Numerical Investigation of Degasification in an Electrocoagulation Reactor


Numerical Investigation of Degasification in an Electrocoagulation Reactor

Höhne, T.; Farhikhteh Asl, V.; Ople Villacorte, L.; Herskind, M.; Momeni, M.; Al-Fayyad, D.; Taș-Koehler, S.; Lerch, A.

In order to enhance retention of particulate and colloidal (organic) matter, chemical coagulation (CC) is often used prior to pressure driven membrane filtration. Electrocoagulation (EC) is an alternative to CC usually carried out in an electrochemical reactor consisting of an electrolytic cell containing at least one anode (sacrificial) and one cathode. The EC combined with a membrane filtration to a hybrid membrane system may be a potential possibility for environmental problems dealing with drinking water treatment, water reuse and rational waste management. In this study, an EC reactor with spiral electrodes was investigated numerically, focusing on modelling with a given design/geometry, configuration and boundary conditions. Two-phase flow interactions between water (liquid) and hydrogen (gas) were modelled via computational fluid dynamics (CFD). Different flow rates (Q=1-1000 l/h) through two batches of the watering stage (Case 1-3) and the degassing stage (Case 4-6) were simulated. Degassing the feed of the membrane system is of high importance in order to achieve stable operation. The results provided information about flow characteristics such as sufficient retention time, water circulation by velocity vectors, undesirable gas penetration into the water inlet channel, gas holdup during watering and degassing, and finally the optimal period for the degasification. The results showed that as the water velocity increases, retention time decreases. The results also showed that thirty seconds seemed the optimal time with the gas holdup of 0.020%, 0.028%, and 0.027% respectively for Case 4, Case 5, and Case 6. Another finding is that the consideration for the most abundant gas holdup for the typical BC was the smallest ratio of water flow to gas flow.

Keywords: hybrid membrane process; electrocoagulation; CFD; hydrogen bubble; degassing optimization

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Publ.-Id: 32954