ABSTRACT
Conventional wastewater treatment mainly emphasizes on primary (physical, chemical), secondary (biological) and tertiary (filtration and disinfection) processes in the treatment facilities, based on these some conventional as well as advanced treatment methods such as activated sludge process, sequential batch reactor, membrane bioreactor, moving bed biofilm reactor and up-flow anaerobic sludge blanket reactor are devised. But treated wastewater from most of the treatment methods still have a significant concentration of inorganic N and P and further generation of huge amounts of sludge limits the applicability of these methods.
Microalgal remediation can be integrated in to conventional and advanced methods to provide efficient, sustainable and affordable solutions that would be applicable not only to high-income and upper middle-income countries but also in lower middle-income and low income countries. Further secondary treated wastewater could be used to cultivate microalgal biomass. For the cultivation of microalgal biomass, there are suspended systems (open ponds, closed photobioreactors, hybrid), immobilized systems (matrix-based, microalgal bio-films) and latest innovative submersible algal cultivation technology. After cultivation, microalgal biomass is harvested by mechanical, chemical, electrical and biological methods; further biomass is valorized that mainly involves thickening and dewatering.
