A Study On The Accumulation Of Salts In The Printing And Dyeing Wastewater Recycling Process And Their Inhibition Characteristics On Microorganism

The printing and dyeing is a high water consumption industry,and the recycling of wastewater has become an important measure of energy-saving and emission-reduction.However,in the printing and dyeing wastewater recycling process,it will cause the accumulation of inorganic compounds in wastewater and impact on the stability of biological treatment system,even the system collapsed.Therefore,it is of great significance to study the accumulation of salts in the printing and dyeing wastewater recycling process and their inhibition characteristics on microorganism.A pilot scale experiment with the treatment of 5 m~3/d had been applied to cultivate activated sludge and study the accumulation.Through combination process of coagulation sedimentation,activated sludge and flotation,10 kinds of typical ions from the dyeing wastewater were studied,including potassium,sodium,calcium,magnesium,iron,manganese,antimony,chloride,sulfate and nitrate.The results showed that the experimental system has different removal effects on these 10 kinds of ions,but the removal rate was very limited.Besides,the concentration of sodium,calcium,antimony,chlorine and sulfate ions in the effluent of floatation tank had a obvious tendency of accumulation.In addition,a mathematical model was proposed for simulating ions accumulation of the WWTP effluent according to the mass balance.Through the comparative analysis,it showed that the concentration of ions mainly depends on its background value in the natural environment,the addition of the printing and dyeing process and the removal efficiency of the wastewater treatment system.At the same time,the influences of these ion changes on the anoxic/aerobic activated sludge in the system were investigated by this recycling experiment.With the increasing of ions in the system,the concentration of aerobic activated sludge and biodiversity gradually were reduced.Besides,the functional bacteria,such as organic-degrading bacteria(ODB),denitrifying bacteria(DNB)and decolorizing bacteria(DLB),were selected as the further research objects.It showed that the structure and diversity of ODB in anoxic/aerobic biological system were mainly influenced by sodium,potassium,calcium,antimony,chlorine and sulfate ions,especially Lactobacillus,Actinobacillus etc.inhibited obviously.Meanwhile,most of the ions in the system had influence on DNB,which made the species and abundance of the dominant species change constantly,and the activity of the denitrification bacteria based on Zoogloea were mainly inhibited by the sodium and manganese ions.Moreover,DLB mainly existed in the anoxic biological system and the decolorization ability was decreased with the concentration of sodium,potassium,calcium,iron,antimony,chlorine and sulfate ions increased.On the whole,the concentration characteristics of these ions took the lead in the biological community structure and diversity of aerobic activated sludge,and the inhibition of the bacteria groups lead to the reduction of biochemical removal efficiency of organic matter and chromaticity,but basically did not affect the removal effect of ammonia nitrogen by the system.