An Anti-Corruption Branch (ACB) investigation has reopened questions about a Delhi Jal Board (DJB) tender for the augmentation and upgradation of sewage treatment plants (STPs) in the national capital, with a source-based timeline placing the key decisions in late 2021, according to a report published 20 August 2026 (NDTV). The case is centred on a Rs 1,546.32-crore block estimate for raising Delhi's STP capacity from 215 MGD to 297 MGD and on the choice of Integrated Fixed-Film Activated Sludge (IFAS) technology with fixed media (NDTV). The tender is the subject of a corruption investigation, and the allegations have not been established in court (NDTV).
Key takeaways
- IFAS technology for STP upgradation in Delhi was proposed on 7 October 2021 and received in-principle approval on 14 October 2021, per a report published 20 August 2026 (NDTV).
- Meetings on 21 and 23 December 2021 finalised the Terms of Reference, with IFAS with fixed media prescribed for 100 per cent of the upgradation, according to the same report (NDTV).
- A proposal dated 28 December 2021 produced a fresh estimate of Rs 1,546.32 crore for raising capacity from 215 MGD to 297 MGD (NDTV).
- A DJB Board meeting in July 2022 ratified administrative approval for a block estimate of the same amount, covering capital and operating expenditure across four STP upgradation packages (NDTV).
- Investigators are examining WhatsApp chats and other digital material that allegedly show confidential tender conditions and draft documents circulating on the phones of accused individuals before the tender was officially issued (NDTV).
How the 2021 timeline was built
The tender trail began on 7 October 2021, when IFAS technology was proposed for the augmentation and upgradation of existing sewage treatment plants in Delhi, according to sources cited in the 20 August 2026 report (NDTV). The proposal received in-principle approval on 14 October 2021, and the process moved into the specification stage at meetings on 21 and 23 December 2021, where the Terms of Reference were finalised with IFAS with fixed media considered for 100 per cent of the upgradation (NDTV).
On 28 December 2021, a proposal routed through then DJB members led to a fresh Rs 1,546.32-crore estimate, based on the TOR prescribing IFAS with fixed media, for increasing existing capacity from 215 MGD to 297 MGD (NDTV). A DJB Board meeting in July 2022, after the sitting minister's May 2022 arrest in a separate case, then ratified administrative approval for a block estimate of the same amount covering capital and operating expenditure for four STP upgradation packages (NDTV).
Digital evidence and the procurement concerns under probe
Investigators are examining WhatsApp chats and other digital material that allegedly show confidential tender conditions and draft documents circulating on the phones of accused individuals before the tender was officially issued, according to sources (NDTV). The Anti-Corruption Branch has alleged irregularities including restrictive technical specifications, conditions allegedly favouring one private bidder, a proposed pilot study that was not conducted, certain treated-effluent parameters being excluded and technical specifications being altered during the process, the report said (NDTV). The Enforcement Directorate filed a prosecution complaint in December 2025 alleging that tender conditions were manipulated to restrict the process to IFAS technology with fixed media, and that one private firm became the sole technology supplier; these are allegations that have not been established in court (NDTV).
Where this sits in Delhi's wider STP build-out
The disputed upgradation sits inside a much larger DJB plan, reported on 6 September 2026, to nearly double Delhi's sewage treatment capacity by adding 18–20 new STPs with a combined capacity of 460 MGD, taking the city total to 1,506 MGD by December 2028 (The Hindu). A DJB officer quoted by the same report said, "It took decades to reach the current sewage treatment capacity of 814 MGD, so adding 460 MGD, which is more than half of the current total capacity, in just three years is nothing short of historic" (The Hindu). The new-STP programme is estimated at around ₹5,000 crore, with the exact number of plants and final cost to be set once tenders are finalised over the next two months (The Hindu).
| Item | Reported figure | Source |
|---|---|---|
| Existing Delhi STP capacity | 814 MGD across 37 STPs | The Hindu |
| Disputed upgradation: from → to | 215 MGD → 297 MGD | NDTV |
| Disputed upgradation block estimate | Rs 1,546.32 crore (four packages) | NDTV |
| New STPs planned (18–20 plants) | 460 MGD additional | The Hindu |
| Upgrades to existing STPs | 62 MGD additional | The Hindu |
| Decentralised STPs (DSTPs) | 170 MGD across 29 plants (28 work orders issued) | The Hindu |
| Target total capacity by Dec 2028 | 1,506 MGD (≈1,500 MGD target) | The Hindu |
| Estimated cost of new-STP programme | ≈₹5,000 crore | The Hindu |
Specification read
Scale for a buyer. The disputed package is a capacity addition from 215 MGD to 297 MGD, an 82 MGD uplift inside a single contract envelope of Rs 1,546.32 crore across four packages (NDTV). Converted to common buyer units, 82 MGD is roughly 372,000 m³/day of incremental treatment duty; a plant in this class is sized for an order-of-magnitude 4–6 million population equivalent based on typical Indian municipal loadings (general industry range, not from the sources). The wider DJB plan adds another 460 MGD of greenfield capacity on top, targeted by December 2028 (The Hindu).
Treatment train this class demands. A municipal STP in the 50–500 MGD band is normally specified as screening and grit removal → primary clarification → biological stage (A2O, MBBR, SBR, MBR or IFAS/MBBR hybrid) → tertiary filtration and disinfection, with sludge handling on a separate line. The procurement event reported here bears specifically on the biological-stage selection: the TOR prescribe IFAS with fixed media for 100 per cent of the upgradation, meaning biofilm carriers added to an activated-sludge basin, which raises mixed-liquor MLSS and nitrification capacity without building new aeration tanks (NDTV). Buyers planning a retrofit of similar scope will be looking at carrier-media supply, aeration-diffuser rebalancing, and a screen at the biology outlet rather than a full civil rebuild; downstream, a Integrated Sewage Treatment package and a dedicated Sludge Treatment line are normally part of the same scope, and the wider DJB build-out sits under the Municipal procurement category.
What it means if your plant looks like this. If you are running a 50–200 MGD municipal works on conventional activated sludge, with influent BOD in the 200–350 mg/L range and ammonia-driven consent pressure, this is the kind of brownfield IFAS retrofit that buyers in India are being asked to bid on today; specification choices at the TOR stage (media type, fill fraction, aeration turn-down, effluent BOD/NH₃-N targets) will set your operating cost for the next decade.
FAQ
What is the headline scale of the Delhi STP upgradation under investigation?
The reported scope is an 82 MGD uplift, from 215 MGD to 297 MGD, covered by a Rs 1,546.32-crore block estimate across four packages, according to a report published 20 August 2026 (NDTV).
What technology was prescribed in the disputed Terms of Reference?
The TOR finalised at 21 and 23 December 2021 meetings prescribe IFAS with fixed media for 100 per cent of the upgradation, per the same report (NDTV).
What is the cost and timeline for the wider Delhi STP build-out?
DJB plans 18–20 new STPs adding 460 MGD at an estimated ₹5,000 crore, with the total city capacity targeted at 1,506 MGD by December 2028; final tender numbers are expected over the following two months, according to a report published 6 September 2026 (The Hindu).
What should a buyer check when an IFAS retrofit is single-technology specified?
Confirm the carrier-media specification (protected surface area, fill fraction, material), the guaranteed effluent BOD, COD and NH₃-N at design and turn-down flow, and whether the tender is open to equivalent biological processes such as MBBR or MBR; the general industry range for IFAS retrofits at this scale is a 12–24 month EPC schedule (general industry range, not from the sources).
