Wastewater prevention measures
The factory area adopts the system of clean water and sewage separation and the rain and sewage separation. Wastewater includes production/engineering auxiliary wastewater and domestic sewage. Industrial wastewater and engineering auxiliary wastewater are divided into nitrogen-containing wastewater, comprehensive wastewater, and water discharged by cooling equipment. Nitrogen-containing wastewater is reused after being treated in the factory; comprehensive wastewater (nitrogen-free wastewater, acid-alkali wastewater, and grinding wastewater) is mixed with domestic sewage after comprehensive treatment, and then transported to the regional wastewater treatment plant. It reaches the Level-A standard under the “Discharge standard of pollution for municipal wastewater treatment plant” (GB18918-2002) and grade-I standard under the “Discharge Limits of Main Water Pollutants for Urban Sewage Treatment Plants in Taihu Lake Area” (DB32/1072-2007) and is then discharged into Ergan River;
Exhaust gas prevention measures
1. Epitaxial wafer plant
The waste gas discharged by epitaxial wafer plant is chiefly epitaxial furnace exhaust. The main components of epitaxial furnace exhaust are ammonia and a small quantity of dust. Exhaust gas from each epitaxial furnace is first filtered by the embedded dust removal filter in the furnace, and then passes through the pipeline to the ammonia recovery and treatment equipment for treatment. The treated exhaust gas is discharged through exhaust funnels. The hydrogen chloride and a small quantity of unreacted chlorine gas generated in the baking process are collected in the pipeline and transported to the lye spraying tower for treatment, and then discharged through the exhaust funnels. Dust, methane, and unreacted arsine and phosphorane generated by the production of epitaxial wafers are filtered by the embedded dust removal filter in the furnace, and then passes through the pipeline to the sodium hypochlorite solution absorption and treatment facility for treatment before discharge through the exhaust funnels.
2. Chip factory
The exhaust gas generated by the chip plant is chiefly acid pickling exhaust gas (sulfuric acid mist) produced by the epitaxial wafer acid pickling process, unreacted silane and laughing gas (nitrogen oxide) during SiO2 passivation and deposition, unreacted chlorine gas during ICP etching, fluoride produced during SiO2 etching, hydrogen fluoride produced during passivation and BOE etching, and hydrogen chloride produced during ITO etching. These are collected and sent to the alkali spraying system for absorption, and then discharged through exhaust funnels. The non-methane hydrocarbon generated by photoetching, and acetone, ethanol, isopropanol, and non-methane hydrocarbon produced by stripping of photoresist and dewaxing are collected and transported to the RTO device for treatment, and then discharged through the exhaust funnels.
3. Canteen
The cooking fume is processed by smoke exhaust ventilator and discharged through the exhaust funnels.
Noise prevention measures
The company’s production equipment is precision equipment with low noise values, and is located in enclosed workshops. The main sources of noise are cooling towers, air compressors, fans, water pumps, gas purifiers, etc. used for engineering auxiliary projects, with a source intensity of 77-85dB(A). In order to minimize the impact of noise on the surroundings, high-efficiency, low-noise equipment is selected. Equipment causing loud noise is located indoors or used at different times. The factory area has a reasonable floor layout. Measures such as noise isolation, vibration reduction, sound absorption, and greening are taken to control factory boundary noise.
The company performs annual tests on wastewater, waste gas and noise every year, and the test results meet national standards. At the end of November 2018, Jiangsu Yanlan Detection Technology Co., Ltd. was commissioned to test the wastewater, waste gas and noise discharged by the company. Detection values stated on the test report No. (2018) HJ (Z) Z (W0952-01) meet the standards.
