Anaerobic Ammonium Oxidation(ANAMMOX) Process For Treatment Of Coking Wastewater

Coking Wastewater, known as complicated mixture of tens of pollutants including phenol, ammonia, cyanide, benzene, pyridine, indole and quinoline, is the waste water formed after the high-temperature pyrolysis of coal, the purification of gas and the refining of chemicals. It is considered as typical refacotory organic wastewater for its high concentration, high chroma, great toxicity and stable quality. These substances do great harm to human beings, fisheries and crops while discharged excessively. It's been an important project to be worked out in need for coking industry that how to solve the wastewater-caused pollution problem, as well as speed up the wastewater disposal.As high NH4+-N concentration in the coking wastewater, biological nitrogen removal is the main technique in treating coking wastewater. The electronic stoichiometric analyses demonstrate that ANAMMOX process has a lot of advantages compared with traditional nitrification and denitrification for nitrogen removal.The goal of this study was to investigate the start-up of ANAMMOX process in a biofilmreactor, feed with coking wastewater,which is the effluent of shortcut nitrification process; Optimized performance influencing factors and identified the bacterium in coking wastewater ANAMMOX bioreactor through molecular biological methods.Which indicates:(1) The study was carried out in two sets of reactor: anaerobic biofilm reactor and Up-flow Anaerobic Sludge Bed (UASB). Compared the two start-up progress of ANAMMOX under the conditions of opaque background, the results illustrated that the two kinds of reactor set up the anammox process successfully in more than 100 days and reach stabilization, completed the ANAMMOX bacteria culture.The experiment of two sets of reactor indicated the anaerobic biofilm reactor set up more rapidly than the UASB reactor, and the removal emciencies for the anaerobic biofilm reactor is better. During the period of stabilization, the maximum ammonia nitrogen removal efficiency of UASB reactor and anaerobic biofilm reactor reached 70%and 90%, respectively;and the nitrite nitrogen removal efficiency of UASB reactor and anaerobic biofilm reactor reached 75% and 92%, respectively.In the experiment, the Oxidation-Reduction Potential (ORP) suggested that the ANAMMOX bacteria reaction kept in a relatively strong oxidizing state.Using the scanning electron microscopy (SEM) observed the morphology of bacteria that it belonged toGram-positive cocci. The biofilm color and morphology changed during the period, bacteria in the UASB was in free state but bacteria in the anaerobic biofilm reactor accreted on the fillers.(2) The start up of ANAMMOX process was investigated by using a anaerobic biofilm reactor inoculated with activated sludge from PanGang chemical plant leachate treatment system.The biofilm reactor was feed with coking wastewater, which is the effluent of shortcut nitrification process. The result indicated that under the conditions of 34°C,pH 7.5～8.5 and HRT of 33h, the start-up of anammox reactor was achieved after 115 days. The influent concentration of NH4+-N and NO2--N are controlled to be 80 mg/L and 90 mg/L, and the volume loading of total nitrogen was 160 mg·L-1·d-1.The maximum removal efficiency of total nitrogen, ammonia nitrogen, nitrite nitrogen reached 75%, 86% and 98%, respectively. It had been proved by the experiment that the high concentration of NO2--N could inhibit the activity of ANAMMOX bacteria. The nitrite concentration tolerated by ANAMMOX bacteria was in the range of 87.5～110mg/L. But the bioreactor recovered in two weeks by reducing the concentration of the nitrogen. The analysis of organics by GC-MS indicated, Phenols could be degraded by microorganisms easily, Anaerobic Ammonium Oxidation showed removal capacity for phenols.The sludge color of ANAMMOX appeared to be brown with the operation on and its shape appeared irregular ellipsoid.(3) The bacterium in coking wastewater ANAMMOX bioreactor was identified through molecular biological methods. These techniques such as DNA extraction from activated Sludge, denaturing gradient gel electrophoresis, DNA cloning and DNA sequencing, were applied to study the ammonia oxidation bacterium in the reactor. The PCR-DGGE results indicated that different bacteria species playing different biological role were domesticated and enriched in different bioreactors under different condition.