BETHLEHEM, Pa. — MacIntosh Services is a large commercial linen rental supply company in the scenic Lehigh Valley area of Northeastern Pennsylvania. From its headquarters here, the company supplies not only table linens and napkins, but also uniforms, chef apparel, aprons and towels to restaurants, hotels and other facilities throughout Pennsylvania and New Jersey.
The company uses more than 90,000 gallons of clean water a day. In fact, MacIntosh Services is the largest single user of municipal water in the Bethlehem metropolitan area.
RECYCLING REDUCES WATER CONSUMPTION
In the course of its operations, the company generates up to 75,000 gallons of wastewater daily. “We try to recycle and reuse at least 40% of the wastewater we generate,” says Gary Shaffer, chief engineer.
In 1996, MacIntosh Services installed a 48-inch-diameter Vibroscreen® circular vibratory screener from Kason Corp., based in Millburn, N.J. The unit’s 80-mesh screen removes most large solid-waste particles before treating the wastewater using standard aeration and flocculation procedures.
“The residue from the screener contains all sorts of solid waste, including not only lint, but also food particles, corks and even gloves,” says Shaffer.
The screener separates bulk solid materials from solids and slurries using multi-plane, inertial vibration. Smaller particles pass through apertures while oversized particles travel across the screen surface in controlled pathways to the screen periphery where they are discharged.
INTERNAL HOLLOW RINGS PREVENT BLINDING
An anti-blinding device prevents fibrous, stringy and sticky materials from blinding the screen.
Untreated wastewater enters the first compartment of a two-compartment wastewater pit, where it’s metered into the screener. Screened water discharges into a storage tank from which it’s pumped through a four-pass heat reclaimer to preheat incoming city water. The wastewater then is pumped to the pit’s second compartment, pumped again to a larger storage tank, and then to the wastewater pretreatment system.
SCREENING DECK INCREASES CAPACITY
As MacIntosh’s business continued to grow, its wastewater volume began to exceed the screener’s capacity. “We really needed to go to a 60-inch unit, but the space we had available simply did not permit it,” says Shaffer.
In 2006, the company added a Kason recycle screening deck atop the existing screener, boosting its capacity from 100-150 gpm to 225-250 gpm without increasing its diameter.
Positioned directly above the screening deck, the recycle deck has a screen of identical mesh. The upper screen deck is fed with more material than it can efficiently screen. Material passing through this deck is directed to the unit’s discharge outlet. The overflow, along with all oversized solid particles, is directed onto the lower screen, where it is screened in normal fashion.
The effluent is treated on-site to remove solid waste, then it’s returned to the City of Bethlehem, or it’s reused at MacIntosh Services. The solid waste is removed as sludge, which is dewatered and pressed into cakes.
“We remove 300-450 tons of sludge a year,” says Shaffer.
“Rapid changes in technology continue to affect every aspect of our business,” says MacIntosh Services President Jim Rodgers Jr. “We continue to invest our resources in new technologies that will help us streamline our operations, increase our efficiency and improve customer service.”