Bioleaching of Metals from Printed Circuit Boards by Mesophilic Lysinibacillus sp.

Document Type : Original Research Paper

Authors

Civil Engineering Department, National Institute of Technology Kurukshetra, Kurukshetra-136119, Haryana, India

Abstract

In view of the rapidly increasing e-waste, bioleaching of metals from e-waste is an economical and ecologically conscientious option to address the issue of its disposal and/or recycling. Bioleaching of heavy metals by using bacteria of the Bacillus genus has been reported in many studies; however, the bioleaching potential of the Lysinibacillus genus is unexplored. In the present study, Lysinibacillus sp. SDG4 was isolated, identified, analysed and used for leaching toxic metals from e-waste printed circuit boards (PCBs). The bioleaching of metals was deciphered and analysed by using scanning electron microscopy (SEM) along with energy-dispersive X-ray spectroscopy (EDX), Fourier transform infrared spectroscopy (FTIR) and inductively coupled plasma-optical emission spectrometry (ICP-OES). The presence of organic acids in the Lysinibacillus primary metabolites was established by FTIR analysis. The presence of functional groups like C–O and C–N in the transmittance band range of 1037.70 to 1658.78 cm-1 wavelength, C–H at 2746.63 and 2964.59 cm-1, O–H at 3412.08 cm-1 and RCO–OH at 582.50 cm-1 suggested the production of metal chelating functional groups by the bacterial strain. The heavy metal profile was determined using ICP-OES analysis. This revealed bioleaching of Al (99.74%), Zn (99.60 %), Cu (93.75%) and Fe (59.24%) in 30 days with a PCB concentration of 1 gm/ml by Lysinibacillus sp. SDG4.  These findings confirmed the display of morphological changes by accumulation of metals by Lysinibacillus sp. SDG4 using SEM-EDX analysis. Thus, the study exhibited the potential of the Lysinibacillus genus in bioleaching metals from e-waste.

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Main Subjects


Abalansa, S., Mahrad, B. E., Icely, J., & Newton, A. (2021). Electronic waste, an environmental problem exported to developing countries: the good, the bad and the ugly. Sustainability, 13(9); 5302. https://doi.org/10.3390/su13095302 
Abatenh, E., Gizaw, B., Tsegaye, Z., & Wassie, M. (2017). Application of microorganisms in bioremediation-review. J. Environ. Microb., 1(1); 2-9. https://www.pulsus.com/scholarly-articles/application-of-microorganisms-in-bioremediationreview.pdf 
Aka, R. J. N., & Babalola, O. O. (2016). Effect of bacterial inoculation of strains of Pseudomonas aeruginosa, Alcaligenes feacalis and Bacillus subtilis on germination, growth and heavy metal (Cd, Cr, and Ni) uptake of Brassica juncea. Int. J. Phytoremed., 18(2); 200-209. https://doi.org/10.1080/15226514.2015.1073671 
Alabssawy, A. N., & Hashem, A. H. (2024). Bioremediation of hazardous heavy metals by marine microorganisms: a recent review. Archives of Microbiology,  206; 103. https://doi.org/10.1007/s00203-023-03793-5
Altschul, S. F., Gish, W., Miller, W., Myers, E. W., & Lipman, D. J. (1990). Basic local alignment search tool. J. Mol. Biol., 215(3); 403-410. https://doi.org/10.1016/S0022-2836(05)80360-2 
Ang, W. L., & Mohammad, A. W. (2020). State of the art and sustainability of natural coagulants in water and wastewater treatment. J. Clean. Prod., 262; 121267. https://doi.org/10.1016/j.jclepro.2020.121267 
Ariffin, N., Abdullah, M. M. A. B., Zainol, M. R. R. M. A., Murshed, M. F., Hariz-Zain, F. M. A., & Bayuaji, R. (2017). Review on adsorption of heavy metals in wastewater by using geopolymer.  MATEC Web Conf., 97; 01093. https://doi.org/10.1051/matecconf/20179701023 
Arshadi, M., Yaghmaei, S., & Mousavi, S. M. (2019). Study of plastics elimination in bioleaching of electronic waste using Acidithiobacillus ferrooxidans. Int. J. Environ. Sci. Technol., 16; 7113-7126. https://doi.org/10.1007/s13762-018-2120-1 
Atagana, H. I. (2009). Biodegradation of PAHs by fungi in contaminated-soil containing cadmium and nickel ions. Afr. J. Biotechnol., 8(21); 5780-5789. DOI: 10.5897/AJB2009.000-9465 
