Study On The Improvement Of Running Performance For LED Wastewater Treatment Process

The GaAs and GaAsP LED products have been widely used in lighting areas, suchas landscape、display and backlight. The LED industry is one of the emerging industriesof strategic importance in China. As the capacity of LED-related industries has beenconcentrated rapidly in China, the poisonous gas and wastewater discharged duringmanufacturing, and the problem of toxic sludge disposal have been taken more andmore seriously in recent years.The wastewater from LED industry is a kind of special arsenic wastewater, treatedby chemical precipitation method with Ca-Fe coagulants. Without engineeringexperiences for reference, the LED wastewater treatment projects are running with thepopular operation mode and parameters from traditional industrial wastewatertreatment.Based on the wastewater treatment project in Shandong Inspur HuaguangOptoelectronics Co. LTD, the efficiency of traditional chemical precipitation method forarsenic removal from LED wastewater was studied. A highly efficient runningtechnology was proposed especially for LED wastewater. The major results of the studywere as follows:(1) As for wastewater with high arsenic and phosphorus concentrations, the currentdosing pattern was very likely to add coagulants into water with low concentration andhigh solid content, leading to a large waste of coagulants. The amount of sludgeconsisted more than80%of the total amount in the whole system. Therefore, theimprovement of treatment performance was of great importance in sludge reduction.(2) A new concept of specific removal mass was proposed to measure theperformance of arsenic removal from wastewater with high arsenic and phosphorusconcentrations, and the influencial factors were discussed. Two new dosing patterns,using algebraic fitting method and designated dosage calculation method respectively,were presented, which could reduce20%of the dosage and sludge amount.(3) As for wastewater with low arsenic concentration, low water qualification ratewas the main reason for bad performance, leading to low effluent emission ratio. Thewater recirculation rate was very high, about80%~90%, which caused high agentdosage and sludge amount. (4) According to different effluent standards, two ways were put forward toimprove the running efficiency of low-concentration wastewater treatment. If thestandard remained at0.5mg/L, it was suggested to change the operation mode toincrease effluent amount with the same coagulants. If the effluent concentration wasconfined to0.1mg/L, the current coagulants should be replaced with a new type ofarsenic removal agent-the403agent, which was more efficient and stable in arsenicremoval.(5) The calculation of treatment cost showed that the improved operation programcost24%less than the current running mode for the whole system. The improvementscheme was proved to be efficient and economical.