Nitrification–Denitrification of Opto-electronic Industrial Wastewater by Anoxic/Aerobic Process

Abstract

This research focused on the biological treatment of high-strength organic nitrogen wastewater, and presented the results from the nitrification and denitrification of an actual industrial wastewater using anoxic/aerobic process. The opto-electronic industrial wastewater often contains a significant quantity of organic nitrogen compounds and has a ratio over 95% in organic nitrogen (Org-N) to total nitrogen (T-N). In this study, a 2-stage anoxic/aerobic process was established and evaluated the efficiency of wastewater treatment. Raw wastewater from an actual TFT-LCD manufacturing plant was obtained as the sample for looking into the feasibility of opto-electronic industrial wastewater treatment. After toxicity identification evaluation (TIE) test of raw wastewater. the inhibition was related to organic nitrogen (TMAH, MEA) and unionized ammonia (free ammonia, NH3) with high pH. Therefore, pH control is important for biological treatment of high-strength organic nitrogen industrial wastewater. Besides. hydraulic retention time (HRT) and mixed liquor recycled rate (MLR) were controlled independently to distinguish between the effects of these two factors. Under suitable HRT ( > 1.7 d) and mixed liquor recycled rate (< 4Q), effluent of NH4-N. NO3-N + NO2-N, and COD can fall below 20 mg/L, 30 mg/L, and 80 mg/L. The anoxic/aerobic process removed 92-98% of the carbon source, and approximately 80% of TKN, 70% of T-N.

Biodegradation of monoethanolamine in aerobic and anoxic conditions

“…(6) and (7). The other difference of acetate and MEA in denitrification is that MEA leaves ammonium after denitrification.…”

“…The wastewater from the purged solution and the regeneration plant contains high concentration MEA that must be appropriately treated to meet the environmental discharge standard. Wastewater from TFT-LCD (thin film transistor liquid crystal display) and PDP (plasma display panel) manufacturing plants also contains as much as 1,000 mg/L of MEA [6]. The disposal of the MEA containing wastewater is a problem because MEA cannot be easily treated in wastewater treatment systems due its toxic effect and slow biodegradability [7].…”

Low-strength electronic wastewater treatment using immobilized cells of TMAH-degrading bacterium followed by activated carbon adsorption

“…[3]. Among these compounds, TMAH, which is utilized in the etching steps of the semiconductor and liquid crystal display manufacturing process, is poisonous and corrosive and also eutrophic to the water environment [4]. TMAH concentration in electric wastewater is relatively high compared to the other contaminants and its removal from wastewater has become a very important issue for the electronic industry [2].…”

Evaluation of potential for reuse of industrial wastewater using metal-immobilized catalysts and reverse osmosis

“…The AMOLED manufacturing industry is growing rapidly, because AMOLED has a simpler structure and better image quality than LCD. However, the fast development of the electronics industry has accelerated its water use, causing such problems as a lack of water and a increasing amount of pollutant discharged into river into rivers (Chen et al, 2003;Chen and Chen, 2004). To address these problems, over 40% of wastewater that is discharged from AMOLED manufacturing is reused (reclamation) as raw water for the production of ultrapure water (UPW).…”