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Thursday, August 05, 2010

HOSPITAL LIQUID WASTE MANAGEMENT -- ETP & STP





STP FLOW CHART
HOSPITAL EFFLUENT TREATMENT PLANT:

CATEGORIES OF BIO MEDICAL WASTE (BMW)
https://www.dpcc.delhigovt.nic.in/bio-medical-waste.html

(Please refer Schedule I , Click here to see the Schedule I)
Category No. 1      Human Anatomical Waste
Category No. 2      Animal Waste
Category No. 3      Microbiology & Biotechnology Waste
Category No. 4      Waste sharps
Category No. 5      Discarded Medicines and Cytotoxic drugs
Category No. 6      Soiled Waste
Category No. 7      Solid Waste
Category No. 8      Liquid Waste
Category No. 9       Incineration Ash
Category No. 10    Chemical Waste
reatment Of Bio Medical Waste 

Category No.1    Incineration /deep burial

Category No.2    Incineration /deep burial

Category No.3    Autoclaving/microwaving/incineration

Category No.4    Disinfection(chemical treatment)/autoclaving/microwaving and 
                            mutilation/shredding.

Category No.5    Incineration/destruction/ and drugs disposal in secured landfills

Category No. 6    Incineration/autoclaving/microwaving

Category No.7    Disinfection by chemical treatment/autoclaving/ microwaving and 
                           mutilation/ shredding

Category No.8    Disinfection by chemical treatment & discharge into drains

Category No.9    Disposal in municipal land fill

Category No.10    Chemical treatment and discharge into drains for liquids and secured 
                              landfill for solids. 
Standards for Liquid Waste



PARAMETERS
PERMISSIBLE LIMITS
pH
6.5-9.0
Suspended Solids
100 mg/L
Oil & Grease
10 mg/L
BOD
30 mg/L
COD
250 mg/L
Bio-assay Test
90% survival of fish after 96 hours in 100% effluent

These limits are applicable to those hospitals which are either connected with sewers without terminal Sewage Treatment Plant or not connected to public sewers. 

For discharge into public sewers with terminal facilities , the General Standards as notified under the Environment (Protection ) Act, 1986, shall be applicable . 
Click here to see the General Standards(Schedule VI) 

Main parameters are given below:




PARAMETERS
PERMISSIBLE LIMITS
pH
5.5-9.0
Suspended Solids
600 mg/L
Oil & Grease
10 mg/L
BOD
350mg/L
Bio-assay Test
90% survival of fish after 96 hours in 100% effluent

DPCC has taken decision that Hospital having 50 beds or more shall install Effluent Treatment Plant (ETP) for the treatment of waste water generated and for recycling of treated effluent for use in horticulture, air conditioning/ cooling plants and flushing of toilet etc. 
In hospitals that have ETP facility, the treatment is carried out using special scientific process and generally involves three stages, primary, secondary, and tertiary levels of treatment. [14]

 Average water consumption 750 liter / bed / day. Please calculate daily water consumption from borewell to over head tank using water meter. 80% of total water in nover head tanks is wasted as waste water. This should be the capacity of the STP to be installed at the hospital. (See table below)
Capacity of overhead tank from where water is distributed = A Liter
Number of times Over Head Tanks Filled up in a day = B Nos
Total water requirement for use at different points = A x B Liter/day
Quantity of Effluent , liter per day = 80 % of ( A x B )
Sourcess of waste water
1. Bed in Hospital= Nos @ 500 liter per bed = Liter
2. Employee in Hospital = nos @ 40 liter per employee= Liter
3. Hostels- Persons = nos @ 150 liters per person. = Liter
4. Kitchen Meals= nos@ 10 liter per meal = Liter
So, Total Quantity of discharge: --------- liter per day
Health Stream Literature Summary - Issue 46 - June 2007
The treatment of hospital waste water: an appraisal
Pauwels, B. and Verstraete, W. (2006) Journal of Water & Health, (4) 405-416.


Primary treatment

Consists of temporarily holding the sewage in a basin where the settled and floating materials are removed and the remaining liquid subjected to secondary treatment. Primary treatment usually removes from 30 to 40% of the BOD. After this treatment the BOD and COD levels usually comes down to 25% of its initial levels.

Secondary treatment

Removes the dissolved and suspended biological matter and is typically performed by indigenous, water borne microorganisms in a managed habitat. This treatment uses microbial degradation, aerobic or anaerobic, to reduce the concentration of the organic compounds. The combined use of primary and secondary treatment reduces approximately 80 to 90% of the BOD. In this stage, there is settling down of the suspended solid contents of the biological waste as thick slurry called sludge, while the treated fluid undergoes tertiary treatment. Through this process, 95% of the pollutants from the waste water are removed.

Tertiary treatment

Uses chemicals to remove inorganic compounds and pathogens. This is the final stage of treatment where the effluent after secondary treatment first is mixed with sodium hypochlorite and then the effluent is passed through dual media filter (DMF) and activated carbon filter (ACF) where sand, anthracite, and activated carbon are used as filtration media. Finally, the treated water is let into a small well to recharge the water table. This treated waste water now can be used for gardening, toilets, and laundry purposes. [15]
Chemical treatment usually involves the use of 1% sodium hypochlorite solution with a minimum contact period of 30 min or other standard disinfectants like, 10-14 gm of bleaching powder in 1 l water, 70% ethanol, 4% formaldehyde, 70% isopropyl alcohol, 2 5% povidone iodine, or 6% hydrogen peroxide

WASTE WATER FLOW RATES IN DIFFERENT UNITS:
Waste water consist primarily of used water, the water that reaches the sewer . For different units it is different as shown in the chart .
Source
Unit
Range l/u/d
Typical l/u/d
Apartment
Person
200-340
260
Hotel resident
Resident
150-220
190
Hotel Employee
Employee
30-50
40
Individual Home
Person
190-350
280
Airport
Passenger
8-15
10
Automobile service station
Vehicle served
150-200
200
Restaurant
Meal
8-15
10
Office
Employee
30-65
55
Laundry
Machine
1800-2600
2200
Laundry
Wash
180-200
190
Hospital medical
Bed
Employee
500-950
20-60
650
40
School
Student
20-65
40
School boarding
Student
200-400
280
For Industries
80% of water used used in production will be released as waste water
Meat processing
Mg
15-20 cu mtr/ Mg
Milk Products
Mg
10-20 cu mtr/Mg
Bread
Mg
2-4 cu mt/Mg
Beer
Mg
10-16 cu mtr/Mg
Whisky
Mg
60-80 cu mtr/Mg
Paper Pulp
Mg
250-800 cu mt/ Mg
Paper
Mg
120-160 cu mtr/Mg
Textile Bleaching (Cotton)
Mg
200-300 cu mtr/Mg
Textile Dyeing (Cotton)
Mg
30-60 cu mtr/Mg
REF : WASTE WATER ENGINEERING : TREATMENT , DISPOSAL AND REUSE--- METCALF & EDDY .