How Should Enterprises Effectively Control Odor Pollution?

With the development of economy and the improvement of people's living standards, the odor pollution caused by municipal facilities such as sewage treatment plants and landfill sites and industrial and agricultural production processes such as chemical industry, food processing, painting operation and livestock and poultry breeding has become one of the focuses of public complaints. Therefore, the treatment of odor pollution is an urgent ecological and environmental problem and people's livelihood problem. We can control the whole process of odor and reduce odor complaints by reducing odor sources, controlling odor diffusion and effective terminal treatment.

01 Source emission reduction

Starting from the source of pollution, the emission of malodorous gases can be fundamentally reduced. Source emission reduction includes two aspects.

1. Through clean production, source substitution, process improvement and other ways to reduce the use and production of odorous substances from the source. 

The replacement of raw and auxiliary materials with low VOCs is the key to promote the prevention and control of VOCs in our province during the Tenth Five-Year Plan period. In 2023, the Action Plan for Continuous Improvement of Air Quality issued by the State Council proposed to "optimize the raw and auxiliary materials and product structure containing VOCs."

Different industries adopt raw and auxiliary materials with low odor or VOCs content according to the process, which can reduce the emission of malodorous gases. Solvent-based paints, inks, adhesives and cleaning agents with low VOCs content, such as water-based, powder, high solid content, solvent-free and radiation-curing, and water-based adhesives with low VOCs content, such as hot melt, solvent-free, radiation-curing, modification and biodegradation, and water-based cleaning agents with low reactivity are used to replace solvent-based paints, inks, adhesives and cleaning agents, so as to reduce odor.

For example, in the wood furniture manufacturing industry, water-based raw materials such as two-component water-based transparent matte finish, water-based brown primer and two-component water-based transparent primer are used to replace oily and odorous raw materials such as oily paint, thinner and white electric oil; Using environment-friendly plasticizer (DOTP) in the production of plastic artificial leather; Steel component manufacturers use water-based antirust paint, etc. 

At the same time, encourage enterprises to actively adopt pollution-free and light-pollution production processes. For example, in leather manufacturing, we advocate the use of low-salt preservation, low-sulfur depilation, high-efficiency liming, low-ammonia deashing and other production processes to reduce the generation of malodorous substances; In the petrochemical industry, efficient technologies and equipment such as fully automatic closed centrifuge and down-discharging closed centrifuge can be adopted to improve the conversion and utilization efficiency of crude oil; For the packaging and printing industry, automatic closed circulation ink supply, LED printing or waterless printing technology, adhesive-free composite technology and so on can be adopted.

2. Reasonably plan the position of odor source and set appropriate protection distance.

Odor emission sources should be as far away from residential areas as possible. Enterprises should strictly implement policies and measures such as buffer zone and retreat distance designated by government departments to avoid building sensitive projects in areas with prominent contradictions, so as to prevent the contradiction of "adjacent buildings and enterprises".

02 Strengthen process control

In the process of production and operation, enterprises should strengthen environmental management and control odor emission to reduce the impact on the surrounding environment, so as to reduce the occurrence of complaints from the masses.

1.Unorganized emission control

Enterprises can determine the appropriate production mode according to the generation law, influencing factors and emission characteristics of malodor. Usually, the process links with malodor/odor (such as VOCs) are carried out in a closed space and a special collection system is set up according to regulations. For open production, it can be collected by enclosing, semi-enclosing or external gas collecting hood, and the suction wind speed during collection should be controlled to reduce unorganized emissions. 

2. Strengthen closed production and leakage management.

For new, modified and expanded projects, enterprises should consider the closed production process and the layout of equipment and facilities from the perspective of device design, and comprehensively consider pipeline transportation, closed loading and unloading vehicles and efficient sealed storage methods. For existing devices, enterprises should consider sealing transformation and negative pressure collection of media (dirty oil, sewage, intermediate products and waste) and equipment and facilities (such as dirty oil tanks, sewage stations and hazardous waste warehouses) with strong volatility and foul smell. 

3. process control

In the process of using products containing malodorous gases such as painting, printing, bonding and industrial cleaning, it is suggested to adopt high-efficiency processes such as electrostatic spraying and solvent-free compounding, and continuous and automatic production equipment such as automatic equipment cleaning device, and outdoor operation without purification and recovery measures should be avoided as far as possible.

03 Improve governance efficiency

Terminal treatment is to deodorize the collected gas and then discharge it, which is the last line of defense to control the emission of malodorous gas.

The traditional terminal treatment technology of malodorous gas mainly includes biological methods, such as biological filter tank method, biological trickling filter method and biological preparation method. Physical methods, such as masking method, dilution method, condensation method and adsorption method; Chemical methods, such as combustion method, oxidation method and chemical absorption method. For complex malodorous gases, several technologies are usually mixed and applied. After treatment, the odor of the gas will be greatly reduced and the impact on people will be minimized. 

At present, the treatment technologies used in China include zeolite wheel adsorption, catalytic incineration (RCO) and thermal incineration (RTO). Enterprises can choose the treatment process or use it in combination according to the type/composition, operation cost, management and maintenance of malodorous gases produced in the production process.

1. zeolite wheel adsorption

The working principle is that the rotating wheel is filled with honeycomb zeolite with strong adsorption capacity, and its core device is the molecular sieve rotating wheel, which reciprocates with the rotation of the rotating wheel to realize adsorption, concentration and purification of organic waste gas. It is suitable for desorption of adsorbents under high temperature conditions, with high safety and regeneration efficiency.

2. incineration method

Incineration methods mainly include thermal incineration (RTO) and catalytic incineration (RCO).

Thermal incineration (RTO) is to treat waste gas by high-temperature oxidation. In order to ensure the efficiency of oxidation reaction, the combustion chamber temperature should reach above 760℃, which is suitable for waste gas with low hydrogen sulfide content, and the construction and operation costs are relatively high. 

Catalytic incineration (RCO) mainly uses noble metal catalyst to generate oxidation reaction at low temperature, which can effectively remove hydrogen sulfide gas. Compared with thermal incineration, catalytic incineration consumes less energy.

"Three-point equipment, seven-point management", even the best equipment, the key lies in good use, good operation and good management. Therefore, enterprises should pay attention to strengthening the operation and management of equipment, and should check it regularly, and it is strictly forbidden to overproduce and overload to treat waste gas. For problems such as lack of professional operators of treatment facilities and difficulties in operation and maintenance of treatment facilities, enterprises can try to introduce the third-party "housekeeper" service for odor pollution prevention and control, borrow wisdom from professional teams, and regularly promote treatment technical assistance, treatment effect evaluation, efficient operation and maintenance of facilities, and intelligent monitoring.

At the same time, the ecological and environmental departments should increase the monitoring of organized and unorganized emissions of enterprises, strengthen the control and monitoring of the emission concentration of odorous substances, strictly control the substances that have an impact on human health, and disclose the monitoring data according to laws and regulations to protect the people's right to know the environmental information of enterprises.

Source | Guangdong Provincial People's Mediation Committee for Environmental Disputes