Physicochemical-Biological Treatment For Nitrobenzene Wastewater And Analysis Of Bacteria Community

NB （Nitrobenzene） is an important primary starting material and frequently released inthe manufacture of pharmaceuticals, dyes, explosives, which is priority control pollutants ofour country. It can cause liver damage, kidney damage and hemolysis effect and is seriousharm to environment and human health. This paper investigated the influence of reactionconditions on the removal rate of NB and COD for high concentrationnitrobenzene-containing wastewater. Eased on experiment, isolating bacterial of NB,degrading characteristics and analyzing bacterial community was studied:1. A process combined coagulation-Fenton oxidation-Fe0reduction had been used onthe pretreatment of high-concentration nitrobenzene-containing wastewater. The influencefactors such as pH and dosage were studied during different treatment stages. Theconcentration of NB dropped from10050mg/L to168mg/L, COD dropped from17350mg/L to1765mg/L, while total removal rates of nitrobenzene and COD reached98%and90%with pH of coagulation4, PFS3300mg/L, pH of oxidation4,[H₂O₂]6000gm/L,[Fe²⁺]168mg/L, pH of reduction3and Fe⁰1500gm/L.2. Two bacterial NBA-1and NBO-1which were able to use NB as the sole source ofcarbon, nitrogen and energy were isolated from sludge separately under aerobic andanaerobic conditions. They were identified as Klebsiella oxytoca sp. according to theirmorphology and16S rDNA sequence analysis. Growth and degradation ability for NB oftwo bacterial were investigated under aerobic and anaerobic. Results indicated that the twobacterial can grow well and degrade NB. Aerobic condition was more suitable for thegrowth of bacteria than anaerobic but less suitable for degradation of NB. NBA-1had betterdegradation ability under anaerobic than others.3. Effects on NB degradation of pH, different additional carbon resources, differentconcentration of glucose, different additional nitrogen resources and different initialsubstrate concentration were investigated. Results showed that, optimal condition waspH8.5and concentration of glucose0.3%. Additional nitrogen resources had little effect onbiodegradation. 4. Taking4-chloronitrobenzene as substrate to indentify biodegradability tochloronitrobenzene of NBA-1under anaerobic, it was found that NBA-1could take4-chloronitrobenzene as sole carbon, nitrogen and energy resources. NBA-1was able todegrade45mg/L4-chloronitrobenzene completely within60h, while its reduction productwas4-chloroanilien.5. Adding NBA-1with expansion of cultivation to simulated wastewater treatmentsystem containing nitrobenzene to investigate stability of system, variations in bacterialcommunity and dominant of NBA-1. Species richness increased by adding glucose whilebiodegradability of system was not changed. After adding4-chloronitrobenzene, ability ofdegradation NB decreased, and community was not changed obviously under anaerobicwhile large number of microorganisms died under aerobic. NBA-1could keep superiority incompetetion under anaerobic, but lose its competitive advantage in aerobic.