carried out producing a flood map for each 

scenario including regulated terrain for 

solution purposes and an optimised drainage 

system capacity for the determined service 

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level capacity. The method is an effective tool for analysis, assessment, planning and design of 

drainage systems and can be used for river systems and other 1-D modelled systems applied to rain 

events. 

A supplementary presentation of the results in 3-D images and video records presenting the 

simulation results on time step basis has been possible to produce. Results can be presented on 

Google Earth and similar online GIS programmes. 

Key word: Flood, GIS hydrological Computation, Climate Change, 1-D hydraulic model, Brøndby. 

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Kemira Oyj/Kemira M&I ABSTRACT Vesa Kettunen ... - Svenskt Vatten

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