The company designs and builds flight controls for aircraft and launch vehicles. Their product line includes thrust vector and steering controls for space vehicles as well as thruster valves, regulators and integrated manifolds for satellite propulsion. Manufacturing of most of these products requires either military spec plating or anodizing to ensure protection from extreme environmental conditions.
Wastewater contains chromic acid, sulfuric acid, fluoride salts and sulfates from the chromium bath. Associated plating baths contain dissolved nickel salts and cadmium. Combined ion exchange regeneration wastes are also present from filter backwash and cyanide and scrubber blow down. The stream also contains TOC, lead, copper, aluminum and traces of manganese.
Waste Disposal Goals
The firm’s goal was to recover and recycle all plating rinse waters and reduce the demand for potable water used in parts rinsing. The company also wanted to down-grade wastewater permits for the plating line and minimize and or eliminate fees paid to the local POTW.
Wastewater Treatment Challenge
The client was using a standard hydroxide precipitation treatment to precipitate metal salts from their existing plating operations. The old wastewater system was clarifier-based and utilized sodium hydroxide, coagulants and flocculants to treat prior to discharge to the local POTW. A sodium hypochlorite system was used to decompose cyanide prior to sewer discharge. The former treatment system was located in a covered concrete enclosure exterior to the main building.
Large amounts of potable water were required for the existing plating systems. The company was using 28,800 gallons of potable water a day, which required extensive wastewater treatment. The excessive potable water usage coupled with the high wastewater treatment costs became an obstacle for the company. The expense and limited availability of potable water in the state of California became the primary driver for upgrading the old system with a state-of-the-art Zero Liquid Discharge (ZLD) System.