The aim of effluent treatment is to enable wastewater to dispose safely, without being a danger to public health and without polluting water sources. Increasingly another important aim is to reuse treated wastewater. A treatment system consists of a combination of unit processes to reduce wastewater contaminants to acceptable level.
Preliminary treatment,sedimentation,biological treatment,disinfection and sludge treatment are important stages of a treatment plant. Biological treatment is to transfer dissolved organic content from soluble form to suspended matter in the form of cell biomass. Aerobic and anaerobic processes will be used depending on the effluent characteristics. Process selection depends on factors such as effectiveness in removing particular contaminant, sludge generation, complexity, energy requirements, construction costs and operation & maintenance costs.
Zero liquid discharge system consists of additional advanced systems consisting of membrane system and evaporation plants.