The study revealed that the pH of cow-dung slurry at the beginning was ; neem-cake, and pongamia-cake, suggesting significant differences in pH among the bio-gas substrates used. Two months after anaerobicdigestion, there was increase in pH with increase in the proportion of cow-dung and also increase in total-N and P in biogas spent slurry after anaerobic-digestion. There was no definite trend with reference to total-K. |