Comparative Phycoremediation Performance of Three Microalgae Species in Two Different Magnitude of Pollutants in Wastewater from Farmhouse

Abstract

The cultivation of microalgae using urban wastewater as a nutrient substrate represents a promising bio-refinery concept that can serve multiple purposes; indeed, it allows for the generation of biomass, which can be used for various applications while meanwhile removing nutrients from wastewater. In this study, the potential of urban wastewater collected at two different time periods in a farmhouse as a nutrient substrate for microalgal growth was assessed. Wastewater samples were treated on a laboratory scale, inoculating reactors with two common species, Chlorella vulgaris (CV) and Scenedesmus quadricauda (SQ), and with an autochthonous strain of Klebsormidium sp. K39 (Kleb), directly isolated from effluents of the same system. The main aim of the study was to compare the microalgae’s performances in terms of wastewater re-mediation and biomass productivity. In the first case study, which involved an effluent with a lower pollutant level, microalgal cultivation showed removal efficiencies in the range of 57–63% for total nitrogen, 65–92% for total phosphorous, 94–95% for COD, and 100% for E. coli. In the second case study, involving an effluent with a higher pollutant level, the remediation performances of the three microalgae strains ranged from 93 to 96% for total nitrogen, from 62 to 74% for total phosphorous, from 96 to 97% for COD, and 100% for E. coli. At the end of the experimental trials, treated waters showed values of pollutants suitable for irrigation use, in accordance with environmental and national legislation, which established specific thresholds for irrigation purposes.

Current challenges of microalgae applications: exploiting the potential of non‐conventional microalgae species

“…Nowadays, the biotransformation of pollutants from wastewater, as xenobiotics, nutrients and CO 2 from polluted air by macroalgae or microalgae is known as phycoremediation. The main aim of the phycoremediation is to depurate wastewater for irrigation or other aims and concurrently, exploiting wastewater as growing medium based on the high concentration of nitrogen and phosphorus 108 . Also the organic‐rich anaerobic digestate, which is difficult to be purified by conventional techniques, is appropriate to be used as a low‐cost nutrient source for the economic viability and sustainability of microalgae production 109 .…”

“…The main aim of the phycoremediation is to depurate wastewater for irrigation or other aims and concurrently, exploiting wastewater as growing medium based on the high concentration of nitrogen and phosphorus. 108 Also the organic-rich anaerobic digestate, which is difficult to be purified by conventional techniques, is appropriate to be used as a low-cost nutrient source for the economic viability and sustainability of microalgae production. 109 Chlorella vulgaris has been extensively exploited for biomass production from food waste, sludge extracts, corn steep liquor, cheese whey, vinasse, tofu wastewater, and industrial dairy effluents.…”