英文關鍵字
water
pipe
sewerage
waterfall
toxic
pollution
environment
concrete
stream
wastewater
garbage
channel
rusty
industry
pipeline
leak
dirty
liquid
rivers
ditch
rust
chemical
background
bio
gas
purify
danger
discharge
sewage
ecology
energy
plant
industrial
nature
oil
production
sanitation
sludge
system
technology
treatment
consumption