2. Markou, G., Mitrogiannis, D., Çelekli, A., Bozkurt, H., Georgakakis, D. & Chrysikopoulos, C.V. (2015). Biosorption of Cu2+ and Ni2+ by Arthrospira platensis with different biochemical compositions. Chem. Eng. J. 259, 806-813. https://DOI.org/10.1016/j.cej.2014.08.03710.1016/j.cej.2014.08.037
5. Aslan, S., Ozturk, M. & Yildiz, S. (2016). Sorption of heavy metals on biosludge. Eur. Sci. J. ESJ, 12(10), ISSN: 1857-7881 (Print), ISSN: 1857-7431 (Online).
6. Jianlong, W., Yi, Q., Horan, N. & Stentiford, E. (2000). Bioadsorption of pentachlorophenol (PCP) from aqueous solution by activated sludge biomass. Bioresour. Technol. 75(2), 157-161. https://DOI.org/10.1016/S0960-8524(00)00041-910.1016/S0960-8524(00)00041-9
7. Liu, D., Tao, Y., Li, K. & Yu, J. (2012). Infl uence of the presence of three typical surfactants on the adsorption of nickel (II) to aerobic activated sludge. Bioresour. Technol. 126, 56 63.http://dx.DOI.org/10.1016/j.biortech.2012.09.02510.1016/j.biortech.2012.09.02523073089
8. Pamukoglu, M.Y. & Kargi, F. (2006). Removal of copper (II) ions from aqueous medium by biosorption onto powdered waste sludge. Process Biochem. 41(5), 1047-1054. https://DOI. org/10.1016/j.procbio.2005.11.01010.1016/j.procbio.2005.11.010
9. Wei, D., Zhang, K., Wang, S., Sun, B., Wu, N., Xu, W., Du, B. & Wei, Q. (2017). Characterization of dissolved organic matter released from activated sludge and aerobic granular sludge biosorption processes for heavy metal treatment via a fl uorescence approach. Int. Biodeterior. Biodegrad. 124, 2017.326-333. https://DOI.org/10.1016/j.ibiod.2017.03.01810.1016/j.ibiod.2017.03.018
10. Yuncu, B., Sanin, F.D. &Yetis, U. (2006). An investigation of heavy metal biosorption in relation to C/N ratio of activated sludge. J. Hazard. Mater. 137(2), 990-997. https:// DOI.org/10.1016/j.jhazmat.2006.03.02010.1016/j.jhazmat.2006.03.02016713077
11. Zhou, Y., Zhang, Z., Zhang, J. & Xia, S. (2016). New insight into adsorption characteristics and mechanisms of the biosorbent from waste activated sludge for heavy metals. J. Environ Sci., 45, 248-256. https://DOI.org/10.1016/j.jes.2016.03.00710.1016/j.jes.2016.03.00727372140
12. Filipkowska, U. & Kuczajowska-Zadrożna, M. (2016). Investigation of the adsorption/desorption equilibria of Cd (II), Zn (II) and Cu (II) ions on/from immobilized digested sludge using biosurfactants. Environ. Earth Sci. 75(9), 814. DOI: 10.1007/s12665-016-5674-6.10.1007/s12665-016-5674-6
14. Cojocaru, C., Diaconu, M., Cretescu, I., Savić, J. & Vasić, V. (2009). Biosorption of copper (II) ions from aqua solutions using dried yeast biomass. Colloids Surf. A: Physicochemical and Engineering Aspects, 335(1), 181-188. https://DOI.org/10.1016/j. colsurfa.2008.11.00310.1016/j.colsurfa.2008.11.003
15. Kumar, R. Bishnoi, N.R. & Bishnoi, K. (2008). Biosorption of chromium (VI) from aqueous solution and electroplating wastewater using fungal biomass. Chem. Eng. J. 135(3), 202-208.https://DOI.org/10.1016/j.cej.2007.03.00410.1016/j.cej.2007.03.004
16. Tunali, Y., Karaca, H., Tay, T., Kivanç, M. & Bayramoglu, G. (2009). Biosorption of Pb (II) from aqueous solutions by a fungal biomass in a batch system: Equilibrium and kinetic studies, Asian J. Chem. 21(8), 6015.
