Overview
According to the CPCB & GPCB legislative regulations, numerous infrastructures such as apartments, commercial construction projects, educational institutions, townships, and area development projects that meet specified conditions must include sewage treatment plants.
To ensure effective and safe operation of the machinery, the guideline regulations address factors such as STP site, STP technology to adopt, STP functioning, and STP maintenance.
Therefore, the GPCB & CPCB has established the following guidelines for STPs:
Guidelines for Sewage Treatment Plants from the CPCB
1. STP Technology
The following are the CPCB approved STP technologies to use:
- The ASP (Activated Sludge Process) is a method of treating sludge that has been activated (only when above 500 KLD sewage is generated).
- Membrane BioReactor is a type of membrane bioreactor that uses membranes to (MBR).
- Bio-Reactor in a Moving Bed (MBBR).
2. STP Unit Requirements
Individual units in sewage treatment plants perform various sewage treatment procedures. The following are the units and their criteria in accordance with the guidelines.
| SL. NO | Unit | Activated Sludge Process(ASP) | Sequential Batch Reactor(SBR) | Membrane Bio Reactor(MBR) | Moving Bed Bio Reactor(MBBR) |
| 1 | Equalization Tank | A minimum holding period of 8 hours is also required. | Similar to ASP | Same as ASP | Same as ASP |
| 2 | Anoxic Tank | Pump the activated sludge back to the anoxic tank for denitrification. | Not required | Same to ASP | Same to ASP |
| 3 | Aeration Tank | Moreover, in the Aeration Tank, dissolved oxygen in excess of 4 mg/L must be maintained. | Same as ASP | Similar to ASP | Same as ASP |
| 4 | Membrane Tank | Not required | Not required | Membranes should be replaced regularly as per its manufacturer’s specifications. | Not required |
| 5 | Sludge Holding Tank | Also sludge holding should be required for the storage of excess sludge prior to dewatering. | Same as ASP | Similar to ASP | Same as ASP |
| 6 | Final Treated Water Holding Tank | The tank’s capacity should be sufficient to hold water for at least two days. | Same as ASP | Same as ASP | Similar to ASP |
| 7 | Sludge Drying Bed | For >500KLD STPs, a horozontal centrifuge system should also be utilised instead of a sludge drying bed. Belt press or screw press system should also be utilised for STPs up to 500 KLD. | Same as ASP | Similar to ASP | Same as ASP |
3. STP Requirements for Mechanical Equipment
The Bar Screen Chamber and Oil & Grease Chamber of STPs installed should have evident and also have simple access. In addition, the equipment should be submersible and easy to remove/dismantle anytime repair is required. Finally, to decrease noise pollution, STP air blowers should have vibration mounts and acoustic enclosures.
4. STP’s location
STPs should be placed beneath driveways, play areas, or clubhouses and also far away from residential areas to avoid causing any inconvenience to residents. STP should also not be used in any building’s basement. To reduce complications caused by rain, flooding, odour, or sound, access to the STP room should be from the ground level or upper basement via well-designed pathways or headroom, rather than from the lowest basement.
5. Standards for Treated Sewage
According to CPCB, the treated sewage must meet the following requirements.
| SL. NO | Parameter | Required Standards |
| 1 | pH | 6.5-8.5 |
| 2 | BOD(5th day) | <10mg/l |
| 3 | COD | <50mg/l |
| 4 | Suspended Solids | <10mg/l |
| 5 | Ammonical Nitrogen | <5mg/l |
| 6 | Total Nitrogen | <5mg/l |
| 7 | Fecal Coliform | <100 MPN/100 ml |
6. Sensor installation guidelines
Sensors for monitoring sewage parameters such as BOD, COD, TSS, flow, and pH are required to be installed. The following are the CPCB’s suggested sensor types and communication protocols.
