Efficiency of constructed wetland systems cultivated with black oats treatment of domestic sewage

Valdeir Eustáquio Júnior,Antonio Teixeira De Matos,Paola Alfonsa Vieira Lo Monaco,Alison Carrro Borges,Lidiane Carvalho De Campos

doi:10.4025/actascitechnol.v34i4.13990

Valdeir Eustáquio Júnior, Antonio Teixeira De Matos + Show 3 more

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https://doi.org/10.4025/actascitechnol.v34i4.13990

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Abstract

The objective of the present work was to evaluate the efficiency of a constructed wetland system cultivated with black oat (Avena strigosa Schreb) for the treatment of domestic sewage effluent from a septic tank, with emphasis on removal of carbonaceous matter, nutrients (N, P and K) and sodium. The experiment was conducted in four constructed wetland system (CWS) with horizontal subsurface flow for secondary/tertiary treatment domestic sewage. The CWS 1, 2, 3 and 4 received, respectively, organic load rates (OLR) of 100, 200, 400 and 600 kg ha -1 day -1 of BOD. Average efficiencies for removal of BOD, COD, total nitrogen, phosphorus, sodium and potassium were, respectively, 69.5, 70.2, 17.8, 26.2, 14.9 and 16.6%. Low efficiency in the removal of nutrients (N, P and K) was due a high OLR applied which provided also a large input of nutrients to the system. Sodium removal efficiency was low because it is a highly soluble ion and is poorly absorbed by plants. In general, lower OLR result in greater pollutant removals from the domestic sewage.

Highlights

With the objective of preserving water resources and protecting public health, new technologies for the treatment of domestic sewage have been sought, especially those of low cost
There was no significant variation in potential of hydrogen (pH) among the influents (Table 1) and effluents from the constructed wetland system (CWS) (Table 3) where the values found are close to neutrality, conditions considered ideal for the development of organic material degrading microorganisms which is in the range of 6.0 to 7.2, as well as improved performance of plant species (BRIX et al, 2002)
The pH values of the effluent (Table 3) are within the limits of 6 to 9 set by the Joint Resolution Normative COPAM/CERH No 01/2008 (MINAS GERAIS, 2008), for characteristics of effluents to be released to water bodies

Summary

Introduction

With the objective of preserving water resources and protecting public health, new technologies for the treatment of domestic sewage have been sought, especially those of low cost. One of these that may be highlighted is the constructed wetland system (CWS) due to its low operational and maintenance costs (KONNERUP et al, 2009), allowing for production of plant species of commercial interest and/or food. This method of wastewater treatment has proven to be efficient in removing organic matter (BOD and COD), total suspended solids. The functions of macrophytes include the extraction of Maringá, v. 34, n. 4, p. 391-398, Oct.-Dec., 2012 nutrients from the wastewater, and the transfer of oxygen to the substrate, providing support (rhizomes and roots) for the growth of biofilm bacteria, and improving the permeability of the substrate and aesthetics of the environment (MATOS et al, 2009a)

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