19. Li, C. & Ju, L.K. (2018). Enhancement of resource recovery and sludge digestion by cultivation of phagotrophic algae with alkali-pretreated waste activated sludge and waste ketchup. Process Saf. Environ. Prot.113 233-241. https://DOI.org/10.1016/j.psep.2017.10.00410.1016/j.psep.2017.10.004
20. Abdelfattah, I., Ismail, A.A., Sayed. F.A., Almedolab. A. & Aboelghait, K.M. (2016). Biosorption of heavy metals ions in real industrial wastewater using peanut husk as effi cient and cost effective adsorbent. Environ. Nanotechnol. Monit. Man. 6: 176-183. http://dx.DOI.org/10.1016/j.enmm.2016.10.00710.1016/j.enmm.2016.10.007
22. Hammaini, A., Gonzalez, F., Ballester, A., Blazquez, M.L. & Munoz, J.A. (2007). Biosorption of heavy metals by activated sludge and their desorption characteristics. J. Environ. Manage.84, 419-426. DOI: 10.1016/j.jenvman.2006.06.015.10.1016/j.jenvman.2006.06.01516979281
24. Laurent, J., Casellas, M., Pons, M.N. & Dagot, C. (2010). Cadmium biosorption by ozonized activated sludge: The role of bacterial fl ocs surface properties and mixed liquor composition. J. Hazard. Mater. 183, 256-263. DOI: 10.1016/j. jhazmat.2010.07.019.10.1016/j.jhazmat.2010.07.019
25. Ong, S.A., Toorisaka, E., Hirata, M. & Hano, T. (2013). Comparative study on kinetic adsorption of Cu(II), Cd(II) and Ni(II) ions from aqueous solutions using activated sludge and dried sludge. App. Water Sci. 3, 321-325. DOI: 10.1007/s13201-013-0084-3.10.1007/s13201-013-0084-3
26. Rao, P.R. & Bhargavi, C. (2013). Studies on biosorption of heavy metals using pretreated biomass of fungal species. Int. J. Chem. Chem. Eng. 3(3), 171-180, ISSN 2248-9924.
27. Yang, C., Wang, J., Lei, M., Xie, G., Zeng, G. & Luo, S. (2010). Biosorption of zinc (II) from aqueous solution by dried activated sludge. J. Environ. Sci. 22(5), 675-680. https://DOI.org/10.1016/S1001-0742(09)60162-510.1016/S1001-0742(09)60162-5
28. Goodwin, J.A.S. & Forster, C.F. (19859. A further examination into the composition of activated sludge surfaces in relation to their settlement characteristics. Water Res. 19(4), 527-533. https://DOI.org/10.1016/0043-1354(85)90045-410.1016/0043-1354(85)90045-4
30. Chang, D., Fukushi, K. & Ghosh, S. (1995). Stimulation of activated sludge cultures for enhanced heavy metal removal. Water Environ. Res. 67(5), 822-827. https://DOI.org/10.2175/106143095X13174510.2175/106143095X131745
31. Durmaz, B. & Sanin, F.D. 2001. Effect of carbon to nitrogen ratio on the composition of microbial extracellular polymers in activated sludge. Water Sci. Technol. 44(10), 221-229.10.2166/wst.2001.0626
32. APHA, AWWA, WPCF (1995) Standard Methods for the Examination of water and wastewater, 19th ed. American Public Health Association/American Water Works Association/ Water Environment Federation, Washington DC, USA.
33. Jamshidi, M., Jamshidi, A. & Mehrdadi, N. (2012). Application of sewage dry sludge in concrete mixtures. Asian J. Civil Eng (building and housing), 13(3), 365-375.
34. Mojapelo, S.K. (2017). Characterisation of wastewater dry sludge for lightweight concrete application, Faculty of Engineering and The Built Environment, Tshwane University of Technology, Master Thesis, 107 p.
