: Karakteristik af slam i en nedsænket membran bioreaktor

Characterization of Sludge in a Submerged Membrane Bioreactor

Bugge, Thomas Vistisen ; Andersen, Morten Boel Overgaard

4. term

Chemistry, Master (Scient)

2009

92

Interessen for membranbioreaktorer (MBR) til spildevandsrensning er vokset siden slutningen af 1980’erne, drevet af behovet for at genanvende vand og skærpede miljøkrav. En vigtig hindring er stadig fouling – ophobning og tilstopning på membraner – som gør teknologien mindre effektiv. Dette projekt undersøger egenskaberne ved slamflokke i MBR-systemer, fordi disse små klumper af mikroorganismer og partikler er en hovedkilde til fouling. I MBR udsættes slamflokke typisk for højere shear (mekaniske kræfter fra omrøring og flow) end i konventionelle anlæg, hvilket forventes at påvirke deres egenskaber. Derfor sammenlignes MBR-slamflokke med konventionelt aktiveret slam. To nedsænkede MBR-systemer blev brugt: et pilotanlæg på et kommunalt renseanlæg og et laboratorieanlæg på Aalborg Universitet, opbygget så det var sammenligneligt med pilotanlægget. Slamflokke fra både MBR og det tilhørende konventionelle aktive slam blev fulgt over driftsperioden med makroskopiske og mikroskopiske analyser. De makroskopiske analyser (målinger af flokstørrelse og -styrke) viste, at begge parametre ændrede sig som følge af shear-niveauet i MBR-systemerne. De mikroskopiske analyser omfattede målinger af sukker, protein og humus samt hydrofob interaktionskromatografi og størrelseseksklusionskromatografi. Disse viste ændringer i slammet, men ændringerne kunne ikke direkte tilskrives shear-niveauet. Trods nogle forskellige driftsparametre gav de to MBR-systemer sammenlignelige forsøgsresultater.

Interest in membrane bioreactors (MBR) for wastewater treatment has grown since the late 1980s, driven by the need to reuse water and stricter environmental regulations. A key barrier remains fouling—buildup and clogging on membranes—which reduces performance. This project examines the properties of sludge flocs in MBR systems, because these small clusters of microorganisms and particles are a main source of fouling. In MBRs, sludge flocs are typically exposed to higher shear (mechanical forces from mixing and flow) than in conventional plants, which is expected to affect their properties. Therefore, MBR sludge flocs were compared with conventional activated sludge. Two submerged MBR systems were used: a pilot unit at a municipal wastewater treatment plant and a lab-scale unit at Aalborg University, built to be comparable to the pilot. Sludge flocs from both the MBR and the associated conventional activated sludge were tracked during operation using macroscopic and microscopic analyses. The macroscopic analyses (measurements of floc size and strength) showed that both parameters changed as a result of the shear level in the MBR systems. The microscopic analyses included measurements of sugars, proteins, and humus, as well as hydrophobic interaction chromatography and size exclusion chromatography. These showed changes in the sludge, but the changes could not be directly attributed to the shear level. Despite some differences in key operating parameters, the two MBR systems produced comparable experimental results.

[This abstract was generated with the help of AI]

MBR ; Wastewater treatment ; Fouling ; MBR ; spildevandsrensning ; Fouling

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