| Dyeing water,as a production of textile industry, usually make a serious pollution of environment. Dyeing water contains the common properties of industrial wastewater, besides the high chroma. In addition, their m assive emissions(about 10% of the total emissions of industrial water) has become one of the major causes of water pollution. The influent wastewater of Ouyahuadu wastewater treatment plant cotains a high proportion of dyeing wastewater, so it’s very difficult to achieve stability compliance based on its current operating situation based on the existing process. In the basis of the actual situation of the wastewater treatment plant and the influent wastewater with a high proportion of dyeing wastewater, this study investigated the effect of different sewage treatment unit and proposed the trouble of the existing process.Investigation shows that the influent wastewater contains some chromogenic substance produces by printing and dyeing or papermaking industral which belongs to Benzene derivatives, such as 2,4-Di-tert-butylphenol. Such materials belong to nonbiodegradable organics. Though they can be reduced after hydrolysis acidification,the efficiency of subsequent biological degradation process is poor. This is the reason why the treatment units have a severe chroma for long time. The changes of the water ’s quality are very severe and they are offen far exceeded the quality of the influent water quality standards,which has been a huge challenge to the biological process.As a mean to enhance the biodegradability of wastewater, hydrolysis acidification process has attracted more and more attention because of it’s low cost, simple operation and no intractable byproducts, etc. The actual hydrolysis tank has an incorrect HRT which is a critical parameter of hydrolysis acidification, so it can’t upgrade the biodegradability of the wastewater. On the contrary, the B/C is lower after hydrolysis acidification. As a follow-up process, continuous plug-flue step feed process without adequate carbon source which adds the difficultity to control DO. At last, it results to the inefficiency of the continuous plug-flue step feed process. As to A2 O, minor nitrification liquid reflux limits the efficiency of removing TN.Therefore based on the status quo,this study focuses on optimizing the operating parameters of the existing process. As to hydrolysis tank, this study has optimized its HRT, and 10 h has been proved to be the most efficient HRT. It is clear that when HRT is 10 h, wastewater ’s B/C can be upgrade from 0.22 to 0.31 after it flows past the hydrolysis tank. The efficiency of hydrolysis tank will drop if the HRT is too long or too short. For A2 O process, this study has strengthened it’s nitrification liquid reflux, and has proved 300% is the optimal parameter. After strengthening, the TN removal is enhanced significantly. N itrogen removal rate increased from 36.9% to 68.6%, which meets the national standard for sewage discharge.. Other indicators are also been strengthened, such as COD and TP,whose removal efficiency increases from 66.8% to 75.9%、 from 86.3% to 90%,respectively. For continuous plug-flue step feed process, this study has proposed a new set of operating parameters, such as influent flow distribution method, nitrification liquid reflux and dissolved oxygen control. Water distribution ratio,which refers to the water distribution in anaerobic and two anoxic ratio,is setted as 0.45: 0.35: 0.2. Nitrification liquid reflux,which refers to reflux by the third aerobic anoxic back to the second anoxic,is setted the ratio as 300%. DO control, referring to the dissolved oxygen concentration, are controlled as 0.8mg/L, 1.5mg/L and 2.5mg/L in three aeration tank. This study has proved that when the average influent concentration of TN is 22.38mg/L, the average concentration of effluent can be reduced to about 10.78mg/L, and the removal rate arrive at 52%,with the maximum of 54.4%. The removal of ammonia has also been strengthened, the removal rate reached to 92.7%, making the ammonia concentration from 14.79mg/L down to 0.998mg/L, which meet the national standard for sewage discharge.. As to COD, the removal rate had also been greatly improved to 82.4%, making the average effluent concentrations stabilize s at 45.62mg/L. Changes in total phosphorus removal efficiency are insignificantly, removal rate is 91.3%, also can meet the national standard for sewage discharge. In summary, as to the wastewater with a high proportion of printing and dyeing wastewater, the parameters this study has proposed is the most appropriate one. Running with these operating parameters, continuous plug-flue step feed process can make each water pollution indicator meet the national standard for sewage discharge. |
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