Environmental aspects Sewage Purification 19 Waste disposal 5 Water 5 Biological treatment 4 Heavy metals 4 Heavy metals removal 4 Sewage disposal plants 3 Activated sludge process 2 Analysis 2 Drugs 2 Electroplating industry 2 Greenhouse gas mitigation 2 Greenhouse gases 2 Measurement 2 Research 2 Textile industry 2 Absorption and adsorption 1 Adsorption 1 Biodegradation 1 Bioremediation 1 Carbon 1 Carbon nanotubes 1 Carbon, Activated 1 Computational intelligence 1 Dairy products industry 1 Design and construction 1 Dosage forms 1 Drainage 1