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Heavy Metal Removal in Wastewater Treatment

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FSI provides a complete system for the removal of heavy metals in most industrial wastewaters.  The system combines the conventional chemical treatment with modern tubular membrane technology to provide the most cost-effective solution. It consists of three major components, 1) a chemical reaction unit, 2) a micro filtration unit, and 3) a dewatering unit. Auxiliary components, such as pumps and tanks complete the system.

The chemical reaction unit adjusts pH levels of the wastewater to precipitate any dissolved metals into suspended solids. The effluent is then fed into a micro filtration unit, WTS, which is the heart of the system, and can process wastewater to meet local discharge requirements or be recycled for reuse.

The typical achievable level for some common heavy metals are shown in Table 1. Limits for the RCRA 8, a group of eight heavy metals that are extremely toxic at even small concentrations and are required to be monitored under the Resource Recovery and Conservation Act, are shown in Table 2. The concentrate from the WTS is then sent to the dewatering unit for final processing. The process details are shown below.

FSI can provide a pilot testing to ensure a proper system design and confirm the effluent quality.

Treatment Processes:

1) The feed water containing dissolved metals is fed to reaction tank #1 where chemicals (such as NaOH) are added to form metal hydroxides, which will precipitate out from water.
2) unhoused modulesThe water is then fed to reaction tank #2 where additional chemicals and coagulant (such as organic polymers, ferric chloride) are added to control pH and further enhance precipitation and the formation of solids.
3) The water is then sent to a concentration tank to be treated by a tubular membrane filtration system, in which the permeate from the TMF is discharged or further processed treated for plant reuse and the concentrate is recycled back to the concentration tank.
4) Solids level in the tank are usually maintained at 3-5% and the settled sludge is periodically removed to a sludge tank.
5) The accumulated sludge is sent to a filter press for de-wetting and then disposed. The excess water from the press is piped back to the concentration tank.

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