Phycoremediation of X-ray developer solution towards silver removal with concomitant lipid production * Swati Sharma, Vijay Kumar Garlapati * Dept. of Biotechnology and Bioinformatics, Jaypee University of InformationTechnology, Waknaghat, HP, 173234, India article info Article history: Received 16 June 2020 Received in revised form 21 September 2020 Accepted 11 October 2020 Available online 14 October 2020 Keywords: X-ray developer solution Characterization Toxicity screening Phycoremediation Lipid production abstract The present research is mainly focusing on the characterization of X-ray developer solution and its toxic tolerance studies with Desmodesmus armatus towards the phycoremediation studies for removal of pollutants, silver, and concomitant lipid production. The characterization results suggested the presence of 1.229 ± 0.004 g/l BOD, 27.29 ± 0.230 g/l COD with a silver content of 0.01791 ± 0.000 g/l. The tolerance and toxicity limits of with X-ray developer solution reveals the remarkable growth of microalgae in 3:1.dilution ratio of BBM in the X-ray developer solutions. The phycoremediation with 19 days period shown the noticeable results with a relative BOD (20.86%), COD (13.88%), with 57.10% corresponding total phosphorous removal. The phycoremediation also has proven better relative silver removal potential of 44.06% on the 19th day with concomitant 1.392% lipid production. Overall, the present study shows the potential phycoremediation strategy of hazardous X-ray developer solutions with possible concurrent lipid production through a sustainable approach. © 2020 Elsevier Ltd. All rights reserved. 1. Introduction Radiography is an integral part of hospitals and medical clinics for the CT scan, X-ray, and mammograms towards the X-ray development to diagnose the health ailments (Ahmad et al., 2019; Khunprasert et al., 2008). The X-ray film processing generates a large amount of solid and liquid wastes generated through the fixing, development, and washing steps. The radiographic chem- icals are generally released from the hospitals and other clinics with higher levels of pH, turbidity, total solids, BOD, and COD limits (Fernandes et al., 2006; Stalikas et al., 2001). Silver holds a prom- inent position in the radiography field in contribution towards the formation of X-ray images. The soluble silver is a significant solid waste generated in the X-ray clinics, and its incorrect policy of disposing of in the surroundings has perilous influence (Ahmad et al., 2019). The improper management of X-ray waste, which contains the highest amount of organic and inorganic pollutants and silver content, affects the water bodies, aquatic life and fish- eries. Hence, the X-ray waste management’s insufficient knowledge and hindered risks associated with the improper disposal have to take care in a sustainable way for eliminating the X-ray waste from the non-hazardous status (Singhal and Gupta, 2019). The researchers practiced several physical and chemical tech- niques (precipitation, electrolysis, and metallic replacement) to recover the silver from X-ray wastes and failed most of the in- stances due to the higher operational cost, toxic byproducts, and high cost associated purification of the obtained crude silver (Yazici et al., 2011). Hence, the urgency of the automation that performs efficient removal of heavy metals in an eco-friendly way (Zhou et al., 2012; Chong et al., 2000). Among different biologicals, microalgae have some noticeable facts such as its higher growth rate, eco-friendly photosynthetic, easily cultivated, can be grown in wastewater cost-effectively (Gillespie et al., 2013; Monteiro et al., 2012). Microalgae capable of producing different bio commodities (Bhatia et al., 2020; Sevda et al., 2019; Jha et al., 2017), uptake metal ions, clean the wastewater (Menger-Krug et al., 2012). The toxic compound in landfill sites degraded by the microalgae and its biomass will produce different macromolecules, serving as the feedstock for various food, pharmaceutical, and biofuel sectors (Chan et al., 2014; Komolafe et al., 2014). The characterization of waste aid in waste treatment and nu- trients availability for microalgal growth. (Zeraatkar et al., 2016). Microalgae can generally tolerate the high concentration of heavy metal for a long time, but determining industrial effluents’ toler- ance limits is a pre-requisite for probable successful * This paper has been recommended for acceptance by J€ org Rinklebe. * Corresponding author. E-mail addresses: shanepati@gmail.com, garlapati.vijaykumar@juit.ac.in (V.K. Garlapati). Contents lists available at ScienceDirect Environmental Pollution journal homepage: www.elsevier.com/locate/envpol https://doi.org/10.1016/j.envpol.2020.115837 0269-7491/© 2020 Elsevier Ltd. All rights reserved. Environmental Pollution 268 (2021) 115837