It is billing time at the city of Evans, Colo., water department. For the past 14 years, Randy, an Evans technician, has devoted days out of every...
Most of this water was storm water that had accumulated in a large holding tank. With a treatment system that included organoclay from Biomin, Inc., in Ferndale, MI., total petroleum hydrocarbon spikes where eliminated. The resultant TPH levels in the effluent where consistently below 5 ppm.
In 1999, drainage from the refinery’s parking lots had resulted in oil and grease passing through the existing treatment system. As a result, hydrocarbon spikes were detected periodically in the holding tank effluent, resulting in frequent, hefty fines. Water analysis reports indicated hydrocarbon levels below the local discharge level of 10 ppm most of the time, but the spikes where a regulatory issue.
A contractor recommended a temporary treatment system to process 2000 to 4000 gpm wastewater for six to 18 months, until all the stored wastewater was clean. The goal of the system design was to be below 5 ppm consistently. This system depended primarily on the organoclay, a bentonite based granule modified with quaternary amines, and blended with anthracite. The water was prepolished with string wound polypropylene pre-filters to remove particulate matter. Polymer flocculant was added in the holding tank to flocculate suspended sediments and globules of floating oil. The system included 75,000 lb of organoclay/anthracite, and ran at 2000 gpm.
Within six months the wastewater was cleaned and discharged, with no spikes, and the organoclay was still not exhausted. It was not necessary to change it out during the operations time.