Odor treatment system in fishmeal factory by electrochemical activation solution

Currently, odor control and treatment at fishmeal factories is an issue attracting great attention from managers, businesses, research units, and especially people living around that area. In fact, the solution that fishmeal factories are using has limited effectiveness in deodorizing, not completely solving the arising odor. Therefore, there is a need for an effective, low-cost and easy-to-implement odor treatment method.

Electrochemical activator solution is researched, developed and widely applied in many countries and fields. Electrochemical activator solution is both a strong oxidizing agent and a high bactericidal, broad spectrum. For odorants, the electrochemically activated solution acts as an oxidizing agent. With bacteria, this solution acts as an antiseptic. Tests have shown that with the same oxidant concentration in terms of active chlorine, this solution exhibits superior oxidizing and disinfecting capacity compared to other solutions. In addition, the electrochemical activator solution is considered to be more friendly to the environment and user than other solutions with the same performance.

Patent No. 2519 "Process and system for treating odor in fishmeal factory with electrochemical activating solution" issued by the National Office of Intellectual Property to Assoc. Prof. Dr. Nguyen Hoai Chau and Dr. Tran Manh Hai, Institute of Environmental Technology, proposed a solution to overcome the difficulty in dealing with odors arising in the fishmeal factory by using an electrochemical activator solution to deodorize all stages of odor generation such as: gathering raw materials, grinding and drying fish, collecting and treating wastewater and waste. 

The deodorization process goes as follows:
- With raw materials: when in contact with electrochemical activating solution, the oxidants present in the solution will directly oxidize the odor to form no or little odor, and at the same time, the oxidant will kill bacteria to limit arising odor arises.

- With the air of the material gathering and wastewater treatment areas: when there is gas/liquid phase contact, the odorants and odor-causing agents are adsorbed and enter the solution, then the oxidizing substances present in the electrochemically activated solution will oxidize to an odorless or low odor substance. With the same amount of solution used, the smaller the size of the mist particles, the higher the contact capacity, the higher the deodorization efficiency. In addition, bacteria in the air are also destroyed when there is contact with this electrochemically activated solution. To increase treatment efficiency, it is necessary to isolate these emissions sources before treatment.

- With exhaust gas from the grinding and drying process: The hot gas generated from the crushing and drying process of raw materials is mainly composed of water vapor and odorants, the temperature is about 120°C to 140°C. Therefore, when the gas temperature is lowered, the water vapor will condense, resulting in the volume of gas to be treated being greatly reduced. Cooling is accomplished through indirect gas/liquid or gas/air contact devices, or a combination of both. The temperature of the gas after cooling before entering the fluidized bed contact tower should be lower than 50°C, then most of the steam will condense into water, and part of the odorants will also enter the condensate. The most difficult thing in exhaust gas treatment is to facilitate phase contact between the substances to be treated and the materials used for treatment. Using the fluidized bed gas/liquid contact process, where the gas flows from the bottom up through the layer of electrochemically activated solution above the plate, the gas/liquid phase contact capacity increases significantly. The contact capacity increases when increasing the number of contact holes on the plate and/or increasing the contact water layer height. Moreover, with the use of an electrochemical activator solution, the absorption capacity increases many times because when the odorants are absorbed into the solution, they will be oxidized and converted to odorless substances, reducing the rate of equilibrium solute in the solution.

The use of electrochemical activator solutions in the treatment of odors arising from fishmeal processing plants achieves two important goals: the treatment of odorants and the killing of bacteria that decompose raw materials into odorous substances, reducing odor generation. Furthermore, the odor treatment system in the fishmeal factory by electrochemical activator can be easily installed and operated.

Translated by Phuong Ha
Link to Vietnamese version




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