Remediation Capacity of Different Microalgae in Effluents Derived from the Cigarette Butt Cleaning Process

Abstract

Microalgal-based remediation is an ecofriendly and cost-effective system for wastewater treatment. This study evaluated the capacity of microalgae in the remediation of wastewater from cleaning process of smoked cigarette butts (CB). At laboratory scale, six strains (one from the family Scenedesmaceae, two Chlamydomonas debaryana and three Chlorella sorokiniana) were exposed to different CB wastewater dilutions to identify toxicity levels reflected in the alteration of microalgal physiological status and to determine the optimal conditions for an effective removal of contaminants. CB wastewater could impact on microalgal chlorophyll and carotenoid production in a concentration-dependent manner. Moreover, the resistance and remediation capacity did not only depend on the microalgal strain, but also on the chemical characteristics of the organic pollutants. In detail, nicotine was the most resistant pollutant to removal by the microalgae tested and its low removal correlated with the inhibition of photosynthetic pigments affecting microalgal growth. Concerning the optimal conditions for an effective bioremediation, this study demonstrated that the Chlamydomonas strain named F2 showed the best removal capacity to organic pollutants at 5% CB wastewater (corresponding to 25 butts L−1 or 5 g CB L−1) maintaining its growth and photosynthetic pigments at control levels.

Exploring the Physiological Multiplicity of Native Microalgae from the Ecuadorian Highland, Italian Lowland and Indoor Locations in Response to UV-B

“…Although some microalgae subjected to enhanced UV-B resulted in a decline in photosynthetic pigments and yield [ 26 ], others are also able to acclimate to UV-B by adjusting their metabolism and preventing damage [ 16 , 27 , 28 ]. In this study, the pigment content in Chlorella sorokiniana strains was differently inhibited by the continuous UV-B, where F4 was unexpectedly more susceptible than LG1 despite only the former having naturally grown in the presence of ambient UV-B [ 21 , 22 ]. In fact, the native habitat of strain F4 was a Mediterranean inland swamp at sea level with an average depth of 2 m and was historically affected by anthropogenic activities [ 29 ].…”

“…Unlike F4, LG1 was acclimated to only PAR light and controlled indoor conditions [ 21 ]. In this study, when LG1 was exposed to acute UV-B for 6 h, it caused a transient reduction in chlorophyll content that was then recovered to control levels when exposure increased to 12 h. This indicated a possible acclimation process in LG1 cells where damage and repair were rebalancing to maintain their physiological performance [ 36 , 37 ].…”

“…Four microalgal strains were used in this work ( Table 2 ). The Chlorella sorokiniana strains F4 and LG1 are part of the collection of the Institute of Agricultural Biology and Biotechnology of the Italian National Research Council located in Pisa and were previously described [ 21 , 22 ]. The strains PEC (related to Pectinodesmus pectinatus ) and ETI (related to Ettlia pseudoalveolaris ) were isolated from the Yahuarcocha lake (Ecuador) and then characterized as described below.…”

“…To identify relationships among the different UV-B treated microalgal strains at the end of the experiment, based on the physiological data, multiple factor analysis (MFA) was carried out as described in Chiellini et al [ 21 ]. The R software packages “FactoMineR” (analysis) and “factoextra” (visualization) were applied (R version 4.2.1; ).…”

“…In the attempts to elucidate the mechanisms maintaining the microalgal cells’ photosynthetic activity in response to UV-B, the production of photosynthetic pigments (chlorophyll a , chlorophyll b , and carotenoids), total antioxidant capacity, total polyphenols, and chlorophyll a fluorescence were evaluated in four strains exposed to acute UV-B irradiation and compared with their control (absence of UV-B). The strains were isolated from different sources: two from the Ecuadorian Yahuarcocha Lake located at 2200 m asl (00°22′10″ N; 78°06′09″ W), one from a recycled cigarette butt’s substrate in a growth chamber [ 21 ], and the last one from the Mediterranean Fucecchio marshland at sea level (43°48′31″ N; 10°48′18″ E) [ 22 ]. Herein, we discuss the distinct ability of each native microalgal strain to cope with acute UV-B, which was related to their respective natural environment and genetic constitutions.…”