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Monday, September 01, 2014
CAN RO REJECT WATER BE TREATED
I WOULD LIKE TO KNOW VARIOUS USES OF RO REJECT WATER EITHER INSTALLED AT HOME OR AT INDUSTRY & CAN RO REJECT WATER BE TREATED AS IT CONTAINS HIGH TDS VALUE & CAN IT BE USED FOR ANY APPLICATION.
Arpita D.Executive at CII-ITC Centre of Excellence for Sustainable Developmenthttp://www.linkedin.com/groups/I-WOULD-LIKE-KNOW-VARIOUS-2845325.S.176004586
Junior manager (Environment Management) at JSW steel ltd
RO reject having high TDS (around 40000-50000) is usually fed to evaporator. hence, only salt is removed from the evaporator. But the cost of constructing an evaporator is very high and if the TDS is lower (around 5000-10000) it can be used in industries for quenching or spraying on raw materials to reduce dust.
Usually RO reject from domestic applications will be under the limit for usage in secondary applications. The same can be used for gardening, toilet flush floor wash etc. From industrial RO systems the usage/recycle/disposal depends purely upon the quality of RO reject stream. TDS levels under 1500 - 2000 mg/l can be used again for equipment wash, floor wash etc. Apart from this usually the reject stream is treated in a waste water treatment unit/Evaporator/Solar pond.
The TDS of reject from RO water will be around 2.5 to 3 times the feed TDS In case of domestic RO and > 4 times in Industrial RO system. As a common use of domestic water which may range from 400 -700 ppm for river water and more in Borewell water. so approximately we may happen to get reject water of 2000 ppm range which can be disposed onland and for irrigation/ gardening .The Prescribed limit of CPCB says it should be within 2100ppm for Gardening. so household RO system rejects can be used for gardening. If it is exceeding in the TDS try to dilute it with fresh water of 20 : 80 ratio or accordingly to suit the TDS level.
From industrial RO systems the usage/recycle/disposal depends purely upon the quality of RO reject stream.
TDS levels under 1500 - 2000 mg/l can be used again for equipment wash, floor wash etc.
Apart from this usually the reject stream is treated in a waste water treatment unit/Evaporator/Solar pond.