Study Of Mercury Form Distribution In Different Stages Of Urban Sewage Treatment Plant

Mercury and its compounds have important uses in the chemical, electrical,instrumentation, pharmaceutical, metallurgy, military and new technology areas. Inthe chemical industry，mercury cathode products chlorine and caustic by salt solutionelectrolysis. Mercury, instead of water, is often used as a heating medium in hightemperature thermostat or distillation apparatus in organic chemical industry. Mercuryis widely used in the manufacture of electrical and instrumentation, such as mercurythermometer, aircraft, night gyrator and load cell. Mercury is also used in themanufacture of various types of electrical switches, mercury light, mercury rectifiers,oscillators, mercury cells, primary batteries, and so on. Mercury can also be used asnuclear reactor coolant and the radiation shielding material.Amalgam, which is formed with mercury and other kind of metal, is used in metalextraction and metal purification in metallurgical industry. For example,Amalgamation can be used in the extraction of gold and silver, and in the purificationof some scattered metal. Gold and silver amalgam can quickly harden, so it is used fordental materials. Mercury compounds have a variety of uses, too. Mercuric oxide isantifouling agent, and it can be used as paint in ocean bottom and depolarization agentin dry cell. Mercuric chloride can be used for tanning, photography and so on.Mercuric sulfide is a red pigment, and it is used for rubber and ink.Mercury and its compounds become one of the most common pollutants in theenvironment because of their wide application. Our country has listed mercury aspriority pollutants.Solid-phase extraction, liquid-phase separation and atomic fluorescence analysiswere used in the study. Mercury and its compounds discharge into the municipalwastewater treatment system with the sewage. Urban sewage treatment plants in Jilinprovince which use different crafts were chose. The concentration of inorganicmercury, methyl mercury and ethyl mercury in each stage of urban sewage treatmentplant was tested. The form changes of mercury in different stages were also analyzed.In this paper, a comprehensive understanding of design, construction and operationstatus of various municipal wastewater treatment plants in Jilin province through information collection, existing monitoring data collection, field survey and fieldmonitoring. We selected representative sewage treatment plants which use differentcrafts, tracked and monitored the concentration of alkyl mercury and total mercury ininfluent and effluent of each step of the process in a long term, and monitored thewater quality in the imports and total discharge port of sewage treatment plant.Various crafts have their advantages and shortcomings. So it is necessary to studypractical engineering, and systematically analyze the processing conditions of totalmercury and alkyl mercury treatment and the main factors in different crafts. It canprovide basis for government to establish total management control and assessmentindex system of alkyl mercury and total mercury. It can provide technical support forthe improvement of alkyl mercury and total mercury treatment efficiency. It is helpfulfor process design optimization and operation optimization of the municipalwastewater treatment plant. The main contents are as follows:1. We chose forty-five municipal wastewater treatment plants in Jilin province. Andthey were investigated. A2O, AO, SBR, CAST, AICS and BIOLAK were chose astypical process and for father research after investigation of process, design and scaledata of sewage treatment plant.2. The concentration of inorganic mercury, methyl mercury and ethyl mercury wasdetected by solid phase extraction-liquid phase separation-atomic Fluorescence.The optimal conditions of SPE activation conditions, modification conditions,enrichment conditions and elution conditions were studied. The optimal condition ofthe separation of inorganic mercury, methyl mercury and ethyl mercury in C18liquid-phase column was discussed. This method is intended to be established as astandard method. And a project has been established by relevant departments already.3. The form distribution of inorganic mercury, methyl mercury and ethyl mercury indifferent stages was got after large amounts of monitoring. The influences of pH value,redox potential and dissolved oxygen to the form transformation of inorganic mercury,methyl mercury and ethyl mercury in the different stages of sewage treatment systemwere analyzed.