Case Study

Aquatech Supplies Zero Liquid Discharge System In Puerto Rico Due To Environmental Regulations

Source: Aquatech International Corporation

AES Puerto Rico Cogeneration Plant (AESPR) is a cogeneration power plant that produces 454 MW of net electricity in its fluidized bed boiler plant in Guayama, which is sold to the Puerto Rico Electric Power Authority (PREPA). In addition, the facility commercially produces approximately 290,000 pounds per hour of pressurized steam for industrial processes of industrial clients in the area such as the neighboring Chevron Phillips Puerto Rico Core Inc. AESPR also produces fly ash, bed ash, and manufactured aggregate for commercial uses.

The cooling tower blowdown (CTBD) stream which contains high solids content cannot simply be discharged from the plant due to environmental regulations and therefore requires Zero Liquid Discharge (ZLD) operation. The existing process for CTBD treatment utilized a 2-stage side stream Reverse Osmosis (RO) system which reduced the wastewater volume by about 75%. Due to the problems in the upstream plant design, the RO recovery was not being achieved.

Even after design reviews with other suppliers and adding of different equipment including multimedia and iron removal filters, and replacement of the RO, within a few months this retrofit experienced the same fouling and low recovery issues.