Combining vermicomposting with pre-composting
Figure 2 illustrates that growth of E. andrei was
retarded when fed on pre-composted waste compared
to fresh waste. Neuhauser et al. (1988) aerobically
digested and then aged sludge prior to feeding to
E. ,fetidu. The effect of the initial digestion on worm
growth was not investigated but ageing sludge for
between 3 to 12 weeks, reduced growth rates from 18
to 14 mg worm ’ d ‘. In our study, composting the
waste for the first 2 weeks significantly reduced
growth rates from 14 to 10 mg worm-’ dm’. There
was no significant difference in growth when fed the
2-week compared to the 4-week pre-composted
material suggesting that the nutritional content of the
waste was most rapidly decreased during the very
early stages of composting. As shown in Fig. 3,
reproduction was also related to the extent of
pre-composting that the wastes received. Microorganisms
are known to be important in the diet of
E.,fetida (Edwards and Fletcher, 1988), and it is likely
that the progressive reduction in the volatile solids
content of the wastes would also have reduced
microbial biomass thereby retarding growth and
reproduction.