Effect of inﬂuent aeration on removal of organic matter from coffee processing wastewater in constructed wetlands Maike Rossmann a , Antonio Teixeira Matos a , Edgar Carneiro Abreu a , Fabyano Fonseca Silva b , Alisson Carraro Borges a, * a Universidade Federal de Viçosa, Departamento de Engenharia Agrícola, Av. Peter Henry Rolfs, s/n, Campus Universitário, CEP 36570-000 Viçosa, Minas Gerais, Brazil b Universidade Federal de Viçosa, Departamento de Estatística, Av. Peter Henry Rolfs, s/n, Campus Universitário, CEP 36570-000 Viçosa, Minas Gerais, Brazil article info Article history: Received 5 October 2012 Received in revised form 21 June 2013 Accepted 28 June 2013 Available online Keywords: Treatment wetland Horizontal ﬂow Agro-industrial efﬂuent Coffee Aeration abstract The aim of the present study was to evaluate the inﬂuence of aeration and vegetation on the removal of organic matter in coffee processing wastewater (CPW) treated in 4 constructed wetlands (CWs), char- acterized as follows: (i) ryegrass (Lolium multiﬂorum) cultivated system operating with an aerated inﬂuent; (ii) non-cultivated system operating with an aerated inﬂuent, (iii) ryegrass cultivated system operating with a non-aerated inﬂuent; and (iv) non-cultivated system operating with a non-aerated inﬂuent. The lowest average chemical oxygen demand (COD), biochemical oxygen demand (BOD) and total suspended solids (TSS) removal efﬁciencies of 87, 84 and 73%, respectively, were obtained in the ryegrass cultivated system operating with a non-aerated inﬂuent. However, ryegrass cultivation did not inﬂuence the removal efﬁciency of organic matter. Artiﬁcial aeration of the CPW, prior to its injection in the CW, did not improve the removal efﬁciencies of organic matter. On other hand it did contribute to increase the instantaneous rate at which the maximum COD removal efﬁciency was reached. Although aeration did not result in greater organic matter removal efﬁciencies, it is important to consider the beneﬁts of aeration on the removal of the other compounds. Ó 2013 Elsevier Ltd. All rights reserved. 1. Introduction The cultivation and processing of coffee fruits (Coffea canephora, Coffea arabica) is an important socioeconomic activity in producing and exporting regions, as in Africa, Asia, Central and South America, and re-exporters, including the United States and some European countries, because it generates a large number of jobs both directly and indirectly. In recent years, many producers have used washing and peeling/pulping in the processing of coffee fruits in an attempt to reduce costs of drying and for quality control. Despite these beneﬁts, wet processing generates large volumes of highly pollutant wastewater, rich in suspended organic material as well as organic and inorganic constituents in solution (Matos et al., 2006). The coffee processing wastewater (CPW) is highly variable, depending on the characteristics of the fruits processed, and the processing type applied. In addition to high organic inputs, CPW is rich in organic matter (as biochemical oxygen demand e BOD) and nutrients (as nitrogen and phosphorus) with ratios generally exceeding 100:5:1, and low pH values. Due to these characteristics, when applying biological treatments, the addition of nutrients and pH correction is necessary to ensure greater efﬁciencies of organic matter degradation (Fia et al., 2007). Several methods, particularly anaerobic, have been proposed for the treatment of CPW. However, studies on the treatment of CPW are scarce (Dinsdale et al., 1997; Jeison and Chamy, 1999; Selvamurugan et al., 2010), and in general the resultant efﬂuent does not meet the environmental requirements for disposal in water bodies. Recently, constructed wetlands (CW) have been proposed for the treatment of raw CPW and for post-treatment of anaerobic systems efﬂuents (Fia et al., 2010a, 2010b, 2010c). The CWs are artiﬁcial projects which utilize natural processes involving vegetation, substrate and the intrinsic microbial com- munity for treatment of wastewater. The plants provide a root mass which assists in ﬁltration, and also provides oxygen essential for the aerobic degradation of organic material present in the waste- water. Examples include oxygen ﬂow rates of 126 mmol h 1 g 1 root dry mass for Juncus ingens (giant rush) (Sorrell and Armstrong, 1994) and 120e200 mmol h 1 g 1 root dry mass for Typha latifolia * Corresponding author. Tel.: þ55 02131 3899 1914. E-mail addresses: maike.rossmann@ufv.br (M. Rossmann), atmatos@ufv.br (A.T. Matos), edgar.abreu@ufv.br (E.C. Abreu), fabyanofonseca@ufv.br (F.F. Silva), borges@ufv.br (A.C. Borges). Contents lists available at SciVerse ScienceDirect Journal of Environmental Management journal homepage: www.elsevier.com/locate/jenvman 0301-4797/$ e see front matter Ó 2013 Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.jenvman.2013.06.045 Journal of Environmental Management 128 (2013) 912e919