Solar enabled waste water treatment
by Nagesh Potluri, Ph.D in Core Competencies Posted on 10/21/2020 02:00 PM
Rapid urbanization and industrial needs have put a strain on the availability of water. Currently, about two billion people living in developing economies don't have access to clean water. They use unimproved water sources or fecally contaminated waters. Sixty-three million people in the US have consumed unsafe water more than once in the past decade. Population growth, regulations, and aging infrastructure have led to a paradigm shift towards the use of Decentralized Wastewater Treatment (DWT). Traditional wastewater treatments cannot remove pharmaceutical wastes, pesticides, and personal care products. Therefore, there is a need to create a sustainable and innovative process that will help lower implementation and operational costs. And will benefit municipal, industrial, and commercial end-users. Developing countries can bolster business opportunities and improve the quality of life by utilizing decentralized water purification schemes.
Advanced Oxidative Process (AOP) relies on the in-situ generated.OH radicals to destroy the pollutants that cannot be removed by conventional treatment methodologies. AOPs are effective in destroying organic pollutants and pathogen microorganisms. Commercial AOP refers to a subset of chemical processes that employ ozone, hydrogen peroxide, and/or UV light. According to Frost & Sullivan's Environment & Water Growth Partnership Subscription, the decentralized wastewater treatment system are a nascent and highly fragmented market with acquisitions, mergers, and regional players' collaborations. Companies such as GE Water, Clearford Inc., EEC, Azud, and Newterra are considered leaders in this space. These companies typically use AOP modules in their decentralized water purification systems. Businesses like Calgon Carbon Corporation, Ch2M Hill Inc, Veolia Environment, and Xylem Inc. sell AOP technologies.
AOP via semiconductor photocatalysis for water treatment has been the subject of extensive research over the past three decades. In the photocatalytic AOP, the electrons excited from the photocatalyst by solar illumination leads to the conversion of the oxygen dissolved in water to highly reactive OH radicals. The .OH radicals react with the organic materials and microbes in the contaminated waters and cause their destruction. Potential benefits of the solar irradiated process for water purification can be realized by improving the photocatalyst efficiencies. Approaches such as the use of metallic co-catalysts of noble metals, semiconductor heterojunction catalyst, and advance nanoscale 2D materials are being actively researched for creating superior photocatalysts. Furthermore, the size-dependent characteristics of the ENM and their interactions with light will help drive improvement in catalytic efficiencies. Nanotechnology-enabled photocatalyst design would reduce the amount of catalyst required and hence the costs of implementing the technology. Environmental concerns related to the leaching of ENM can be addressed by adopting a fixed-catalyst reactor configuration.
To prevent photocatalyst wash out and aggregation; ENM may be anchored to large particle supports. The Mass transfer challenges associated with such immobilized-ENM systems are being addressed through alternative photochemical reactor designs. It is important to get the job done- it is not always required to rely on new materials. Unique performance attributes and synergies can sometimes be obtained by integrating new and old materials-technology strategies. Technical advancements in ENMs would help create in situ-production of the precursor compounds, such as hydrogen peroxide from Ozone through solar irradiation. This technology breakthrough could offer practical ways of eliminating the need for the storage, transport, and continual dosing of the harsh chemicals used in the AOP process.
Despite scientific literature's availability, there has been a delay in adopting the solar-enabled process due to the risk-aversiveness and technology gaps. Utilization of advanced ENMs, proper reactor design, and system engineering is expected to address the technology and business risks. With a deep strategic knowledge of innovative materials, ChemPrise is uniquely positioned to support the adoption of the Solar enabled Decentralized Wastewater Treatment technologies.
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