Treatment of Balili River in Benguet, Philippines with constructed wetland planted with dominant local macrophytes

Abstract

Phytoremediation using local macrophytes was explored in Balili River, Philippines. The macrophytes used were Amaranthus spinosus, Eichhornia crassipes, Eleusine indica and Pennisetum purpureum planted in pilot-scale constructed wetlands and subjected to varying hydraulic retention time (HRT) treatments. Results showed that these macrophytes have high phytoremediation performance in almost all water quality parameters. Also, HRT significantly affected the pollution reduction efficiency of the macrophytes. Significant pollution reduction was observed as early as HRT 1 day, but the optimal HRT for all the macrophytes was 3–4 days. At optimal HRT, the pollution reduction efficiency of the four macrophytes ranged from 96% to 99.9% for TSS, 87% to 95% for BOD, 85% to 99% for NO₃, 85% to 96% for PO₄ and 99.9% for total and fecal coliform. Also, Hg and Pb were significantly reduced. Results of TSS, DO and NO₃ passed the water quality standard, while BOD and PO₄ were slightly above. But total and fecal coliform, amidst the high reduction rate, was still not within the permissible level for Class A water. Among the macrophytes, P. purpureum generally have the best pollution reduction efficiency. Our study revealed comparable or even better pollution reduction efficiency of local macrophytes than commonly used ones such as Phragmites spp. and Typha spp.

Keywords:

• Phytoremediation
• constructed wetland
• Balili River
• aquatic macrophytes
• hydraulic retention time

Acknowledgments

The authors would also to express their appreciation to Edgar Alimambo and Prof. Maricel Guron for all the help during the data gathering part. Thank you and to God be the glory!

Additional information

Funding

This study is part of the PhD dissertation titled, “Phytoremediation Performance of Aquatic Macrophytes of Balili River in A Pilot-Scale Constructed Wetland” funded by SEARCA thru their PHD Research Program and DOST-ASTHRDP thru Student Research Support Fund (SRSF).