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SASS: Stand Alone Sun-flow System

SASS is a sustainable and stand-alone water treatment system, requiring only sunlight to operate, that can be used for the removal of persistent organic pollutants (POPs) from water resources.

What it does

SASS treats POPs polluted water in small and medium industries or low resource settings. SASS is a stand-alone system using only sunlight to operate. It is developed to be a low cost, sustainable and user-friendly solution to treat polluted water.

Your inspiration

According to United Nations, by 2025, more than 300 zones around the world, including many in low resource areas will have water conflicts. This global concern motivated us to design a nature inspired water treatment system. Our pilot prototype takes advantage of sunlight, especially in areas with the high light intensity like Australia, and natural cellulose materials. The available processes in the market are either not efficient enough or produce a secondary pollutant that needs to be disposed in the environment. This prototype seeks to provide a sustainable treatment of POPs such as fluorinated compounds in low resource settings.

How it works

SASS is a stand-alone system with two main compartments: 1) a catalyst synthesised out of the earth abundant ingredients; 2) a spiral channelled system. Together, the system is a compact, continuous, and sustainable design to harvest sunlight as a power source. The catalyst contains zinc oxide and cellulose sublayer that gets activated with sunlight to break down organic pollutants. Contaminated water in the treatment tank is circulated throughout the system using a pump for the desired treatment time. At the end of the treatment cycle, the water is discharged from the system. When the UV intensity is less than the minimum photocatalytic reaction requirements, the mounted UV lights in the apparatus turn on at an appropriate intensity to maintain the reaction rate. The UV lights then work at the maximum intensity during the night. Solar panels and a battery provide the power for the lights while a micro controller manages the flow of water through the system.

Design process

The design idea evolved from continuous treatment of water in the environment and what Mother Nature has provided. Our journey started in 2018 with a batch reactor, artificial UV light and initial zinc oxide catalysts. Before reaching the final design, we tested four prototypes including a batch design in 2018 (prototype I), a continuous glass tube in 2019 (prototype II), semi-stand-alone process in 2020 (prototype III), and fully stand-alone apparatus in 2021 (prototype IV). Efficiency, long term performance, and efficacy were our main concerns. Efficiency was tested using model organic pollutant dyes. The long-term performance was tested by running the process in multiple cycles and negligible reduction in functionality was observed. Efficacy was examined using a variety of persistent organic pollutants such as per- and polyfluoroalkyl substances (PFAS), dioxane solvents, industrial dyes, and real wastewater samples, until degradation to below health and environmental advised levels were achieved. In the final design, a battery charged by a solar panel is used to power the LED UV lights during the night and daylight period where the UV levels are not high enough. The control system has been designed to be as user friendly and simple as possible for all ranges of customers.

How it is different

There is a lack of sustainable and economical methods to treat persistent organic pollutants, especially for low resource settings. The materials used in this system are from abundant and cheap sources. SASS, due to its unique design, provides an easy-to-use integrated solution for the treatment of persistent organic pollutants in low resource areas. It is not dependant on energy provided from the fossil fuel or health and environmental hazardous chemicals and can get scaled up to meet the usage and demands of the environment in which it is employed. The simplistic design and use of a most user-friendly process control design mean that no intervention is needed during the process, hence requiring less labour and maintenance than traditional water treatment designs possess. Finally, the compact size and shape of the system mean that it can be placed in different kinds of environment compared to traditional treatment processes which require more footprint.

Future plans

We envisage that in the near future the SASS will be scaled up to accommodate for treatment of larger water streams. Further research needs to be conducted into the most efficient method of harvesting energy from UV light and their configuration to maximize the volume of water treated. Once the control system has been finalized, we plan to implement purpose-built microcontrollers to manage various sensors and control the flow of contaminated and treated water.


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