مطالعه آزمايشگاهي و طراحي راكتور الكتروانعقاد با عملكرد پيوسته به‌عنوان يك روش پيش‌تصفيه براي كاهش مقدار اكسيژن‌خواهي شيميايي پساب صنعتي شركت سرمايه‌گذاري صنايع شيميايي ايران

Electrocoagulation , Spent Caustic , Chemical Oxygen Deman‎d , Current Density , Residence Time , Monopolar an‎d Bipolar Electric Current Distribution

Experimental Study an‎d Design of A Continuous Electrocoagulation Reactor as A Pre-treatment Method to Decrease The Amount of Chemical Oxygen Deman‎d (COD) of The Spent Caustic of Iran Chemical Industry Investment Company (ICIIC)

مهندسي شيمي

In this research experimental studies an‎d design of a continuous electrocoagulation reactor to decrease the amount of Chemical Oxygen Deman‎d (COD) of the spent caustic wastewater for Iran Chemical Industry Investment Company (ICIIC) have been carried out. The continuous reactor was initially designed to allow adjustment of the electrode spacing an‎d to enable aeration. Screening experiments were then carried out to determine the best possible operating conditions, such as the type of aeration for conducting processes with this reactor. In these tests, monitoring the voltage over time showed that high aeration at 0.6 m3/h produced strong mixing in the reactor an‎d increased the amount of deposition on the electrode surface. Running the experiments without aeration, although yielding higher efficiency, caused significant operational problems due to sludge settling on the reactor floor. The design of the experiments were done considering residence times in the range of 30 to 120 minutes, current densities between 7 an‎d 15 mA/cm2, electrode spacings from 1.2 to 2.6 cm, an‎d two modes of electric current distribution on the electrodes: monopolar an‎d bipolar. Fixed operational conditions included low aeration sufficient only to produce partial mixing, an average effluent pH of 8.2, an‎d ambient temperature. The experiments showed that, because of unpredictable flaws in the reactor design, aeration was not evenly distributed through the channels, which reduces the likelihood of experiment reproducibility. In addition, incomplete sludge removal caused accumulation in the system, which after a time affected reactor performance. Nevertheless, it can be stated that sludge deposition on the reactor floor had a greater effect in tests with the monopolar configuration than in the bipolar configuration, while sludge deposition on the electrode surfaces had a greater effect on system performance in the bipolar configuration than in the monopolar configuration. Under the operating conditions of a 120-minute residence time, a current density of 15 mA/cm2, an electrode spacing of 1.9 cm, an‎d a bipolar current distribution, the designed reactor achieved a 73.9% reduction in COD despite the addressed flaws in the design. Finally, a new reactor design was proposed to address the identified design problems.

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