英文關鍵字
background
bad
biological
canal
casing
chemical
contaminants
corrosion
cure
danger
defective
dirty
drain
drainage
dump
ecology
effluent
environment
environmental
factory
flow
flowing
garbage
industrial
industry
life
liquid
natural
pipe
pipeline
plant
pollution
river
rust
rusty
sewage
sewer
smell
stream
substance
technology
toxic
treatment
tube
unhygienic
waste
wastewater
water