RAIMUNDO SOBRINHO, J.; http://lattes.cnpq.br/7384474220529593; RAIMUNDO SOBRINHO, José.
Résumé:
The treatment of polluted surface water by simple and economic methods is
becoming more and more necessary for the survival of rivers and lakes as well as it
presents an opportunity of reusing these waters for irrigation. With this purpose the
present research was carried out at Campus II of the Federal Paraiba University
(Campina Grande, Paraiba, Brazil), to evaluate an artificial wetland system using
Typha spp. The system consisted of 10 Brasilit tanks of 250 L, filled with small stone
pieces ( 19 mm) and was fed in batch with stream water, that passes through Campus
II of this University, with calculated discharge for a hydraulic detention of 5 and 10
days and having a subsurface flow. In 8 of these tanks 8 propagulos of Typha spp
were planted while the other two tanks having no macrofitas were used as controls.
The efficiency of the system was evaluated in terms of physical, chemical and
biological water quality parameters measured for affluent and effluent water of the
tanks. The statistical analysis of the results was made on two data groups: one that
obtained along with six months of the preset research work ( January to June 2001)
and the other obtained during first year of the work ( January to December 2000 ),
making a total of eighteen months. The results showed that the system presented
significant efficiency for the water purification. For the two periods of the water
hydraulic detention the verified mean removals in the last six months were: 82 and
89% turbidity; 83 to 88% biochemical demand of oxygen BOD5; 100% ammoniacal
nitrogen; 84 to 86% total phosphrorus; 96% of the soluble ortophosphate and 99% of
feacal coliforms. The temperature and the pH stayed practically constant, while other
parameters suffered higher increments as: electric conductivity (83 to 106%),
bicarbonates (64 to 90%), chlorates (134 to 220%), sodium (165 to 228%), calcium
(96 to 114%), magnesium (103 to 141%), total alkalinity (67 to 92%) and total
hardness (92 to 111%). A comparison of these results with those of previous 12 months, especially corresponding to similar climatic period (first semester) it can be
said that the performance of the system improved along with time with the growth of
the plants and their radicule system. The variance analysis at 5% level of significance
showed differences for the following parameters: total solids, ammoniacal nitrogen,
nitrates, phosphorous, feacal coliforms and estreptococos coliforms. The Tukey test
also applied to these two periods did not indicate any significant difference for the
effluents of the vegetated tanks for the hydraulic detention time of 5 and 10 days on
the variables as: electrical conductivity, turbidity, pH, alkalinity, hardness, BOD5,
ammoniacal nitrogen, total phosphorous; feacal coliforms and estreptococos
eoliforms. These effluents when compared with those of controle tanks, showed
significant differences for: electrical conductivity, bicarbonate, sodium, calcium,
magnesium, hardness, coliforms and estreptococos feacal. It is concluded that the
surface waters contaminated with domestic drain can be treated through the
constructed wetlands use with 5 days hydraulic detention time. These systems are
characterized by their construction simplicity and maintenance and presents an
alternative for the better utilization of the scarce hydraulic resources of semi-arid
region of Northeast of Brazil.
