In cases where waste brine disposal is a concern, Orica Watercare has a range of waste management options. Waste brine can be treated on-site to produce either greatly reduced volumes of brine or solid waste that will be easier to dispose of. Alternatively, Orica Watercare can provide a service to collect and dispose of waste brine in 4500-5000 gallon tanker loads where required (smaller loads are possible if truck access is restricted). Waste disposal charges are on a per gallon of waste basis and depend on the location of the water treatment plant.
A brief summary of waste disposal options is as follows:
As the volume of waste generated is relatively small (less than 0.05% of plant throughput), it may be possible to discharge this volume gradually to a local sewer connection.
Off-Site Disposal / Treatment
If disposal to a local sewer connection is not possible, waste could be collected in bulk tanker loads and transported off-site to a wastewater treatment plant for treatment/disposal. The disposal cost for this option should be investigated locally, considering hauling costs and any fees for treatment/discharge.
Use of an Alternative Regenerant
If the presence of chloride in the brine waste restricts disposal to sewer or land application, sodium bicarbonate (NaHCO3) can be used in the place of salt (NaCl) for MIEX® Resin regeneration thereby eliminating the presence of chloride in the waste.
Alternatively, if the presence of sodium in the waste restricts disposal options, potassium chloride (KCl) or magnesium chloride (MgCl) can be used to eliminate sodium from the waste stream.
Waste Recycling with Nanofiltration or Coagulation
Waste brine can be treated by Nanofiltration (NF) to filter out over 98% of the TOC, allowing over 75% of the waste to be reused, which significantly reduces the volume of waste requiring disposal and also recovers much of the salt used for regeneration. The capital and operating cost of the waste treatment/recycling process is relatively small due to the very low waste volume generated from the MIEX® Process. See Technical Note on Nanofiltration Recycling of Waste.
It is also possible to remove TOC from waste brine by coagulation so that the brine can then be recycled back into the resin regeneration process. Similar salt savings and waste volume reductions are achieved as for Nanofiltration recycling.
Zero Liquid Discharge
It is also possible to operate a MIEX® Process with a zero liquid waste discharge (ZLD). ZLD is achieved by first using a nanofiltration (NF) recycling system to reduce brine waste volumes by up to 80% followed by an evaporation process to reduce the small volume of concentrate from the NF system to a solid waste for landfill disposal with other water treatment sludges.