| With the continuous development of industrial technology in China,electroplating technology has entered a period of rapid development,which is widely used in aerospace and other advanced machining fields.The electroplating wastewater always contains lots of heavy metal ions such as chromium,nickel and cyanide,which are all carcinogenic,teratogenic and mutagenic.Hence,electroplating has become one of the three high pollution industries in the world.This study takes the project transformation of an electroplating wastewater treatment system of a company in Xi’an as an example to make a systematic study on the quality and efficiency of its treatment system.The company’s original wastewater treatment system was built and put into use in 2008.As the national environmental protection requirements have become more stringent,problems have gradually shown that the deficient original construction standards,the waste of energy consumption by designed volume of water,some defective facilities,lack of efficient deep treatment system,and lack of intelligent automatic control,etc.The unstable efficiency of wastewater treatment has presented.Therefore,the wastewater treatment system quality improvement and efficiency improvement project was initiated.By effectively using the original equipment and facilities,the design and rational layout were optimized,and the transformation design for wastewater reaction facilities,advanced treatment processes,automatic control systems was proposed.After a comprehensive analysis of the operation and economy of the transformed wastewater treatment system,it provides important theoretical and practical support for the improvement of the electroplating wastewater treatment system in my country’s manufacturing enterprises.In view of the problem of the original system construction standards not meeting the long-term development,waste of energy consumption,and inadequate water reaction.The ferrous sulfate removing cyanide was replaced by alkaline chlorination,through improving the design standards and upgrading the treatment process.It improves the removal efficiency of cyanide in the system through two-stage cyanide breaking,and synchronously reform other waste water reaction tanks,discard the original underground waste water reaction tanks,and build new waste water reaction tanks of various roads on the ground.For the problem of lack of advanced treatment system,the addition of an advanced treatment system centered on the "ultrafiltration/ reverse osmosis" multiple physical and chemical combined treatment unit was constructed to ensure the purification water quality.To solve the problem of low level of system automation control and achieve continuous water intake,continuous treatment,continuous water output,automatic control operation,online monitoring,the entire water treatment process is monitored,managed,and operated by PLC automatic control system.After the upgrade and renovation,the treatment system was continuously monitored for 90 days.The results showed that the water outlet test items are in line with the highest standards of Electroplating Pollutant Discharge Standards GB21900-2008 Table 3 for environmentally-weak areas where the resources was over-explored.Total chromium,total nickel,total cyanide,suspended matter,pH value and other detection indicators have been fully met.And the expected quality and efficiency targets have been achieved.The monitoring results fully proved that the multiple physical and chemical combination process of "chemical treatment and ultrafiltration and reverse osmosis membrane separation technology" has a good removal efficiency on mixed electroplating wastewater.After upgrading and reconstruction of this project,the operation cost of treating 1m3 electroplating wastewater is 56.31 yuan,which is about 14 yuan less than before.The implementation of this project not only saves economic costs and management costs,but also achieves the discharge of wastewater up to standard,which is worth promoting. |
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