"Membrane Bioreactors" are often discussed in the context of:
Answer & explanation
Answer: (d) Wastewater treatment technologies
A membrane bioreactor (MBR) is a sewage and industrial-effluent treatment system. It joins the usual biological step, in which microbes break down organic waste, with fine membrane filtration that holds back solids and bacteria, so it produces clean, reusable water from a much smaller plant than conventional settling tanks.
- ✓ (d) The US EPA describes MBRs as a secondary-treatment technology for municipal wastewater that combines a suspended-growth biological reactor with microfiltration, removing nitrogen, phosphorus, bacteria and organic load.
- ✗ (c) Vaccine and biologics production uses bioreactors (fermenters) too, but the term 'membrane bioreactor' refers to the filtration-based wastewater process.
- ✗ (b) Nano drug-delivery systems use carriers such as liposomes and nanoparticles; they are not membrane bioreactors.
Remember · Membrane bioreactor = activated-sludge (microbial) treatment + membrane micro/ultrafiltration; compact, high-quality effluent fit for reuse. Used for sewage and industrial wastewater.
📘 Read it in NCERT: Class 12 Biology, Ch 8 (practise this chapter)
Sources
- US EPA: Wastewater Management Fact Sheet, Membrane Bioreactors ↗ “The membranes can be designed for and operated in small spaces and with high removal efficiency of contaminants such as nitrogen, phosphorus, bacteria”
- NCERT Class 12 · Biology, Chapter 8 “A major component of this waste water is human excreta. This municipal waste-water is also called sewage. It contains large amounts of organic matter and microbes.”
Question and answer: UPSC's official GS Paper I (2024, Series A) — paper ↗ · answer key ↗. Explanation: Minimalist IAS, checked 30 Sept 2026 (how we verify). ·