Treatment of Wastes from
Food Manufacture and Coffee Processing
R. K. CHALMERS, Parmer
Bostok Hill and Rigby
Public Analysts and Consulting Chemists
Birmingham, England
INTRODUCTION
Waste waters from food manufacturing are varied in nature and in strength.
Basically, however, all are more or less amenable to biological sewage-type
treatment. Troubles, when they arise, are almost always due to me excessive
strength rather than the nature of such wastes. Slaughterhouses, canneries, distilleries and some processing factories are well known sources of very strong wastes.
Even so, abnormal difficulties do not arise where discharges originate in cities
with large sewage treatment works. With trade waste discharges to small sewage
disposal works, on the other hand, the problems posed are usually substantial. In
the food manufacturing industry a great deal can be done to minimize the discharges at the source. Dry cleaning of plant, efficient washing of containers, exclusion of blood from slaughterhouse discharges and recovery of solubles from
distillery wastes are all cases in point.
When General Foods Corporation decided to move their Alfred Bird's British
factory from the City of Birmingham, Warwickshire, to the small town of Banbury,
Oxfordshire, they met the problem posed by a receiving sewage disposal works too
small for their waste waters, and had to reduce the problem at the source. This
caused a critical look at their wet processes, and since something had to be done,
it was done.
Trade effluents arose from the manufacturer of custard powders, jelly products,
dog food, rice products, and instant coffee. In Birmingham these effluents were
discharged, untreated, into the city sewers. There were no restrictions upon the
organic strength of the dishcarges, but acceptance charges were proportional to
the strength ofthe effluent, ana these were high -- 2s. 6a! per 1000 gals.
Such a trade discharge was acceptable at Birmingham, with a total sewage
flow at that time of 82 MGD, and a trade waste flow mat was substantially from
metal-finishing sources. The discharge was not acceptable at the much smaller
town of Banbury.
The effluent is a very strong organic waste.   As discharged at Birmingham it
had a BOD. of 6, 000 to 8, 000 mg/1.
o
When this work started in 1963 the dry weather flow at Banbury Sewage Disposal Works was 1. 5 MGD. Extensions were in progress to allow for: 1) Improvement of the effluent from the already overloaded sewage disposal works, and 2) A
population increase of four to 5, 000 people.
It was known that the untreated trade effluent from the factory could be
treated wholly at a sewage disposal works, given sufficient capacity. Its discharge
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