Research On Improvement Of Mercury-containing Sewage Treatment Process

Mercury and its compounds are highly toxic and corrosive.In view of mercury can be transported for long-distance in the atmosphere.It can also be persistent in the human environment.At the same time,mercury can accumulate in a variety of biological ecosystems,have a significant adverse impact on human health and the environment.The treatment of mercury-containing wastewater has become an important issue in global environmental protection.Many of high mercury-containing gas fields in China will produce large amounts of mercury-containing wastewater.Improper handling can cause significant damage to the environment and human health.But the domestic mercury gas field sewage treatment technology research in the initial stage,there is no mature process applications.This paper based on the analysis of mercury-containing wastewater treatment technology at home and abroad.Test of the treatment in KL2 mercury-containing wastewater and experimental study on treatment of mercury containing wastewater in KS gas field.We have proposed an improved process for KS mercury-containing wastewater treatment.It is helpful to control mercury emission from mercury-containing gas field wastewater.This paper investigates the relevant content at home and abroad.The current situation and research progress of mercury-containing wastewater treatment were studied.The principle and characteristics of the treatment process such as sulfide precipitation method,flocculation sedimentation method,chelate precipitation method,adsorption method,ion-exchange resin method and membrane separation were analyzed and evaluated.Sulfide precipitation cannot control excess sulfide degree.Flocculation sedimentation method is affected by water quality.It is difficulty to dispose sludge,there is no appropriate method to treat it.In the treatment of wastewater containing high salinity and high organic matter,the adsorption method is easy to scale and block,which leads to the decrease of service life and the increase of cost.Ion exchange resin is not suitable for the dissolution of solid waste water,organic matter can also cause ion exchange resin pollution.Membrane separation method is not only suitable for the primary treatment of mercury containing wastewater in the gas field,but also has strict requirements on the influent water quality.In engineering application,several methods of mercury removal are often combined according to the actual situation.In addition,the technology of removing oil and suspended solids is combined with the technology of removing mercury from wastewater Have a greater advantage.The chelating precipitation method has the advantages of simple process,good treatment effect,low treatment cost and stable sediment fonnation with mercury.It has a great advantage in heavy metal wastewater treatment.Based on the field experiment of 5m3/h mercury containing wastewater treatment equipment designed by KL2 gas field,the field test and application effect of mercury containing wastewater treatment equipment are analyzed and evaluated.Analyze and detect the water quality of each equipment import and export.The actual operation data of the KL2 mercury containing wastewater treatment test device is mastered.Field test results show that flocculation sedimentation method be used as a pretreatment for high mercury containing wastewater,which can effectively remove most of mercury in raw water.However,mercury content in the wastewater without adsorption was still higher.In the experiment of mercury containing wastewater treatment in KL2 gas field,the experimental device is combined with the technology of removing suspended matter and the technology of removing mercury from wastewater,forming a comprehensive treatment process.The combination of flocculation sedimentation and adsorption can effectively reduce the operation cost of mercury containing wastewater treatment,and the operation is simple.However,the KL2 experiment can not be adapted to the treatment of mercury containing wastewater under special conditions.Reseach mercury-containing wastewater treatment additives scheme in KS gas field.The experiment is designed for the additives scheme in the KS gas field.Combined use of polymeric aluminum salt(SM-2),20 million molecular weight anionic polyacrylamide(PM-2)and ZJS-1 heavy metal ion trapping agent can obviously improve the removal effect of mercury and the removal effect of suspended matter.The new additive can deal with mercury containing wastewater under special working conditions.In the experiment,the optimum adding order of the three kinds of chemical reagents is as follows:inorganic flocculant,heavy metal ion trapping agent,organic flocculant.The optimal dosage of each agent is as follows:SM-2 dosage is 90mg/L,ZJS-1 is 2ml/L,PM-1 is 2mg/L.Studied experimental effects of pH,temperature,oxidizing agents for the new treatment program additives mercury Sewage.More economical is to control the pH value around 7.Oxidants on the treatment effect is greatly improved,the dosage of oxidants in 400?l/L.The new additive solution can effectively treat the wastewater containing mercury in the range of 20 ??60?.Through 15 consecutive days of experiment in KS gas field,we discover that the combined additive scheme can effectively ensure that the treated mercury content in the mercury-containing gas field is below 10?g/L.And water quality and stability,to meet the mercury-containing wastewater treatment requirements.According to the characteristics of KS gas fields wastewater and the KL2 gas fields'results of the test apparatus,we have proposed an improved process for KS mercury-containing wastewater treatment.The process optimizes the water treatment additive scheme and simplifies water treatment processes.The oil-water separator and the adsorption device are canceled.Compared new improved technology and original process of project investment and annual operating costs,we found that project investment decreased by 44%,annual operating costs decreased by 21%.