Atuchin, V. V., Asyakina, L. K., Serazetdinova, Y. R., Frolova, A. S., Velichkovich, N. S., & Prosekov, A. Y. (2023). Microorganisms for bioremediation of soils contaminated with heavy metals. Microorganisms, 11(4); 864. https://doi.org/10.3390/microorganisms11040864   
Bajestani, M. I., Mousavi, S. M., & Shojaosadati, S. A. (2014). Bioleaching of heavy metals from spent household batteries using Acidithiobacillus ferrooxidans: statistical evaluation and optimization. Sep. Purif. Technol., 132; 309-316. https://doi.org/10.1016/j.seppur.2014.05.023 
BAN. (2002). Exporting harm: the high-tech trashing of Asia, The Basal Action Network. Retrieved March 22, 2024, from https://wiki.ban.org/images/e/e1/Exporting_Harm_canada.PDF. 
Borthakur, A., & Sinha, K. (2013). Generation of electronic waste in India: current scenario, dilemmas and stakeholders. Afr. J. Environ. Sci. Technol., 7(9); 899-910. https://www.ajol.info/index.php/ajest/article/view/94952 
Brito, E. M. S., Barrón, M. D. C., Caretta, C. A., Goñi-Urriza, M., Andrade, L. H., Cuevas-Rodríguez, G., Malm, O., Torres, J. P., Simon, M., & Guyoneaud, R. (2015). Impact of hydrocarbons, PCBs and heavy metals on bacterial communities in Lerma River, Salamanca, Mexico: investigation of hydrocarbon degradation a River, Salamanca, Mexico: investigation of hydrocarbon degradation potential. Sci. Total. Environ., 521-522; 1-10. https://doi.org/10.1016/j.scitotenv.2015.02.098 
Bueno, B. Y. M., Torem, M. L., Molina, F., & de Mesquita, L. M. S. (2008). Biosorption of lead (II), chromium (III) and copper (II) by R. opacus: Equilibrium and kinetic studies. Miner. Eng., 21(1); 65-75. https://doi.org/10.1016/j.mineng. 2007.08.013  
Bullen, H. A., Oehrle, S. A., Bennett, A. F., Taylor, N. M., & Barton, H. A. (2008). Use of attenuated total reflectance Fourier transforms infrared spectroscopy to identify microbial metabolic products on carbonate mineral surfaces. Appl. Environ. Microbiol., 74(14); 4553-4559. https://doi.org/10.1128/AEM.02936-07 
Canovas, D., Cases, I., & De Lorenzo, V. (2003). Heavy metal tolerance and metal homeostasis in Pseudomonas putida as revealed by complete genome analysis. Environ. Microbiol., 5(12); 1242-1256. https://doi.org/10.1111/j.1462-2920.2003.00463.x 
Cesaro, A., Belgiorno, V., Vaccari, M., Jandric, A., Chung, T. D., Dias, M. I., Hursthouse, A., & Salhofer, S. (2018). A device-specific prioritization strategy based on the potential for harm to human health in informal WEEE recycling. Environ. Sci. Pollut. Res., 25(1); 683-692. https://doi.org/10.1007/s11356-017-0390-7 
Chandane, P., Jori, C., Chaudhari, H., Bhapkar, S., Deshmukh, S., & Jadhav, U. (2020). Bioleaching of copper from large printed circuit boards for synthesis of organic-inorganic hybrid. Environ. Sci. Pollut. Res., 27; 5797-5808.  https://doi.org/10.1007/s11356-019-07244-x 
Chen, S., Yin, H., Ye, J., Peng, H., Liu, Z., Dang, Z., & Chang, J. (2014). Influence of coexisted benzo[a]pyrene and copper on the cellular characteristics of Stenotrophomonas maltophilia during biodegradation and transformation. Bioresour. Technol., 158; 181-187. https://doi.org/10.1016/j.biortech.2014.02.020 
Cheng, Y. W., Khan, M. R., Ng, K. H., Wongsakulphasatch, S., & Cheng, C. K. (2019). Harnessing renewable hydrogen-rich syngas from valonization of palm oil mill effluent (POME) using steam reforming technique. Ren. Eng., 138; 1114–1126. https://doi.org/10.1016/j.renene.2019.02.040 
Crini, G., & Lichtfouse, E. (2019). Advantages and disadvantages of techniques used for wastewater treatment. Environ. Chem. Lett., 17, 145-155. https://doi.org/10.1007/s10311-018-0785-9 
Das, N. (2010). Recovery of precious metals through biosorption- a review. Hydrometallurgy, 103(1-4); 180-189. https://doi.org/10.1016/j.hydromet.2010.03.016 
Deswal, S. and Deswal, A. (2017). A basic course in environmental studies. (New Delhi: Dhanpat Rai and Co. P. Ltd.).