35. Mun, K.J. (2007). Development and tests of lightweight aggregate using sewage sludge for nonstructural concrete. Construct. Built. Mater. 21(7), 1583-1588. https://DOI.org/10.1016/j. conbuildmat.2005.09.00910.1016/j.conbuildmat.2005.09.009
36. Ata, A., Nalcaci, O.O. & Ovez, B. (2012). Macro algae Gracilaria verrucosa as a biosorbent: A study of sorption mechanisms. Algal Res. 1(2), 194-204. https://DOI.org/10.1016/j. algal.2012.07.001.10.1016/j.algal.2012.07.001
37. Chen, H., Dou, J. & Xu, H. (2017). Removal of Cr (VI) ions by sewage sludge compost biomass from aqueous solutions: Reduction to Cr (III) and biosorption. Appl. Surf. Sci. 425, 728-735. http://dx.DOI.org/10.1016/j.apsusc.2017.07.05310.1016/j.apsusc.2017.07.053
38. Rocha, C.G., Zaia, D.A.M., da Silva Alfaya, R.V. & da Silva Alfaya, A.A. (2009). Use of rice straw as biosorbent for removal of Cu (II), Zn (II), Cd (II) and Hg (II) ions in industrial effl uents. J. Hazard. Mater. 166(1), 383-388. https://DOI.org/10.1016/j.jhazmat.2008.11.07410.1016/j.jhazmat.2008.11.074
39. Nouha, K., Hoang, N.V. & Tyagi, R.D. (2016). Fourier transform infrared spectroscopy and liquid chromatography- mass spectrometry study of extracellular polymer substances produced on secondary sludge fortifi ed with crude glycerol. J. Mater. Sci. Eng. 5:3. http://dx.DOI.org/10.4172/2169-0022.100024010.4172/2169-0022.1000240
40. Yahaya, Y.A., Don, M.M. & Bhatia, S. (2009). Biosorption of copper (II) onto immobilized cells of Pycnoporus sanguineus from aqueous solution: Equilibrium and kinetic studies. J. Hazard. Mater. 161(1), 189-195. https://DOI.org/10.1016/j.jhazmat.2008.03.10410.1016/j.jhazmat.2008.03.104
42. Yin, C., Meng, F. & Chen, G.H. (2015). Spectroscopic characterization of extracellular polymeric substances from a mixed culture dominated by ammonia-oxidizing bacteria. Water Res. 68, 740-749. http://dx.DOI.org/10.1016/j.watres.2014.10.04610.1016/j.watres.2014.10.046
43. Chassary, P., Vincent, T. & Guibal, E. (2004). Metal anion sorption on chitosan and derivative materials: a strategy for polymer modifi cation and optimum use. React. Funct. Polym. 60, 137-149. https://DOI.org/10.1016/j.reactfunctpolym.2004.02.01810.1016/j.reactfunctpolym.2004.02.018
44. Guzman, J., Saucedo, I., Revilla, J., Navarro, R. & Guibal, E. (2003). Copper sorption by chitosan in the presence of citrate ions: infl uence of metal speciation on sorption mechanism and uptake capacities. Int. J. Biol. Macromolecules. 33(1), 57-65.https://DOI.org/10.1016/S0141-8130(03)00067-910.1016/S0141-8130(03)00067-9
46. Crittenden, J.C., Trussell, R.R., Hand, D.W., Howe, K.J. & Tchobanoglous, G. (2005). Water Treatment: Priciples and Design, 2nd Edition, John Wiley and Son, Inc. 1947p.
47. Aslan, S. & Topcu, U.S. (2015). Adsorption of nickel and copper from water by waste nitrifi cation organisms, ISITES2015- -3rd International Symposium on Innovative Technologies in Engineering and Science, pp: 1955-1963, Valencia, Spain, 2015.
48. Katal, R., Baei, M.S., Rahmati, H.T. & Esfendian, H. (2012). Kinetic, isotherm, and thermodynamic study of nitrate adsorption from aqueous solution using modifi ed rice husk. J. Industrial Chem. 18, 295-302. http://dx.DOI.org/10.1016/j.jiec.2011.11.03510.1016/j.jiec.2011.11.035
49. Demirbas, E., Dizge, N., Sulak, M.T. & Kobya, M. (2009). Adsorption kinetics and equilibrium of copper from aqueous solutions using hazelnut shell activated carbon. Chem. Eng. J. 148(2), 480-487. https://DOI.org/10.1016/j.cej.2008.09.02710.1016/j.cej.2008.09.027
50. Aslan, S., Polat, A. & Topcu, U.S. (2015), Assessment of the adsorption kinetics, equilibrium and thermodynamics for the potential removal of Ni2+ from aqueous solution using waste eggshell. Journal of Environmental Engineering and Landscape Management, 23:3, 221-229, DOI: 10.3846/16486897.2015.1005015.10.3846/16486897.2015.1005015
