Safety Analysis of Industrial Wastewater Pilot Plant for the Removal of Pollutants from Microelectronic Industry Effluents

Abstract

A technical safety analysis has been performed for the treatment of a real industrial wastewater plant. The process has been developed to remove organic and inorganic pollutants contained in the residual solutions from microelectronic industry, LFoundry srl (Avezzano, Italy). The treatment of three effluents (WW1, WW2 and WW3) has been studied at the laboratory and pilot scale. WW1 contained tetramethyl ammonium hydroxide (TMAH, on average 2 g/L), instead the WW2 and the WW3 contained nitrates, fluorides and acetic acid. TMAH effluent was aerobically treated by an activated sludge system, instead the second and the third wastewaters were chemically treated with lime in the presence of aluminum sulfates to precipitate the impurities. The experiments have been performed in batch and continuous mode and the results on lab scale have been used to design the equipment of the pilot plant. The plant has been realized in two 40 feet standard containers and can treat the three types of industrial effluents produced by LFoundry. The safety analysis has been performed by using hazards and operability method (HAZOP) in order to identify the main hazards of the wastewater treatment and to assess an upgrading of the existing plant at the full scale. The pilot plant is almost completely automatic, this minimizes operator input and hence the probability of human errors during the operations performed directly in the plant, that could have more harmful consequences. The analysis has been performed to point out the causes of failure, the consequences and the possible actions to identify and reduce the anomalies of the system. These activities have been performed within European Life Bitmaps Project (Grant Agreement N. LIFE 15 ENV/IT 000332).