Ehi-Eromosele, C. O., Adaramodu, A. A., Anake, W. U., Ajanaku, C. O., & Edobor-Osoh, A. (2012). Comparison of three methods of digestion for trace metal analysis in surface dust collected from an e-waste recycling site. Nat. Sci., 10(10); 42-47. file:///C:/Users/kuk/Downloads/natureandsciencepaper.pdf 
EU. (2012). Directive 2012/19/EU of the European Parliament and of the Council of 4 July 2012 on waste electrical and electronic equipment (WEEE). Off. J. Eur. Union, L197; 38-71. https://eur-lex.europa.eu/legal-content/EN/TXT/PDF/?uri=CELEX:32012L0019 
Forti, V., Balde, C. P., Kuehr, R., & Bel, G. (2020). The global e-waste monitor: quantities, flows, and the circular economy potential. United Nations University, Tokyo, Japan. https://ewastemonitor.info/wp-content/uploads/2020/11/GEM_2020_def_july1_low.pdf 
Fourest, E., & Roux, J. C. (1992). Heavy metal biosorption by fungal mycelial by-products: mechanisms and influence of pH. Appl. Microbiol. Biotechnol., 37; 399-403. https://doi.org/10.1007/BF00211001 
Garlapati, V. K. (2016). E-waste in India and developed countries: management, recycling, business and biotechnological initiatives. Renew. Sustain. Energy Rev., 54; 874-888. https://doi.org/10.1016/j.rser.2015.10.106 
Grant, K., Goldizen, F. C., Sly, P. D., Brune, M. N., Neira, M., van den Berg, M., & Norman, R. E. (2013). Health consequences of exposure to e-waste: a systematic review. Lancet. Glob. Health, 1(6); e350-e361. https://doi.org/10.1016/S2214-109X(13)70101-3 
Green, M. R., & Sambrook, J. (2012). Molecular cloning – a laboratory manual. (New York: Cold Spring Harbor Laboratory Press) https://www.cshlpress.com/pdf/sample/2013/MC4/MC4FM.pdf 
Guin, S. D., & Deswal, S. (2023). Status, health effects and remediation techniques of e-waste – a review. Pollution, 9(4); 1676-1705. https://doi.org/10.22059/POLL.2023.358554.1897 
Hall, T. A. (1999). BioEdit: a user-friendly biological sequence alignment editor and analysis program for Windows 95/98/NT. Nucl. Acids. Symp. Ser., 41; 95-98. https://www.academia.edu/2034992/BioEdit_a_user_friendly_biological_sequence_alignment_editor_and_analysis_program_for_Windows_95_98_NT 
Hoseinzadeh, S., Aliloo, A. A., Shahabivand, S., & Ghaderi M. (2023). Trichoderma tomentosum Ts141 as a potential candidate for bioremediation of cadmium, lead, and nickel ions. Pollution, 9(3); 1128-1139. https://jpoll.ut.ac.ir/article_91349_a49cabecd0b02dc80e90989b2b75dcc4.pdf 
Igiri, B. E., Okoduwa, S. I. R., Idoko, G. O., Akabuogu, E. P., Adeyi, A. O., & Ejiogu, I. K. (2018). Toxicity and bioremediation of heavy metals contaminated ecosystem from tannery wastewater: a review. J. Toxicol., 2018; 2568038. https://doi.org/10.1155/2018/2568038 
Islam, A., Ahmed, T., Awual, M. R., Rahman, A., Sultana, M., Aziz, A. A., Monir, M. U., Teo, S. H., & Hasan, M. (2020). Advances in sustainable approaches to recover metals from e-waste-a review. J. Clean. Prod., 244; 118815. https://doi.org/10.1016/j.jclepro.2019.118815 
