ABSTRACT
Pig farming has excelled in Brazilian livestock whose meat production has been considered the third largest in the world. Conversely, these production systems have great environmental polluting potential. In addition, anaerobic systems have been used for swine wastewater treatment, requiring complementation to reduce loads of nutrients and for further agricultural reuse. This paper evaluated the combined effect of two treatment units in removing organic matter in the form of chemical oxygen demand (COD). The combined units consisted of an upflow anaerobic sludge blanket (UASB) reactor with working volume of 96 L, followed by a constructed wetland system (CWS) with a capacity of 237 L. The experiment was conducted at three stages of hydraulic retention time (HRT) variation. The HRT was of 59, 19.5, and 5 hours for the UASB, and of 146, 48, and 13 hours for the CWS. The volumetric organic loading rates (VOLRs) were 1.2, 1.3, and 13.0 kg.m-3d-1 of COD in the USBAR. The surface application rates (SAR) in the CWS were 850, 656, and 6335 kg.ha-1.d-1 of COD. The associated units removed 0.07, 0.07, and 0.96 kg.d-1 of total COD, as well as 0.03, 0.07 and 0.14 kg.d-1 of soluble COD. The final effluent characteristics did not reach environmental standards for being released into water bodies in any of the stages; however, its nutritional potential should be considered for use in agricultural production.
organic load; Cynodon spp; surface application rate; biological treatment; wetland system
