Two-stage hybrid constructed wetlands system for industrial wastewater treatment

Abstract EN

A two-stage hybrid system with a continuous flow rate was constructed to treat highly polluted industrial wastewater of Al-Najibiyia Power Plant in Basrah city, Iraq.

The system consisted of a Horizontal Subsurface Flow System (HSSF) planted with Phragmites australis (Cav.

) followed by a Surface Flow System (SF) planted with Hydrilla verticillata (L.

f.

) Royle in series and there were two similar systems on the opposite side representing the contaminated control system.

The experiment was conducted for 72 days.

Several water quality parameters were measured in both raw and treated wastewaters, including pH, Biological Oxygen Demand (BOD5), Chemical Oxygen Demand (COD), Total Suspended Solids (TSS), and turbidity, in addition to some ions such as Sulfate ion (SO4-2) and Chloride ion (Cl).

The system performance results showed that the pollutants removal rate in the presence of plants was high reached to: BOD5(65.85 % ), COD (91 % ), TSS (88.83 % ), turbidity (83.65 % ), SO4ˉ2 (55.11 % ) and Clˉ (23.88 % ) as compared to the systems without plants which achieved BOD5(44.72 % ), COD (64.54 % ), TSS (68.73 % ), turbidity (66.05 % ), SO4ˉ2 (33.41 % ) and Clˉ (9.9 % ).

The results revealed that constructed wetlands (CWs) are a good option for industrial wastewater treatment compared to other expensive conventional treatment technologies.

It is also revealed that the presence of plants has an influential role in wastewater treatment.

Moreover, it could be concluded that a hybrid CWs system could enhance the pollutants removal efficiency better than single constructed wetlands.