Jinal, H. N., Gopi, K., Prittesh, P., Kartik, V. P., & Amaresan, N. (2019). Phytoextraction of iron from contaminated soils by inoculation of iron-tolerant plant growth-promoting bacteria in Brassica juncea L. Czern. Environ. Sci. Pollut. Res., 26; 32815-32823. https://doi.org/10.1007/s11356-019-06394-2 
Kadivar, S., Pourhossein, F., & Mousavi, S. M. (2021). Recovery of valuable metals from spent mobile phone printed circuit boards using biochar in indirect bioleaching. J. Environ. Manag., 280; 111642. https://doi.org/10.1016/j.jenvman.2020.111642 
Kalia, P., Zia, A., & Mladenović, D. (2022). Examining country development indicators and e-waste under the moderating effect of country development levels and e-waste policy. Int. J. Qual. Reliab. Manag., 39(7); 1601-1616. http://dx.doi.org/10.1108/IJQRM-09-2021-0335 
Kaliyaraj, D., Rajendran, M., Angamuthu, V., Antony, A. R., Kaari, M., Thangavel, S., Venugopal, G., Joseph, J.,  & Manikkam, R. (2019). Bioleaching of heavy metals from printed circuit board (PCB) by Streptomyces albidoflavus TN10 isolated from insect nest. Bioresource and Bioprocessing, 6; 47. https://doi.org/10.1186/s40643-019-0283-3 
Kang, K. D., Kang, H., Ilankoon, I. M. S. K., & Chong, C. Y. (2020). Electronic waste collection systems using internet of things (IoT): household electronic waste management in Malaysia. J. Clean. Prod., 252; 119801. https://doi.org/10.1016/j.jclepro.2019.119801  
Karwowska, E., Andrzejewska-Morzuch, D., Łebkowskaa, M., Tabernackaa, A., Wojtkowskab, M., Telepkob, A., & Konarzewskab, A. (2014). Bioleaching of metals from printed circuit boards supported with surfactant-producing bacteria. J. Hazard. Mater., 264; 203–210. https://doi.org/10.1016/j.jhazmat.2013.11.018 
Kudrat-E-Khuda (2021). Electronic Waste in Bangladesh: its present statutes, and negative impacts on environment and human health. Pollution, 7(3); 633-642. https://jpoll.ut.ac.ir/article_82532_9e2dbf67dd1a23022e123b344ef22157.pdf 
Kumar, S. & Deswal, S. (2020). Estimation of phosphorus reduction from wastewater by artificial neural ntwork, random forest and M5P model tree. Pollution, 6(2); 417-428. https://jpoll.ut.ac.ir/article_75230_aa0b9ce34924e9df5265d493119a81c0.pdf 
Kumar, S. & Deswal, S. (2021). A review on current techniques used in India for rice mill wastewater treatment and emerging techniques with valuable by-products. Environmental Science and Pollution Research, 28(7); 7652-7668. https://doi.org/10.1007/s11356-020-11898-3 
Kumar, S., Stecher, G., Li, M., Knyaz, C., & Tamura, K. (2018). MEGA X: molecular evolutionary genetics analysis across computing platforms. Mol. Biol. Evol., 35(6); 1547-1549. https://doi.org/10.1093/molbev/msy096 
Kumar, V., Rout, C., Singh, J., Saharan, Y., Goyat, R., Umar, A., Akbar, S., & Baskoutas, S. (2023). A review on the clean-up technologies for heavy metal ions contaminated soil samples. Heliyon, 9(5); e15472. https://doi.org/10.1016/j.heliyon.2023.e15472  
Leedjarv, A., Ivask, A., & Virta, M. (1996). Interplay of different transporters in the mediation of divalent heavy metal resistance in Pseudomonas putida KT2440. J. Bacteriol., 190(8); 2680-2689. https://doi.org/10.1128/jb.01494-07 
