Abstract:

In order to solve the problem of high nitrogen load caused by large fluctuation of wastewater in a printing and dyeing industrial park， a combined coagulation－iron carbon microelectrolysis－sodium hypochlorite oxidation process was used to treat the high nitrogen wastewater. The experimental results showed that the COD removal rate in coagulation stage reached 83.12% under the conditions of no adjustment of initial pH， ferrous sulfate and polyacrylamide dosage of 400 and 15 mg/L， respectively. Under the conditions of initial pH of 4， iron-carbon mass ratio of 1∶1， iron dosage of 60 g/L， gas-water ratio of 5∶1 and HRT of 120 min， iron-carbon microelectrolysis was applied to the coagulation effluent. The effluent pH increased to 6.91， and the removal rates of COD and NO₃ ^--N were 50.26% and 53.66%， respectively， with NH₄ ⁺-N as the main reduction product of NO₃ ^--N. The microelectrolysis effluent was treated with sodium hypochlorite. Under the conditions of no adjustment of initial pH， sodium hypochlorite to total Kjeldahl nitrogen mass ratio of 8.5∶1 and reaction time of 30 min， the removal rates of TN and NH₄ ⁺-N were 88.56% and 97.75%， respectively. After intermittent treatment of combined process， the effluent COD≤55 mg/L， TN≤14 mg/L and NH₄ ⁺-N≤1 mg/L， met the direct discharge requirements in Table 2 of the Discharge standards of water pollutants for dyeing and finishing of textile industry（GB 4287—2012）. After calculating， the cost of chemical agent of the process is 5.09 Yuan per ton.

Key words: printing wastewater, coagulation, iron carbon microelectrolysis, sodium hypochlorite

摘要：

某印染工业园内的印花废水水量波动大，导致综合污水处理厂氮负荷高。采用混凝—铁碳微电解—次氯酸钠氧化组合工艺对该高氮废水进行处理。实验结果表明，在不调节初始pH、硫酸亚铁与聚丙烯酰胺投加量分别为400、15 mg/L的条件下，混凝阶段的COD去除率达到83.12%。在初始pH为4、铁碳质量比为1∶1、铁投加量为60 g/L、气水比为5∶1、HRT为120 min的条件下，对混凝出水进行铁碳微电解，出水pH升至6.91，COD和NO₃ ^--N的去除率分别为50.26%、53.66%，NH₄ ⁺-N为NO₃ ^--N的主要还原产物。用次氯酸钠氧化法处理微电解出水，未调节初始pH、次氯酸钠与总凯氏氮质量比为8.5∶1、反应时间为30 min时，TN、NH₄ ⁺-N的去除率分别为88.56%、97.75%。经该组合工艺间歇处理后，出水COD≤55 mg/L、TN≤14 mg/L、NH₄ ⁺-N≤1 mg/L，可达到《纺织染整工业水污染物排放标准》（GB 4287—2012）表2的直接排放要求。经核算，该工艺的药剂成本为5.09元/t。

关键词: 印花废水, 混凝, 铁碳微电解, 次氯酸钠

CLC Number: 

• X703