During discharge from Laundry Washing Unit, a high polluted wastewater called effluent is discharged into municipal sewer network. Wastewater from domestic, commercial or industrial mixed with at a single point is concentrated and it exceeds legislation limit. Due to this reason, laundry effluent can not to be discharge directly into the municipal wastewater treatment plant. Therefore, a performance "Laundry Effluent Treatment Plant" is highly recommended.
It is difficult to characterize the laundry effluent, because washing is not same and it varies. The application of the technique depends upon various factor like the type of the fabrics, the amount of sailings, type of stains, the stain removal chemicals used, the use solvents for dry-cleaning etc.
Except Domestic laundry, both Commercial and Industrial Laundry is wildly used detergents, Soaps Sodas and other cleaning agents for stain removal, oil and dirt from the cloths. Therefore, surfactants are major ingredient of laundry effluent and thus a special care should be taken to treat and disposal of laundry effluent treatment.
Laundries in the textile sectors are very typical; accordingly discharged effluent will be very special and it is difficult to treat because they produce different types of pollutants including dye. In general a laundry effluent may be flowing physical and chemical properties.
Temperature- 30-40⁰C, pH- 6-9,
TSS- 100-200mg/l, BOD- 250-300mg/l,
COD- 400-600mg/l, DO-0.5-1.2mg/l,
Turbidity- 40-150mg/l, Oil & Grease- up to 30mg/l.
Other tan these, some heavy metals is present in the laundry effluent.
Hardness- up to 100mg/l, Fe- 0.01-0,06mg/l Cu- 0.o1-0.05mg/l.
But, in the case of Industrial and Commercial Laundries, BOD and COD will be high and generally lies in-between as stated below.
Temperature-40-45⁰C pH- 6-9,
TSS- 400-1000mg/l, BOD- 250-500mg/l,
COD- 1000-2000mg/l, DO- 0.5-1.2mg/l,
Turbidity- 40-150mg/l, Oil & Grease- up to 30mg/l.
Other than these, some of heavy metals are present in the laundry effluent.
Hardness- up to 100mg/l, Fe- 0.01-0,06mg/l Cu- 0.o1-0.05mg/l.
Laundry effluent has low biodegradability in the past, because of the extensive use of synthetic detergents. Recently, however, biodegradable products are widely use due to legislation and to an increased environmental awareness.
Treatments: In normal, Chemical treatment process is sufficient to get desired results as per standard norms. Because of BOD and COD are low. The process can be describe as 1) Primary Treatment/Sedimentation/O & G removal, 2) Coagulant/Flocculation, 3) Filtration and Disinfection. The process flow will be as shown in picture-1,
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| Pic-1, Process Flow Diagram. |
But, in the case of Commercial and Industrial Laundries, only Chemical or Biological treatment process is not sufficient to treat effluents due to high BOD and COD and other pollutants. In this cases, both Chemical flowed by Biological Treatment process should be apply. The process can be describe as 1) Primary Treatment/Sedimentation/O & G removal, 2) Coagulant/Flocculation, 3) Biological Treatments, 4) Filtration and Disinfection. The process flow will be as shown in picture-2,
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| Pic-2, Process Flow Diagram |
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| A Typical Chemical Laundry ETP Installation. |
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| A Typical ETP of both Chemical and Biological Process. |
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