University of Bath

Safe Drinking Water using Capacitive Deionization for East Africa

This Fellowship aims to provide fluoride-free water to East African communities by utilizing the state-of-the-art capacitive deionization (CDI) technology.

The overall goal of the Fellowship is to provide fluoride-free water to East African communities by utilizing the state-of-the-art capacitive deionization (CDI) technology. First of all, a unique type of fluoride-selective electrodes will be prepared for the first time; secondly, decentralized solar-powered CDI systems will be implemented and tested in rural areas of Tanzania; finally, a sustainability assessment of the CDI technology will be conducted in the context of developing countries.

Project outline

WP 1: The fluoride-selective electrodes will be fabricated by depositing polyaniline (PANI) on the surface of porous carbon spheres (PCS). The intrinsic adsorption capacity of the electrodes for fluoride will be evaluated without applying electricity. The adsorption kinetics, isotherms, thermodynamics and adsorption mechanisms will be studied.

WP 2: Lab-scale capacitive defluoridation experiments will be performed to investigate whether the PANI-modified electrodes are fluoride-selective. The schematic is shown in Figure 1. Both the constant voltage and the constant current operation modes will be conducted. System performance, including effluent concentration, energy consumption, water recovery, and electrode regeneration, will be evaluated.

WP 3: Photovoltaic solar panels with proper output voltage and current will be directly connected to the CDI unit as external DC power. To investigate whether the solar-powered CDI system can deal with natural water in East Africa, a series of pilot experiments will be conducted in several field sites in Tanzania. System performance under different water compositions and operating conditions will be evaluated over a prolonged period.

WP 4: The factors affecting the sustainability of water supplies in developing countries, including (1) community demand, (2) local financing and cost recovery, and (3) operation and maintenance, will be assessed comprehensively. Village authorities will be involved in the implementation of the CDI systems and a training base that can handle such technology will be established with the ultimate aim to manufacture such systems locally.

Science

CDI is an emerging technology which gets increasing popularity. However, selective remove of certain ions remains one of the largest challenges for CDI. This becomes even more difficult when it comes to fluoride, because fluoride has a very high hydration energy (hydration enthalpy). I will make a breakthrough in this issue by developing the fluoride-selective electrodes. In addition, there are currently no research on the integration of CDI and renewable energy technologies in the context of developing countries, not to mention any sustainability assessment. My fellowship will fill these knowledge gaps as well.

Impact

The project will directly benefit a large population of people living in remote areas in Tanzania. Safe drinking water supplied by the CDI technology will protect children from dental and skeletal fluorosis. Women and girls no longer need to walk long distance to collect water for their families. Demonstration of health benefits and improvement on quality of life will stimulate a willingness to adopt innovative technologies at community scale.