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Optimerad industriavloppsrening - Polymerflockning och massbalans

Nilsson, Anna LU (2020) VVAM05 20201
Chemical Engineering (M.Sc.Eng.)
Abstract (Swedish)
Industriavloppsreningen på pappers- och dissolvingmassabruket Södra Cell Mörrum (SCM) har nyligen uppgraderats med ny utrustning för att minska utsläppen till vatten, och därmed möta rådande och framtida utsläppsvillkor samt krav på tillämpning av BAT (bästa tillgängliga teknik). Tillbyggnaden av reningsverket innefattar bland annat ett polymerflockningssteg, tre nya skivfilter, ett system för automatisk pH-justering och en bandförtjockare för avvattning av slam.
Detta examensarbete har syftat till att optimera driften av denna nya industriavloppsrening genom att upprätta en massbalans för slam samt utreda hur en effektiv polymerflockningsprocess bäst kan uppnås. Detta för att bidra till uppfyllandet av SCMs projektmål: <10 mg/l... (More)
Industriavloppsreningen på pappers- och dissolvingmassabruket Södra Cell Mörrum (SCM) har nyligen uppgraderats med ny utrustning för att minska utsläppen till vatten, och därmed möta rådande och framtida utsläppsvillkor samt krav på tillämpning av BAT (bästa tillgängliga teknik). Tillbyggnaden av reningsverket innefattar bland annat ett polymerflockningssteg, tre nya skivfilter, ett system för automatisk pH-justering och en bandförtjockare för avvattning av slam.
Detta examensarbete har syftat till att optimera driften av denna nya industriavloppsrening genom att upprätta en massbalans för slam samt utreda hur en effektiv polymerflockningsprocess bäst kan uppnås. Detta för att bidra till uppfyllandet av SCMs projektmål: <10 mg/l suspenderade ämnen i effluenten från industriavloppet.
Massbalansen konstruerades i Excel, med indata från onlinemätare för flöde och susphalt. Resultatet blev ett verktyg som ger en översikt av belastningen på industriavloppsreningens olika komponenter samt fungerar som en enkel modell, med möjlighet att teoretiskt rikta om vissa rejektvatten- och slamflöden och se effekterna. Utförda massbalansberäkningar tyder på att både slam från de nya skivfiltren och rejektvatten från det gamla slamskivfiltret bör ledas till den nya bandförtjockaren för att uppnå maximalt slamuttag från industriavloppsreningen. För att massbalansen ska gå ihop krävs vidare justeringar av vissa onlinemätare och insamling av mer data under normala driftsförhållanden.
Optimeringen av polymerflockningen innefattade en litteraturstudie, en utredning av den automatiska beredningen och doseringen av polymerlösning samt laboratorieflockningstester (”jar tests”). Slutsatsen blev att katjonisk polyakrylamid med medelhög molekylvikt och laddningsdensitet är ett lämpligt flockningsmedel för industriavloppsreningen på SCM, med en optimal dos på ca 9-12 kg torrt polymergranulat per ton suspenderade ämnen i avloppsvattnet. Det finns även goda möjligheter till återflockning av det slam som avskilts på skivfiltren genom tillsats av ytterligare 2-3 kg polymer per ton susp, för att på så vis förbättra slamavvattningen i bandförtjockaren.
Med onlinemätare korrekt justerade utifrån jämförande analyser, en fungerande flockningsprocess, lämpliga filterdukar på skivfiltren och välplanerad styrning av de interna flödena av slam och rejektvatten finns goda möjligheter att uppnå projektmålet på <10 mg/l suspenderade ämnen i effluenten från industriavloppet.





