Harry Harman, a professional engineer with consulting firm Baxter & Woodman, got a call one day from an official with the Village of Gilberts, Illinois. The official asked him to review a set of documents from the U.S. Environmental Protection Agency (EPA) sent to the village regarding the 5-year renewal of its national pollution discharge elimination system (NPDES) permit.
Baxter & Woodman was formed in 1946 and is headquartered in Crystal Lake, Illinois.
The permit includes a set of standards developed by the EPA regarding allowable wastewater contaminant concentrations when discharging is done into streams and rivers by industry or public wastewater treatment facilities of cities, villages, and townships.
Reviewing the report, Harman quickly noticed a more stringent limit on permissible levels of barium.
Here was a potential conundrum, but one that had already been addressed.
No treatment systems available would remove the barium without also determining an outcome that exceeded radium limits recently established by the Illinois Emergency Management Agency – Division of Nuclear Safety (IMEA-DNS).
Background data
As an aside, barium is a soft silvery metallic alkaline earth element. Because of its high chemical reactivity, barium is never found in nature as a free element. Its hydroxide was known in pre-modern history as barite. This substance doesn’t appear as a mineral, but can be prepared by heating barium carbonate.
As is well known, radium is also an alkaline earth metal. Pure radium is almost colorless, but it readily combines with nitrogen on exposure to air, forming a black surface layer. All isotopes of radium are highly radioactive.
EPA drinking water standards for removal of radionuclides were mandated to meet the 5 picocuries per liter (pCi/L) limit for combined radium. As radium is removed from the raw water and manifests itself either in the drinking water treatment media or at a wastewater treatment facility the management of these treatment residuals is subject to regulation by IEMA-DNS. Specific details on requirements for land application, field sampling, disposal and annual reporting were codified in the resulting rule.
Relationship building
The village of Gilberts is a long-time client of Baxter & Woodman.
As a consulting engineering firm for water, wastewater, and other municipal and civil services, it works closely with village managers and officials to maintain drinking water treatment and wastewater treatment systems.
Fortunately, Harman is especially familiar with the water’s chemical make-up and had earlier devised a method for capturing the contaminated water treatment byproduct, recognizing beforehand the potential for more strict limits on water discharge into sanitary sewers as well as streams and rivers.
The system, called by some the "Harman barium/radium removal process," involves diverting wastewater from ion-exchange softeners into a batch-operation treatment tank.
Inside the tank, ballast and treatment chemicals introduced as catalyst aid in settling the barium- and radium-contaminated sludge produced during the pre-treatment process. The ballast increases material weight, causing the solids to settle quickly and efficiently inside the tank.
The pre-treatment system operates in batch-mode to coincide with the batch regeneration of the ion exchange softeners. Following the treatment cycle, settled solids are sent through a filter for dewatering, then to a municipal landfill for disposal.
The barium removal system helps the Village of Gilberts meet the new discharge requirements.
Baggage in bulks
In completing the barium removal system for the village of Gilberts, Harman needed equipment to make the ballast feed system work efficiently. He contacted Maggie Beauchamp, sales engineer with Gull Material Handling Co., known for design and sourcing of material-handling equipment.
A custom Hapman bulk-bag unloader contributes to achievement of the needed results.
The ballast, a sand-like material, is received, securely positioned and hooked with a fork truck on the steel base frame. The unloader keeps the bag in place. Its features include a portal to access the bag spout for tie-off and an integral transfer hopper. The hopper allows the ballast to discharge from the bag without flooding the feeder below. The feeder automatically meters the material at a rate of four cubic feet (400 pounds) per hour. The metered ballast enters a pneumatic conveying system that carries the material to the treatment tank.
"The bulk-bag unloading system allowed me to control the settling process," notes Harman. Its customizability, small footprint and feeder-assembly accuracy were among the reasons for success.
Barium levels in the wastewater came down almost immediately from 6 mg/l to 0.6 mg/l. This concentration level was well within the new EPA guidelines, allowing the village to discharge the wastewater. In addition, the HBRP system reducing levels in the biosolids from 100 pCi/gram to 13pCi/gram so it could be used for fertilizer on local farm fields and the dewatered solids safely disposed at the local landfill.
Hapman has powder and bulk handling equipment and systems for food, chemical, pharmaceutical, plastics and other industrial processors.
