| Recent years, Traditional Chinese Medicine (TCM) industry has developedrapidly in our country. It’s GDP average annual growth rate is more than20%andalso has a broad development prospect. But at the same time，the environmentproblems caused by TCM wastewater are becoming increasingly acute. TCMwastewater has the main characteristic of complex compositions, high concentrationof organic contaminant and poor biodegradability, these features determined that itis difficult for treatment and the conventional wastewater treatment processes cannot make the effluent meet the standard. At present，study on specfic TCMwastewater treatment method is relatively less, In this paper，EGSB reactor wasused in TCM wastewater treatment for the first time. At the same time this paperstudied its feasibility and characteristic of granules in EGSB to provide referenceand guides to practical application of engineering.This paper took the wastewater in a TCM factory in Harbin as the subject ofstudy, the wastewater was acidic and with high COD、SS、TN、TP and chroma，inaddition, the wastewater contains a strong acid smell. Through a small pilot plant,EGSB reactor was used in TCM wastewater treatment, studied the startup of reactor,factors and performance of TCM wastewater treatment by EGSB, changes ofgranular sludge characteristics and so on.The research results indicated that the EGSB reactor was inoculated by sewagesludge and synthetic glucose wastewater was used to cultivate granular sludge. Afterabout a month granular sludge was formed in EGSB reactor. During this process theCOD removal rate increased gradually. During stable operation the COD removalrate was between94%to98%. The EGSB reactor started-up successfully andcultivated good characteristic granular sludge.The effects of influent COD concentration, hydraulic retention time (HRT) andreflux ratio (R) on the treatment efficiency were investigated. The results indicatedthat the optimal parameters of TCM wastewater treatment by EGSB are: T=25℃,COD≈5000mg/L，HRT=9h, R=1. In this condition, the average COD removal ratewas96.7%, the removal organic load rate could reached to13.74kg.COD/(m3.d),pH=6.6~7.6, VFA concentration at about1.0mmol/L, ALK concentration at about30~35mmol/L, and the average methane yield was0.28m3CH4/(kg.COD). This studyalso found that the COD concentration had little influence on treatment effeciencyof EGSB reactor and too short HRT caused granular sludge disintegration in thereactor which resulted in poor quality of treated water. When the temperaturebetween25℃~30℃, the EGSB reactor had a high treatment efficiency, But when the temperature was20℃, the effluent water represented poor quality rapidly, theaverage methane yield also appeared a significant reduction and some other badeffects. What’s more, the resulting impacts were not easy to recover in the shortterm. Increasing the reflux ratio can offset the bad influence of temperaturereduction to some extent. But the average methane yield was still not easy torecover.The microorganism of granular sludge in the EGSB reactor mainly includedBrevibacterium, filamentous bacteria and some small cocci, when the reactoroperating parameters was appropriate, the bacteria was rich and winding with eachother, the filamentous fungus and Brevibacterium were dominant species. Too shortHRT caused the EPS concentration increased rapidly which also increased theresistance of the mass transfer process, resulted the granular sludge autolyzed. Asignificant reduction of temperature resulted in the number of bacteria decreasedand the activity of anaerobic granular sludge was also inhibited, Increase the refluxratio increased the number of bacteria, but the length of both filamentous fungi andbacillus was reduced.Shocked by Traditional Chinese Medicine the size of granular sludge in thereactor was decreased. But after the domestication, the increase of influent CODwas conducive to enhance the particle size; Too short residence time and thetemperature of20℃caused partial disintegration of granular sludge, particle sizedecreased; Increasing the reflux ratio of the reactor was conducive to the growth ofgranular sludge; In different periods, the biomass content and the mechanicalstrength of the granular sludge were closely related to the effluent water quality.When the mechanical strength and biomass content were high the effluent waterquality was also high. In optimal conditions, The granular sludge which particle sizeis greater than1000μm was about50%, the VSS/SS was84.21%, and themechanical strength was82.46%.This study analysised the methanogenic activity and coenzyme F420content ofdifferent operating phases of granular sludge found that: coenzyme F420content andmethanogenic activity showed a good correlation and the trends were similar; Atsuitable operating parameters the methanogenic activity and coenzyme F420contentwere both at high level. In the suitable range, the increase of influent CODconcentration, temperature and the reflux ratio could increase the granular sludgemethanogenic activity and coenzyme F420content to some extent.Calcium and magnesium contents have some relevance with particle sizedistribution of the sludge and effluent water quality. At all periods of this study, theCa2+,Mg2+contents of the granular sludge appeared significant changes, highcalcium and magnesium contents was conducive to the reactor’s operation. StudiedSMP of each operational phase we found that: When the reactor was running well, some benzene series of the TCM wastewater were removed after treatment, whichindicated that hazardous substances in TCM wastewater were effectively removedafter treatment by EGSB. But when the effluent water quality was bad, there were alot of aromatic compounds, carbohydrates, humic acid and coenzyme F420fromdissolved cells in the SMP. But the EPS nature of different operation phases had nosignificant changes. |
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