| This thesis regards the area of Laizhou saline groundwater as the research object. According to the results of chemical composition analysis to find out the harmful substances and try to remove them out off there to make the water reach the farming standards. Basis on the chemical composition analysis results of main indicators in this test water samples, it can be seen that the salinity is too high enough for salt and fresh water mix. What is more, the lead ions content in this water area is seriously overweight. The accumulation of heavy metals must impact the farming biological growth and be detrimental to people’s health. Therefore, we conduct the following experimentation to reduce it.1, The salinity of the fresh water and the underground water in this Salt and Fresh Water Mixed Trials Test are 59856 mg/l, and 8246 mg/l. The change of different proportion of the amount of date is various; while the trend is basically the same. Experiencing a span of 2～8h after mixing, the pH stayed between 7.5 to 8.6, and the volume ratio of freshwater stayed 50%～70%. The salinity was between 22 and 35, which was suitable for the needs of the turbot water pH, salinity.2, The initial pH of underground salt water and the mixture of freshwater were acidic. And the lead ions were dissolved in them. However, when the mixed water samples were placed in the open system, it presented us that the pH was increasing, and the amount of hydroxyl was grown. Small portion of lead ions react with them to create strong lead oxide precipitation, which was difficult to remove. Lead ion content decreased. After the pH value of water was basic stable, the amount of lead ions was mainly unchanged. But the content of lead ion in mixed water samples was below the standard. When the mixed water samples were in the open system, the release of carbon dioxide in the mixed solution made more bicarbonate transform into the carbonate which will react whit the calcium and magnesium ions to generate precipitation. So, it must decline the total number of ions in solution, as well as lift the pH value in the water solution.3, After comparing various methods for removal of lead ions in saline groundwater and analyzing the properties and applications of caustic soda, hydrated lime, alum, ferrous sulfate, fly ash, bentonite, zeolite, we chose to use hydrated lime, zeolite saline groundwater in the lead ion removal experiment.4, Modified clinoptilolite experiments show that:the most appropriate concentration of the modified zeolite clinoptilolite modified concentration was 1.2mol/l sodium chloride, 0.6mol/l sodium hydroxide,1.2mol/l hydrochloric acid and 0.9mol/l ammonium chloride. It also showed us that the adsorption capacity of lead ions in the freshwater after the ammonium modified until one hour was the strongest.5, Modified zeolite freshwater lead ions in the static adsorption test showed us:four kinds of methods using in modified lead in fresh water all have a high removal rate. The most effective mean was the ammonium modified zeolite in 80min remaining concentration of 0.016 mg/l, the removal rate of 98.40%, which was followed by sodium hydroxide modified zeolite, the removal efficiency of 96.10%. During the 0-5min period, decline extent of ammonium was the largest and, which was followed by sodium hydroxide. In the span of 5-10min hydrochloric acid witnessed largest decline, the date of sodium chloride presented the second. After 10min, ammonium chloride was the first one to reach stable, as well as hold the lowest residual concentration of lead ions. In summary, the modified zeolite was an effective way to wipe lead ion out off freshwater.6, Static adsorption test, the modified zeolite of lead ions in the simulation of underground salt water test:all of the four kinds of modification methods to remove lead ion out off saline groundwater were pretty low. The relative high rate of the four methods was ammonium chloride modified zeolite.The lowest residual concentration was 0.770mg/l and the removal efficiency was 23.0%.7, Hydrated lime precipitation of lead ions in salt and freshwater test:The test showed us the hydrated lime processing containing 1mg/l of lead ions in salty and freshwater optimal dosage of 400mg/l and 800mg/l, brackish water through hydrated lime minimum remaining amount of lead ions in the treatment was 0.076,0.074.The experiment also showed that the saline groundwater in high concentrations of magnesium ion does not lead ion competitive sedimentation, while high salinity environment will affect the low concentration of lead ions react with hydroxyl. |
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