1. Scrubber tower

The commonly used equipment is a packed scrubber tower. Chemical absorption liquid is sprayed from the top of the tower downward, and the waste gas flows upward. The malodorous gas fully contacts and reacts with the absorption liquid and is thus removed. The ratio of the absorption liquid to the exhaust gas flow rate (liquid/gas ratio) is generally 1-3 L/m 3, and the gas empty tower flow velocity is generally 0.5-1m/s.

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2. Chemical absorbent

Commonly used chemical absorbents include the following types: alkaline solution/acidic solution/sodium hypochlorite solution

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Alkaline absorption solutions commonly used are solutions containing 1-10% sodium hydroxide, which are very effective in eliminating hydrogen sulfide. For other substances that often cause odors in wastewater treatment plants, such as methyl mercaptan, methyl sulfide, dimethyl sulfide, and low-level fatty acids, this method can achieve excellent treatment results.

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Acid washing is mainly used to eliminate odors caused by alkaline gases such as ammonia and trimethylamine. Generally, sulfuric acid (a solution of 0.5-5%) is often used as the washing solution.

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Sodium hypochlorite is generally used together with acidic or alkaline absorption solutions. For methyl sulfide that is difficult to eliminate by other methods, the control effect of sodium hypochlorite absorption solution is very good. When treating high-concentration odors from sewage treatment plants, the concentration of sodium hypochlorite solution (effective chlorine concentration) is approximately 500-2000ppm. When dealing with lower-concentration odors, sodium hypochlorite solution with a concentration of approximately 50-500 PPM is used. In terms of the performance of various oxidants, sodium hypochlorite is the cheapest and has a good effect, so it is the most commonly used.

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Sodium hypochlorite in solution exists in the form of hypochlorous acid (HOCl) :NaOCl+ H2O→HOCl+ NaOH...... At pH 7.5, the available chlorine in hypochlorite solution exists in the form of 50% HOCI and hypochlorite ions (OCl-). At pH=10, only 0.3% of available chlorine exists as HOCl. At pH 11 or 12, HOCl almost completely dissociates into useless hypochlorite ions, so pH value control is very important.

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Plant liquid enhances washing and deodorization

The diluted plant extract in the storage tank is lifted by the circulating pump to the sprayer in the washing container for spraying. The sprayed liquid is returned to the storage tank through the packing layer and then recycled by the circulating pump. The induced draft fan draws the malodorous gas into the washing container through the collection pipeline. After the malodorous gas is evenly distributed by the air distribution plate, it moves in the opposite direction with the spray liquid into the packing layer. The airflow is cut and distributed in multiple directions and fully contacts and reacts with the diluted plant extract on the surface of the packing. At this time, the flow rate of the malodorous gas is slow, and the residence time in the container is long, forming a semi-liquid phase. The surface of the filler with plant extract liquid forms a filtering effect on it. The malodorous gas flowing out of the filler layer is washed by the spray liquid and then discharged through the exhaust port, thus eliminating the odor.

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Natural plant liquid is a highly effective deodorant. After reacting with the scrubber, the content of odors such as hydrogen sulfide and ammonia will be reduced by more than 95%. Therefore, this process is widely applicable to deodorization in various sewage treatment plants (stations), garbage transfer stations, landfill sites, composting plants, sludge storage areas and other places, as well as for waste gas purification in production workshops of petroleum, chemical, synthetic rubber, pharmaceutical, food processing, papermaking and other industries.

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Biological Deodorization technology

The biofiltration deodorization process adopts the "microbial" degradation technology. It utilizes deodorizing microorganisms growing on the filter material to degrade H2S, SO2, NH3 and most volatile organic malodorous substances, with a deodorization rate that can reach 98-99%. The biofilm formation and adjustment were carried out using the superior strain cultivated and domesticated by Tongji University, which features a short biofilm formation period and good treatment effect. The system has a lifespan of over 10 years and can operate normally outdoors within a temperature range of -20℃ to 40℃. It can operate throughout the year, running continuously for 24 hours a day, and its treatment process does not cause secondary pollution. The processing system is mainly made of fiberglass reinforced plastic, which has good corrosion resistance.

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The core of the biological deodorization system consists of high-efficiency biological filter (pool) towers, composite fillers conducive to the attachment and growth of microorganisms, and dominant microbial strains. Under suitable environmental conditions, microorganisms in the filter (pool) tower form a biofilm on the surface of the packing material. They utilize the inorganic and organic substances in the waste gas as carbon sources and energy, maintain their life activities by degrading malodorous substances, and decompose malodorous substances into odorless substances such as water, carbon dioxide and minerals, achieving the purpose of purifying malodorous gases.

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