| The"14th Five-Year"period is at the key point of continuous improvement of China’s ecological environment,and China’s economy has begun to shift from high-speed development to high-quality development and green development.In this context,more attention has been paid to the centralized collection and treatment of industrial wastewater and resource recycling,and industrial park wastewater plants have become the core proposition to meet the discharge standards and improve quality and efficiency.The industrial wastewater treatment plant represented by the wool industrial park has problems such as low operating load and poor stability due to large fluctuations in influent water and complex water quality conditions.This study takes the wool industrial park wastewater in Shandong Province as the research object and aims to build a new wool park wastewater treatment technology integration by combining Integrated fixed-film activated sludge(IFAS)and electrocoagulation process.The research aims to solve the problem of meeting water quality standards of the park wastewater plant under complex water quality conditions and how to increase the quality and efficiency of the treatment of difficult degradable substances.The main findings are as follows:Validation of the biological treatment efficiency of IFAS systems under complex salinity conditions by operating with different salinity gradients and periodic salinity fluctuations.The results showed that the ammonia and COD removal rates decreased by 5%and 16%respectively under the influent limit of 1.6%salinity.Only 19%of COD was removed at 3%salinity.In addition,the IFAS process would adapt faster in the periodic 1.6%salinity fluctuation experiment,the maximum decrease of COD removal rate was reduced from 21%to 11%and the number of days affected was reduced in the second fluctuation,and nitrogen removal had almost no effect.The A/O-IFAS biological nitrogen removal system was constructed for stable nitrogen removal from wool park wastewater.At 791.4±294 g COD/(m~3·d)organic volumetric load,more than 97%ammonia nitrogen removal and more than 72%COD removal can be achieved.Optimized HRT is shortened from 72h at WWTP to 30h.The analysis of the system removal contribution showed that there is a complementary relationship between the anoxic reactor,aerobic reactor 1 and aerobic reactor 2 for pollutant removal.High-throughput sequencing analysis of biofilm and suspended sludge of the A/O-IFAS system revealed Proteobacteria and Chloroflexi as the dominant phylum on suspended sludge and biofilm.The highest abundance of Nitrospira phylum in aerobic pool 1.The study established an electrocoagulation tertiary treatment system to explore the influencing factors and perform response surface optimization.The experiments were optimized at the initial p H of 6.6,the current density of 35.6 m A/cm~2,and the reaction time of 40.5 min.The COD and TN removal rate were 57.8%and 19.4%under these conditions,and the actual experimental verification results were close to the predicted value,with the COD of 189 mg/L,which was far below the COD limit of500 mg/L.The pilot experiments of electrocoagulation demonstrated the efficient treatment capacity in the pilot scale.And the COD was reduced to 209 mg/L below 500 mg/L,the COD limit in the water plant effluent.The COD removal rates of 60.91%,47.23%,55.74%and 51.29%within 3 hours were achieved by electrocoagulation compared with conventional Fenton,electro-Fenton and electrocatalytic oxidation processes in tertiary treatment,respectively.It indicates that the electrocoagulation process has a high suitability for the tertiary treatment of wastewater from wool industrial parks. |
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