OCEMS Requirements in India: Which Sensors Does Your Industry Need?
OCEMS Requirements in India: Which Sensors Does Your Industry Need?
Wastewater produced in an industrial process doesn’t wait for a technician to arrive for grab samples. It might change in quality in a few hours’ time, and when lab results become available, it could be too late – the cost of damage might be already paid either financially or environmentally. That’s the reason why regulatory authorities in India become more concerned with continuous monitoring of discharge rather than periodic one. Knowing the OCEMS requirements in India is the first step to compliance for any facility. The article describes what an Online Continuous Emission Monitoring System does, in which industries it is required, what sensors to pay attention to, and what to consider when choosing equipment for your facility.
The owners of chemical plants, textile dyeing facilities, and common effluent treatment plants must have heard about the OCEMs requirements in India during compliance seminars. What they often don’t know is which sensors to use and why. We’ll tell you everything you should know about it practically.
What Is OCEMS and Why Is It Important for Indian Industries?
OCEMS means Online Continuous Emission Monitoring Systems. As the name suggests, it is a collection of sensors, data loggers, and transmitters that continuously monitor parameters related to pollution rather than going for spot sampling at specific intervals.
These two words emission monitoring and effluent monitoring tend to be confused quite often. While emission monitoring deals with monitoring the release of pollutants in the atmosphere, such as stack gases, particulate matter and other related parameters; effluent monitoring, which is the subject of discussion in this article, deals with monitoring the quality of liquid effluents coming out of a treatment plant before discharging into a river, drain or sewer line. Effluent monitoring system is just like a continuous emission monitor but it monitors the water instead of air.
What’s the importance of that? Spot sampling is likely to miss temporary pollution spikes and even before you have your test results in hand, an unplanned discharge event might have taken place already. Continuous monitoring will bridge this gap. It also helps plant managers in getting an early warning of deviations in the process of treatment of the effluent.
The OCEMS needs in India go beyond compliance. In fact, on a practical level, understanding OCEMS is essential for any treatment process that carries consequences in the event of failure.
Which Industries Require OCEMS in India?
All industries don’t need online effluent monitoring systems; however, there are many sectors which use large amounts of water and cause a lot of pollution and hence, these are included. Following are some of the most common sectors categorized by CPCB and SPCB which require OCEMS in India:
- Pharmaceutical and chemical industries – these industries produce effluents containing high organic and chemical load. Therefore, it becomes essential to continuously monitor COD, pH and other such parameters.
- Textile and dyeing industries – the effluents produced by these industries are well known for their varying pH, TSS and color load.
- Pulp and paper industries – pulping processes generally produce effluents having high BOD and COD levels.
- Distilleries and food processing industries – fermentation and processing products from these industries generally have high organic loads.
- Common Effluent Treatment Plants (CETPs) – as these plants treat waste from several industries, continuous monitoring becomes helpful in identifying non-compliances early.
- Sewage Treatment Plants (STPs) – especially large municipal/institutional STPs are increasingly requiring continuous monitoring.
If there is an obligation to have OCEMS in a certain facility, which specific parameters need to be monitored depend on the CPCB or SPCB regulations regarding that industry category, the discharge volume, and location of the facility with respect to sensitive water bodies. For example, two facilities from the same industry may be obliged to fulfill different conditions: one might discharge effluents to a river while another into a municipal sewerage system. This is why it is important to check the specific consent conditions for SPCBs for each facility separately.
Which Sensors Are Used in OCEMS for Effluent Monitoring?
Engineers working at plants often face difficulties in selecting a proper sensor technology for monitoring a particular parameter. The following are the sensors which are used to satisfy the OCEMS requirement in India for effluent monitoring.
pH Sensor — Monitor Acidity and Alkalinity
pH is one of the most basic parameters in effluent monitoring. It has impact on the effectiveness of biological processes, pipe corrosion, and aquatic toxicity. Continuous pH sensor monitors any significant fluctuations in acidity/alkalinity, which cannot be identified by grab sampling.
Usually, treatment plants have a pH sensor fitted at both inlet and outlet in order to satisfy requirements of process control and compliance reporting.
COD Sensor – Measure Organic Pollution Indicators
COD stands for Chemical Oxygen Demand and measures the amount of oxygen needed to chemically oxidize the pollutants in the wastewater. It is an indicator of the level of pollution by organics. Online COD sensors use UV absorption or optical techniques rather than chemical digestion carried out in laboratories to measure COD. Hence, one should be aware of the way of measuring and calibration procedure of COD sensor chosen as it may vary with the effluent’s turbidity and color.
BOD Sensor — Assess Organic Load
BOD stands for Biochemical Oxygen Demand and refers to the oxygen taken up by microorganisms during oxidation of organic pollutants in water. Traditionally, this test was carried out over a period of five days in the laboratory. However, it is difficult to carry out online monitoring of BOD over such a period of time; hence, online BOD sensors use estimation methods that are based on COD, UV absorbance or respirometry methods.
TSS and Turbidity Sensors — Monitor Suspended Particles
TSS and turbidity are parameters which also monitor suspended particulate matter although in a different way – TSS being monitored through weight whereas turbidity measures the scattering effect on light.This is have applications in detecting any disturbance in the processes such as a loss of efficiency of the settling tank or filter bypass. For industries such as textiles and food processing in which there is a huge variation in the solids loading, TSS sensors act as warning indicators before all other parameters get affected.
