英文關鍵字
industrial
water
treatment
basin
winter
time
snow
waterworks
facility
pool
big
tube
pipe
bubbling
dirty
fluid
equipment
modern
technology
environment
aeration
pollution
sewage
recycling
factory
tank
waste
plant
purification
ecology
sludge
cleaning
bacterium
wastewater
processing
sanitary
nature
contamination
biomass
slimy
pipeline
polluted
recycle
toxic
organism
secondary
system
panorama