温度变化对DO和ORP作为过程控制参数的影响

前对DO和ORP作为控制参数的研究仅局限在恒定温度下,而实际工程中,由于各种原因很难维持反应器内温度在一个水平上,因此,开展了变温度下DO和ORP作为过程控制参数的可行性研究.采用SBR法研究了不同曝气量、初始MLSS浓度和进水COD浓度等条件下温度对反应过程中DO和ORP变化的影响.结果表明,环境温度的波动极大地影响了反应器内DO的变化趋势,而ORP的变化趋势基本不受影响.并从理论上探讨了DO受温度影响的原因,提出当环境温度变化时,采用ORP作为控制参数更能反映有机物的降解情况.试验中还发现,ORP凹点出现的时间与进水COD浓度有关,ORP的上升速率与COD降解程度有关.通过对ORP导数图进行分析,发现ORP二阶导数近似为0时,COD已不再降解.联合ORP凹点和二阶导数近似为0两个条件,可以实现SBR法处理豆制品废水的在线控制,合理安排曝气量和曝气时间,最终达到节约能源的目的.

Temperature Effects on DO and ORP in the Wastewater Treatment

At present, there are some problems in the study of DO and ORP as control parameters, because the researches are usually developed in the invariable temperature. However, environmental temperature is changing in the wastewater treatment. The effect of environmental temperature on DO and ORP as control parameter was studied specially in some experiments carried on a sequencing batch reactor (SBR) fed with soybean wastewater in this paper. Results show that the law of variation in DO during organism removal were influenced with the environmental temperature, at different experiment condition of aeration intensity, MLSS concentration or inflow nutrition concentration, but the variation in ORP were not influenced with it. The reason that the DO was influenced was also discussed. This paper brought forward that the control parameter using ORP was accurate and reliable when environmental temperature changed. In addition, inflow COD concentration and the time that ORP concave value appeared was connected, and the speed that ORP in curve ascended related with the COD concentration during the degradation. So the end point of degradation may be estimated by applying ORP derivative. United ORP concave value and its derivative, it can be made on-line control of aeration intensity and aeration time.