Application of Biofilm Technology in Monosodium Glutamate Wastewater Treatment

Monosodium Glutamate (MSG) production generates substantial wastewater, causing severe environmental pollution and contradicting environmental protection laws and regulations in our country. Most MSG manufacturers have implemented various treatment measures, but there remains no practical method for effectively treating high-concentration organic wastewater, leaving the problem unresolved at its core.

MSG production wastewater can be categorized into three types based on pollutant content:

1. High-concentration, high-acidity organic wastewater, known as ion-exchange tailwater.
2. Other medium to high-concentration organic wastewater types.
3. Cooling and temperature reduction water that can be discharged directly without treatment.

Ion-exchange tailwater is the residual “waste liquid” left after extracting glutamic acid using ion exchange. It contains abundant organic matter, as well as small amounts of inorganic salts such as N, P, K, and trace elements. These substances are essential nutrients for crops, and if not utilized properly, they not only cause severe environmental pollution but also result in wasteful resource utilization.

Starch wastewater, sugar refining wastewater, fermentation wash water, and ion-exchange tailwater all fall under the category of medium to high-concentration organic wastewater. These types of wastewater must be treated before discharge.

Cooling and temperature reduction water, apart from having elevated temperatures, do not contain any pollutant substances and can be discharged directly.

In accordance with national and provincial environmental requirements, monitoring and acceptance adhere to the “Comprehensive Emission Standards for Water Pollutants” (GB8978—88) level 2 standards for the MSG industry and comprehensive emission standards.

To address the distinctive characteristics of wastewater, a comprehensive utilization approach with classified treatment techniques is employed. High-concentration, high-acidity organic wastewater, i.e., ion-exchange tailwater, is treated through multi-effect evaporation and granulation to produce organic-inorganic compound fertilizer, achieving “zero emissions” while yielding economic benefits.

Other medium to high-concentration organic wastewater types, such as starch wastewater and sugar refining wastewater, undergo anaerobic-aerobic biological treatment to meet emission standards. The treatment process involves anaerobic pretreatment and aerobic combined treatment.

This process demonstrates stability, reliability, and effective results, with effluent BOD5, COD, and other pollution indicators (except NH3—N) meeting emission standards. It generates minimal sludge, and sludge dewatering is relatively easy, simplifying the treatment process. Moreover, this process can withstand fluctuations in water quality and quantity, offering flexible and reliable operation. It mainly comprises two technologies: anaerobic treatment and aerobic treatment.

Anaerobic technology utilizes both anaerobic biofilm and Upflow Anaerobic Sludge Bed (UASB) processes.

2.1.1 Anaerobic Biofilm Wastewater Treatment Facilities

The adopted anaerobic biofilm wastewater treatment technology effectively addresses the pollutants in high-concentration organic wastewater (CODcr approximately 20,000 mg/l, pH approximately 2) such as CODcr, NH3—N, SO42—, and pH, significantly contributing to the treatment of ion-exchange tailwater from MSG production.

However, it has the drawback of operating in unfavorable environmental conditions and the uncontrolled emission of ammonia gas.

2.1.2 Anaerobic UASB Wastewater Treatment Facilities

In recent years, anaerobic treatment of high-concentration organic wastewater in the fermentation industry has developed rapidly in China and is relatively mature. The UASB (Upflow Anaerobic Sludge Bed Reactor) used by this group is a new, highly efficient wastewater treatment equipment developed in recent years, revolutionizing traditional anaerobic reactor technology. The new anaerobic reactor exhibits uniqueness in influent mode, water distribution system, mixing, and three-phase separator design, making it an ideal device for high, medium, and low concentration wastewater treatment projects. The facility operates stably, recovers biogas, and is highly efficient.

Aerobic technology utilizes Sequencing Batch Reactor (SBR) aerobic facilities, which is an advanced organic wastewater treatment process. Several small and medium-sized wastewater treatment plants in China have employed this technology, yielding good treatment results and ammonia nitrogen removal capabilities.

The MSG industry employs SBR, which performs well in treating MSG wastewater containing CODcr and BOD5. However, as the actual influent NH3—N concentration is much higher than the design concentration, the ammonia nitrogen removal rate falls short of the design target. Since the aerobic facility has a relatively short trial operation time, the ammonia nitrogen removal capacity should be further explored to facilitate complete nitrification and denitrification processes and enhance ammonia nitrogen removal efficiency.

The application of biofilm technology in MSG wastewater treatment offers efficient and environmentally compliant solutions. Through a combination of anaerobic and aerobic processes, different types of wastewater can be effectively treated to meet emission standards. These processes not only address environmental concerns but also utilize valuable resources, showcasing the industry’s commitment to sustainability and responsible production.

Xian CHIWATEC Water Treatment Technology es una empresa de alta tecnología especializada en varios dispositivos de procesamiento de agua. Aparte de estos productos individuales, que cubren una serie de tipos y series, también podemos ayudar con proyectos de ingeniería integrales relacionados. Gracias a nuestro arduo trabajo y dedicación desde nuestra fundación, ahora somos uno de los fabricantes de equipos de tratamiento de agua de más rápido desarrollo en el oeste de China.

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