Research On The Bio-toxicity Of Coking Wastewater Treated By Biological And Advanced Processes

Coking wastewater contains large amounts of toxic substance, but the existingwastewater discharge standard of China is lack of biological toxicity index, andconventional indexes such as COD and ammonia nitrogen can not accurately reflect thepotential impact on the ecological environment. The purpose of this study is to revealthe variation of the typical toxicity indexes of coking wastewater treated by biologicaland advanced treatment and the chemical characteristics of toxic substances, in order toprovide theoretical basis for discharge standard of toxicity and ensure the ecologicalsecurity of discharge of coking wastewater.Use actual coking wastewater for experiment, and study the treatment effect ofAnaerobic/Anoxic/Oxic-membrane(A1/A2/O-MBR) process for routine indexes such asCOD, ammonia nitrogen and total nitrogen when the process operated stably. Then thebiological effluent was treated by advanced processes, namely Fenton oxidation andactivated carbon adsorption. Study on the optimal conditions to for both processes tomake the final effluent meeting the new discharge standard.Luminescent inhibition test using Qinghai Vibiro Q67was employed to evaluatethe acute toxicity of coking wastewater. Results showed that the acute toxicity of cokingwastewater is about16Toxicity Unit(TU). A1/A2/O-MBR process has good treatmenteffect on acute toxicity, but there is still about28%TU residues in the effluent.Acute toxicity of Fenton effluent containing about1.2mg/L residual chlorine increasedslightly. The toxicity is totally eliminated after dechlorination, indicating that residualchlorine is the reason for Fenton oxidative toxicity. Activated carbon adsorption isecological safe which can remove COD and acute toxicity of wastewater at the sametime.Recombinant AR gene yeast was employed to study the androgenic andantiandrogenic activity of coking wastewater. Results showed that coking wastewaterhas no obvious androgenic effect, but has antiandrogenic activity of about2.8E-04mol/L flutamide equivalent. A1/A2/O-MBR process has good treatment effecton antiandrogenic activity of coking wastewater, which is almost completelyremoved, and advanced treatment makes no significant changes to antiandrogenicactivity. Coking wastewater and effluents of different treatment processes were separatedinto several components by solid phase extraction(SPE) and ultrafilter membraneseparation. Then biological toxicity test and chemical analysis such as UV spectrometry,three dimension fluorescence spectrometry(TDFS) and GC-MS were employed to eachcomponent and the chemical characteristics of the toxic substances were estimated. It isfound that both acute toxicity and antiandrogenic activity mainly exist in polarcomponents. Aromatic protein-like substances in region II of three-dimensionalfluorescence spectra is most likely to be acute toxic and constitutes the main residualtoxicity of biological treatment effluent. Results of GC-MS scan show thatA1/A2/O-MBR process has good removal effect on phenol and methyl phenol, whilenaphthalene, naphthol and quinoline are typical toxic residues in MBR effluent.Antiandrogenic activity substance may be aromatic protein-like substances in region IIor microbial by-products-like in region IV.