由於半導體產業之產品的多樣化，以及製程的的改變，造成原物料使用上，也產生許多變化。其中半導體之發光二極體(簡稱LED)製造，因產品製程的需求，而大量使用之原料氣體－NH3，造成廢氣具有高濃度的特性。其廢氣中NH3排放濃度達數萬ppm，甚至高達十幾萬ppm，以往酸鹼共排之處理防制設備及操作方式已無法有效去除污染物。因此，本研究對象以某製造發光二極體之實廠，所排放含氨廢氣處理防制設備之處理效率作為探討。目前處理設備是以雙塔串聯之填充式濕式洗滌塔來處理含氨廢氣。經本次實驗後，不僅排放濃度可低於法規排放標準之35 mg/m3，更可每月節省17.1%的處理成本，其最佳之處理操作參數如下：控制洗滌液之pH6.0~6.5，可有效去除污染物並降低硫酸藥劑的使用；提高洗滌液之溢流率，降低洗滌液電導度，並維持於40~50 mS/cm；增加其液氣比以有效提高去除效率。 雖然以雙塔串聯之填充式濕式洗滌塔去除含氨廢氣效果頗佳，但其廢氣中含氨濃度極高，如能有效回收處理再利用，不僅可降低空污防制設備的運作成本，也可減少因濕式洗滌塔所產生之廢水，而流入至廢水處理設施所造成廢水處理的負擔；更可經由回收處理再利用，增加額外的收益，此乃值得持續研究之方向。Due to the rapid change and diversification of products, semiconductor industry has to adopt different processes and material to meet the needs of new products in a faster path nowadays. Ammonia (NH3) gas has been widely used by this industry, especially for manufacturing Light-Emitting Diode (hereafter, LED). High emission of waste gas containing ammonia from this manufacturing process may occur if the ammonia is not properly treated. Traditional way of processing the NH3 waste gas that contains tens or even hundreds thousands ppm is now considered of low efficiency and cannot effectively remove the pollutant from gas streams. Therefore, this study focuses on the emission characteristics and ammonia removal efficiency of an anonymous LED factory located in Taiwan. The factory applies a series of packed wet scrubbers for processing ammonia-containing gas streams. The stack sampling results indicate that the ammonia emission can be kept below the regulation’s standard of 35 mg/m3 and 17.1% reduction of processing cost can be achieved. The above-mentioned experimental results can be reached by controlling the operating parameters as following. Firstly, the pH values of the scrubbing should be controlled at 6.0~6.5 for effective removal of ammonia and decreasing the consumption of sulfuric acid. Secondly, controlling the overflow rate of scrubbing liquid to maintain the conductivity at 40~50 mS/cm proves to provide high efficiency in removing ammonia from gas streams. Nevertheless, if the gas stream containing high-concentration ammonia that was treated with the series of packed wet scrubber can be processed to recover ammonia would be even better from the perspectives of resources utilization and reduction of the costs related to the treatment of the wastewater generated from the scrubbing process. This concept should be further investigated in the future for the benefits of semiconductor industry and the environment.
