Biogas is an alternative energy that can be used as gas fuel. In previous studies, biogas production using water hyacinth and vegetable waste produced a minimal volume of biogas compared to using cow dung as raw materials. Thus, to optimize the volume of biogas produced, in this study the raw materials of water hyacinth and vegetable waste were mixed with dry cow dung. In this study, there were three treatment variables, namely determining the optimal percentage of raw materials with fixed cow dung starter, determining the percentage of starter using the optimal percentage of raw materials, and determining the pH of the mixture using optimal raw materials and starters. To measure the volume of biogas used a miniature biodigester with a capacity of 600 ml with the fermentation method. The measurement of the volume of biogas is carried out every 24 hours and is stopped when there is no gas production for three days to obtain data on the volume of biogas per day and its accumulation. The result showed that the production of biogas with the percentage of raw materials
and 10% cow dung starter produced the highest volume of biogas for 4% water hyacinth and 6% dry cow dung of 817 ml
for six days, while for vegetable waste raw materials 5% and manure. dry cattle 5% 329.5 ml for six days. Making biogas
with cow dung starter percentage produced the highest volume of biogas for water hyacinth and dry cow dung of 817 ml
at 10% starter for six days, while vegetable waste and dry cow dung were 542.5 ml at 15% starter for six days. In the last treatment, biogas production with mixed pH variations produced the highest biogas volume at pH 7 for both raw materials for six days of 817 ml and 542.5 ml. Thus, the optimal percentage of raw materials for water hyacinth is 4% and dry cow dung 6% in 10% cow dung starter and a mixed pH of 7, while for vegetable waste raw materials 5% and dry cow dung 5% on a starter 15% and a mixed pH of 7