| The pickling waste liquid generated during the processing of steel and metal products is defined as hazardous waste(HW17)in the National Hazardous Waste List(2021 edition)due to its corrosiveness and toxicity.If discharged without reasonable treatment and disposal,it poses great harm to the environment and human health.At present,most small and medium-sized enterprises that produce acid pickling wastewater do not establish specialized treatment facilities due to their small production scale.They are regularly transported by hazardous waste disposal units to designated locations for safe landfill.Although this disposal method meets the national requirements for the management of pickling waste liquid,it has shortcomings such as occupying a large amount of environmental resources,high disposal costs,and environmental risks of leakage during transportation.This study attempts to propose a new treatment system for pickling wastewater.The new system combines treatment devices with mobile platforms,utilizing the movable characteristics of vehicle mounted platforms,to treat pickling wastewater on site in various small and medium-sized enterprises.The treated wastewater meets the discharge standards,and the precipitated sludge is treated as hazardous waste,thereby significantly reducing the volume of hazardous waste and achieving reduction requirements.The core of the new system is to design a mobile pickling wastewater treatment device.In order to complete the design of a mobile pickling wastewater treatment device,this study takes a certain metal processing plant pickling wastewater as the experimental object.Through experiments such as alkaline agent selection,optimal reaction conditions determination,coagulant selection,and simulation of the treatment effect of inclined plate sedimentation tank,various design parameters of the mobile device were determined.Based on the experimental results,the optimal alkaline reagent for p H adjustment process selection is Na OH,with a dosage of 116.8g/L,a minimum adjusted p H of 9.0,a minimum hydraulic retention time of 7 minutes,and a stirring rate of 450r/min;The optimal coagulant for coagulation process selection is PAC,with a dosage of 2.5mg/L,a minimum hydraulic retention time of 8min,and a stirring rate of 150r/min;Through the comparison test of sedimentation tanks,it was confirmed that the minimum hydraulic retention time required for inclined plate sedimentation tanks is lower than that of ordinary sedimentation tanks,which is14 minutes.Therefore,inclined plate sedimentation tanks were selected as the sedimentation process tank type,with a sludge volume of 50m L/L and a sludge moisture content of 45.3%;The optimal acid agent for p H secondary adjustment process selection is dilute hydrochloric acid(20%),with a dosage of 15m L/L and a minimum hydraulic retention time of 3min.Based on the above experimental data and combined with existing vehicle models in the market,the onboard platform and external spatial parameters of the mobile device were determined.Based on this,a preliminary design of a mobile pickling wastewater treatment device has been completed and an economic benefit analysis has been conducted.The innovation of this study lies in proposing a new system for treating pickling wastewater,which applies mobile devices for the first time in pickling wastewater treatment.The design of a mobile pickling wastewater treatment device has been completed through various design parameters determined through experiments.The new system can effectively reduce the number of small and medium-sized enterprises’ acid washing wastewater as hazardous waste landfill disposal,solve the shortcomings of the existing acid washing wastewater treatment system for small and medium-sized enterprises,and have great application value. |
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