**Notes/thanks/other declarations**

Praise and gratitude for the presence of Allah SWT who has bestowed His mercy and grace so that the author can complete the part of the book with the title Biogas Production from Water Hyacinth chapter. In completing this chapter, we would like to thank the Environmental Engineering Diponegoro University and the water hyacinth biogas research team for their guidance and support. We hope the research that has been done can bring benefits to all people.