ADDIS ABABA UNIVERSITY, ETHIOPIA
Research focus: ecotoxicology, wastewater treatment and water quality
The management of wastewater from hospitals requires particular attention, especially because of its often high concentration of infectious agents. Among these infectious agents even antibiotic resistant bacteria are not uncommon. Untreated wastewater poses a danger to people and ecosystems and healthcare wastewater is even more dangerous. In Ethiopia, wastewater from hospitals is sometimes directly discharged into rivers or lakes. Even when released to the sewerage without pre-treatment, there is still a riskof wastewater being misdirected,for example due to pipe obstructions. Such scenarios point to the necessity of wastewater treatment directly at hospitals in developing countries.
Mahder’s study was aimed to characterise hospital raw wastewater and evaluate the treatment efficiency of a species of bulrush (Typha latifoila) and a species of reed (Phragmites karka) in constructed wetland cells that received healthcare wastewater collected from Tikur Anbessa (Black Lion) Specialized Referral Hospital. Constructed wetland is cost effective, easily manageable and efficient for the treatment of wastewater of any kind after primary treatment, particularly for developing countries like Ethiopia.
The constructed wetland in Mahder’s study has four parallel aligned cells.One serves as a control cell with no plants while the others are planted with Typha latifoila, Phragmites karka, and a mixed plantation of both plants respectively. The treatment efficiency of these cells was observed by measuring physico-chemical and biological water quality parameters. The raw wastewater was characterised by extremely high organic matter, nutrient load,low concentration of heavy metals, and high concentration of infectious agents as well as antibiotic resistant Escherichia coli.
Overall, the highest removal for most pollutants was detected in the cell with mixed plantation. Mahder sees this as a good indication forusing a combination of the two aquatic plants in a study for large-scale hospital wastewater treatment. In addition, she recommends further investigation on the removal efficiency of wetland cells for coliforms and antibiotic resistant bacteria.
The jury was truly convinced by the work of this young, engaged scientist because of her practical approach to a highly relevant problem especially in developing countries, addressing the UN Sustainable Development Goal No. 6: Ensure access to water and sanitation for all.