abominate
bacterium
biology
biomass
circle
clean
dirt
dirty
disdain
ecology
engineering
environmental
excremental
excretion
factory
foul
garbage
global
industry
nasty
natural
nature
plant
plastic
pollute
pollution
processing
protection
purity
recycle
reduce
reflection
refuse
repulsive
responsible
rubbish
sedimentation
sewage
smell
trash
treatment
unhygienic
warming
waste
wastewater
wastrel
water