| N-Nitrosodimethylamine（N-Nitrosodimethylamine,referred to as NDMA）is a kind of nitrosamine compound with extremely strong carcinogenic ability.This article mainly studies the use of PAC/PDMDAAC composite coagulant to enhance the coagulation coupling filtration process for the removal efficiency of NDMA in the autumn Yangtze River water（Nanjing section）.First,while broadening the detection range of the existing NDMA measurement method in the laboratory,the stability of the filter device was studied;then,at the intersection of the turbidity additions such as serialized composite medicament and inorganic medicament determined by the experiment,strengthened The coagulation conditions of the coagulation coupling filtration process are used to study the removal efficiency of various water quality parameters,especially NDMA;finally,the selected dosage points of 1 composite agent and 1 inorganic agent are used to strengthen the coagulation coupling.Preliminary study of the filtration conditions of the filtration process on various water quality parameters,especially the removal efficiency of NDMA.The main research contents are as follows:（1）Preparation of key experimental conditions.On the one hand,in order to expand the measurement range of NDMA at lower concentrations in water samples,based on the20-100 ng/L trace-level NDMA detection method established by the research group,by adjusting the concentration factor and based on the original solid phase extraction conditions In addition,the linear relationship between the concentration of NDMA standard solutions in the range of 5-25 ng/L and 100-500 ng/L and the HPLC peak area was determined,and the precision and the recovery rate of standard addition were completed at the same time.The results showed that the linear correlation of the HPLC determination standard curve of low,medium and high NDMA content were all higher than0.9993;the relative standard deviations were all lower than 1.98%;the recovery rate of standard addition was 96.00%-100.67%.On the other hand,in order to improve the stability of the filtration process operation,the quality of the filler and the time used to filter 1 L of tap water were used as indicators to adjust the column heights of the same filler quartz sand,the quartz sand gradation and the activated carbon grade under the same column height.The combined filtration rate stability lays a foundation for the subsequent research on the removal efficiency of the water quality parameters of the packing column conditions of the filtration process.（2）Preliminary study on the efficiency of the enhanced coagulation coupling filtration process at the equal turbidity equal addition point.In order to study the removal efficiency of the PAC/PDM enhanced coagulation coupling filtration process under the sedimentation water turbidity（1.0-1.5 NTU）on the water quality parameters,by using PAC and 9 kinds of compound coagulants,the turbidity of the raw water is 25.0-50.0 NTU.Yangtze River water,within the range of 1.0-1.5 NTU for the residual turbidity control of the sedimentation water,the dosing points of PAC and the sedimentation water of each compound agent,such as turbidity,etc.,focus on the enhanced coagulation to the sedimentation water and the coupled filtration to the filtered water including NDMA The removal efficiency of the water quality parameters included.The results showed that the total removal rate of the composite agent was 0.00-1.06%,0.00-25.71%,0.00-16.94%higher than the inorganic agent in the CODMn,ammonia nitrogen,NDMA enhanced coagulation stage and the coupled filtration stage,respectively.The removal rate of turbidity,CODMn,ammonia nitrogen and NDMA of the composite coagulant PAC/PDM（1.60,10:1）in the enhanced coagulation process are:96.97%,40.00%,20.00%and47.89%respectively;the above research results Laid the foundation for the follow-up research on filtering conditions.（3）Preliminary exploration of filtration conditions in the enhanced coagulation coupling filtration process.In the study,a PAC/PDM（1.60,10:1）composite coagulant and PAC inorganic agent were selected as the drugs for the filtration process research.Preliminarily explored the removal of various water quality parameters,especially NDMA,in the treatment of micro-polluted raw water by filtering conditions of three quartz sand column heights with the same particle size gradation,three quartz sand gradations with the same column height,and three activated carbon gradations.The results show that for raw water containing 190.14 ng/LNDMA at a height of 32 cm quartz sand column,the highest NDMA removal rate reached 88.96%and 96.50%after the precipitation water with equal turbidity and other dosage points was used through the coupled filtration process.,The NDMA content of the filtered water was reduced to approximately 21.00 ng/L and 6.65ng/L,respectively.At the same time,it is found in the study of filtration process conditions that the adjustment of the quartz sand gradation and the use of activated carbon filter media help to improve the efficiency of filtering and removing water quality parameters. |
