Experimental Study On The Application Of Highly Effecive Bacteria To Enhance OAO Process In Treatment Of Coke Plant Wastewater

The coke plant wastewater is a typical difficult biodegradational indusrty wastewater and produced during the making coke, gas purification and collection of coking products process.There are many organic and inorganic compunds(such as phenol, cyanide, polycyclic, aromatic, fluoride, ammonium and heterocylic compunds containing nitrogen, oxygen and sulfur) in the wastewater. If the wastewater was discharged in to water body without treatment or could not meet the discharge standard, it was harmful to environment. The coking wastewater ttreatment has already been a great problem in the wastewater treatment fields of home and abroad. The biological and chemical treatment methods are widely used in almost coking plant, however, the highly effective bacteria bioaugmentation has become a research hotspot in the field of wastewater treatment for its no changes in the existing pricess, low-cost treatment, significant treatment effect and so on.Currently, coke sewage effluent can not reach standard steadily, especially the chemical oxygen demand(CODcr) and ammonia nitrogen(NH₃-N). The experiment was mainly studied on the improvements caused by the self developed highly effective bacteria adding into the aerobic- anoxic-aerobic (OAO) process to treat coke plant wastewater. The dominant contaminants degrading potential was investigated after the augmentation in the OAO process treatment. The influences of pH, temperature, dissolve oxygen(DO) and hydraulic retention time(HRT) effects the removal of CODcr, NH₃-N and volatile phenol in the preaeration tank. The study emphasized on the total hydraulic retention time(HRT) and reflux ratio had the effects on the removal rate of CODcr, NH₃-N and volatile phenol in coking wastewater. Several useful results acquired in this study are as below.1. The activated sludge system denitrification system startup period was accelerated and shorted by highly effetive bacteria. After the bioaugmentation, the effuent CODcr decreased from 210mg/L to 162mg/L, NH₃-N decreased from 48mg/L to less than 15mg/L.2. When the preaeration tank of OAO process pH value 6⁹, it could not obviously influence on the removal CODcr and volatile phenol, however, DO and temperature are critical factors to removal the removal CODcr and volatile phenol. In order to meet the denitrification demand in anoxic reactor and activated sludge growth, the preaeration tank CODcr degradation should be controled under 40%⁶0%, meanwhile the DO1.0².0mg/L, pH7.5⁸.0, temperature 28³1°C.3. The total hydraulic retention time(HRT) of OAO process can influence significantly the removal of CODcr and NH₃-N. When the HRT is less than 88h, eliminating rate will increase with prolongation the total HRT. The CODcr and NH₃-N could be respectively reached to 169.1g/L and 14.79mg/L, as the HRT is 88 hour.4. The recycling ratio almost no effect on NH₃-N removal, but especially important for total nitrogen. When the HRT is 88h and recycling ratio respectively is 1:1, 2:1, 4:1, the NO3—-N respectively 90.84mg/L, 58.94mg/L, 50.98mg/L. there is a tendency to decrease the total nitrogen. 5. When the HRT is 88h and recycling ratio is 2:1, the CODcr and NH₃-N could be reduced from 1411.7, 139.1mg/L to 167.2, 14.79mg/L separately, it will reached the national emission standard through coagulation depth treatment.6. After the higher concertration of phenol shock, the CODcr and NH₃-N removal rate decreased obviously and water quality deterioration. Due to the high effective bacteria augmentation, the influence of CODcr removal will recovery quickly, however, it will take some time to recovery of nitrification.