Remediation Of Nitrobenzene In Underground Water By Zero Valent Iron And Bacteria

Nitrobenzene (NB) is an important chemical raw material, which can be use wildly inorganic chemistry industry, such as synthetic dyes, pharmaceuticals, pesticides, rubber andplastic additives and synthetic detergent. It also used as explosives, spices and pharmaceuticalproducts. Because of its mutagenicity, recalcitrance, and tendency to accumulate in theenvironment, many countries have listed it as a priority pollutant. With the rapid developmentof fine chemicals, such as dyes, paints, pharmaceuticals and other industries, the demand ofNB significantly goes up. Due to the wastewater treatment leakage, the remnants of the tailwater, and the accident emissions, a continuous increase in the amount of nitrobenzene entersinto the groundwater environment, which threat to groundwater as a source of drinking watersafety.In this thesis, NB is the target pollutant to remove by a combined system withzero-valent iron and anaerobic microorganisms. Bath experiments were carried out toinvestigate the character of nitrobenzene reduction in the combination of zero valent iron andanaerobic microorganism under different electron accepting and nutritional conditions. Theresults showed that the coordinated system of nitrobenzene reduction is better thanzero-valent iron and anaerobic microorganisms alone, NB removal achieved at75.7%in12d;NB removal was5.96times and1.31times better, respectively. The combined system canprolong zero-valent iron’s service life. It achieved an ideal result with the influent pH value of7and the zero-valent iron dosage of250mg/L. It was proved that only by zero-valent ironcorrosion generated H2can be used as the electron donor utilized by the microorganisms; butFe2+can be used as the inorganic nutrient elements to promote synergies in the restorationprocess.There is a small amount of organic matter exist in groundwater which promote theremediation effect of NB by combined system. Facilitating role in the reduction ofnitrobenzene showed inhibition of the oxygen in the collaborative system, which is due tooxygen and nitrobenzene compete for electronics, but AN, the product in NB reduction, is easily mineralized under aerobic conditions. However, anline, the product of NB reduction,was easily mineralized under aerobic condition, which enhanced NB degradation and avoidedsubsequent processing. Nitrate has a competitive inhibition on NB reduction by combinedsystem, Nitrate coordinated system repair nitrobenzene pollution competitive inhibition, thehigher the influent nitrate concentration, the stronger the inhibition. What’s more, thereduction product can be used as electronic donor when denitrification by microorganism,which lowers the AN concentration in effluent. There is no an obvious inhibition by sulfate inNB reduction.The combined system was also effect in treating the NB and nitrate pollution; theeffluent concentration of AN was so low to avoid secondary pollution. Nitrate reduction waspriority to NB, and the inhibition effect of NB reduction was strengthened as high nitrateinitial concentration. High concentration of NB was toxic to denitrifying bacteria, whichlower the effect of remediation.The Fe~0/anaerobic microbial combined system was effectively using in groundwaterremediation, which was polluted by NB, and has advantages of fast, long-term. Commonmatter, such as organic compounds, dissolved oxygen and anion, will not lower the effect ofNB remediation. Therefore, the establishment of a combined system of Fe~0/anaerobic can beeffectively applied in the NB-containing groundwater pollution remediation.