Research Of High-salt And High-organic Wastewater Treatment Using Freezing-based Process

With the increase of population and economic development,global industrialization is accelerating.A considerable amount of high-salt and high-organic waste water will be produced in the industrial production process.This type of waste water has a complex composition,with a salt content of more than 1% and high organic matter.The composite process based on the freezing process is used to treat this kind of wastewater,and the pollutants are separated by physical methods,no chemical agents are added.The required equipment is simple and easy to operate.When a natural cold source or a suitable artificial cold source is available,it has practical and theoretical value and is worthy of further exploration and research.This paper studies the removal effect of high-salt and high-organic simulated wastewater from four parts: The first part of the work is the freezing and centrifugal method(FCM).Firstly,the removal effect of high-organic simulated wastewater,high-salt simulated wastewater and high-salt high-organic simulated wastewater is compared based on the centrifugation time.Then in the high-salt and high-organic simulated wastewater,the influence of the centrifuge speed on the removal effect was studied.The second part of the work is the freezing,gravity-induced and centrifugal method(FGCM).Using ambient air as a natural heat source,the effects of gravity melting rate and ambient temperature on the removal effect was studied.And compared the difference between the removal effect of FGCM experiment and experiment time under the environmental temperature of different seasons.The third part of the work is the freezing,microwaving and centrifugal method(FMCM).The effect of microwave time on the removal effect was studied,compared experimental effect of FGCM under the same melting rate.The microwave heating and gravity melting were combined to construct a freezing,microwaving,gravity-induced and centrifugal method(FMGCM),and the experimental effects of the three methods were compared.The fourth part of the work compares the freezing composite method with the multi-stage freezing method.Then,according to the "Integrated Wastewater Discharge Standard"(GB8978-1996),the purification requirements that can be achieved by different freezing composite methods are analyzed.The main conclusions of this article are as following:1)For FCM.With the increase of centrifugal time and centrifuge speed,the removal effect increases.However,after the centrifugal time exceeds 2 min and the centrifuge speed exceeds 2000 r/min,continue to increase the centrifugal time and centrifuge speed,which will not significantly improve the removal effect.Compared with the treatment of high-organic wastewater and high-salt wastewater,the freezing and centrifugal method can simultaneously remove organic matter and salt in the high-salt and high-organic wastewater,which saves time and has a small loss of the removal rate.2)For FGCM.With the extension of the gravity time,the gravity melting rate increases,and the removal effect also increases.FGCM has a significant impact on the removal of organic matter and salt,at the same time,the higher the ambient temperature,the faster the processing rate,and the lower the ambient temperature,the better the removal effect.In actual engineering,if the gravity melting process takes place in the ambient temperature of the natural heat source,the pollutant removal rate in winter is slightly higher,the processing time in summer will be greatly shortened.3)For FMCM and FMGCM.With the extension of the microwave time,the removal effect increases.The use of microwave heating technology can effectively remove organic matter and salt in wastewater.At the same wastewater purification rate,the FMCM treatment experiment takes the shortest time,but the removal effect is not as good as FGCM.The removal effect of FMGCM is similar to that of FGCM,and experiment time is between FGCM and FMCM.In actual engineering,different composite processing methods can be reasonably selected on the basis to the processing requirements of different situations.4)Comparing the experimental research of multi-stage freezing process.FCM treatment can only reach the salt removal rate of level 2 freezing.FGCM can reach the removal effect of level 4 freezing at most.FMCM and FMGCM can reach the removal effect of level 3 and 4 freezing at most respectively.The freezing composite method is under a higher wastewater purification rate.Moreover,the concentration of organic matter in the purified water after treatment is similar to the salinity,but the salt concentration of the purified water after treatment by the multi-stage freezing method is greater than the concentration of organic matter.5)Compare relevant sewage discharge standards.FCM is difficult to meet the wastewater discharge standards of relevant industrial enterprises,but it can meet the salinity requirements of biochemical treatment.FGCM can almost meet the standard limit for wastewater discharge of all industrial enterprises within the applicable scope.FMCM can only meet the level 3 standards for the discharge of industrial wastewater such as sugar and pharmaceuticals,salinity reaches grade C.While FMGCM can meet the level 2 standard for the discharge of industrial wastewater such as alcohol and pharmaceuticals,salinity reaches grade A.