Constructed wetlands for phytoremediation of industrial wastewater in Addis Ababa, Ethiopia

Abstract

Brewery industries generate large amounts of wastewater rich in organic matter originating from the brewing process, and they are among the major polluting industries. This study aimed to assess the phytoremediation of brewery wastewater using horizontal subsurface flow constructed wetlands (HSFCWs) vegetated with Typha latifolia and Pennisetum purpureum for organics removal and plant growth analysis. Six parallel pilot-scale HSFCWs were constructed and operated to assess potential of treating wastewater sourced from St. George brewery factory located in Addis Ababa, Ethiopia. Three units were planted with T. latifolia and the other three with P. purpureum with one control without plants for each species. Primarily settled wastewater was fed evenly to them by gravity. Wastewater quality, plant growth analysis and system efficiency were observed during the experiment following standard methods. Both plants grew and established well, however, T. latifolia had more biomass and vigorous growth and showed good phytoremedial capacity to remove organic pollutants. Average removal efficiencies for BOD5 and COD were significant (p < 0.05), up to 87% (inlet BOD5 of 748–1642 mg l−1) and up to 81% (inlet COD of 835–2602 mg l−1) and T. latifolia slightly outperformed P. purpureum. Estimated biomass of significant (p < 0.05) value (0.61–0.86 kg DW m−2) was produced. HSFCWs are green and environmentally sustainable technology that offers promising alternative wastewater treatment method in developing countries of tropical climate due to its low-tech nature. Integrating treatment and biomass production needs further improvement.