PhD candidate conducts a study on the ability of biochars to purify hospital wastewater

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A recent study was conducted to investigate the efficiency of carbonized materials commonly called biochars produced by cookstoves and from different agricultural wastes to remove pharmaceuticals and personal care products from hospital wastewater. The study was carried out by Mukarunyana Brigitte, a University of Rwanda academic and PhD candidate at Umeå University in Sweden under the existing bilateral partnership between Rwanda and Sweden.

Graphical Abstract

The study emphasized the sustainable waste management approach in combination with relevant adsorption experiments based on real hospital wastewater.

Biochars can be produced from various biomasses, such as agricultural wastes, household solid wastes, animal wastes, and wood wastes. Hospital wastewater has been analysed using modern technology, and many pharmaceuticals have been detected. Biochars produced by cookstoves and from different agricultural residues have been applied to remove pharmaceuticals and personal care products. Results showed that cookstove biochars can remove these pollutants, the removal rates varied depending on the type of biochar and the substance to adsorb.

What is the problem ?

Humans consume pharmaceuticals to neutralize pathogens and control diseases. Most of the consumed pharmaceuticals are excreted either in a non-metabolized form or as metabolites with similar or different properties to the original compounds. These pollutants along with personal care products enter the aquatic environment system via wastewater flows and impact the water quality worldwide since they have ecotoxicological effects and increase antimicrobial resistance. Therefore, adequate treatment of wastewater is crucial to mitigate the environmental impact of pharmaceuticals.

“Hospitals are especially interesting since the consumption of pharmaceuticals and personal care products per person is high and their levels in untreated hospital effluent are among the highest detected levels in the world” Mukarunyana said.

She added that techniques used by hospitals to treat wastewater are mainly based on physicochemical and biological processes to remove solids, organic pollutants and nutrients.

“However, these techniques are reported to be ineffective in removing pharmaceuticals and personal care products. So, the issue was to find efficient and affordable technology of treating hospital wastewater”. This prompted her to investigate other adsorption techniques using as cookstove biochars which are low-cost and locally sourced materials.

The study relevance in African context

In the context of sub-Saharan Africa, Rwanda included, agriculture is the main income activity resulting in the production of agricultural biomasses like peels, pulps, husks, crop residues, etc. Although dried agricultural biomass is traditionally used in cooking, an important quantity of it is considered waste and an appropriate protocol for their disposal is not yet clearly established which increases challenges in waste management. By using cookstoves that pyrolysed biomass, the heat or energy for cooking is generated and carbonaceous materials or biochars resulting from that pyrolysis are produced as well. These biochars can have various applications including wastewater treatment as adsorbents. This is a sustainable way of reducing waste streams and valorizing agricultural biomass by transforming what was considered waste into raw materials. In addition, both wastewater samples and agricultural biomass (coffee and rice husks, sugar cane bagasse) used in this study have been taken in Rwanda. Moreover, biochars are economically efficient and environmentally friendly materials, they are easy to produce and raw materials are locally sourced. Thus they are prime candidates to be used in Rwanda in treating emerging water pollutants like pharmaceuticals and personal care products.

Mukarunyana Brigitte, a University of Rwanda academic and PhD candidate at Umeå University in Sweden under the existing bilateral partnership between Rwanda and Sweden.