Case Study: Italy's ENEL Power Installs ZLD Plant For La Spezia For FGD Wastewater Treatment

Wastewaters from FGD treatment plant can no longer be discharged into the sea due to tough Italian and EU environmental regulations. In order to overcome this major environmental problem, ENEL decided to feed the absorbers with fresh and recirculated waters and install the Zero Liquid Discharge (ZLD) plant so that no industrial wastewater discharges are allowed by the entire power plant.

To overcome the problem, ENEL selected the Softening – Evaporation – Crystallization (SEC) process to treat the wastewaters and reuse/conserve fresh waters. Aquatech supplied, installed, and commissioned the ZLD plant as an EPC contractor with local associates.

The SEC plant comprises of three treatment tanks where lime, sodium sulfide, and coagulant are added. 1 x 100% Softener Clarifier is used for removal of suspended solids, temporary hardness, and precipitated metal hydroxides. Followed by 1 x 100% softener clarifier (calcium reduction by soda ash dosing) for removal of permanent hardness, 1 x 100% Falling Film type Brine Concentrators (equipped with Vapor Compressor), 1 x 100% Crystallizer (equipped with a Thermocompressor) and 2 x 50% Belt Filter Presses. The plant also includes several chemical dosing systems, storage tanks, pumping systems, electrical works (MCC, cable trays, cabling etc), controls & instrumentation.