Plastic tubular digesters were adapted to Andean conditions by
providing digesters insulation and substituting a simple roof used
in Tropical regions by a greenhouse. In this manner, the liquor
temperature remained fairly constant at around 20 C [24,31].
Nevertheless, the systems remained within the psychrophilic
temperature range, and produced less biogas than mesophilic ones,
i.e. digesters located in Tropical regions