References
    -  D.D. Noriega, P.L. Arias, H.R. Barbosa, F.B.M. Arraes,
    G.A. Ossa, B. Villegas, R.R. Coelho, E.V.S. Albuquerque,
      
 R.C. Togawa, P. Grynberg, H. Wang, A.M. Vélez, J.W. Arboleda,
    M.F. Grossi-de-Sa, M.C.M. Silva,
 A. Valencia-Jiménez,
    Transcriptome and gene expression analysis of three
    developmental stages of the coffee berry borer, Hypothenemus
    hampei, Sci. Rep., 9 (2019) 1–14, doi: 10.1038/s41598-019-49178-x.
-  A. Samoggia, B. Riedel, Consumers’ perceptions of coffee health
    benefits and motives for coffee consumption and purchasing,
    Nutrients, 11 (2019) 1–21, doi: 10.3390/nu11030653. 
-  A.P.M. Velenturf, P. Purnell, Resource recovery from waste:
    restoring the balance between resource scarcity and waste
    overload, Sustainability, 9 (2017) 1–17, doi: 10.3390/su9091603. 
-  N. Zarrinbakhsh, T. Wang, A. Rodriguez-Uribe, M. Misra,
    A.K. Mohanty, Coproducts from coffee, BioResources, 11 (2016)
    7637–7653. 
-  W.K. Garde, S.G. Buchberger, D. Wendell, M.J. Kupferle,
    Application of Moringa oleifera seed extract to treat coffee
    fermentation wastewater, J. Hazard. Mater., 329 (2017) 102–109. 
-  P. Jagdale, D. Ziegler, M. Rovere, J.M. Tulliani, A. Tagliaferro,
    Waste coffee ground biochar: a material for humidity
    sensors, Sensors (Switzerland), 19 (2019) 1–14, doi: 10.3390/
    s19040801. 
-  F.M. Ferraz, Q. Yuan, Organic matter removal from landfill
    leachate by adsorption using spent coffee grounds activated
    carbon, Sustainable Mater. Technol., 23 (2020) 1–6, doi: 10.1016/j.
    susmat.2019.e00141. 
-  N. Azimah Ahmad, M.A. Abu Hassan, Z. Zainon Noor,
    A. Mohammed Evuti, J. Mohammed Danlami, Optimization
    of nickel removal from electroless plating industry wastewater
    using response surface methodology, 
 J. Teknol. (Sciences Eng),
    67 (2014) 33–40.
-  J. Virkutyte, E. Rokhina, V. Jegatheesan, Optimisation of electro-Fenton denitrification of a model wastewater using a response
    surface methodology, Bioresour. Technol., 101 (2010) 1440–1446. 
-  J. Wu, D. Yu, H. Sun, Y. Zhang, W.W. Zhang, F.Meng, X. Du,
    Optimizing the extraction of anti-tumor alkaloids from the stem
    of Berberis amurensis by response surface methodology, Ind.
    Crops Prod., 69 (2015) 68–75. 
-  M.A. Bezerra, R.E. Santelli, E.P. Oliveira, L.S. Villar,
    L.A. Escaleira, Response surface methodology (RSM) as a
    tool for optimization in analytical chemistry,Talanta, 76 (2008)
    965–977. 
-  H.A. Hasan, S.R.S. Abdullah, N.T. Kofli, S.K. Kamarudin,
	  Removal of NH4+–N ion in drinking water treatment using
    locally isolated heterotrophic nitrifier, Desal. Water Treat.,
  50 (2012) 294–301. 
-  L. Ma, Y. Han, K. Sun, J. Lu, J. Ding, Kinetic and thermodynamic
    studies of the esterification of acidified oil catalyzed by
    sulfonated cation exchange resin, J. Energy Chem., 24 (2015)
    456–462. 
-  M.J. Chen, K.N. Chen, C.W. Lin, Optimization on response
    surface models for the optimal manufacturing conditions of
    dairy tofu, J. Food Eng., 68 (2005) 471–480. 
-  W.E.F. American Public Health Association in American Water
    Works Association, Standard Methods for the Examination of
    Water and Wastewater, 2014. 
-  U. Mukundan, S.S. Ratnoji, COD removal from sewage by
    activated carbon from rice husk-an agricultural by product, Int.
