206 madras fisheries bulletin vol. xiii, 



Effluent Water. 



98. This is not a commercial but a technical product, the 

 utilization of which is a matter of difficulty, while if not utilized 

 it is either wasted or is a source of nuisance. The following 

 remarks do not apply to the waters used daily for washing out the 

 factory, but to the waters proceeding from the fish themselves and 

 from the boiling pans and presses. 



In boiling the fish a considerable quantity of water is necessary 

 and this, added to that in the fish tissues (about 70 per cent of the 

 weight of the fish), means a large quantity of water issuing from 

 the presses and receiving pits, and this water contains an appreci- 

 able quantity of organic matter especially when coarse-meshed 

 coir bags are used. Owing to the organic contents (albuminous, 

 gluey), etc., this effluent water, even when fresh, possesses a some- 

 what unpleasant odour, and when stale rapidly becomes a nuisance 

 owing to putrefaction. In most factories the water is sent straight 

 into the sea ; in America the factories are either on the shore or 

 even built out over the water, so that the effluent water and useless 

 refuse are readily and safely disposed of. On the Madras West 

 Coast nearly all factories are on the edge of the beach and the 

 water is, or should be, easily serit into the sea. But it is not 

 uncommon, especially when the sea has receded (as at Tanur) or 

 the monsoon has flung up sand ridges, for the water to be passed 

 into the deep sand of the beach where it putrifies and causes a 

 serious nuisance, not necessarily, or even probably, dangerous to 

 health but objectionable from its foul odour. But the very cause 

 of the nuisance, viz., the presence of organic matter, shows that the 

 water may be a by-product of some value and should, if possible, 

 be utilized. In America it is reported (R. L. Greer) that a consi- 

 derable amount of sediment collects at the bottom of various 

 separating tanks, especially of the " catch-all " tanks into which 

 all effluent waters are sometimes run for the saving of any oil or 

 material. The solid sediment, called " gurry," is removed, 

 pressed, and the cake added to the general mass of guano ; the 

 water is run into the sea. But in one factory (perhaps in several 

 according to other information) it has been found possible to 

 evaporate the " stick-water " (effluent water) till a pasty residue 

 (" stick ") is obtained which contains about 9 per cent of ammonia 

 { = 7^4 per cent nitrogen). Whether the evaporation of such a 

 mass of water gives profitable results seems doubtful though it 



