Assessment of the Impacts of Phyto-Remediation on Water Quality of the Litani River by Means of Two Wetland Plants (Sparganium erectum and Phragmites australis)

Abstract

Water pollution from human activities is largely a result of the discharge of wastewater and industrial waste into rivers. Phytoremediation, the technique that uses plants to remove pollutants from the polluted waters, is a growing field of research because of its various environmental advantages. This study aims to evaluate the efficiency of a constructed wetland in removing pollutants and treating the polluted waters of the Litani River in Lebanon, by means of two aquatic plants, Phragmites australis and Sparganium erectum. Results showed that the levels of the physicochemical and biological parameters measured on water samples at downstream of the wetland were lower than those obtained at upstream. Results revealed that average removal efficiency was 41% for chemical oxygen demand (COD), 54% for biological oxygen demand (BOD5), 97% for nitrate (NO3−), 40% for nitrite (NO2−), 67% for phosphate (PO43−), while it was negative (−62%) for sulfate (SO42−), indicating an increase in sulfate content in the treated effluent returning to the river. On the other hand, most of the effluent chemical and biological characteristics were within the provisional discharge limits of effluent to water body set by the Ministry of Environment (MoE) and Lebanese Wastewater Reuse Guidelines of the Food and Agricultural Organization of the United Nations (FAO). Statistical analyses also showed significant variations (p < 0.5) among the two sampling sites along the wetland. Our findings clearly demonstrate that phytoremediation is a viable solution to remove pollutants in a competitive environment and improve the quality of contaminated waters by acting as a sink for various contaminants. The gained experience may be scalable to other sites and environments across the country.

The Use of Constructed Wetlands to Treat Effluents for Water Reuse

“…According to the Brazilian regulation ABNT 13969/97, the treated effluent could be reused to wash floors and pavements and irrigate gardens and landscapes. In systems involving largescale (35,000 m 2 ) SCW without microalgae, results revealed that there was an increase in the sulfate concentration (SO 4 −2 ) [53]. Such an increase might be due to the denitrifying bacteria activity, since chemolithoautotrophic bacteria reduce nitrate, while the S-oxidant bacteria oxidize sulfide to return SO 4 −2 during denitrification.…”

“…Such an increase might be due to the denitrifying bacteria activity, since chemolithoautotrophic bacteria reduce nitrate, while the S-oxidant bacteria oxidize sulfide to return SO 4 −2 during denitrification. This bacterial activity might explain the high NO −3 removal and the SO 4 −2 release in CW, which requires post-treatment so that the effluent can be reused [53].…”

Efficiency of Water Hyacinth (Eichhornia crassipes) in the Phytoremediation of Copper-Contaminated Waters of Lake Tempe, South Sulawesi Indonesia

“…Water hyacinth exposed to Cu(II) 50 ppm in the contaminated water were subjected to the 30-day phytoremediation after coming into contact with water. Atomic Absorption Spectrophotometer (AAS) was used to measure the amount of zinc in the sample 4 times at 10-day intervals [11].…”