aerial view
biological treatment
circle
circular
clean
dirty
ecology
effluent
environment
environmental
facility
factory
filtration
industry
plant
pollution
process
purification
purified
purity
recirculation water
recycle
recycled
recycling
sanitary
sedimentation
sedimentation tank
separation
sewage
sewage treatment
sewer
sewerage
station
system
tank
technology
treatment
treatment plant
waste
wastewater
wastewater treatment
water
water aeration
water cleaning