機器
aerial
air
aircraft
bacterium
biology
biomass
circle
cleaning
construction
dirty
ecology
environment
europe
facility
factory
flight
flow
fly
garbage
industrial
industry
manufacture
manufacturing
plant
poland
power
process
processing
production
purification
purified
purity
recycle
recycled
recycling
reduce
removal
road
sewage
sludge
smell
station
tank
treatment
tree
unpleasant
urban
view
waste