How to design the capacity of ETP for hospitals and criteria by CPCB?

Effluent treatment plants (ETPs) are essential for treating wastewater and ensuring that it does not pose a threat to public health or the environment. Hospitals, in particular, generate large amounts of wastewater from various sources. This wastewater must be treated before being discharged into the environment.        

Here we will discuss how to design the capacity of an effluent treatment plant for hospitals, focusing specifically on the effluent generated in laboratories and operation theatres. We will also look at the design criteria specified by the Central Pollution Control Board (CPCB).

What is hospital effluent consisting of?      

Hospital wastewater may contain a wide range of potentially dangerous substances at high concentrations, including microbiological pathogens, radioactive isotopes, disinfectants and sterilizants, medicines and their metabolites, chemical compounds, heavy metals, pharmaceuticals, etc. Hospital wastewater is divided into the following categories:

· Blackwater: It is highly polluted wastewater consists of fecal matter, urine, food residues, toxic chemicals etc.           

· Greywater: It is low contaminated wastewater with residues from bathing, washing, laboratory processes and many such.

· Stormwater: Which consist of rainwater from roofs, grounds and other areas in hospitals.

STANDARDS FOR LIQUID WASTE        

The effluent generated or treated from the premises of occupier or operator of a common bio medical waste treatment and disposal facility, before discharge into the sewer should conform to the following limits:

 Also the Sludge from Effluent Treatment Plant shall be given to common bio-medical waste treatment facility for incineration or to hazardous waste treatment, storage and disposal facility for disposal.

Design Criteria:        

The Central Pollution Control Board (CPCB) and Pollution Control Board (PCB) have laid down guidelines for designing ETPs for hospitals. These guidelines provide the technical specifications for designing an effective ETP that meets the required quality standards. The design criteria for an ETP for hospitals include the following:

· Type of Treatment: The effluent generated from hospitals, including the laboratory and operation theatre, is classified as hazardous waste. The effluent treatment process should include pre-treatment, primary treatment, secondary treatment, and tertiary treatment to achieve the desired quality standards.

· Flow rate: The design of an ETP should take into account the maximum flow rate of effluent generated by the hospital. The maximum flow rate is calculated based on the peak load factor of the hospital, which is the maximum number of patients and staff present in the hospital at any given time.         

· Retention time: The retention time of the effluent in the treatment process is critical in achieving the desired quality standards. The retention time is calculated based on the type of treatment and the quality of effluent generated by the hospital.           

· Treatment process: The treatment process should be designed to remove all the pollutants present in the effluent. The primary treatment involves physical treatment, such as screening and sedimentation. The secondary treatment involves biological treatment, such as aerobic and anaerobic digestion. The tertiary treatment involves advanced treatment, such as activated carbon adsorption and membrane filtration.       

· Sludge handling: The design of an ETP should also take into account the handling of sludge generated during the treatment process. The sludge generated during the treatment process should be treated before disposal.

Design of Capacity for ETP 

The capacity of an effluent treatment plant is determined by the quantity and quality of wastewater generated in a hospital. In the case of laboratories and operation theatres, the wastewater generated is typically high in organic and inorganic content, including chemicals, pathogens, and other contaminants.        
The design of the capacity of an effluent treatment plant for hospitals involves the following steps:

· Step 1: Calculation of Design Flow Rate    

The design flow rate is calculated based on the total wastewater generated in the hospital. The flow rate is typically calculated in litres per day (LPD) and is based on the number of beds, the number of patients, and the quantity of water consumed per patient. The following formula is used to calculate the design flow rate:   
Design Flow Rate (LPD) = Number of Beds x Water Consumption per Bed x Number of Patients              

· Step 2: Calculation of Retention Time       

The retention time is the time for which the wastewater remains in the effluent treatment plant before being discharged. The retention time is calculated based on the type of treatment processes used and the discharge standards specified by the CPCB and Pollution Control Board norms. The following formula is used to calculate the retention time: 

                        Retention Time (Days) = Volume of ETP / Design Flow Rate      

· Step 3: Selection of Treatment Processes  

The type of treatment processes used in an effluent treatment plant depends on the characteristics of the wastewater generated. In the case of laboratories and operation theatres, the wastewater generated is high in organic and inorganic content and may contain pathogens and other contaminants.  
The treatment processes used typically include primary treatment, secondary treatment, and tertiary treatment.     

1. Primary treatment involves the removal of large solid particles and suspended solids from the wastewater. This is typically done through physical processes such as screening, sedimentation, and flotation.           

2. Secondary treatment involves the removal of organic matter from the wastewater through biological processes such as activated sludge, trickling filters, and rotating biological contactors.   

3. Tertiary treatment involves the removal of remaining contaminants from the wastewater through chemical or physical processes such as disinfection, filtration, and adsorption.     
The selection of treatment processes is also based on the discharge standards specified by the CPCB and Pollution Control Board norms. The treatment processes must be able to meet the discharge standards for various pollutants.      

· Step 4: Sizing of Treatment Units   

The treatment units in an effluent treatment plant must be sized based on the design flow rate and retention time. The sizing of the treatment units is critical to ensure that the treatment processes are efficient and effective in meeting the discharge standards.

Summary:      

In short, designing the capacity of an effluent treatment plant for hospitals requires a thorough understanding of the characteristics of the wastewater generated and the discharge standards specified by the regulatory bodies. The design criteria specified by the CPCB and Pollution Control Board norms provide a framework for designing effluent treatment plants that are effective in treating wastewater and ensuring that it does not pose a threat to public health or the environment. By following these design criteria, hospitals can ensure that their effluent treatment plants are efficient, effective, and compliant with the regulatory standards.

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