Nyckelord: avloppsvattenrening, massaindustri, industriavlopp, polymerflockning, suspenderade ämnen, massbalans, slam (Less)
Abstract
The industrial wastewater treatment at the Södra Cell Mörrum (SCM) paper and dissolving pulp mill was recently upgraded with new equipment to reduce emissions to water, aiming to meet current and future effluent requirements and comply with BAT (Best Available Techniques). The new extension of the water treatment facility mainly consists of a polymer flocculation step, three rotating disc filters, a system for automatic pH adjustment and a belt thickener for sludge dewatering.
The aim of this master thesis has been to optimize the operation of the new wastewater treatment by creating a mass balance for sludge and investigating how to make the flocculation process work efficiently, thereby contributing to the fulfillment of SCM’s project... (More)
The industrial wastewater treatment at the Södra Cell Mörrum (SCM) paper and dissolving pulp mill was recently upgraded with new equipment to reduce emissions to water, aiming to meet current and future effluent requirements and comply with BAT (Best Available Techniques). The new extension of the water treatment facility mainly consists of a polymer flocculation step, three rotating disc filters, a system for automatic pH adjustment and a belt thickener for sludge dewatering.
The aim of this master thesis has been to optimize the operation of the new wastewater treatment by creating a mass balance for sludge and investigating how to make the flocculation process work efficiently, thereby contributing to the fulfillment of SCM’s project goal: <10 mg/l suspended solids in the industrial wastewater effluent.
The mass balance was created in Excel, using input data from online meters measuring flows and concentrations of suspended solids. The result was a tool that provides an overview of the mass load on the components of the industrial wastewater treatment, while also functioning as a simple model that can predict the effect of redirecting certain flows of reject water and sludge. Performed mass balance calculations indicate that sludge from the new disc filters as well as reject water from the old disc filter thickener should be led to the new belt thickener to achieve maximum sludge outtake from the wastewater treatment. Further adjustments of certain online meters are required for the mass balance to add up, as well as collection of more data during stable process conditions.
The optimization of the polymer flocculation included a literature review, an investigation of the automatic preparation and dosage of the polymer solution as well as laboratory jar tests. It was concluded that a cationic polyacrylamide with an intermediate molecular weight and charge density is suitable for use as flocculating agent in the industrial wastewater treatment at SCM, with an ideal polymer dose of 9-12 kg per tonne of suspended solids in the wastewater. It is also possible to re-flocculate the sludge from the disc filters by further polymer addition of 2-3 kg per tonne of suspended solids, thereby improving the belt thickener dewatering.
With the online meters well-adjusted based on comparative lab analyses, a functioning flocculation process, suitable filter media in the disc filters and proper control of the internal sludge and reject water flows, there is great potential to reach the project goal of <10 mg/l suspended solids in the industrial wastewater effluent.





Keywords: wastewater treatment, pulp industry, industrial wastewater, polymer flocculation, suspended solids, mass balance, sludge (Less)
Please use this url to cite or link to this publication:
author
Nilsson, Anna LU
supervisor
organization
course
VVAM05 20201
year
type
H2 - Master's Degree (Two Years)
subject
keywords
avloppsvattenrening, massaindustri, industriavlopp, polymerflockning, suspenderade ämnen, massbalans, slam, vattenförsörjningsteknik, avloppsteknik, water engineering, environmental engineering
language
Swedish
id
9017968
date added to LUP
2020-06-15 16:28:25
date last changed
2020-06-15 16:28:25
@misc{9017968,
  abstract     = {The industrial wastewater treatment at the Södra Cell Mörrum (SCM) paper and dissolving pulp mill was recently upgraded with new equipment to reduce emissions to water, aiming to meet current and future effluent requirements and comply with BAT (Best Available Techniques). The new extension of the water treatment facility mainly consists of a polymer flocculation step, three rotating disc filters, a system for automatic pH adjustment and a belt thickener for sludge dewatering. 
The aim of this master thesis has been to optimize the operation of the new wastewater treatment by creating a mass balance for sludge and investigating how to make the flocculation process work efficiently, thereby contributing to the fulfillment of SCM’s project goal: <10 mg/l suspended solids in the industrial wastewater effluent. 
The mass balance was created in Excel, using input data from online meters measuring flows and concentrations of suspended solids. The result was a tool that provides an overview of the mass load on the components of the industrial wastewater treatment, while also functioning as a simple model that can predict the effect of redirecting certain flows of reject water and sludge. Performed mass balance calculations indicate that sludge from the new disc filters as well as reject water from the old disc filter thickener should be led to the new belt thickener to achieve maximum sludge outtake from the wastewater treatment. Further adjustments of certain online meters are required for the mass balance to add up, as well as collection of more data during stable process conditions. 
The optimization of the polymer flocculation included a literature review, an investigation of the automatic preparation and dosage of the polymer solution as well as laboratory jar tests. It was concluded that a cationic polyacrylamide with an intermediate molecular weight and charge density is suitable for use as flocculating agent in the industrial wastewater treatment at SCM, with an ideal polymer dose of 9-12 kg per tonne of suspended solids in the wastewater. It is also possible to re-flocculate the sludge from the disc filters by further polymer addition of 2-3 kg per tonne of suspended solids, thereby improving the belt thickener dewatering. 
With the online meters well-adjusted based on comparative lab analyses, a functioning flocculation process, suitable filter media in the disc filters and proper control of the internal sludge and reject water flows, there is great potential to reach the project goal of <10 mg/l suspended solids in the industrial wastewater effluent. 
 
 
 
 
 
Keywords: wastewater treatment, pulp industry, industrial wastewater, polymer flocculation, suspended solids, mass balance, sludge},
  author       = {Nilsson, Anna},
  keyword      = {avloppsvattenrening,massaindustri,industriavlopp,polymerflockning,suspenderade ämnen,massbalans,slam,vattenförsörjningsteknik,avloppsteknik,water engineering,environmental engineering},
  language     = {swe},
  note         = {Student Paper},
  title        = {Optimerad industriavloppsrening - Polymerflockning och massbalans},
  year         = {2020},
}