emsi

Advantages: Low investment costs, simple construction
Disadvantages: Clearing away of inconvenient material (such as stones) can be troublesome. Some materials (e.g. long grasses) can cause motion of swimming layers.

Energy

Biogas

A combustible gas (composed primarily of methane) produced when sewage or manure is fermented in the absence of oxygen. The solid material that remains in the digester after fermentation can be used as an organic fertilizer...