CONTEXT

• Nearly 80% of global wastewater is discharged untreated, per UN (2017).
• UN SDG Goal 6.3 targets improved water quality, reduced pollutants, and 50% reduction in untreated wastewater by 2030.
• Wastewater sources: urban sewage, industrial effluents, mining runoff—rich in recalcitrant organics like pharmaceuticals, pesticides, and hydrocarbons.
• Traditional biological methods, though cost-effective, are insufficient for stubborn pollutants, necessitating advanced or hybrid techniques.

CONCEPT

• Biological Treatment: Preferred for economy; limited for non-biodegradable waste.
• Bioremediation: Uses beneficial bacteria/algae to oxidize pollutants and improve BOD/DO; used in urban lake clean-ups.
• Advanced Oxidation Processes (AOPs): Employ photocatalysis, ozone, UV/H₂O₂ to generate hydroxyl radicals for non-selective degradation of pollutants.
• Membrane Filtration: Used in tertiary treatments, often combined with photocatalysis or nanomaterials for improved results.
• Electrocoagulation and Adsorption: Supplementary treatments to remove particulates and dissolved contaminants.

CURRENT

• Bengaluru Case (2004): ₹5 crore bioremediation project at Bellandur Lake failed due to continued sewage inflow; succeeded partially at Madivala Lake with no fresh pollution.
• Oxidation Methods (1994 study): UV-TiO₂ treatment removed 70% organics, improved biodegradability, though energy-intensive.
• Nagaland University: Developed bio-based soft technologies using microbes, algae, and plants in energy-efficient, self-sustaining systems.
• Chinese Innovations:
  • Metagenomics + metal enzymes: Achieved complete nitrate removal from mine water.
  • Anaerobic SBR + SBBR: Removed 93% nitrogen from pharma waste.
  • Bimetallic systems (Fe-Cu): Achieved 99% phosphorus removal from organophosphorus pesticides.
  • Membrane bioreactors: Reached 85% efficiency in sulfamethoxazole removal.
• Material Advances:
  • Zeolites: Effective adsorbents for organics.
  • Graphene oxide + zero-valent iron: Enhanced photoactivity for better degradation.
• Hybrid Technologies:
  • NIT Rourkela: Developed nanocomposite ceramic membranes combining microbubbles + photocatalysis, achieved 95.4% dye degradation, 94% COD reduction.

CONCLUSION

• Hybrid and AOP-based systems, aligned with local contexts, offer cost-effective, scalable solutions.
• Strategic integration of biological, chemical, and material innovations is vital to achieving UN water targets by 2030.

MAINS QUESTION

1. Analyze the importance of achieving UN SDG Goal 6.3, which targets improved water quality and reduced pollutants. Discuss the role of advanced wastewater treatment technologies in achieving this goal.
2. Evaluate the effectiveness of hybrid technologies, such as combining biological treatment with AOPs or membrane filtration, in treating wastewater. Provide examples of successful implementations