含汞气田污水水质分析及研究

Study on the characteristics of gas field mercury-containing waste-water

不同含汞污水处理技术有不同的特点和汞形态适用条件,进行含汞气田污水的水质特点、总汞浓度及汞形态的分析,对气田污水脱汞处理工艺的选择具有十分重要的意义。通过对某含汞气田天然气处理厂污水水质分析研究表明:含汞气田污水呈酸性,属高浓度Cl-、高矿化度、高浓度有机污水,具有强腐蚀性、易结垢的特点;污水中各种汞形态均存在,非溶解态汞占比小,溶解态汞占比达97%以上;溶解态汞中有机汞占比小,无机汞占比大,其中二价汞占比达99%以上;且高浓度Cl-下,溶解态汞主要以络合物形式存在,汞氯络合物稳定性高。为实现有效脱汞,选择污水脱汞处理工艺时需充分考虑络合汞脱稳问题,并应对总汞浓度及汞在水中存在形态进行全面分析。

With their distinctive characteristics,different mercury-containing waste-water treatment technologies are applicable for different water quality and mercury forms.Analysis of the water quality characteristics,total mercury concentration and mercury form is of great importance in the selection of the process for the removal of mercury from gas field waste-water.The results of a study on the effluent water quality of a mercury-containing natural gas treatment plant show that waste-water from the mercury-containing gas field is an acidic,highly chlorinated,mineralised and concentrated organic effluent,which is highly corrosive and prone to scaling;all kinds of mercury forms are present in the waste-water,with a small percentage of non-dissolved mercury and over 97%dissolved mercury.Organic mercury accounts for a small proportion of the dissolved mercury while the remaining proportion is inorganic mercury,with divalent mercury accounting for over 99%.In addition,the dissolved mercury exists mainly as a complex in high chloride ion environment,and the mercury-chlorine complex is highly stable.In order to achieve effective mercury removal,the mercury-containing waste-water treatment process should be selected with due consideration to the destabilisation of mercury complexes and a thorough analysis on the total mercury concentration and the presence of mercury forms in the water should be carried out.