sealed plastic septic tank

Yube Boitumelo Siyangaphi, Joseph Kabimba and Kebonyemang Mashabe and I have built a three stage biodigestor at the worker's camp at CSU base camp, Selinda wildlife reserve, Botswana. It consists of a fiberglass-sealed 1000 liter horizontal digestor tank (primary digestor), a 200 liter used steel oil drum with a telescoping gas collector made from a second oil drum, chopped in two (with 5 cm cut out all around) and then brazed (torch welded) back together so it fits inside the first drum (5 leaks had to be patched with metal expoxy).