Desempenho de sistemas alagados construídos, cultivados com diferentes espécies vegetais, no tratamento de águas residuárias da suinocultura

• Autor(a) principal: Freitas, Wallisson da Silva
• Data de Publicação: 2006
• Tipo de documento: Tese
• Idioma: por
• Título da fonte: LOCUS Repositório Institucional da UFV
• Texto Completo: http://locus.ufv.br/handle/123456789/683
• topic: Áreas alagadas; Águas residuais; Purificação; Plantas aquáticas; Suino; Esterco; Wetland systems; Wastewater; Aquatic plants; Swine dejects; CNPQ::CIENCIAS AGRARIAS::ENGENHARIA AGRICOLA::ENGENHARIA DE AGUA E SOLO

Swine swine feedlot is an activity generating a great wastewater volume (ARS), so causing serious environmental problems. The application of the constructed wetland systems (SACs) is distinguished among the available solutions for this wastewater treatment. Taking into account the shortage of specific technical information about the treatment of ARS by the application of SACs, especially using different vegetal species under tropical conditions, this study was carried to evaluate the spatial behavior (along SACs length) and time behavior (over 7-day period under monitoring) of SACs, as well as their efficiency in removing the pollutants and the ability of three vegetal species in extracting the nutrients. So, five tanks measuring 24m x 1.1m x 0.7m and damp-proof with butyl canvas were infilled with a 0.4m crushed stone (zero) were constructed in the Drainage and Hydraulic/Irrigation Experimental Area pertaining to the Agricultural Engineering Department - UFV. The ARS was previously treated, by applying a filtration process consisting of 0.7m height organic filters from which the filtering beds were constituted by sugarcane bagasse. The effluents of the filters were applied to SACs at 0.8 m3 d-1 flow rate corresponding to a hydraulic detention time about 4.8 days. In the treatments so-called SAC1, SAC2 and SAC3, the following were planted: Typha latifolia L., Alternanthera philoxeroides (Mart.) Griseb. and Cynodon dactylon Pers.. In SAC4, the Alternanthera was planted in the 1st third of the tank, Typha latifolia L. in the second, and Cynodon dactylon Pers in the third. In SAC5, no planting was performed, it was the control. Samples were collected from both affluent and effluent of the filters, as well as in the sample collecting points positioned at 4, 8, 12, 16, 20 and 24 m (outlet) in each SAC. In the collected wastewater samples, the following were analyzed: pH, electric conductivity, redox potential, and turbidity. In addition, the following concentrations were determined: total solids (ST), total suspended solids (SST), total dissolved solids (SDT), BOD5, COD, N-total, NH4+, NO3-, P-total, K, Na, Cu, Zn, total coliforms and E. Coli. During the experimental period, three cuts were performed in those plants cropped in SACs, in order to evaluate the dry matter productivity and nutrient extraction capacity. All plants showed satisfactory performance for productivity and nutrient extraction, as well as dry matter productivity around 22, 26 and 28 t ha-1 for Typha latifolia L., Alternanthera philoxeroides (Mart.) Griseb. and Cynodon dactylon Pers.. The plants removed 5 to 10% Total-N, 2 to 5% Total-P, 11 to 25% K, and 0.6 to 5% Zn, with prominence for Alternanthera that was the species provided with higher extracting capacity. Concerning to SACs efficiency in treating ARS, the following were obtained: efficiencies above 85% in removing SST, BOD, COD and Zn; above 50% in removing Total-N, NH4+, Total-P and ST; and from 18 to 48% in removing K, Na and SDT in all SACs under analysis. The Cu removal was very sensible to the loads applied, as ranging from 17 to 90%. Although the plants showed high pollutant removals and the Alternanthera was distinguished among all of them, in general no significant differences occurred in the quality of the effluents, neither in the removal efficiency by those five SACs. Almost total removals of ST, SST, COD, BOD, Total-P and Zn occurred at the initial 12 meters of the tanks. Besides, no tendency for alteration was observed in the efficiency of the systems during the operational time. The reduction in the counting of the total coliforms ranged from 90 to 99.9%, but from 85.4 to 100% for E. coli. Despite no significant differences occurred among the efficiencies of those five SACs, the use of the cropped SACs is suggested, relative to the uncropped ones, because the first one rather generates lower effluent volumes, therefore lower pollutant loads from the effluent. In relation to the plant to be used, either Alternanthera is recommended because shows higher nutrient concentrations in dry matter or the Cynodon dactylon Pers in case the producer wants to use it in animal feeding.