inside modern wastewater treatment plant. closed sewage reservoir with dirty water

bacterium basin chemical clean cleaning dirty drain ecology effluent environment environmental equipment facility factory filter filtration flotation flow greywater heat industrial industry inside machine metal modern pipe pipeline plant pollution pool processing pump purification purified purity recycle recycling reduce removal reservoir sanitary sanitation sedimentation separation sewage sewer sludge smell steel tank technology treatment tube turbidity valve vat waste wastewater water