Leur, A. V., & Walter, D. (2019). From waste to jobs: decent work challenges and opportunities in the management of e-waste in India. International Labour Office (ILO), Sectoral Policies Department, Geneva, Switzerland. https://www.ilo.org/wcmsp5/groups/public/---ed_dialogue/---sector/documents/publication/wcms_732426.pdf 
Liu, S. H., Zeng, G. M., Niu, Q. Y., Liu, Y., Zhou, L., Jiang, L. H., Tan, X. F., Xu, P., Zhang, C., & Cheng, M. (2017). Bioremediation mechanisms of combined pollution of PAHs and heavy metals by bacteria and fungi: a mini review. Bioresource Technol., 224; 25-33. https://doi.org/10.1016/j.biortech.2016.11.095 
Ma, X. K., Wu, L. L., & Fam, H. (2014). Heavy metal ions affecting the removal of polycyclic aromatic hydrocarbons by fungi with heavy-metal resistance. Appl. Microbiol. Biotechnol., 98(23); 9817-9827. https://doi.org/10.1007/s00253-014-5905-2    
Madoni, P., Davoli, D., Gorbi, G., & Vescovi, L. (1996). Toxic effect of heavy metals on the activated sludge protozoan community. Water Res., 30(1); 135-141. https://doi.org/10.1016/0043-1354(95)00124-4 
Magoda, K., & Mekuto, L. (2022). Biohydrometallurgical recovery of metals from waste electronic equipment: current status and proposed process. Recycling, 7(5); 67. https://doi.org/10.3390/recycling7050067  
Manna, A., Sundaram, E., Amutha, C., & Vasantha, V. S. (2018). Efficient removal of cadmium using edible fungus and its quantitative fluorimetric estimation using (Z)-2-(4 H-1, 2, 4-Triazol-4-yl) iminomethylphenol. ACS Omega, 3(6); 6243-6250. https://doi.org/10.1021/acsomega.8b00342 
Michalak, I., Chojnacka, K.,  & Marycz, K. (2011). Using ICP-OES and SEM-EDX in biosorption studies. Microchimica Acta, 72; 65-74. https://doi.org/10.1007/s00604-010-0468-0 
MoEFCC. (2022). E-waste (management) rules, 2022. Ministry of Environment, Forest and Climate Change, Government of India. https://cpcb.nic.in/uploads/Projects/E-Waste/e-waste_rules_2022.pdf 
Narayanasamy, M., Dhanasekaran, D., & Thajjudin, N. (2021). Bioremediation of noxious metals from e-waste printed circuit boards by Frankia. Microbiol. Res., 245; 126707. https://doi.org/10.1016/j.micres.2021.126707 
Narayanasamy, M., Dhanasekaran, D., Vinothini, G., & Thajuddin, N. (2018). Extraction and recovery of precious metals from electronic waste printed circuit boards by bioleaching acidophilic fungi. Int. J. Environ. Sci. Technol., 15; 119-132. https://doi.org/10.1007/s13762-017-1372-5 
Ozer, A., Ozer, D., & Ekiz, H. I. (2005). The equilibrium and kinetic modeling of the biosorption of copper (II) ions on Cladophora crispata. Adsorption, 10; 317-326. https://doi.org/10.1007/s10450-005-4817-y 
Paiment, A., Leduc, L. G., & Ferroni, G. D. (2001). The effect of the facultative chemolithotrophic bacterium Thiobacillus acidophilus on the leaching of low-grade Cu-Ni sulfide ore by thiobacillus ferrooxidans. Geomicrobiol. J., 18(2); 157-165. https://doi.org/10.1080/01490450118265 
Panigrahi, S., & Panigrahi D. P. (2023). Characterization of a pigmented Brevundimonas sp. isolated from red mud pond sample of bauxite mine. Journal of Environmental Biology, 44; 359-366. https://www.jeb.co.in/journal_issues/202305_may23/paper_14.pdf 
