Coliform removal in a constructed wetland system used in post-swine effluent treatment

Fabiana De Amorim,Ronaldo Fia,Luiz Fernando Coutinho De Oliveira,Cláudio Milton Montenegro Campos,Jaíza Ribeiro Mota E Silva

doi:10.4136/ambi-agua.2402

Abstract

This study evaluated the efficiency of a constructed wetland system (CWS) in removing total coliforms (TC) and thermotolerant coliforms (ThC) of swine wastewater, as a complementary treatment to an anaerobic system. At Stage 1, the experimental system was combined using a vertical flow constructed wetland system (VFCWS) cultivated with Tifton 85 grass in series with a horizontal subsurface flow constructed wetland system (HFCWS1) cultivated with Taboa. In HFCWS1, the hydraulic detention times (HDT) were 4.7, 3.1 and 2.3 days and the surface application rates (SAR) were 294, 319 and 397 kg ha-1 d-1 of COD, in Phases I, II and III, respectively. At Stage 2, the experimental system was combined using a horizontal subsurface flow constructed wetland system (HFCWS2) cultivated with Tifton 85 grass, HDT were 6.1, 2.0 and 0.5 days and the SAR were 850, 656 and 6.34 kg ha-1 d-1 of COD, in Phases I, II and III, respectively. In Stage 1, it was verified that the VFCWS was more efficient in coliform removal when compared to HFCWS1. When only HFCWS were compared, coliform removal in Stage 1 was between 1 and 2 log units in HFCWS1. In the stage 2, the HFCWS2 was more limited, with the highest removal efficiencies during Phase I of 1.6 and 0.8 log units for TC and ThC, respectively. In general, the association resulted in efficiencies that ranged from 96.4 to 99.0% for TC, 94.2 and 97.6% for ThC, equivalent to the average removal of 1.2 to 2 log units, considered satisfactory.

Highlights

Agricultural business is the largest consumer of water in its various stages of production, and the scarcity of water resources in quantity and quality warns of the necessity to improve processes of treatment and reuse of water
This work aimed to evaluate the removal of total coliforms (TC) and thermotolerant coliforms (ThC) of swine wastewater treated in a constructed wetland system (CWS) as a complementary treatment to the anaerobic system, and to verify the contamination of the aerial part of the plant grown in the CWS
Winward et al (2008) reported that seasonal changes in temperature could strongly influence the coliform removal in CWS, in which was a positive correlation between the removal of bacteria and the temperature rise

Summary

Introduction

Agricultural business is the largest consumer of water in its various stages of production, and the scarcity of water resources in quantity and quality warns of the necessity to improve processes of treatment and reuse of water. Wastewater from pig farming has some of its components (organic matter, nitrogen, phosphorus, copper, etc.) in concentrations that are sufficiently high to constitute a risk of ecological imbalance when disposed inappropriately in watercourses Once it is well monitored, the use of this type of wastewater in agricultural arises as an alternative to its disposal, with the benefit of recycling nutrients for crops (Cavalett et al, 2006). In order to do that, the fertigation of pastures and fodder has been recommended, according to Matos (2007), as an alternative for the use of these effluents due to the rapid growth and the formation of large root mass of these cultures It must consider the desired levels of purification for reuse or disposal final destination, in accordance with the established conditions for the quality of water bodies receptors (Conama, 2011) or further uses, defining from these, respective processes and treatment systems

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Conclusion