Ammonia and Nitrogen Sensors
For those industries having the discharge limit of nitrogen, sensors for ammoniacal nitrogen and total nitrogen come into consideration. Such sensors monitor the nitrogen compounds which, if uncontrolled, lead to eutrophication in the water bodies receiving discharges from such industries. Not all industries require nitrogen monitoring, but only those industries which have a nitrogen limit mentioned in the SPCB consent conditions.
Multiparameter Water Quality Monitoring Systems
Instead of individual sensors for each parameter, many sites have chosen to use multiparameter water quality monitors that integrate pH, TSS, turbidity, and more in one installation point, rather than having an individual point for each parameter, thus reducing the cabling hassle and the maintenance process, and sometimes lowering the cost of ownership than when using single-parameter systems.
CPCB and SPCB OCEMS Requirements in India: What Should Industries Check?
It is advisable to check with the regional State Pollution Control Board (SPCB) for the exact OCEMS requirement in India before purchasing any equipment because conditions can differ from one state to another and also based on the category of the industry. In general, some of the things the industries should verify are:
- The parameters to be monitored along with the limits of discharge for each parameter.
- The location where the sensors need to be installed along with the specifications like sampling chamber and flow conditions.
- The transmission of the data to a centralized server within required time intervals as demanded by most of the SPCBs.
- Calibration, maintenance, and verification – most of the guidelines specify the calibration schedule and verification of sensor accuracy at regular intervals by a third party.
- Logging of the data and alarm configurations for the breaches of threshold values, and submission of reports to the SPCB.
Needless to say, each industry does not need to have the same type of sensors installed. The sensors that may be installed for one pharmaceutical unit will not necessarily be the same as those required for a textile dyeing unit in the same state. The only reliable method of establishing this is to check the requirements set out in your specific consent to operate.
How to Choose the Right OCEMS Sensors for Your Industry
When you have understood OCEMS requirement in India regarding the equipment, it will become easier for you to choose equipment. Practical checklist of a buyer:
- Identify applicable regulatory requirements – begin with the SPCB consent order and not the catalog of general-purpose sensors.
- Define required measured parameters – either pH, COD, BOD, TSS, ammonia, or combination thereof based on your industry category.
- Determine effluent characteristics and sensor’s measuring range – the presence of high turbidity or color will interfere with optical sensors, so make sure the measurement principles of the sensor fit your effluent.
- Determine required measurement accuracy, calibration and maintenance – frequently manual calibration procedure implies extra expenses, so make sure the price of a sensor compensates for that.
- Determine compatibility of sensor’s output and its ability to be integrated into SCADA or data logging system.
- Check applicability for compliance monitoring purposes – not all laboratory-type sensors are suitable for unattended field use.
Hasty choice will result in replacement of equipment in one-two years because of its unsuitability to effluent characteristics. Short technical consultation will save some money in future.
How Fluidings Supports Online Water Quality Monitoring
Fluidings offers various types of online water quality sensors that cater to the various parameters monitored through OCEMS, as per the Indian requirements, such as pH/ORP sensors, COD sensors, TSS and turbidity sensors, ammonia and nitrogen sensors, as well as multiparameter water quality monitoring systems. Our products have been designed to work continuously without any need for attendance in industrial and wastewater plant settings in a cost-effective manner.
Every organization will have its own set of discharges as well as different requirements under SPCB consent, and hence we would recommend you to choose sensors that suit your parameters and requirement, and not just go for a one-size-fits-all kind of package. If you are considering installing a new OCEMS or upgradation of your existing system, take a look at our product line-up for sensors above or reach out to us on our contact page / quotation request page.
What should be checked by industries before buying OCEMS?
Prior to purchasing, it is important to know the exact parameter and limit requirements of your SPCB, measurement range and nature of your effluent, calibration and maintenance needs of your sensor, and finally, output of the data from the sensor compatible with your system. Not doing so frequently results in purchase of another equipment once a mismatch is identified.
Conclusion
Satisfying OCEMS requirement in India requires knowing your discharge characteristics and requirements, and not in purchasing the most advanced equipment available in the market. No matter whether you run pharmaceutical plants, textile dyeing units, or CETPs, the correct combination of pH, COD, BOD, TSS, and nitrogen sensors will vary depending on the exact specifications of your SPCB consent order and effluent characteristics. By getting this right at the beginning, you can save money, avoid risks, and have an effective treatment process. If you are planning a new installation or evaluating your current OCEMS system, please see our selection of online water quality sensors, or contact us for consultation on your requirements.
Frequently Asked Questions About OCEMS in India
What is OCEMS? How does it function?
OCEMS stands for Online Continuous Emission Monitoring Systems and makes use of sensors that monitor pollution parameters online as opposed to manual sample analysis from time to time. In the case of effluent, sensors keep measuring pollution parameters such as pH, COD, and TSS, relaying information to the central system in the process.
Which Industries need OCEMS in India?
Industries that are water intensive or pollutive in nature need OCEMS systems in India and include sectors such as pharmaceuticals, chemicals, textiles, pulp & paper, distilleries, food processing, CETPs, and larger STPs among others. This will depend on the category you fall under as well as the conditions of SPCB consents.
Which Sensors Are Needed in Online Effluent Monitoring?
Typical sensors are PH, COD, BOD, TSS and Turbidity, and ammonia or nitrogen sensors as part of multiparameter monitoring systems.
What should be checked by industries before buying OCEMS?
Prior to purchasing, it is important to know the exact parameter and limit requirements of your SPCB, measurement range and nature of your effluent, calibration and maintenance needs of your sensor, and finally, output of the data from the sensor compatible with your system. Not doing so frequently results in purchase of another equipment once a mismatch is identified.