50. Kilic, M., Varol, E.A. & Putun, A.E. (2011). Adsorptive removal of phenol from aqueous solutions on activated carbon prepared from tobacco residues: equilibrium, kinetics and thermodynamics. J. Hazard. Mater. 189, 397-403. http://dx.DOI.org/10.1016/j.jhazmat.2011.02.05110.1016/j.jhazmat.2011.02.05121420235
52. Sljivic, M., Smiciklas, I., Plecas, I. & Mitric, M. (2009). The infl uence of equilibration conditions and hydroxyapatite physico-chemical properties onto retention of Cu2+ ion. Chem. Eng. J. 148, 80-88. http://dx.DOI.org/10.1016/j.cej.2008.08.00310.1016/j.cej.2008.08.003
53. Ghasemi, Z., Seif, A., Ahmadi, T.S., Zargar, B., Rashidi, F. & Rouzbahani, G.M. (2012). Thermodynamic and kinetic studies for the adsorption of Hg (II) by nano-TiO2 from aqueous solution. Adv. Powder Technol. 23(2), 148-156. https://DOI.org/10.1016/j.apt.2011.01.00410.1016/j.apt.2011.01.004
54. Rahchamani, J., Mousavi, H.Z. & Behzad, M. (2011). Adsorption of methyl violet from aqueous solution by polyacrylamide as an adsorbent: Isotherm and kinetic studies. Desalination, 267(2), 256-260. https://DOI.org/10.1016/j.10.1016/j
55. Doğan, M., Ozdemir, Y. & Alkan, M. (2007). Adsorption kinetics and mechanism of cationic methyl violet and methylene blue dyes onto sepiolite. Dyes Pig. 75(3), 701-713. https://DOI. org/10.1016/j.dyepig.2006.07.02310.1016/j.dyepig.2006.07.023
56. Mezenner, N.Y. & Bensmaili, A. (2009). Kinetics and thermodynamic study of phosphate adsorption on iron hydroxide- eggshell waste. Chem. Eng. J. 147(2), 87-96. https://DOI. org/10.1016/j.cej.2008.06.02410.1016/j.cej.2008.06.024
57. Ahmad, R., Kumar, R. & Haseeb, S. (2012). Adsorption of Cu2+ from aqueous solution onto iron oxide coated eggshell powder: Evaluation of equilibrium, isotherms, kinetics, and regeneration capacity. Arabian J. Chem. 5, 353-359. https://DOI.org/10.1016/j.arabjc.2010.09.00310.1016/j.arabjc.2010.09.003
58. Chairat, M., Rattanaphani, S., Bremner, J.B. & Rattanaphani, V. (2005). An adsorption and kinetic study of lac dyeing on silk. Dyes Pig. 64, 231-241. http://dx.DOI.org/10.1016/j.dyepig.2004.06. 09.10.1016/j.dyepig.2004.06.09
59. Ayoob, S., Gupta, A.K., Bhakat, P.B. & Bhat, V.T. (2008). Investigations on the kinetics and mechanisms of sorptive removal of fl uoride from water using alumina cement granules. Chem.Eng. J. 140(1), 6-14. https://DOI.org/10.1016/j.cej.2007.08.02910.1016/j.cej.2007.08.029
61. Wardani, A.K., Hakim, A.N., Khoiruddin, Destifen, W., Goenawan, A. & Wenten, I.G. (2017). Study on the infl uence of applied voltage and feed concentration on the performance of electrodeionization in nickel recovery from electroplating wastewater, Proceedings of the 1st International Process Metallurgy Conference (IPMC 2016) AIP Conf. Proc. 1805. DOI: 10.1063/1.4974415.10.1063/1.4974415
62. Davidson, J. (2010). Removal of nickel (II) from aqueous solutions by polymer-enhanced ultrafi ltration, A major qualifying project submitted to the faculty of Worcester Polytechnic Institute in partial fulfi llment of the requirements for the Bachelor of Science Degree, Shanghai, China Project Center 73 p.
64. Ramamurthi, V., Priya, P.G., Saranya, S. & Basha, C.A. (2009). Recovery of nickel (II) ions from electroplating rinse water using hectorite clay. Modern App. Sci. 3(9), 37. http:// dx.DOI.org/10.5539/mas.v3n9p3710.5539/mas.v3n9p37
65. Deng, L., Su, Y., Su, H., Wang, X. & Zhu, X. (2007). Sorption and desorption of lead (II) from wastewater by green algae Cladophora fascicularis. J. Hazard. Mater. 143 2007. 220-225. https://DOI.org/10.1016/j.jhazmat.2006.09.00910.1016/j.jhazmat.2006.09.00917049733