59    COMPARISON OF PILOT- AND LABORATORY-SCALE
UPFLOW ANAEROBIC FILTERS TREATING DAIRY
WASTEWATER
B. Kasapgil, Senior Research Associate
G. K. Anderson, Senior Lecturer
O. Ince, Senior Research Associate
Department of Civil Engineering
University of Newcastle upon Tyne
Newcastle upon Tyne
United Kingdom NE1 7RU
INTRODUCTION
A considerable effort has been made in order to develop the anaerobic digestion processes specifically for treating industrial wastewaters. With the present state of process technology, anaerobic
digestion represents an attractive alternative to aerobic processes which do not only have high-operating costs but also generate large quantities of excess sludge and which, in turn, is costly to dispose.
Anaerobic processes offer the potential for energy savings and an ability to operate at organic
loadings far in excess of equivalent types of aerobic reactors, which will ultimately result in more
economic industrial wastewater treatment. Industrial dairy plants in the U.K. generally have a large
waste load to treat and dispose of consisting of medium strength wastes containing soluble, colloidal
and suspended solids with a concentration of BOD which is often too high for conventional aerobic
treatment.
Domestic sewage, molasses distillery, pharmaceutical, dairy, vegetable processing, slaughterhouse
and synthetic stillage wastewaters were widely studied using anaerobic upflow filters by Young and
Dahab (1983), Genung et al. (1982), Riera et al. (1982), Sachs et al. (1982), Arora and Routh (1981)
and Perkins et al. (1975).3-4-6*9*10-14 Pohland and Malina (1992)7 reported that anaerobic upflow filter
processes were applicable to wastewaters with low (>1000 mg/L COD) to intermediate (< 20,000
mg/L COD) concentrations. However, much higher COD loads applied in full-scale anaerobic filters
with above 80% COD removal efficiencies have been reported by Anderson et al. (1986), Seyfried and
Austermann-Haun (1990), and Racault (1990).I,8,n The treatment of both strong and weak organic
effluents was also demonstrated by Newell (1981) with up to 85% COD removal, while 90-99% COD
removal from dairy wastewaters using anaerobic filters was reported by Stafford and Etheridge
(1983).12 Organic loading rates of up to 16 kg COD/m3.d in full-scale anaerobic upflow filters were
reported by Young and Yang (1986).15 Laboratory- and pilot-scale upflow filters have been operated
at hydraulic retention times (HRT) values of three hours to several days and at organic loading rates
of 0.4 to 27 kg COD/m3.d (Henze and Harremooes, 1983).5 Full-scale industrial applications employ
HRT values in the range of one to ten days and COD loadings from 4 to 16 kg COD/m3.d (Switzen-
baum, 1983).13
The design of an anaerobic digester unit has normally been based on loading rates and retention
times criteria. Scaling-up to full-scale installation, in practice, is based upon experimental data of
treatability/feasibility studies obtained at either laboratory- or pilot-scale reactors. However, fluid
flow pattern, organic loading rate, solid retention time, microbial growth rate, microbial attachment,
etc., would differ within small and large reactors. Therefore, pilot-scale studies are extremely useful
in data collection and would enable the selection of plant items such as pumps, heaters, etc. After a
satisfactory laboratory-scale study had been carried out, a pilot-scale investigation on the treatment of
a dairy wastewater using upflow anaerobic filter was studied. This paper will therefore outline a
comparative study on performance of laboratory- and pilot-scale upflow anaerobic filters treating a
wastewater from a milk bottling and cream packaging plant.
49th Purdue Industrial Waste Conference Proceedings, 1994 Lewis Publishers, Chelsea, Michigan 48118. Printed in
U.S.A.
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