Figure 8 shows the gas production from poultry waste in four slots of hydraulic retention time. In first slot from 0-10 day’s maximum amount of gas about 25% is produced. From 1120 days gas production decreases to about 22%. In the third slot from 21-30 days the gas production is about 18%. From 31-40days gas production increases slightly to about 21%. From 41-50 days gas production decreases to about 12%. Finally, from 51-54 days gas production reduces to about 1.8% and gas production almost ceases after the 54thday. 3.3. Water Hyacinth as Fermentable Material Figure 9 shows the gas production from water hyacinth. The average digester temperature was about 32ºC. It shows that the hydraulic retention time for water hyacinth is about 36 days and gas production starts at the 4th day. Maximum gas is produced at the 26thand 27thwhich is0.012 m3.