Parga, J. R., Valenzuela, J. L, & Francisco, C. T. (2007). Pressure cynanide leaching for precious metal recovery. JOM, 59; 43-47. https://doi.org/10.1007/s11837-007-0130-4 
Patel, B., Jinal, H. N., Chavan, S. M., & Paul, D. (2023). Bacteria isolated from e-waste soil enhance plant growth and mobilize trace metals in e-waste-amended soils. International Journal of Phytoremediation, 25(7); 900-906. https://doi.org/10.1080/15226514.2022.2118230 
Patel, S., & Kasture, A. (2014). E (electronic) waste management using biological systems-overview. Int. J. of Curr. Microbiol. and Appl. Sciences, 3(7); 495-504. https://www.ijcmas.com/vol-3-7/Shuchi%20Patel%20and%20Avani%20Kasture.pdf 
Patel, V., Jain, S., & Madamwar, D. (2012). Naphthalene degradation by bacterial consortium (DV-AL) developed from Alang-Sosiya ship breaking yard, Gujarat. India. Bioresour. Technol., 107; 122-130. https://doi.org/10.1016/j.biortech.2011.12.056 
Pethkar, A. V., Kulkarni, S. K., & Paknikar, K. M. (2001). Comparative studies on metal biosorption by two strains of Cladosporium cladosporoides. Bioresource Technology, 80(3); 211-215. https://doi.org/10.1016/S0960-8524(01)00080-3 
Rehman, Z. U., Junaid, M. F., Ijaz, N., Khalid, U., & Ijaz, Z. (2023). Remediation methods of heavy metal contaminated soils from environmental and geotechnical standpoints. Sci. Tot. Environ., 867; 161468. https://doi.org/10.1016/j.scitotenv.2023.161468   
Robinson, B. H. (2009). E-waste: an assessment of global production and environmental impacts. Sci. Total Environ., 408(2); 183-191. https://doi.org/10.1016/j.scitotenv.2009.09.044 
Sansotera, M., Navarrini, W., Talaeemashhadi, S., & Venturini, F. (2013). Italian WEEE management system and treatment of end-of-life cooling and freezing equipments for CFCs removal. Waste Management, 33(6); 1491-1498. https://doi.org/10.1016/j.wasman.2013.03.012 
Santhiya, D., & Ting, Y. P. (2005). Bioleaching of spent refinery processing catalyst using Aspergillus niger with high-yield oxalic acid. J. Biotechnol. 116(2); 171-184. https://doi.org/10.1016/j.jbiotec.2004.10.011 
Sethurajan, M., Aruliah, R., Karthikeyan, O. P., Balasubramanian, R. (2012). Bioleaching of copper from black shale ore using mesophilic mixed populations in an air up-lift bioreactor. Environ. Eng. Manage. J., 11(10); 1839-1848. https://www.researchgate.net/publication/272171777_BIOLEACHING_OF_COPPER_FROM_BLACK_SHALE_ORE_USING_MESOPHILIC_MIXED_POPULATIONS_IN_AN_AIR_UP-LIFT_BIOREACTOR 
Shabani, M. A., Irannajad, M., Azadmehr, A. R., & Meshkini, M. (2013). Bioleaching of copper oxide ore by Pseudomonas aeruginosa. Int. J. Miner. Metall. Mater., 20; 1130-1133. https://doi.org/10.1007/s12613-013-0845-x  
Sinha, A., Pant, K. K., & Khare, S. K. (2012). Studies on mercury bioremediation by alginate immobilized mercury tolerant Bacillus cereus cells. Int. Biodeterior. Biodegrad., 71; 1-8. https://doi.org/10.1016/j.ibiod.2011.12.014 
Srinath, T., Verma, T., Ramteke, P. W., & Garg, S. K. (2002). Chromium (VI) biosorption and bioaccumulation by chromate resistant bacteria. Chemosphere, 48(4); 427-435. https://doi.org/10.1016/S0045-6535(02)00089-9 
