ORDER : SUNITA AGARWAL, C.J. 1. Perused the affidavit dated 09.10.2025 of the Municipal Commissioner, Ahmedabad Municipal Corporation (AMC) filed in compliance of the order dated 08.08.2025, wherein it is sought to be stated that two STPs, namely 106 MLD Old Pirana and 60 MLD Old Pirana were constructed in the year 2005 and 2010; respectively, based on the best available treatment technologies at the relevant point of time. New treatment norms have been prescribed by the National Green Tribunal (NGT) in the year 2018 and these STPs, as such, do not meet the prescribed NGT norms. However, treatment in these STPs has been substantially improved over the past two years with the consistent repairing works carried out by the AMC. 2. The short term and midterm repairing work, as per the blueprint submitted by the AMC, before this Court have already been completed. However, upgradation work as long term solutions to make the two STPs compliant, as per the NGT norms, as committed to commence in the month of June 2024, have not yet started. 3. It is, however, stated that the long term work has been delayed in view of the issues related to financial sustainability of the upgradation work, inasmuch as, it was found that it would be to the advantage of AMC if a Tertiary Treatment Plant (TTP) is developed along with the upgradation work, which will allow the AMC to monetise the sale of treated water. It is sought to be stated that nearby industrial associations of Narol have shown interest in purchasing tertiary treated waste water for their industrial processes and in the meeting held on 30.09.2025, it has been finally decided that an STP of 200 MLD capacity with TTP of 150 MLD capacity will be commissioned. A Special Purpose Vehicle (SPV) will be formed by the AMC, NTIEM (Narol Textile Infrastructure and Environment Management, a representative body carrying treatment of industrial waste water of Narol area) and the agency selected for the said work. 4. It is, thus, submitted that the delay in execution of long term upgradation work of the existing STPs, namely 106 MLD and 60 MLD Old Pirana has been occasioned on account of efforts being made by all the stakeholders to make the project sustainable and efficient. 4. It is, thus, submitted that the delay in execution of long term upgradation work of the existing STPs, namely 106 MLD and 60 MLD Old Pirana has been occasioned on account of efforts being made by all the stakeholders to make the project sustainable and efficient. It is further contended that the timeline for the abovereferred work has been chalked out and the AMC may require some more time to bring the final decision on record. 5. Taking note of the above, we find that the decision taken on 30.09.2025, it appears, is to establish a new STP of 200 MLD capacity with TTP of 150 MLD capacity, so as to treat the sewage water for sale to the industries. However, with the said decision, it does not seem to us that the two old STPs, namely 106 MLD and 60 MLD Old Pirana would be decommissioned, as there is no such categorical statement in the affidavit. Moreover, establishment of a new STP with the TTP is a future planning which would take time and there is no plan for the interregnum. As per the original blueprint, long term solution work was to commence in June’ 2024 and to be completed by June’ 2026. The issue raised before us is about the financial sustainability of the upgradation work, which according to the stand of the AMC itself, would be to the advantage of AMC if a TTP is developed along with the upgradation work. Ultimately, there is no plan for upgradation work of the existing STPs in the affidavit placed before us. 6. It seems to us that the proposal for addition of an STP of 200 MLD capacity with TTP with 150 MLD capacity, which will be commissioned through the Special Purpose Vehicle to be formed along with the industrial association, is an independent project and has no bearing on the upgradation work of two existing STPs namely, 106 MLD and 60 MLD Old Pirana. 7. As there is no clarity on this aspect in the affidavit of the Municipal Commissioner, AMC, we require Mr.G. H. Virk, the learned advocate for the AMC to explain the same, who sought time to get further instructions on the aforesaid aspect. 8. 7. As there is no clarity on this aspect in the affidavit of the Municipal Commissioner, AMC, we require Mr.G. H. Virk, the learned advocate for the AMC to explain the same, who sought time to get further instructions on the aforesaid aspect. 8. As regards the update about the bio-remediation work, it is placed on record that there is a reduction in pollutants in the waste water in the range of 65% in all at 9 bio- remediation sites, which are in operation, as per the report of the Central Laboratory. For the requirement of making an assessment as to the sufficiency of the existing infrastructure of STPs and new STPs under construction so as to to treat the entire volume of sewage water and to meet the norms prescribed by the NGT, with a view to achieve zero release of waste water, it is submitted that AMC had engaged the services of Institute of Infrastructure Technology, Research and Management (IITRAM) twice, in the year 2022 and 2024. However, to commence the said exercise afresh, the work is to be awarded to IITRAM, which could not be awarded because of prolonged monsoon as any measurement during monsoon cannot deliver correct results. The AMC will soon complete the process to direct IITRAM to measure the flow at various outfalls of Sabarmati river as also the flow of bio- remediation set up done by the AMC in the recent past as well as to meet the directions in the order dated 08.08.2025 passed by this Court. 