Treatment Of Coking Wastewater By Bio-augmentational Techniques And Correlation Analyze

The composition of coking wastewater is very complex, it contains a large quantity of refractory organics such as polycyclic aromatic hydrocarbons(PAHs)and heteromatic compounds, is a kind of typical refractory wastewater. The removal rate of the refractory organics by the conventional activated sludge process is low, which results in a relatively high value of COD in effluent, so the quality of effluent can not reach the national draining standard. Compared with the current treatment processes, this paper puts forward the opinion of treating the coking wastewater by the optimal bio -augmentational techniques.This paper carried out a further study on the degrading capacity of PAHs of the 8 preponderant bacterial strains screened and separated from the activated sludge from a coking-plant, and then CN1, CN2 and DB3, the three strains which have better degrading capacity was selected out.From a series of experiments, we found that proper quantity of co metabolic substrates can improve the COD removal rate, and the more nutrient the co metabolic substrates are, the better the improvement is; the bio-augmentational technique of using the preponderant strains can also improve the COD removal rate, and the optimal quantity is 10% (weight of strains/MLVSS). From the results of inserting mixed strains, we found that : (1) the synergism can improve the COD removal rate greatly, and the antagonism exists as well. (2) the combination of the three strains has the best effect. From further experiments, combination of co-metabolic substrates and preponderant bacterial strains was determined as the optimal bio - augmentational technique.From the analyze of the results obtained, we found that: the degradations of the PAHs by the strains obey the zero-order or first-order reaction generally, and the degrading capacity are both related with the strains themselves and the structures of thetarget compounds, and we got the mathematical equation to describe therelation between inserting quantity of co metabolic substrates and the COD removalrate, and the mathematical equation to describe the relation between theinserting quantity of preponderant strains and the COD removal rate.The systemically study on the treatment of refractory organics in coking wastewater by bio -augmentational techniques and correlation analyze is rare in China, so I hope the results obtained in the paper can offer beneficial basic materials to further study.