Context: The Energy and Resources Institute (TERI), New Delhi, has developed a technology called The Advanced Oxidation Technology or TADOX® that will ensure affordable and sustainable Zero Liquid Discharge (ZLD) compliance set by the Central Pollution Control Board (CPCB) for Common Effluent Treatment Plants (CETP) in industrial clusters.
The Advanced Oxidation Technology or TADOX®
- TADOX utilises UV-Photocatalysis as an Advanced Oxidation Process (AOP) during the secondary treatment stage of wastewater treatment leading to oxidative degradation and mineralisation of targeted pollutants.
- At Secondary Treatment Stage, the wastewater has already undergone some initial treatment, typically involving biological processes that remove organic matter.
- UV-Photocatalysis:
- UV Light: TADOX® introduces ultraviolet (UV) light to the wastewater, which has high energy and sanitation potential.
- Catalyst: The water also contains a catalyst, most commonly titanium dioxide (TiO2), which helps the UV light to trigger the chemical reaction.
- Oxidative Degradation: When UV light hits the catalyst, it energises the TiO2 particles. These energised particles then react with water molecules (H2O) to create highly reactive hydroxyl radicals (OH•). These hydroxyl radicals are very powerful oxidisers, meaning they readily attack and break down a wide range of pollutants in wastewater, including organic matter, colour, and micropollutants.
- Mineralisation: The breakdown process by hydroxyl radicals does not just break down the pollutants into smaller pieces. It completely mineralises pollutants, often converting them into simple molecules like carbon dioxide (CO2) and water (H2O).
- TADOX® could be integrated and retrofittable in existing treatment systems making it a viable option as a novel Decentralised Wastewater Treatment Technology (DWTT) applicable in upcoming and existing infrastructural projects, townships, commercial complexes, green buildings, and smart cities.
Significance:
- It reduces dependence and load on biological and tertiary treatment systems to achieve Zero Liquid Discharge (ZLD).
- It reduces the production of sludge to 0.5 kg per metre cube (as compared to standard treatments which produce around 30-40 kg per cubic metre, since a lot of chemicals are used in the wastewater treatment). Further, the sludge produced in the process is non-toxic.
- It can bring down capital expenditure on ZLD by 25-30% and operating expense by 30-40% for industrial wastewater treatment.
- It can reduce Chemical Oxygen Demand (COD), Biological Oxygen Demand (BOD), dissolved organics, pathogens, Persistent Organic Pollutants (POPs), and Micropollutants.
- It improves biodegradability, thereby preventing biofouling of membranes and enhancing life span and efficiency of RO systems as also overall load on evaporators like Multiple Effect Evaporators and Mechanical vapour recompression (MVR).