Dear Jacky,

Regarding your interest for the process (Figure 4: http:/ias.unu.edu/proceedings/icibs/ic-mfa/karki/fig4.jps) the followings are our reply and the comments.

(a) Waste water flows

The anaerobic digestion of the latrine waste will yield semi-liquid materials - both solid sludge and liquid effluent (also called biogas
slurry). In the beginning, it was visualized that biogas slurry would be collected into two compost pits. It was planned to mix organic residue with the biogas slurry in the compost pit by rotation. That is, when first pit is completely filled in with slurry and vegetable materails, it is left for about 3 months for decomposing and drying.Then, the same process would be continued in the second pit.

However, as you have rightly pointed out, the excess of liquid has created waterlogging conditions and it became imperative to drain out the liquid portion (waste water). For this purpose, an underground temporary waste water collection tank has been constructed.

(b) Solid Flows

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. However, for handling the compost, it must be pathoges-free (see below).

(c) Pathogens flows

This is the most important consideration as human faeces harbour pathogens and as the plant is located in water table area, there is every danger to pollute the underground water. Therefore, for water testing against pathogens two observation wells were erected to draw the sample for testing. The first test of underground water had revealed no pathogens. However, the test needs to be conducted periodically.

(d) Nutrient Flows

Good quality of compost can be made by treating the orgainc waste of human and animal original. Such compost which is very rich in plant nutrient contents has immense value for the farmers because they have to be not only dependant upon the imported and costly mmineral fertilizer but also they obtain valuable biofertizer on time locally.

We will be pleased to hear further comments and suggestions on this issue and request the participants for active discussions.

Best regards
Amrit & Upendra