Characteristics of organic wastes 51It can be taken away by water in a flume or taken away by a conveyor. The feathers
can be reused as a material for mattresses.
Next the heads, feet and innards are removed. The removal of innards is done by
hand and they are disposed of by a wet or dry viscera line. In a dry line the innards
are removed and taken to a disposal skip by conveyor or by vacuum. In a wet line
they are taken by a water flume to be separated later.
The final stages are washing by a fixed amount of water per fowl, then spin
chilling and freezing or washing (with the addition of chlorine for disinfection),
drying and vacuum sealing.
The following are the possible causes of pollution in the poultry processing
effluent:
- Blood - if not recovered; this has a high BOD 5.
- Feather water and flume: if a wet flume is used, this can have a high
proportion of dissolved or emulsified fats. - Wet viscera: requires screening to remove the solid matters.
- Wash and spin chiller discharge: note that chlorine is introduced in the
wash water.
Characteristics of slaughter house and meat-packing wastes
Effluents from slaughter houses and meat-packing houses are usually heavily
polluted with solids, floatable matter (fat), blood, manure and a large variety of
proteinaceous compounds. The composition depends very much on the type of
production and facilities. The main wastes originate from lairage, killing, hide
removal or dehairing, paunch handling, rendering, trimming, processing and
clean-up operations. The BOD 5 and solids concentrations in the plant effluent
depend on in-plant control of water use, by-products recovery, waste separation
at the source and plant management.
When considering effluent disposal, the first consideration is water
consumption. The range of wastewater production from abattoirs is 5-15 m^3 /ton
live weight. For the poultry industry a typical discharge lies between 10 and 55
L per bird (Brolls and Broughton 1981).
In terms of BOD 5 , typical loads from abattoirs and meat processing are 6-12
kg/ton live weight at UK abattoirs, usually at a concentration of 1,000 - 3,000
mg/L. From poultry packing, the effluent is normally about half the strength of
the abattoir wastewater, with a BOD 5 content of 13-23 kg/1,000 birds (Brolls
and Broughton 1981)
Some characteristics of slaughter house wastewaters, as reported by Brolls and
Broughton (1981), are given in Table 2.17, while those of meat-packing wastes are
given in Table 2.18. Table 2.19 shows the wastewater characteristics of a poultry
processing plant in Thailand.