biogas

sludge

produce

natural

organic

material

fuel

special

tank

sewage

water

treatment

remains

digester

storage

rot

producing

equipment

industrial

remain

bio

process

machine

step

industry

store

tube

pipe

steel

biofuel

outdoor

generator

ecology

waste

plant

big

sedimentation

building

huge

purified

factory

utility

flocculation

static