Recycling System Turns Gray Water Green

Water pollution control is one of the world’s top concerns. Many nations, fueled by growing public pressure, are tightening the regulations on what may

Water pollution control is one of the world’s top concerns. Many nations, fueled by growing public pressure, are tightening the regulations on what may and may not be discharged into sewers or disposed in landfills. Much of the responsibility in meeting these strict guidelines is placed on companies and industries using water in their processes.

To comply with these regulations, industries are often faced with exorbitant hauling costs, expensive off-site treatment, increased municipal user fees, and the burden of cleaning up wastewater ponds. Noncompliance results in heavy fines and may even lead to complete plant shutdown. Therefore, the most sensible and cost-effective solution is to clean up wash water at the source.

Hanson Aggregates West Region was facing a welcome population boom around its San Diego base, but thanks to restrictive zoning laws, maintaining plants’ environmental integrity was challenging. Being one of the leading heavy building material companies, Hanson kept up with demand and expanded with two new ready mixed facilities: Oceanside and National City.

The challenge was to produce maximum yardage with minimal space, while maintaining Hanson’s environmental compliance and stewardship. One of the first installations was a Jadair Redi-Wash washout system to recover sand and stone. The Jadair saved space because it provides concrete reclamation and water handling within the machine, eliminating the need for ponds.

After reclaiming the aggregate, the suspended cement and fiber additives settle out. This spent cement is dredged, dried and hauled away; and, the clarified water is sent back to the batch or reused for truck washout. Yet, the small yard area necessitated constant water cleanup, frequent dredging, and minimal sludge drying time. And, there never seemed to be an end to shoveling and hauling the cement paste.

Hanson-Oceanside generates as much as 30,000 gallons of gray concrete slurry water per day. The operation recycled as much water as possible, storing the excess volume that could not be reused in containers. The dredged sludge was scooped and hauled away at an average of nine truckloads a day. Labor, machinery wear and tear, storage fees, space, hauling costs, and environmental compliance became a way of life, a byproduct of the boom.

When Hanson Aggregates West Region Area Managers Gary McCall and Craig Tieck walked the aisles of the World of Concrete in 2006, they certainly did not expect to solve a problem that seemingly did not have a solution. They visited a booth featuring a working demonstration of an ALAR AutoVac Water Recycling System. With more than 2,000 installations worldwide, ALAR officials presented their filtration system as a mechanical alternative for treating and recycling concrete process water, meeting environmental regulations, minimizing waste, and reducing operation costs. Hanson’s managers saw that the demo unit was filtering iron oxide pigment water, but they were skeptical the system could handle thick concrete mud. Still, they decided to give the process a try.

Months later, a pilot unit was rented and tested at the Oceanside facility. The AutoVac was put to the test by processing a slipstream of concrete slurry water that measured around 200,000 ppm TSS. The result was crystal clear, _-micron filtrate water that measured less than 25 ppm TSS. The dry solid material came off the filter at about 30 percent moisture content by weight. The trial was a success, and a full-scale system was ordered.

In January 2007, Hanson-Oceanside took delivery of an Automatic ALAR AutoVac AV640. The area managers say that, on the first day of operating the ALAR, they reduced their truckload sludge hauling from nine truckloads down to 1_ trucks.

What surprised the company was that over a year’s time, the AutoVac began to outperform their initial expectations. The systems not only provided recyclable water and remarkably dry solids, but also cleaned up the yard water and maintained 8-9 pH levels in the runoff. Craig Tieck claims there is no residual dust, dried up flakes of concrete, or layers of buildup on the lot. Hanson has maintained a clean facility by processing all the water and even devised a method of filtering wastewater through the ALAR, using its own concrete byproduct as a filter media.

Admixtures and other chemicals were also reduced. Operators are now adjusting the batch facility to keep up with this newfound process. The ALAR enhanced Hanson’s ability to stay in compliance by treating and recycling the concrete process water at a lower cost than conventional do-it-yourself methods; and, the local agencies continue to praise the positive changes coming from the plants. Hanson’s problems of real estate, yard water cleanup, and hauling costs were solved.

The implementation of the AutoVac has garnered much interest in the ready mixed industry, which, in turn, has spilled over into the aggregate world. Tieck says management has welcomed dozens of industry leaders to tour the Hanson plants and show them what is being done. We have always believed in promoting good ideas and equipment in our industry, he explains.
Û ALAR Water Recycling Systems, 708/479-6100; [email protected];