Jacky Foo [foo@SWIPNET.SE] asked
>In your paper you wrote:
>>The community latrine was put for common use with effect from
>>15 March 1998. It is visited by 250 regular and 35 occasional
>>users per day. With about daily available 115 kg of human excreta
>>as raw material for feeding the biodigester
>
>how much of solids (estimated or measured) do you think will
>leave the digester into the compost pits ?

With daily input of about 115 kg of human feaces , the daily output is expected to be around 80 kg solid materials (i.e. 70 percent of the daily input).

>>The solid sludge that is mixed with vegetable residues is planned
>>to be used by the agricultural community to fertilize their soil or it to
>>fertilize horticultural plants or to raise forest nursery.
>
>(c) how much of vegetable residues are put into each compost pit ?

The quantity of the vegetable materials to be used for compost making should be around five times more than the quantity of available slurry. This means, for 80 kg of slurry or effluent produced per day about 400 kg of vegetable materials will be required for making compost.

>>As planned, two compost pits with dimension of 1.5 m x 1.5 m x 8 m
>>were constructed close to the biodigester for collection, treatment
>>and utilization of slurry as fertilizer. The design and construction of
>>twin compost pits permit to fill and empty each pit by turn. Thus,
>>in case the first pit is filled in completely, it is left for drying for
>>couple of week and the use of the second one is done
>
>Q: is a compost pit 1.5 m x 1.5 m x 8 m or is this the total
>measurement for both the compost pits that are beside each other ?

There are two compost pits close to the digester. Each of the compost pit will measure 1.5 m x 1.5m  x 8 m  for collection and for mixing the slurry and vegetable materials for making compost. Thus, the total volume of the two compost pit would be around 3.6 cu.m (1.8 cu.m x 2). Let us calculate the whole thing as follows:

Production of slurry/effluent per day = 80 kg day
Addition of vegetable materials         = 400 kg/day
Total materials for composting per day = 80 kg + 400 kg = 480 kg/day
Total quantity of materials (slurry & vegetable materials) for composting per year = 175 Metric ton

>(d) how much of solids did you get out of each compost pit when
>the compost matured ?
>
>(e) how much of these go to the watchman's vegetable garden and
>how much of this go to the forest / horticulture nursery ?

Assuming that about 40 percent volume will be reduced when the compost will get matured, roughly 100 metric tons of the matured compost will be available for use as fertilizer. Out of this amount of  fertilizer, the watch uses only a small fraction, say about 10% and 90% is supposed to be distributed to the farming community for fertilizing their soils.

Best regards
Amrit & Upendra