Abstract
In this chapter, detailed descriptions of four typical systems are presented including “Six-in-One” biogas system (SIOBS), biogas-persimmon cultivation and processing system (BCPS), wastewater treatment plants (WWTPs), and the “Three-in-One” biogas project (TIOBS). The similarities and differences of how it is constructed, operated, and maintained are addressed. Besides, the unique characteristics are also depicted, containing digestate process in SIOBS, digestate reuse, and biogas utilization for persimmon cultivation in BCPS, biogas–sludge use in WWTPs, and comprehensive utilization in TIOBS.