EFFECT OF INITIAL SUBSTRATE PH ON VERMICOMPOSTING USING PERIONYX EXCAVATUS (PERRIER, 1872)

In view of the growing awareness about vermicomposting technology in recycling different types of organic wastes, this study was conducted to investigate the effect of initial substrate pH on vermicomposting. The substrate pH and ash content were evaluated as a function of time. The data showed an exponential relationship between substrate pH and time of vermicomposting while a phase Bode plot of a single zero system relationship between the ash content and time of vermicomposting. The model parameters of these relationships also had very good correlation with the initial substrate pH. On the basis of obtained correlation between model parameters and initial substrate pH, generalized predictive models for the substrate pH and ash content have been evolved in terms of the duration of vermicomposting and the initial substrate pH. Plots of the predictive and experimentally observed values indicated a high robustness of predictive models. The study also revealed that the earthworm species Perionyx excavatus performs well in a wide range of substrate pH. Near neutral initial substrate pH was found to be optimal for stabilization of waste with minimal processing time. The substrates having strong acidic initial pH were found to be less suitable for vermicomposting.