| SL. NO | Parameter | Measurement type | Sensor type | Communication Protocol |
| 1 | pH | Inline | Ion Selective Glass Electrodes | RS 485 Communication with Modbus |
| 2 | TSS | Inline | Turbidity to TSS correlation with Nephelometric technique | RS 485 Communication with Modbus |
| 3 | BOD | Inline | UV-Vis Spectrophotometry & combustion(Double beam with entire spectrum scanning | RS 485 Communication with Modbus |
| 4 | COD | Inline | UV-Vis Spectrophotometry & combustion(Double beam with entire spectrum scanning | RS 485 Communication with Modbus |
| 5 | Flow | Inline | Electromagnetic Flow Measurement | RS 485 Communication with Modbus |
7. Caution Board at STP
At STP areas, proper cautionary signboards should be shown, and safety standards should be observed. For maintenance personnel and the general public, “Danger” Sign Boards should also be placed at the STP location. At sewage water taps, the phrase “water not suited for drinking” shall be prominently displayed.
8. Sewage Treatment
The treated water should also be used for toilet flushing, which should be done with a dual plumbing system.
9. STPs’ Modular Operations
STPs that operate in a modular manner should be developed/constructed in smaller units so that they can be used according to the load or occupancy of people according to CPCB. The occupancy in the early stages of significant projects where a higher capacity of STPs is required cannot meet the operational standards of the STP. As a result, the element should be taken into account throughout the planning stage.
GPCB conditions underwater act:
The below mentioned are just some of the conditions under water act:
- The total water usage shall not exceed 4.000 KL/Day, as broken down in form D, which was filed as part of a consent application under the 1974 Water Act. Domestic: 1.000 KL/Day a) Industrial: 3.000 KL/Day b) Industrial: 3.000 KL/Day.
- The total amount of wastewater generated per day must not exceed 0.800 KL per day, as specified in form D, which was filed as part of a consent application under the Water Act of 1974. Domestic: 0.800 KL/Day a) Industrial: 0.000 KL/Day b) Industrial: 0.000 KL/Day
- Sewage shall be disposed of in a septic tank/soak pit system or separately treated in a Sewage Treatment Plant (STP). They have to meet the following requirements, with treated sewage being used for irrigation/plantation on land. Alternatively, sewage and also industrial effluent will be treated in the same ETP.
- The industrial effluent generated by the manufacturing process and other auxiliary industrial operations shall not be discharged. Thus the unit must carefully adhere to zero liquid discharge (ZLD).
- The unit must provide suitable storage facilities for the effluent, such as acid-resistant brick-lined impermeable tanks or HDPE tanks.
- In the Effluent Treatment Plant, the unit must make a permanent arrangement. Any by-pass line or system, as well as any loose or flexible pipeline, shall not be kept in the ETP.
- To monitor the amount of effluent, magnetic flow metres must be put at the intake and outflow of effluent collection tanks/ETPs.
- The unit must have suitable and also have safe effluent sampling facilities for wastewater contained in the ETP/final STP’s collecting/discharge tank.
STP Parameter (GPCB Norms) Outlet
| SL. NO | Parameter | Permissible Limit |
| 1 | pH | 6.50 – 8.50 |
| 2 | Suspended Solid | 100 mg/L |
| 3 | Oil & Grease | 10 mg/L |
| 4 | Phenolic compounds | 1 mg/L |
| 5 | Sulphides | 2 mg/L |
| 6 | Ammonical Nitrogen | 50 mg/L |
| 7 | Total Chromium | 2 mg/L |
| 8 | BOD | 20 mg/L |
| 9 | TDS | 2100 |
| 10 | Chlorides | 600 mg/L |
| 11 | Sulphates | 1000 mg/L |
| 12 | COD | 100 mg/L |
Bottom Line
We follow all these GPCB & CPCB guidelines and also work for our client’s requirements. By adhering to the GPCB principles, we at Jateen Trading Co. focus our efforts on improving pollution control and also for the management in the environment.
Do you find this article interesting? Then please check out the rest of the blogs too. We’re sure that you’ll find them fascinating and valuable as well. To know more about us, please do visit our website. You can contact us for any queries or for any help. We are happy to hear from you!