Thompson, J. D., Higgins, D. J., & Gibson, T. J. (1994). CLUSTAL W: improving the sensitivity of progressive multiple sequence alignment through sequence weighting, position-specific gap penalties and weight matrix choice. Nucl. Acids. Res., 22(22); 4673-4680. https://doi.org/10.1093/nar/22.22.4673 
Torres, E. (2020). Biosorption: a review of the latest advances. Processes, 8(12); 1584. https://doi.org/10.3390/pr8121584 
Uddin, M. K. (2017). A review on the adsorption of heavy metals by clay minerals, with special focus on past decade. J. Chem. Eng., 308; 438-462. https://doi.org/10.1016/j.cej.2016.09.029 
Usharani, K., Sruthilaya, K., & Divya, K. (2017). Determination of nitrate utilization efficiency of selective strain of Bacillus sp. isolated from Eutrophic Lake, Theerthamkara, Kasaragod, Kerala. Pollution, 3(1); 55-67. https://jpoll.ut.ac.ir/article_59573_ef781a875a889b29bff4abe9d5b0e875.pdf 
Verma, A. K., Raghukumar, C., Parvatkar, R. R., & Naik, C. G. (2012). A rapid two-step bioremediation of the Anthraquinone dye, Reactive Blue 4 by a Marine-derived fungus. Water Air Soil Pollut., 223; 3499-3509. https://doi.org/10.1007/s11270-012-1127-3 
Vishan, I., Sivaprakasam, S., & Kalamdhad, A. (2017). Biosorption of lead using Bacillus badius AK strain isolated from compost of green waste (water hyacinth). Environ. Technol., 38(13-14); 1812-1822. https://doi.org/10.1080/09593330.2017.1298674 
Waghmode, M. S., Gunjal, A. B., & Patil, N. N. (2021). Bioleaching of electronic waste. Pollution, 7(1); 141-152. https://jpoll.ut.ac.ir/article_79315_b32ebf7c2fb2ca301e5686fda4880278.pdf 
Wang, J., Bai, J., Xu, J., & Liang, B. (2009). Bioleaching of metals from printed wire boards by Acidithiobacillus ferrooxidans and Acidithiobacillus thiooxidans and their mixture. J. Hazard. Mater., 172(2-3); 1100-1105. https://doi.org/10.1016/j.jhazmat.2009.07.102 
Widmer, R., Oswald-Krapf, H., Sinha-Khetriwal, D., Schnellmann, M., & Boni, H. (2005). Global perspectives on e-waste. Enviro. Impact Assess. Rev., 25(5); 436-458. https://doi.org/10.1016/j.eiar.2005.04.001 
Wrobel, M., Sliwakowski, W., Kowalczyk, P., Kramkowski, K., & Dobrzynski, J. (2023). Bioremediation of heavy metals by the genus Bacillus. Int. J. Environ. Res. Public Health, 20(6); 4964. https://doi.org/10.3390/ijerph20064964 
Yuan, Z., Ruan, J., Li, Y., & Qiu, R. (2018). A new model for simulating microbial cyanide production and optimizing the medium parameters for recovering precious metals from waste printed circuit boards. J. Hazard. Mater., 353; 135-141. https://doi.org/10.1016/j.jhazmat.2018.04.007 
Zaved, H. K., Rahman, M. M., Rahman, M. M., Rahman, A., Arafat, S. M. Y., Rahman, M. S. (2008). Isolation characterization of effective bacterial solid waste degradation for organic manure. KMITL Sci. Tech. J., 8(2); 44-55. https://www.thaiscience.info/journals/Article/KLST/10559616.pdf  
Zhang, K., Wu, Y., Wang, W., Li, B., Zhang, Y., & Zuo, T. (2015). Recycling indium from waste LCDs: a review. Resour. Conserv. Recycl., 104(A); 276-290. https://doi.org/10.1016/j.resconrec.2015.07.015