Study On Treatment Dyeing/Printing Wastewater With Novel Combined Bio-packing Tower

Wastewater discharged by printing and dyeing industry, which is a main effluent department in our country, is characterized by great capacity, high-color and complex component. Dye emission into the water body would reduce the diaphaneity of water and cause great damages to the environment and people's health through biological enrichment. As a result, the study of treatment of dye/printing wastewater is of great importance and immediate significance. At present, the biological degradation was the main method used to treat the printing and dyeing wastewater due to its wide adjustability to quantity and quality of wastewater, high tolerance to large biomass content, the absent of sludge bulking problems and the high processing efficiency. Therefore, the studies of bio-film reactor have been paid much attention recently.As bio-film carrier, packing is the key part of wastewater treatment in aerobic process. A novel saddle-backed combined packing with superior characteristics was developed in order to meet the requirement of the biological attaching oxidation process. Apart from the good wear-ability,pressurized,anticorrosion,innocuity and good mechanics, the combined packing is also superior to common saddle-backed packing in dispersing liquid or gas flow in packing tower. As a result, the combined packing has a larger overall liquid volumetric oxygen mass transfer coefficient. The packing parameters are that: the porosity is 0.93; specific surface area is 292.5m2/m3, which is larger than the original packing with the specific area of 170m2/m3; the biological membrane quantity attached on the combined packing is 2.81 times as large as that on the original packing. The dynamic curve of oxygen mass transfer was measured experimentally. The comparison between the two formulas showed that the former KLa is bigger than that of latter at the same aeration flux by about 30～100%.Parallel experiments between the new combined packing tower and the ordinary packing tower were conducted. The influence of dye concentration,carbon source concentration,processing time,dye concentration,pH value,aeration amount,species of packing and ultrasonic pretreatment on the decolonization of FGS using bio-film reactor was analyzed. The experimental results indicated that the degradation of FGS in the novel combined packing tower is faster than that in the ordinary packing tower. The degradation efficiency of imitating wastewater with FGS of 40 mg/Lwas about 80% after 8 h treatment while the new combined packing tower and only 45% in the ordinary packing tower after the same treatment. The coupling technology could greatly reduce FGS wastewater disposing time compared with the degradation results obtained only by using biological aerated packing tower, or by couplinng the ultrasonic pretreatment with biological degradation. Pretreated by ultrasonic for 1h, 2h, 3h at combining frequency of 60kHz+80kHz+100kHz+125kHz, the time required to obtain FGS biological degradation efficiency above 50% could be reduced by 2 h,2.5 h,3 h respectively. Lower concentration of carbon source is needed to reach normal operation of the reactor and the processing result is prefect. However, FGS has the inhibition to the bio-membrane. The optimal operating conditions are that: the pH=7, the glucose concentration is 800 mg/L and the aeration rate is 1.4m3/h. The order of influence on the disposal results was obtained through the orthogonal experiment: dye concentration > glucose concentration > aeration amount >pH value.A static dynamic mathematic model of degrading dyeing/printing wastewater by Bio-Packing Tower has been deduced by using theoretical formula and fitting experimental data: . Good agreement of the calculated value with the experimental results is achieved, and the deviation between them was less than 8%.Therefore, the formula can be used to predicte the substrate concentration under the conditions of initial concentration S 0,aeration amount q and biochemical reaction time t in the reactor.The experimental results indicate that the removal efficiency of and chroma of the industry wastewater pretreated by ultrasonic is bigger than that treated only with biological packing tower at the same conditions. Continuous ultrasonic reactor coupling with bio-packing tower was used to treat industry printing/dyeing effluent. The removal of and chroma was got using different combined technology. The results show that the combined technology of ultrasonic pretreatment–(active carbon) -biology is most favorable to treat the effluent with 600～1000 mg/L and chroma 320. Under the optimized experimental conditions, the removal efficiency of and chroma can reach 92% and 95% respectively within about 9 h by using the combined technology. The final effluents could reach the first grade emission standard of GB 4287-1992.