55    IMPROVEMENT IN PERFORMANCE OF AN ANAEROBIC
CONTACT DIGESTER USING A CROSSFLOW
ULTRAFILTRATION MEMBRANE TECHNIQUE FOR
BREWERY WASTEWATER TREATMENT
O. Ince, Research Associate
G.K. Anderson, Senior Lecturer
B. Kasapgil, Research Associate
Department of Civil Engineering
University of Newcastle upon Tyne
United Kingdom
INTRODUCTION
Membrane technologies which are applied to water and wastewater treatment systems are of recent
interest in environmental engineering, particularly in product recovery from wastes from agro-
industries and in the separation of biomass from the effluent in biological treatment systems.
Its potential application in anaerobic treatment systems is related to the need for retaining an
adequate quantity of active biomass which has always been one of the major problems encountered in
completely mixed biological reactors.
Higher organic loading rates can be achieved in the treatment of industrial wastewaters using
anaerobic techniques than by aerobic systems which have always been limited by problems such as
adequate oxygen transfer, settling of biomass, excessive sludge production, stability under load
changes and economic considerations. However, a major problem encountered in most anaerobic
treatment systems is the retention of a sufficient quantity of active biomass. The retention of a higher
concentration of biomass in a digester will give improved digester performance in terms of gas
production and improved effluent quality.
Various methods have been reported in a wide range of reactor configurations for the separation of
biomass from final effluents.1"9 However, in full-scale applications these methods have been limited
by the settling problems of biomass particularly at high concentrations. For example, the anaerobic
contact process was the first of many advanced anaerobic digester technologies but settlement of
biomass does not occur when the concentration of mixed liquor suspended solids in the digester
exceeds 10 g/L. This has restricted its application in the treatment of high strength industrial wastewaters for economic reasons.
In order to overcome the above problems the membrane anaerobic reactor system has been developed which has resulted in many advantages compared to other systems, some of which are summarized below:
1. It enables the retention of a high concentration of active biomass thus minimizing the
required reactor volume,
2. it prevents biomass loss in the effluent resulting in greater stability under load changes
and variations in influent characteristics,
3. it provides an effluent almost free of suspended solids,
4. it eliminates the need for a sedimentation tank thus minimizing the biomass separation
problems caused by system overloads which in turn is a major problem inherent in
suspended growth processes and
5. it enables positive control of solid retention time (SRT) and hydraulic retention time
(HRT).
This paper will, therefore, discuss the performance of a newly developed crossflow ultrafiltration
membrane anaerobic reactor system (CUMAR) at very high biomass concentrations for the treatment
of wastewaters from typical food and drink industries.
48th Purdue Industrial Waste Conference Proceedings, 1993 Lewis Publishers, Chelsea, Michigan 48118. Printed in
U.S.A.
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