**3. Conclusions**

Water hyacinth was considered as waterweed, which has become a problem that damaged the environment, the system irrigation, and agriculture. Water hyacinth leaves that contained cellulose, nitrogen, essential nutrients, and high fermentation contents can be used for biogas production. The use of the L-AD method with TS 3.38% produced the most biogas yields than using the SS-AD method with TS 24.13 and TS 17.67 or the L-AD method with TS 6.76%, with the amount of biogas yield for TS 3.38% was 369 ml/g TS.

Based on the results of research on the effect of the C/N ratio on biogas productivity using L-AD method, the optimum C/N ratio was found in the C/N ratio 30 with the resulting biogas yield of 157.544 ml/g TS. The optimum C/N ratio for biogas production from water hyacinth leaves using the solid-state anaerobic digestion method was 32.09.
