煤气洗涤废水化学氧化过程中反应进程控制

PROCESS CONTROL OF CHEMICAL OXIDATION REACTION OF THE COAL-GAS WASHING WASTEWATER

采用次氯酸钠作氧化剂对煤气洗涤废水进行化学氧化处理,在原水温度、pH等反应条件下,研究了COD去除率与氧化还原电位(ORP)的相互对应关系,并探讨了温度和pH对结果的影响。结果表明,在原水温度为55℃、pH为6.35的条件下,NaClO投加量为2.4%时,煤气洗涤废水的COD去除率可达到80%,此时的ORP值为198mV。原水的ORP值与氧化剂投加量、pH有密切的相关性。随着NaClO投加量的增加,废水ORP值呈增长趋势,而当废水pH升高时,其ORP值呈下降趋势。在原水pH基本稳定的条件下,其综合ORP指标与COD去除率有稳定的对应关系。试验证明,以ORP值作为煤气洗涤废水氧化剂投加量的实时监控指标在实践中是精确可行的。

The experiment about treating the wastewater from the coal-gas washing by chemical oxidation with the oxidant of sodium hypoehlorite was done. The corresponding relationship between the removal rate of COD and oxidation-reduction potential （ORP） was learned under original water temperature and pH. Whether did temperature and pH affect the results were discussed. The results indicated that the COD removal rate of the coal-gas washing wastewater got up to 80% when the dosage of NaCIO was 2.4%（the volume ratio of NaClO to wastewater）, with original water temperature 55 ℃ and pH 6.35. In this case, the wastewater＇s ORP was 198 mV. The ORP of original wastewater was closely related to the dosage of oxidant and pH of the wastewater. The ORP increased with the adding dosage of NaCIO while the ORP declined with the rising ofwastewater＇s pH. The relationship were corresponding one to one each other between the comprehensive ORP and the COD removal rate of the coal-gas washing wastewater when the pH of original water was basically stable. Based on this experiment, it is accurate and feasible to choose the ORP as the real-time monitoring index of oxidant＇s dosage in practices.