In modern industrial practices, wastewater as a commodity has now become a potential resource rather than a disposable by-product. If treated efficiently, it can be reused at any stage along the production chain. Not only does it provide a cost-efficient water supply alternative, but it also helps relieve the pressure on freshwater consumption.
Wastewater Treatment is the process of removing suspended and dissolved contaminants from wastewater so that it can either be used again or so that the effluent parameters are reduced to environmentally acceptable levels before being disposed of.
The different wastewater treatment processes are as follows:
Suspended Solids Removal
Suspended solids are small, insoluble particles present in the water as suspension. Suspended Solids Removal is carried out through the use of clarifiers, which filter out the relatively large as well as dense particles through the process called sedimentation.
Sedimentation quality is verified based on the tank depth, wastewater properties, temperature, overflow rate, detention period, properties & the size of suspended solids.
Colored wastewater, which can either occur due to the introduction of chemical dye or due to the decay of organic matter, may result in the water becoming unusable, even after treatment, which can be resolved through the process of color removal.
Coagulation-flocculation, photo catalysis ion-flotation, and degradation are the different methods that can be applied. Coagulation-flocculation is a commonly used process that treats wastewater with the use of chemicals like lime, ferric chloride, alum, and ferrous sulphate.
pH control is a critical process in the treatment of wastewater as it improves (as well as maintains) the quality of the water supply along the manufacturing pipeline. The set point for the pH value is determined based on the future utilization of the treated water.
The process is implemented with the use of a treatment tank, pumps’ mixer, pH controller and probe, discharge valve, and level sensor. The process is carried out at the initial stages of wastewater treatment.
The formation of foam in clarifiers, digesters, and aeration tanks, is a significant issue in the sewage treatment plants, which results in operational inefficiencies during wastewater management.
Foam control is implemented by the introduction of surfactants and hydrophobic particles. The surfactant collects on the hydrophobic particles, while the particles themselves line up at the water-air interface to form a film of water between air bubbles, thus stabilizing the foam.
By reducing contaminants in wastewater, microorganisms in the activated sludge act as an aid in wastewater treatment. This treatment method helps in the removal of contaminants organically.
Bioaugmentation is the process by which certain microorganisms that promote further decomposition of water pollutants are added to the sludge to support water treatment.
While some microorganisms aid in wastewater treatment, other microbes act as deterrents, or are harmful if the water is to be consumed.
To reduce the microbes in the wastewater, processes like sanitation, disinfection, decontamination sterilization or antisepsis can be implemented. These processes can be microbe-specific, like antisepsis, and can be implemented to make the water safe for commercial use (decontamination) or to make the water potable (sanitation).
Heavy Metal Control
In current times, heavy metal control in wastewater treatment is an even more essential process to ensure that the water isn’t hazardous to the environment & the ecosystem.
Flotation, chemical precipitation, adsorption, electrochemical deposition, and ion exchange are the different processes that can be implemented, amongst which chemical precipitation is the most conventional method.
Through the process of sludge dewatering, sludge is separated into solid and liquid components. It is carried out to optimize further waste disposal processes as well as improve its cost-effectiveness.
Gravity thickening, flotation, centrifugation, and gravity belt thickening are the types of processes that can be implemented in sludge dewatering.