| Environmental pollution caused by new pollutants(microplastic)is one of the major environmental problems currently facing today,and a large number of emissions are also involved in industrial point sources.From the perspective of engineering control technology,this study focuses on microplastic pollution in industrial wastewater.Based on the investigation and evaluation of industrial pollution control technologies and demonstration projects in Taihu Lake Basin,the distribution characteristics of microplastics in key industries in Taihu Lake Basin and the interception effect of typical industrial point source pollution treatment technologies on microplastics were discussed,which provides theoretical basis and technical support for the subsequent in-depth treatment of water environmental pollution and the control of new pollutants mainly microplastic.The main research conclusions are as follows:(1)Assessment results of industrial pollution control technology in Taihu Lake Basin show that:(1)Typical pollution treatment technologies for printing and dyeing wastewater have removal rates of 80.0%～98.0%,84.0～98.0% and 89.0%～95.0% for total nitrogen,total phosphorus and COD respectively.Printing and dyeing wastewater can achieve better treatment effect and meet the reuse standard,after treatment of antimony toxic pollutants in the wastewater also reach the relevant national standards.After advanced treatment,the effluent biological toxicity of complex and refractory toxic chemical wastewater decreased from grade Ⅰ to grade Ⅳ;The utilization of ammonia in high concentration ammonia-nitrogen wastewater is realized while the recovery rate of aniline compounds in high concentration aniline wastewater is more than 90.0%;The separation rate of oil and water of complex emulsion was increased to85.0%,and the volume of residual floc was compressed from 45.0%～90.0% to 12.0%.And the electroplating wastewater treatment technology realizes the resource recovery of copper and nickel ions on the basis of ensuring the water quality to meet the standard discharge technology.In terms of mixed wastewater treatment technology,"MBR denitrification and phosphorus removal technology with enhanced endogenous denitrification" solves the contradiction of nitrogen and phosphorus removal to carbon source demand;The water quality of the effluent from sewage treatment plant after advanced treatment by oxidation pond or wetland is obviously better than grade A standard.(2)From the overall technical field investigation and evaluation results: since the implementation of the water project,the various technologies developed have the characteristics of low engineering equipment requirements,easy to expand the scale of treatment compared with the traditional process,and have produced significant economic and environmental benefits,but there are some problems when the technology demonstration into the project.As for the demonstration of industrial wastewater treatment,the printing and dyeing park did not timely report and adjust the process when the inlet water quality changed greatly,causing high cost and waste of resources.In addition,due to the cancellation of the company or lack of late maintenance,resulting in the shutdown or intermittent operation of the project.(2)The concentration of microplastics in the wastewater of key industries in Taihu Lake Basin(printing and dyeing,chemical industry,electroplating industry and sewage treatment plant)is significantly higher than that of natural water bodies,and the concentration of microplastics in the wastewater of Taihu Lake Basin is significantly higher than that of water bodies of other industries due to the mechanical action of textile fragmentation and shedding.Most of the microplastics in printing and dyeing wastewater are transparent strips and most of the components are PET.In the wastewater,the largest particle size is about 1.0 mm,and the microplastics above 3.5mm are relatively small,averaging below 8.0%.The composition of microplastics in chemical wastewater is complex(most of them are strip).The particle size of microplastics in wastewater from different chemical plants has no obvious characteristics.Most of the microplastics in electroplating wastewater are PP,and the particle size is mainly distributed in the range of 0.2-1.5 mm,and strip microplastics account for the largest proportion.The microplastics in the mixed wastewater are mostly PP and PET with particle size less than 1.0 mm.Strips also account for the highest proportion.(3)Industrial pollution control technologies of key industries in Taihu Lake Basin have significant removal or interception effect on microplastics(removal rate is 61.4%～ 98.4%).In the aspect of dyeing wastewater treatment,"magnetic microsphere resin adsorption advanced treatment technology" has a better removal effect on colored microplastics;The membrane combination process in "New composite hydrolytic acidification technology" can remove 98.4% of microplastics,and is more suitable for the removal of microplastics with small particle size compared with coagulation and precipitation;The "characteristic pollutant antimony grading control technology" has a good removal effect on microplastics with particle size of 1.5～2.0 mm.In the treatment of chemical wastewater,"magnetic nanoparticle coupled membrane separation technology for efficient demulsification of complex emulsion" has a better effect on PP removal."Novel and efficient catalytic conversion technology of complex and difficult to degrade toxic chemical wastewater" can remove 95.4% of microplastics,and can degrade microplastics at the same time."Two-phase anaerobic + two-stage aerobic low energy consumption treatment technology" because the two-stage aerobic stage adopts two sludge reflux,the removal rate of microplastics is not high,which accounts for88.2%.The PS content of electroplating wastewater is higher than that of electroplating wastewater due to the removal of microplastics by ion exchange resin and chelating resin;"Two-stage cation exchange resin + first-stage chelating resin adsorption technology" has no removal effect on microplastics;The proportion of microplastics in electroplating wastewater has no obvious change.In mixed wastewater treatment,most of microplastics can be removed after primary and secondary treatment."MBR denitrification and dephosphorization technology with enhanced endogenous denitrification has a good removal rate of microplastics with a particle size of 0.3～0.5mm,which can be used to remove microplastics with small particle size."Tailwater wetland purification Technology" has no obvious removal effect on 0.0-0.3 mm microplastics,but has better removal effect on flake and granular microplastics. |
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