A Zero Discharge Success Story
Abstract:Complete wastewater recovery and reuse since 1996 at the largest lead acid battery manufacturing and recycling complex in the world.
Robust design and materials selection by AECOM has produced sustainability in the water treatment infrastructure at East Penn Manufacturing Co. (East Penn) located in the Borough of Lyons and Richmond Township, Pennsylvania. East Penn operates the largest lead acid battery manufacturing complex in the world coupled with an integrated battery recycling facility on a 416 acre site in rural Pennsylvania. The challenges of water supply and wastewater management made a zero liquid discharge (ZLD) facility a key factor to their sustained growth over the past 13 years. During this period the manufacturing facilities have more than doubled in size while the water treatment infrastructure has kept up with these demands. East Penn is now the largest industrial employer in Berks County, Pennsylvania with over 5,000 employees.
The water treatment facilities originally designed and constructed in 1993 to 1995 and commissioned in early 1996 have continuously recovered distilled water and commercial grade anhydrous sodium sulfate by-product from the sulfuric acid based process wastewater. These facilities are segregated into two distinct operations; wastewater pretreatment (brine purification) and water/salt recovery. The brine purification operations begin with the screening of plant debris and flow equalization followed by a 3-stage neutralization and iron coprecipitation process. The pretreated wastewater is clarified using stainless steel inclined plate clarifiers followed by filtration. The purified brine is held in two large (300,000 gallon) tanks for feed to a falling film mechanical vapor recompression evaporator that recovers approximately 85 percent of the feed as distilled water. The concentrate from the evaporator is held in interim storage for feed to a forced circulation crystallizer with mechanical vapor recompression. The recovered condensate from the crystallizer is combined with the distilled water from the evaporator and is passed through a heat exchanger to heat the evaporator feed and to cool the product water leaving the system. The combined distilled water is stored in two large (300,000 gallon) tanks for distribution to the manufacturing facilities as process water. Duplex 180 gpm reverse osmosis (RO) systems produce make-up water for distribution along with the recovered distillate.
The sodium sulfate crystals formed in the crystallizer are harvested in a belt and platen pressure filter. The salt cake is fed into a natural gas fired turbo-tray dryer to produce anhydrous sodium sulfate for sale. The salt is stored in two 80 ton silos for dry bulk transport to customers. The iron based pretreatment sludge is consumed in the on-site secondary lead smelter as a beneficial charge admixture.
AECOM is currently managing the construction and commissioning of an expansion to the existing water treatment facilities. The expansion will provide duplicate evaporator and crystallizer systems and appurtenant equipment to fortify the water and wastewater infrastructure of the plant. The additional capacity and redundancy reduces the risk of interruption to operations and provides for systematic preventative maintenance without disrupting plant production. The water treatment plant expansion is planned to go online in August 2009.
Document Type: Research Article
Publication date: January 1, 2009
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