9. It is further submitted that adding to the existing infrastructure, the AMC has planned three new STPs for the additional capacity of 400 MLD to the city’s need, which will be commissioned in and around 2030. These three new STPs are at the nascent stage of preparation of DPR (Detailed Project Report). 10. Progress report regarding five new STPs as per the blueprint submitted before this Court has been placed to submit that Phase-1 of 125 MLD out of 375 MLD STP has been progressed at 70% and with the commissioning of the first 125 MLD stream of 375 MLD Vasna, the existing 126 MLD Vasma STP would be decommissioned. The progress for 30 MLD Sola STP is shown as 71%. It is stated that 75 MLD Vinzol STP is expected to be completed by 15.02.2026. The progress for 30 MLD Sola STP is shown as 71%. It is stated that 75 MLD Vinzol STP is expected to be completed by 15.02.2026. The updated progress report about 15 MLD Jagatpur STP and 425 MLD Pirana STP has been placed on record. As per the progress report of 425 MLD Pirana STP, drawing approval has been completed; the environment and social impact assessment has been approved by the World Bank; the consent to establish has been received from GPCB; raft concreting work is in progress. 11. With the above, it is submitted that all new STPs would be compliant with the NGT norms. 12. For three existing STPs, namely 180 MLD Pirana, 240 MLD Vasna and 70 MLD Vinzol, the progress report of the long term solutions for upgradation of the plants has been placed on record and it is stated that the work is expected to be completed by March’ 2026 for the above three STPs. 13. Taking note of the above, we may further proceed to have a look at the status of the seven CEPTs in the quarterly report of the Joint Task Force for the period from June to September 2025. As per the said report, the samples of the treated water released by seven CEPTs contain lot of chlorine. It is submitted that parameters such as TDS comprising of (FDS, Calcium, Magnesium, Sodium Potassium Carbonates, Chlorides, Sulphides) and colour of treated trade effluent do not meet the required norms. 14. The conclusion is that the CETPs have adopted new treatment technology based on chlorination. The use of chlorination as a method to remove residual COD and colour from industrial waste water is increasing rapidly in CETPs. It is submitted that the industrial waste water generated from Chemical and Dye and Dye intermediate industry is characterised with low BOD / COD ratio and thereby, a low biodegradability leading to significant concentration of COD and colour in biologically treated waste water. While advances oxidation processes such as Fenton’s Treatment and Ozonation can minimize residuals COD and colour, the overall cost of these treatments is high. As compared to these methods, chlorination is equally efficient and has negligible overall cost. 15. However, while chlorination is inexpensive, its use in waste water treatment is to be judiciously evaluated. While advances oxidation processes such as Fenton’s Treatment and Ozonation can minimize residuals COD and colour, the overall cost of these treatments is high. As compared to these methods, chlorination is equally efficient and has negligible overall cost. 15. However, while chlorination is inexpensive, its use in waste water treatment is to be judiciously evaluated. Chlorine reacts with a wide variety of organic compound present in the waste water and generate a range of chlorinated organic compound which are known to have potential toxicity, mutagenicity (ability of a substance to cause permanent changes to the genetic material of the organism), carcinogenicity (ability of a substance to cause cancer) and teratogenicity (ability of a substance to cause birth defects in a developing fetus). Moreover, a high concentration of residual chlorine in treated waste water, when discharged to a river, causes many adverse effects on aquatic life such as damage to gills of fish, breathing impairment, reduction in growth rate and even death. Use of chlorine also increases TDS in treated waste water. 16. During the visit of Joint Task Force in September 2025, CETPs at Vatva, Odhav and Naroda, they were found to be using substantial amount of chlorine to remove residual COD and colour after the biological treatment. Whereas, one CEPT namely M/s Narol Dyestuff Enviro Ltd. is installing chlorine treatment as a sole treatment for waste water. The chlorination process being used by three CETPs at Vatva, Odhav and Naroda is to the extent of 4.55 kg per kg COD removed, 5 kg per kg COD removed, 6.5 kg per kg COD removed; respectively. Thus, in the case of CETPs using substantial quantity of chlorine, generation of residual chlorine and chlorinated organic compounds will be high, aggravating the situation in the recipient water body, namely river Sabarmati. The CETPs, thus, are required to look for alternatives to address the potential toxicity in treated waste water. 17. It is further stated that there are many small and medium scale industries, which are very important for economy but these industries are generating large amount of waste water, which are most polluting to the environment. The CETPs, thus, are required to look for alternatives to address the potential toxicity in treated waste water. 17. It is further stated that there are many small and medium scale industries, which are very important for economy but these industries are generating large amount of waste water, which are most polluting to the environment. These industries do not have their individual treatment plants due to lack of financial funds and land requirement so waste water in these industries are treated in CETPs but the pollutants in the waste water released by them being complex inorganic and non-biodegradable organics, are difficult to be treated with conventional biological processes like activated sludge process contribute to higher chemical oxygen demand (COD). 