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poster - International Conference of Agricultural Engineering

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Table 2. Daily affluent concentration <strong>of</strong> Ammonia nitrogen, Nitrate and Total Phosphorous with<br />

minimum and maximum in the CWs during the period studied.<br />

Minimum and<br />

NH³ + NO -3 TP<br />

maximum<br />

concentrations<br />

(mg.L -1 )<br />

24.8 – 76.9 1.1 – 3.0 2.2 – 5.2<br />

At Table 3 one observes the average retention for the amount <strong>of</strong> NH³ + , NO -3 e TP, in<br />

accordance with the non-parametric statistics in the Mann-Whitney test, at 5% significance. A<br />

statistical difference was registered for the amount <strong>of</strong> NO -3 at CW1 with Heliconia<br />

psittacorum with 31.0% average retention in AP period. SIM et al. (2008) obtained an<br />

average Nitrate retention <strong>of</strong> 58.6% with hydraulic retention time (HRT) <strong>of</strong> 4 days. YOUSEFI &<br />

MOHSENI-BANDPEI (2010) observed that the highest efficiency the Nitrate retention, from<br />

53.5 to 62.5%, occurred with HRT <strong>of</strong> 4 to 5 days. The HRT <strong>of</strong> this CW was <strong>of</strong> 1.4 days, which<br />

could have influenced in this retention, when comparing to the authors mentioned. Heliconia<br />

psittacorum, (CW1) had a good recovery after pruning, which did not occur at Cyperus<br />

alternifolius (CW2) whose development was below expected, with smaller size and death <strong>of</strong><br />

some plants. During the AP period all variables, in both CWs, presented positive efficiencies.<br />

During the AP period there were negative efficiencies, probably influenced by the plant<br />

senescence.<br />

Table 3. Average retention efficiency (%) for the amount <strong>of</strong> Ammonia nitrogen, Nitrate and Total<br />

Phosphorous during the period studied: before pruning (BP) and after pruning (AP)<br />

Period CW1 CW2<br />

NH³ + NO -3 TP NH³ + NO -3 P T<br />

BP 19.4 18.6 11.7 8.8 14.4 9.2<br />

AP -0.6 31.0 -1.8 -0.5 -7.0 -6.8<br />

CW1 – Heliconia psittacorum; CW2 – Cyperus alternifolius<br />

4. Conclusions<br />

- Among the variables analyzed, the amount <strong>of</strong> Nitrate at CW1 vegetated with<br />

Heliconia psittacorum presented a statistical difference in the period after pruning, with an<br />

average retention <strong>of</strong> 31%;<br />

- In the period BP the CWs did not present a statistical difference, and all variables in<br />

both CWs obtained positive averages;<br />

- Macrophyte Cyperus alternifolius did not accept pruning. Its regrowth was below<br />

expected and there was death <strong>of</strong> some plants, unlike Heliconia psittacorum which had a<br />

good recovery after pruning;<br />

- Monitoring at an hourly scale allowed the data transference to longer temporal scales<br />

with higher security and efficiency, permitting to better understand the dynamics from the<br />

CWs;<br />

- The use <strong>of</strong> ornamental plants in the CWs reduced the public rejection to the sewage<br />

treatment, transforming this place in a “garden wetland”.<br />

5. References<br />

APHA; AWWA; WPCF. (1998). Standard methods for the examination <strong>of</strong> water and<br />

wastewater. Washington: American Public Health Association,. 20. ed.

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