Biological treatment of swine wastewater—Conventional methods versus microalgal processes

Background: Swine wastewater (SWW) contains abundant organic carbon, nitrogen, and phosphorus, posing a significant risk of pollution and eutrophication with direct environmental release. Therefore, its proper treatment before environmental release is imperative. Conventional SWW treatment methods like stabilization ponds, aerobic processes, and anaerobic digestion are energy-intensive, with limited nitrogen and phosphorus removal and challenges in secondary sludge disposal. Methods: Conventional methods described above, in addition to bacterial methods, have been discussed in detail. Microalgal bioremediation is an emerging technology for bioremediation and resource recovery from a circular economy perspective. Significant findings: Conventional methods are dissimilatory and do not recover nutrients. On the other hand, the nutrients in SWW serve as a beneficial growth medium for microalgae. With its suitable nutritional composition, the resulting microalgal biomass can serve as supplements for livestock and aquaculture feed, generating additional revenue in microalgae-based SWW treatment. Microalgae-based processes enhance the SWW treatment efficiency and mitigate the common issue of secondary sludge pollution found in conventional treatment methods. This review offers comprehensive insights into traditional and microalgae-based SWW treatment methods and provides a comparative analysis of the various techniques and future research perspectives.