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Journal of the Academy of Hospital Administration

Effluent Treatment Plant: Why and How

Author(s): Ravikant*, Vikrant Chitnis**, S P Jaiswal***, D S Chitnis****, Kamlakar Vaidya*****

Vol. 14, No. 1 (2002-01 - 2002-06)

Key Messages:

  • Hospital effluent has high load of multiple drug resistant bacteria and discharging to municipal system could be a grave public health harard.
  • Effluent treatment plant with terminal chlorination helps in treating the effluent to within prescribed limits, and also provides water for irrigation and sanitary clearing.
  • It is proved to be a cost effective method in a teritary care hospital.

Abstract:

Hospital effluent not only has aberrant physico-chemical characteristics but also has high loads of multiple drug resistant bacteria and discharging of the effluent in a municipal sewage system could be a grave public health hazard. Effluent treatment plant (ETP) with terminal chlorination needs to be added up to safeguard the dangers of the hospital effluent. However, most of the hospitals believe it to be an unaffordable proposal.

The Choithram Hospital and Research Centre is a 350 bedded tertiary care center spread over 26 acres of land with huge green belts, requiring 5 lac liters of water per day. The scarcity of water affected the hospital activities and irrigation of green belt.

The ETP was setup at Choithram Hospital Research Centre, Indore and the treated effluent has all the physico-chemical characteristics within the specified limits and is free from viable multiple drug resistant bacteria. The treated effluent water is available for irrigation and sanitary cleaning and as a result saves 3 lakh liters of potable water. Further, the ETP provides 5000Kg/month sludge to be used as manure. Thus, the ETP has been proved to be ecofriendly cost effective proposal.

Keywords: Hospital effluent, multiple drug resistant bacteria, Effluent treatment plant, sludge

Introduction

Biomedical waste can be a hazard to the hospital staff and community. This has forced the introduction of Bio Medical Waste (Management and Handling) Rules 1998. (1) in which the responsibility of the management of the bio-medical waste rests on the "generators" of the waste that is the hospitals. So far, solid infectious and hazardous waste has received greater attention than the liquid waste in the form of effluent. Our surveillance study (2) revealed that besides deviations in the physico-chemical parameters such as pH, suspended solids, biological oxygen demand (BOD) and chemical oxygen demand (COD), hospital effluent has a high load (0.58 to 40%) of multiple drug resistant (MDR) bacteria. Hence, the effluent discharged in municipal sewage can be a grave hazard to the community. The MDR bacteria may cause infections in community members and would pose serious therapeutic problem and can be more dangerous if their drug resistance is transferred to other sensitive pathogens in the city sewage. With this threat, the appropriate effluent treatment plant is considered to be extremely expensive and out of reach proposal by most of the hospitals in India.

Our hospital is a 350-bedded tertiary care center with a huge campus and green belt spread over 22 acres of land and the water requirement of the hospital exceeds 5 lakh liters/day. The municipal water supplies are inadequate and with the scanty rainfall and increased city population, the tube wells are inadequate and with the scanty rainfall and increased city population, the tube wells are also giving reduced water yield resulting in to water crisis for the hospital activity. Hence, the present ambitious project of commissioning effluent treatment plant (ETP) was undertaken with the following objectives:

1. To make the effluent safe with reference to physico-chemical characteristics.

2. To inactivate the viable MDR bacteria in the effluent.

3. To recover 3 lakh liters/day of treated effluent water for irrigation of green belt and sanitary cleaning purpose.

4. To use sludge from the ETP as manure for the green belt.

Materials and Methods

Hospital size: Choithram Hospital and Research Centre is a 350-bedded tertiary care center with a daily OPD attendance of 475 patients. The hospital employs a staff of 750 persons. Daily hospital water requirement: Patients, relatives, hospital activity and residential area: 354000 liters. (Breakup shown in Table-1). Irrigation of gardens and green belt: 146000 liters. Total daily water requirement: 500000 liters.

Table-I: Water consumption and effluent generation at Choithram Hospital and Research Centre.

Area Consumption litres/day Effluent litres/day
Laundry 23000 20000
Boiler 9000 5000
A.C. Plant 12500 10000
Public toilet 12500 11000
Centeen 12500 11000
Dialysis 4500 4000
Operation theatre 9000 8000
Labour room 4500 3000
Burn unit 4500 3000
Pathology 12500 11000
CSSD 4500 3000
Total 500000 339000

Sources of water: The water resources are described in Table - 2.

Table-2 Water sources at Choithram Hospital and Research Centre.

Source Location V Knotch in inches Depth in feet Horse power Water liters/hour No. hours run daily Liters/day
1. Last corner 4 300 12.5 27000 4 108000
2. Mango tree 3 180 7.5 13500 4 44000
3. Centre 4 325 12.5 27000 4 108000
4. Behind project 2 270 5 11250 3 33750
5. School Well - 45 5 11250 3 33750
6. Goshala 2 180 7.5 13000 2 27000
7. Open - 45 7.5 13500 3 40500
8. Narmada (City supply) - - - Meter 0.5-1 105000

Foot note: Water quantities based on depth of wells, V knotch, horse power of motor and no. of hours run/day. All the water is collected in four underground water tanks and chlorinated before use.

ETP:

The ETP plant was designed and erected at the hospital by the firm. The construction work was completed in 6 months at the cost of Rs. 14 lacs and commissioned in November 2001. The schematic flow sheet of ETP is depicted in Fig. 1.

Fig. 1: Schematic Flow Sheet of Effluent Treatment Plant

Figure 1

Principle and Functioning of ETP:

Bar screens: For screening and removal of coarse suspended solids from the effluent while it passes through the bar scanner.

Oil and grease Trap: Removes the floating oil and grease from the effluent.

Equalization tank: Collects and equalizes the raw effluent.

Aeration tank:Mixes the effluent and provides excess of air (oxygen). The aerobic bacteria in the biomass oxidize the suspended and dissolved organic matter. The organic matter is biodegraded by the bacterial mass. Complex carbon compounds are degraded and CO2 generated. Complex organic nitrogen compounds are degraded to form ammonia, nitrite and nitrates.

Clarifier tank: Separates suspended biological material. Part of the sludge is returned to aeration tank to provide biomass for the treatment and excess is flown to sludge drying bed.

Filter feed tank: The treated effluent is stored before passing to pressure sand filter.

Pressure sand Filter: Removes the fine suspended mater from the treated effluent.

Chlorine contact tank: Chlorine is added continuously to inactivate the microbial population.

Clean treated effluent water tank: Holds water before lifting to high-level storage tanks.

Results

The analysis of the hospital effluent before and after effluent treatment is shown in table-3 all the physico-chemical parameters are absolutely within the specified limits after the effluent treatment. The chlorination results in complete inactivation of the MDR bacteria and thus makes the effluent water safe.

Table-3 Physico-chemical and Bacteriological analysis of effluent water

Parameter Value before ETP Value after ETP Limit
Total viable bacterial count 9 X 104 Nil -
MDR Coli-form [%] 1.5 Nil Nil
Chem. Oxygen Demand [mg/liter] 280 22.56 <250
Biological oxygen demand 45 3.6 <30
Total Solids 1066 630 <2200
Total dissolved solids >mg/ltr. 942 630 <2100
Total suspended solids mg/ltr. 124 <2 <100
PH 7 8.8 6.5-9

The daily input of effluent is approximately 339000 liters/day and approximately 3 lakh liters of treated water is recovered. The treated effluent water is used for irrigation and sanitary cleaning and as a result of which the hospital no more faces the water shortage. Further, more than 5000 Kg. of dried sludge is available per month to use as manure for the gardens.

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