Biodigester design for cow farm

Hello. I am looking for info (design / costs) on biodigesters for a small rural enterprise: a small cow farm also producing cheese. The objective would be both to treat animal faeces, produce compost, but also to produce gas, with two options: using gas for converted petrol engines (quite common in rural Brazil), or production of hot water and steam for cheese production. Would you know of existing experiences / designs? Thank you!