NAMS 2002 Workshop - ICOM 2008

Membrane Fouling - General Topics – 5
Monday July 14, 11:45 AM-12:15 PM, O’ahu
Scale-up of Lab Investigations on Fouling in MBR Potentials and
Limitations
M. Kraume (Speaker), Technische Universität Berlin, Chair of Chemical Engineering, Germany,
matthias.kraume@tu-berlin.de
D. Wedi, Engineering Office ATM
T. de la Torre, Berlin Centre of Competence for Water
J. Schaller, Technische Universität Berlin, Chair of Chemical Engineering, Germany
V. Iversen, Technische Universität Berlin, Chair of Chemical Engineering, Germany
A. Drews, Technische Universität Berlin, Chair of Chemical Engineering, Germany
Objective Despite the large number of publications, membrane fouling still is not
well understood due to the complexity of the interacting phenomena and the
multitude of module and reactor configurations as well as wastewaters and
operating conditions. To reduce the number of influencing factors, often lab trials
are carried out where only the parameter of interest is to be varied. These are
either filtration experiments (e.g., filtration mechanisms, fouling rate) carried out
with real or model feeds, biological investigations (e.g., soluble microbial
products (SMP) occurrence), a combination of both (e.g., fouling propensity of
SMP formed under different conditions) or concern suited cleaning protocols.
However, the outcomes of such studies are frequently inconsistent or even
contradictory. The representativeness of conclusions drawn from such trials is
thus highly questionable - both quantitatively and qualitatively. In the light of such
contradictions, this paper aims at answering the question how representative of
full scale operation lab trials are or indeed can be, i.e., what can be expected
from them at all considering their inherent differences from technical operating
conditions. Summarizing the different experiences, guidelines for a ‘good
laboratory practice’ will be derived concerning appropriate experimental set-ups
and corresponding test protocols.
Results
Initially, types of experiments and distinct differences are analyzed. In the
second part, results from own experiences in lab (1-140 L), pilot (1.5 m³) and full
scale (250-9,200 p.e.) together with data from literature are exemplarily
discussed to highlight potentials and limitations of different experimental
approaches. In general, lab scale experiments are an indispensable tool for
fundamental fouling research. With regards to their value and applicability to full
scale it will be stated that: · Properly done short-term experiments based on
suited protocols can be used to characterize the filterability and the relative
fouling propensity of different sludges. The absolute values of measured fouling
rates, however, are never appropriate to describe long-term operation in full