APPLICATION OF ANAEROBIC PACKED-BED REACTORS
TO INDUSTRIAL WASTEWATER TREATMENT
G. K. Anderson, Senior Lecturer
Division of Public Health Engineering
University of Newcastle upon Tyne
Newcastle upon Tyne NE1 7RU
United Kingdom
T. Donnelly, Project Manager
K. J. McKeown, Director
Biomass International
Houston, Texas 77292
Industrial wastewaters, especially those from the food and beverage industries, may contain very high concentrations of biodegradable organic matter. If discharged into a freshwater body the overall effect is to remove the essential and life-giving dissolved oxygen by
chemical and biochemical reactions, and if discharged into a municipal sewerage system the
effect will be to overload the existing facilities at the wastewater treatment plant. Consequently, considerable pressure is applied, mainly through lesiglative means, to the offending industry to reduce this organic load by the most efficient and economic means available.
The initial choice available is that the biological treatment stage should be either aerobic or
anaerobic, or in some cases a combination of these two systems in series. Comparisons between the two systems have been made [ 1,2] and will not be elaborated on here.
Anaerobic digestion processes in their various forms are being actively considered for,
and applied in, a broad spectrum of industrial effluent treatment schemes throughout the
world. The onset of spiralling energy costs in the early 1970s coupled with an acute awareness of environmental pollution provided the incentive for intensive research and development of anaerobic fermentation in the United Kingdom, both in the public sector at universities and by the private sector as typified by the advances made in recent years at Biomass
International.
This research has led to the design, construction and operation of a number of anaerobic
systems which have been developed specifically to provide the industrialist with a cost-
effective, reliable and flexible method of effluent treatment and energy recovery. Before
considering the systems available and the various problems which may be encountered
during these reactions, the basic pathways of the conversion of proteins, carbohydrates and
lipids, to biomass, gases and other end-products should be shown (Figure 1).
The production of a valuable fuel (methane) from wastewater is an obvious attraction
since it can be shown that for every kg COD utilized about 0.35 m3 methane could be produced. There are also many other aspects of an anaerobic system which are possibly less
obvious but in many cases more attractive to the industrialist who is considering its use, and
these include:
L very low sludge production;
2. ability of biomass to lie dormant for several months and then be fully operational within
two to three days (of great value when seasonal wastewaters are to be treated);
3. capability of operation on a stop/start basis;
4. no environmental nuisance, since the process by its very nature is totally enclosed and
all the exhaust gas is either burned in a gas utility or an automatically controlled flare-
stack;
5. low nutrient requirement;
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