Experimental Study On Pretreatment Of Copper And Nickel Wastewater With High Concentration By Loading Flocculation Process

The rapid development of electroplating industry in China has brought about a sharp increase in emissions of heavy metals and electroplating sludge,at the same time,the emission standards of heavy metal pollutants are also increasingly stringent.In this environment,it is very important to adopt new strengthening technology as loading flocculation process and obtain in-depth knowledge of the properties of electroplating sludge.The test raw water of this project is a high concentration of copper and nickel wastewater,which is based on the comprehensive wastewater from an electroplating factory in Shenzhen.After determining the best flocculation pH of simulated wastewater is 10,treating simulated wastewater by traditional flocculation process and substrate sludge loading flocculation process respectively,tthe best process parameters of the two processes are determined through the effluent concentration of copper and nickel ions,the speed of sludge settlement,the difficulty degree of dewatering of sludge and the cost for control,thereinto,,traditional flocculation,PAC=30mg/L,APAM=6mg/L;substrate sludge loading flocculation,PAC=20mg/L,APAM=4mg/L and substrate sludge dosage =100mL/L.The comparison and analysis of the two processes showed that the loading flocculating process of substrate sludge has obvious advantages in enhancing the treatment effect,saving the dosage of the medicament,increasing the sedimentation rate of sludge and shortening the dewatering time of the sludge.It is also observed in the experiment that the influence of PAC dosage on the CST value of sludge under these two processes is greater than that of APAM.In the single factor test of pre treatment of high concentration simulated copper and nickel wastewater with loading flocculation process under different kinds of loading agents,the size and dosage of the loading agent are changed.In the experiment,the performance index curves of quartz sand,zeolite powder,magnetic powder and iron powder have different changing rules,which are closely related to the characteristics of the particle shape,internal structure,surface adsorption and density of the medium itself.From the treatment effect,dewatering and settling properties of the obtained sludge and the cost saving,the optimum technological parameters for each loading process to treat the test water are respectively: quartz sand,200-300 mesh,4g/L;zeolite powder,200-300 mesh,4g/L;magnetic powder,300-400 mesh,1g/L;iron powder,300-400 mesh,4g/L.Taking traditional flocculation as the baseline,different kinds of loading flocculating processes were compared under their respective best technological parameters.In terms of treatment effect,the addition of different kinds of loading agents increased the removal efficiency of copper and nickel ions in different degrees,the effect of magnetic powder and substrate sludge was best,and the removal rate was increased by 45.72% and 40%,respectively;in terms of improving dewatering performance of sludge,the sludge dewatering time is shortened only by substrate sludge,the CST value of the sludge is 38.4s,which shortens 7.9s than the traditional process.all other loading agents increase the difficulty of sludge dewatering;in terms of improving this three indicators of sludge settling capacity,volume and moisture content,the iron powder,zeolite powder and quartz sand had the best effect;in terms of the change of the floc growthand the distribution of floc size before settlement,the quartz sand,zeolite powder and substrate sludge have the most significant effect on the growth of floc particles in loading flocculation.In the loading flocculation without special demand,the substrate sludge is recommended as the loading agent.Compared with the traditional flocculation,it can reduce the effluent concentration and improve various indexes of sludge;compared with the other loading agents,no additional loading materials are needed,and the separation of the loading agent and sludge is not needed in the later period,and the cost of equipment and management costs is greatly saved.