18. This requires some chemical oxidation process in which non-biodegradable organics are oxidised and chlorination is one of the oxidation processes. During chlorination process, non-biodegradable organics can be oxidized reducing the residual colour and COD to the accepted level but chlorine also reacts with organic matter in waste water and besides fully oxidising them, it produces a variety of chlorinated organic compounds which are harmful to aquatic life, flora and fauna in the river system. 19. Chlorinated organics are also a risk to human health if the treated water is used for irrigation and farming. Chlorinated waste water when utilized in farming, can be toxic to crops and can alter the soil’s chemical and biochemical properties, potentially increasing the mobility of heavy metals in the soil and into the human digestive system. In CETPs, chlorination is used at the tertiary stage to kill micro-organisms and break down non-biodegradable organic pollutants, which are difficult to treat through biological methods. It is a key step to the overall treatment process, ensuring that the final effluent meets discharge norms by using a chlorine compound, before it is released in water bodies like rivers and lakes and used for agriculture and domestic purposes. 20. It is, therefore, needed that CETPs should place checks and balances on its member unit in reference to the trade effluent water released by each of the member unit forwarded to CETPs for being treated. There is a need to follow the chlorination process in treatment of trade effluent water. 21. 20. It is, therefore, needed that CETPs should place checks and balances on its member unit in reference to the trade effluent water released by each of the member unit forwarded to CETPs for being treated. There is a need to follow the chlorination process in treatment of trade effluent water. 21. In the affidavit of GPCB, it is submitted that the adoption of chlorination in excess of the norms is not the solution, inasmuch as, there is a potential increase in the level of toxicity in water of river Sabarmati with the use of chlorine by CETPs. With the view to achieve simultaneous reduction in COD and reduce risk of toxicity of water of river Sabarmati, GPCB has assigned the project to Ahmedabad Textile Industries Research Association (ATIRA) for carrying out study of “Optimization of Chlorine Dosing for COD removal in the final treated effluent of CETPs of NEPL and GESCSL located in Ahmedabad (East) Region”. ATIRA has already started work of collection of samples from CETPs and is going to submit the draft report tentatively on 26.11.2025. In the meantime, GPCB has issued advisory notices to the CETPs for using optimal quantity of chlorine and carrying out Bio-assay Test before discharge of treated water. 22. As regards the vision of re-utilization of treated industrial waste water from CETPs by the member industries, to achieve ‘Zero Liquid Discharge’, it is submitted that scientists from CSIR – NEERI had carried out inspection of all seven CETPs and two industrial outfalls, namely outfall of mega-pipeline and outfall of NTIEM CETP into River Sabarmati at V. N. Bridge, Narol. The team is collecting samples for conducting feasibility study. The GPCB, through its Regional Office, Ahmedabad (East) carries out the monitoring of all seven CETPs as well as two industrial outfalls for verifying the compliance status with regard to the prescribed outlet norms. 23. With its report, the Joint Task Force has further brought on record a notification dated 9th September’ 2024 of the Ministry of Environment, Forest and Climate Change to notify the Environment (Protection) Second Amendment Rules, 2024, which came into force on the 1 st Day of September, 2024. In Schedule 1, at serial No.’55’ are the entries related to Common Effluent Treatment Plant (CETP) providing inlet quality standards and treated effluent quality standards. 24. In Schedule 1, at serial No.’55’ are the entries related to Common Effluent Treatment Plant (CETP) providing inlet quality standards and treated effluent quality standards. 24. The said rule aligns the role and responsibility of the State Governments, State Board or the committee to check compliance of the notified discharge standards for CETPs or if any more stringent standards or Zero liquid discharge condition is laid down by the Board or committee. The said rule also laid down the roles and responsibilities of CETP operating agencies. 25. Having perused the roles and duties assigned in the rules framed by the Central Government under the Environment (Protection) Act’ 1986, we require seven CETPs as also the GPCB to file their affidavits to bring on record the compliance report of the said notification. 26. Besides the above, there are other industries running in the area of jurisdiction of the Ahmedabad Municipal Corporation, which according to the learned counsel for the AMC are running on Zero Liquid Discharge norms / conditions laid down by the GPCB. 27. We require GPCB and the AMC to constitute a joint team to make a joint inspection of such units which are running on Zero Liquid Discharge norms prescribed by GPCB, and to prepare a report about such industries being compliant to the prescribed norms so as to ensure that they may not be discharging industrial water into AMC’s pipeline. 28. The report of the joint team of the AMC and GPCB shall be submitted before this Court on the next date fixed. Put up on 09.01.2026 at 02:30 PM.