    J. Innov. Res. Sci. Eng. Technol., 4 (2015) 5003–5007. 
-  S. Bamukyaye, W. Wanasolo, Performance of egg-shell and fishscale
    as adsorbent materials for chromium(VI) removal from
    effluents of tannery industries in Eastern Uganda, Open Access
    Lib. J., 4 (2017) 1–12, doi:10.4236/oalib.1103732. 
-  S. Venkata Mohan, J. Karthikeyan, Removal of lignin and tannin
    colour from aqueous solution by adsorption onto activated
    charcoal, J. Drug Res., 97 (1997) 183–187. 
-  S.B. Daffalla, H. Mukhtar, M.S. Shaharun, Characterization
    of adsorbent developed from rice husk: effect of surface
    functional group on phenol adsorption, J. Appl. Sci., 10 (2010)
    1060–1067. 
-  W. Chou, C. Wang, Y. Huang, Removal of gallium ions from
    aqueous solution by using tea waste by adsorption, Fresenius
    Environ. Bull., 19 (2010) 2848–2856. 
-  A.A. Ahmad, B.H. Hameed, Reduction of COD and colour of
    dyeing effluent from a cotton textile mill by adsorption onto
    bamboo-based activated carbon, J. Hazard. Mater., 172 (2009)
    1538–1543. 
-  L. Wang, A. Wang, Adsorption properties of congo red from
    aqueous solution onto N,O-carboxymethyl-chitosan, Bioresour.
    Technol., 99 (2008) 1403–1408. 
-  Y.B. Onundi, A.A. Mamun, M.F. Al Khatib, M.A. Al Saadi,
    A.M. Suleyman, Heavy metals removal from synthetic
    wastewater by a novel nano-size composite adsorbent, Int. J.
    Environ. Sci. Technol., 8 (2011) 799–806. 
-  I. Osasona, K. Aiyedatiwa, J.A. Johnson, O.L. Faboya, Activated
    carbon from spent brewery barley husks for cadmium ion
    adsorption from aqueous solution, Indones. J. Chem., 18 (2018)
    145–152. 
-  H. Zhang, C. Chen, E.M. Gray, S.E. Boyd, Effect of feedstock
    and pyrolysis temperature on properties of biochar governing
    end use efficacy, Biomass Bioenergy, 105 (2017) 136–146. 
-  Zikmund, J.C. Babin, W.G. Carr, B. Griffin, Business Research
    Methods, AESS Publication, New York, 2013, 
 p. 668.
-  C. Sing, J. Yu, Copper adsorption and removal from water
    by living mycelium of white-rot fungus Phanerochaete
    chrysosporium, Water Res., 32 (1998) 2746–2752. 
-  P. Hadi, J. Barford, G. McKay, Synergistic effect in the
    simultaneous removal of binary cobalt-nickel heavy metals
    from effluents by a novel e-waste-derived material, Chem. Eng.
    J., 228 (2013) 140–146. 
-  M. Mamatha, H.B. Aravinda, E.T. Puttaiah, S. Manjappa,
    Adsorption of ferrous and ferric ions in aqueous and industrial
    effluent onto Pongamia pinnata tree bark, Int. J. Chem. Mol.
    Nucl. Mater. Metall. Eng., 6 (2012) 43–51. 
-  K. Draper, T. Tomlinson, The Potential for Biochar to Deliver
    Greater Sustainability for Coffee Cultivation and Processing:
    A White Paper, Ithaka Institute and International Biochar
    Initiative, Switzerland, 2015. 
-  I. Kiran, T. Akar, A. Safa Ozcan, A. Ozcan, S. Tunali, Biosorption
    kinetics and isotherm studies of Acid Red 57 by dried
    Cephalosporium aphidicola cells from aqueous solutions, Biochem.
    Eng. J., 31 (2006) 197–203. 
-  S. Wong, N.A. Ghafar, N. Ngadi, F.A. Razmi, I.M. Inuwa,
    R. Mat, N.A.S. Amin, Effective removal of anionic textile dyes
    using adsorbent synthesized from coffee waste, Sci. Rep.,
    10 (2020) 1–13. 
-  M. Rahman, T. Ahmed, I. Salehin, M. Hossain, Colour removal
    from textile wastewater using date seeds activated carbon,
	  Bangladesh J. Sci. Ind. Res., 52 (2017) 31–42.