Process and Technology Description

Membranes are being used increasingly for the removal of dissolved and colloidal contaminants in wastewater streams. Reverse osmosis (hyperfiltration) is well known for its ability to concentrate ionic species while ultrafiltration has found broad utility for the removal of dispersed colloidal oil, non-settlable suspended solids, and larger organic chemical molecules. One of the major problems these processes have faced is the fouling or blinding of the membranes after limited use. Various approaches have been developed in an effort to minimize this deterrent. Cross-flow filtration, where the contaminants are constantly flushed or washed from the membrane surface by the feedwater stream, is one of these approaches. The unit goes farther. Rather than a thin 

At the American Creosote Works site, groundwater was pumped from a well to an above ground storage tank where a quiescent period of several hours allowed oil and suspended solids to coalesce and separate. The feedwater stream to the filtration unit was drawn from the mid-section of the storage tank to minimize introduction of these materials. The pump that drew material from the tank also provided the compression for the system to operate, approximately 750 psig. 

The permeate leaving the filtration unit was sampled as required and then discharged in accordance with permit requirements. The concentrate was collected in a smaller 

The hyperllltration system, which consists of porous stainless steel tubes internally coated with specially formulated chemical membranes, has been demonstrated to successfully treat water contaminated with a number of hazardous or toxic materials. In this system, contaminated ground and surface waters are pumped through the 

In the study, the relatively heavy concentrations of contaminants in the feed material for the hyperfiltration unit precluded effective use of other tighter types of membranes as the first pass barrier due to the potential for fouling. Optimally, a combination system employing the initial membrane used here to remove high molecular weight contaminants, followed by a tighter membrane to remove lower weight phenolics from the permeate of the first membrane would have been more likely to provide the full spectrum of contaminant removal desired. 

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