SANITAKY NOTES. KHARTOUM 
Trenching 
ground 
Septic tank 
system 
Sewage farm 
7.S 
The place of final disposal, both at Khartoum and Khartoum North, is shown on the 
map {piiije 75). At Khartoum it is well away from the town, lies in an out-of-the-way corner, 
and the land drains towards the White Nile away from what may eventually he the town 
water supply, which is about 34 miles distant from the trenches. 
The chief disadvantage to the place, which is the only suitable one, is that if the Nile 
again rose to its highest maximum, a small portion of the trenching area would be submerged. 
As a rule the water level does not come nearer than a quarter of a mile to the most westerly 
line of trenches. 
The deep four-foot trenches previously in use have been abandoned for shallow trenches 
about 18 inches deep, 16 feet long and 3 feet wide. Nine-inch trenches were tried, but were 
found too shallow. 
Even with proper trenching, flies breed out in great numbers, and the surrounding ground 
on which the buckets are cleaned is fouled. To some extent this can be remedied by spraying 
with formalin and by drenching the surface soil with the hot water in which the buckets are 
washed. This is derived from the refuse destructor, into which boilers were fitted, a good 
supply being available. The buckets receive a final wash in a disinfectant and deodorant 
solution. 
So far, the weak spot in this disposal scheme has been the absence of any attempt at 
cultivation. A large area of soil, about eight acres in all, has been trenched, but there has not 
been a sufficient supply of water to enable us to grow such crops as might be utilised in the 
feeding of the municipal animals. Moreover, wages being comparatively high and a consider¬ 
able number of men having to be constantly employed in digging and filling in the trenches, 
the annual cost of this method is hy no means insignificant. It was with a view to obviate 
these disadvantages, and at the same time to carry out some experimental work likely to be 
useful in the future, that I devised a plan of treating the sewage by a septic tank process. 
I am not aware that such a scheme has been previously attempted with a so-called dry earth 
system. I hoped it might serve because, as stated, very little earth is used in the pails. At 
the British Barracks, wdiere we have taken over the conservancy, izal is employed, and sand is 
used by the majority of British residents, hut elsewhere this is not the case owing to the lavage 
practised by Mohammedans. Hence the sewage may be described as semi-liquid, containing as 
it does a considerable quantity of sullage water. Again I thought that by using iron tanks 
exposed to the full power of a tropical sun, great heat would be generated, tending to produce 
rapid biological action and a speedy liquefaction of the solid part of the sewage. It was evident 
that labour would be saved, that the building of a good cleaning platform of brick and cement 
would prevent folding of the surface soil, and that the disjiosal of the excreta would take place 
much more rapidly—a matter of some import. At first an open and a closed metal tank were 
used, and the pail contents were diluted with water derived from a well served by a hand pump, 
the proportion being 1 of sewage to 3 of water. It was remarkable what a good effluent could 
be obtained in 48 hours, and how little sludge remained. The effluent was quite good enough to 
he run directly upon the soil, and several crops of dura were grown on the land irrigated by it. 
Unfortunately, the smell from the open tank constituted a nuisance when the wind shifted to 
the south, and, as one was anxious to test a brick and cement tank against an iron tank, one 
ot the former type was erected and the open metal tank was converted into a filter tank. 
All this took time to arrange and complete, and hence I am unable to give any full account 
of the results obtained. It is evident, however, that to make the process a success, an engine 
and pump to furnish sufficient water from the well wull be a necessity. It is essential that the 
pail contents be diluted. One has tried keeping the crude pail contents in the brick and 
cement tank. Liquefaction certainly takes place, and there is not a great deal of sludge, but 
the effluent is strong, and speedily undergoes offensive decomposition. 
