Smartphone-Technology for Water Disinfection Process

Safe, free of bacteria and readily available clean water is important for public health, whether it is used for drinking, domestic use, food production or recreational purposes.

Cause of undisinfected water:

Drinking undisinfected water may cause many diseases such as diarrhea, cholera, typhoid, or even death. According to the US Centers for Disease Control and Prevention (CDC) report in 2017, waterborne diseases cause about 7,000 death, 477,000 emergency department visits, and $3.8 billion for disease associated treatment. Therefore, access to clean water free of bacteria is the essential and basic need for public health [1].

What is the disinfection of water?

The water treatment process to remove/inactivate bacteria is called disinfection. Generally, chlorine disinfection is a common technique to use control bacteria in water but it is limited by chemical transportation, storage, and the production of carcinogenic by-products. This type of commercial technique also suffer from different drawbacks, including long treatment time, short product lifespan, and/or fouling problems.

Why needed a smart technique for getting clean water?

The conventional disinfection in centralized facilities and distribution systems is usually not applicable to decentralized areas [2]. Consequently, it is critical to developing point-of-use (POU) disinfection methods. Therefore a new smart technique is needed for the treatment of water with simple, low cost, robust, and energy-efficient. In recent years, electrochemical disinfection has become a more feasible approach because of its versatile reactions, high inactivation efficiency, and low cost [3].

Figure 1. Schematic showing the smartphone-based water disinfection using a coaxial-electrode copper ionization cell (CECIC) [4].

Smartphone-powered disinfection process:

Recently, J. Zhou et al., have introduced a new technique as a smartphone-powered disinfection system for point-of-use (POU) bacterial inactivation [4]. In their report an integrated system with the smartphone battery used as a power source, and a customized on-the-go (OTG) hardware connected to the phone to realize the desired electrical output. They also handled this total function through a downloadable mobile application; it has the following features such as the electrical output, either constant current (20–1000 μA) or voltage (0.7–2.1 V), can be configured easily through a user-friendly graphical interface on the screen. In this device, a coaxial electrode copper ionization cell (CECIC) is used as an external configuration for inactivates bacteria by low levels of electrochemically generated copper with low energy consumption (Figure 1). The CECIC utilized both electrochemically generated Cu ions and the non-uniform electric field brought by the coaxial-electrode design to provide a new method for POU water disinfection. In this study, they took an E. coli bacteria for disinfection process and they observed a high inactivation efficiency of this bacteria Escherichia coli (E. coli, ~6 logs) with a low level of effluent Cu (~200 μg L⁻¹) in the water samples within a range of salt concentration (0.2 - 1 mmol L⁻¹) with the current control. Such an integrated disinfection system along with its high performance in different water matrixes demonstrates its feasibility to be applied in real-world cases to provide bacteria-free drinking water.

 “The smartphone based power workstation provides a versatile and accurate electrical output with a simple graphical user interface. The disinfection device is robust, highly efficient, and does not require complex equipment. As smartphones are pervasive in modern life, the smartphone-powered CECIC system could provide an alternative decentralized water disinfection approach like rural areas and outdoor activities”.

              --- Xing Xie, Georgia Institute of Technology, USA.

Why smartphone as a powerful source of this present technologies?

• Smartphones are potentially an excellent alternative of power sources because of their pervasive existence in the modern life.
• Smartphones can provide a user-friendly graphical interface, high-class energy storage and output (the lithium ion battery), and a highly programable platform.
• Smartphone-dependent applications have been developed for water monitoring and sensing.
• The rapid detection of bacterial density, heavy metal, and salinity using smartphones has been reported with the advantages of compact size, low cost, and user friendly.
• Prof. Xie mentioned that smartphones have never been used as a mobile power bank to conduct water disinfection.

Merits of Smartphone-powered water disinfection process:

1. The outstanding antimicrobial effect, low cost, and little human toxicity make copper an excellent disinfectant with no concerns of carcinogenic byproducts.
2. The copper ionization systems have been used for disinfection in drinking water, wastewater, hospitals, cooling towers, etc.
3. The coaxial-electrode configuration of the CECIC brings additional mechanisms to assist water disinfection.
4. The simple but superior coaxial-electrode design is promising to replace the traditional parallel-plate-electrode design.
5. The smartphone-powered disinfection system provides a convenient alternative for the POU disinfection.
6. The smartphone brings strong enough batteries and friendly user interfaces, while the OTG system realizes a controllable and precise electrical output with a compact design.
7. As smartphones are more and more prevalent, the smartphone-powered CECIC system can particularly benefit some remote regions where the construction of water grid is not cost-efficient.

Demerits of Smartphone-powered water disinfection process:

1. A critical issue related to the CECIC is the compromised performance in complex water matrices.
2. Water conductivity directly affects the ionization with a fixed voltage, which can be partially solved by current control.
3. The decrease of disinfection performance still exists when treating water samples with higher conductivities.
4. The effect of inorganic ions, organic matters, and particles on the disinfection should also be considered for future research.
5. In terms of other waterborne pathogens, such as viruses and protozoa, the use of copper ions has shown an outstanding disinfection effect in other studies.
6. Nevertheless, future research should examine if the CECIC also inactivates viruses and protozoa more efficiently than conventional Cu ions.
7. Another problem that should be addressed is the scaling-up of the CECIC device.
8. The circuit design can be optimized to enhance the efficiency of the smartphone energy workstation. Lower energy will be consumed by reducing the internal resistance of the OTG module, which results in higher overall efficiency.

The SNB team recommended this article to readers because with more research efforts; the smartphone-based CECIC disinfection system has the potential to be widely used in real life because of its low cost and versatile working modes. This designed technology will provides an energy-efficient and easily accessible method for POU water disinfection, especially in remote regions without centralized water treatment facilities.

References

1. K. M. Benedict, et al. Morbidity Mortal. Wkly. Rep. 66, 1216 (2017).
2. J. K. Kumar, and A. B. Pandit, Drinking Water Disinfection Techniques. (CRC Press, 2012).
3. C. A. Martínez‐Huitle, and E. Brillas, Angew. Chem. Int. Ed. 47, 1998 (2008).
4. J. Zhou, et al., npj Clean Water 40, 1 (2020).

Blog Written By

Dr. A. S. Ganeshraja

Assistant Professor

National College, Tiruchirappalli

Tamil Nadu, India

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Dr. K. Rajkumar

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