Wastewater Treatment Technologies

Wastewater treatment technologies have received steadily greater attention across the world in response to environmental, economic, and societal limitations increasingly posed by conventional wastewater systems. Most all-modern wastewater treatment plants consist of primary treatment, secondary treatment, tertiary treatment, zero liquid discharge (ZLD), and sludge dewatering units. Primary treatment consists of the following components: screening, oil and grease trap, equalization, coagulation, primary clarification, and dissolved air flotation. Secondary treatment of wastewater is classified into three categories: biological treatment, advanced oxidation treatment, and membrane treatment. Tertiary treatment consists of the following processes: disinfection, pressure filtration, and demineralization. Concerning sludge treatment process selection, the "zero landfill" concept should be applied so that no waste is sent for disposal to landfill or to incineration without energy recovery: therefore waste is either totally eliminated at source or recycled off site. ZLD is a wastewater management system that ensures that there will be no discharge of industrial wastewater into the environment.