Flavor Production Wastewater: Challenges and Conventional Pretreatment Techniques

Flavor production is widely applied in various industries, including the food and daily chemicals industries. The organic components of wastewater from flavor production contain a large amount of aromatic hydrocarbons, aromatic compounds, and their derivatives—more than twenty types in total. Among them, substances such as phenols, toluene, and benzaldehyde, which inhibit microbial growth, are also present. In processes such as washing reaction tanks, a large amount of surfactants is added.

Therefore, flavor production wastewater is characterized by high concentrations, large fluctuations in water quality, and the presence of substantial organic substances that inhibit microbial growth. The pollution sources in the water are complex, making it difficult to directly perform biochemical treatment. This makes it one of the more challenging industrial wastewaters to treat. 

Given that the biodegradability of flavor production wastewater is low, pretreatment is often required before the wastewater undergoes biological treatment. Pretreatment methods that can be used include micro-electrolysis, micro-electrolysis-catalytic oxidation, wet oxidation, and ozone oxidation. The specific pretreatment method to choose can be determined based on the results of pilot-scale testing. 

After pretreatment improves the biological degradation properties of the wastewater, it is directed to a regulating tank for homogenization. Subsequently, the flavor production wastewater enters the biochemical stage of the treatment process, where it can undergo anaerobic treatment, denitrification, organic matter degradation, and nitrification in sequence.

Overall, the features of flavor production wastewater are as follows:

- Aromatic Compounds in Wastewater: The presence of a large number of aromatic compounds (including benzene rings, toluene, phenols) makes the wastewater highly challenging to conventional biological treatment, thus reducing the effectiveness.

- Biological Treatment Challenges: The inhibitory nature of the wastewater requires a careful approach, combining both physical and chemical treatments (e.g., using ozone oxidation or catalytic oxidation) to break down complex compounds and enhance the effectiveness of subsequent biological processes.

- Pretreatment for Improved Biodegradability: Methods like micro-electrolysis work by breaking down complex organic molecules into simpler, more biodegradable compounds, which allows the subsequent biological treatment processes to be more effective. Catalytic oxidation methods can target specific pollutants like phenols and toluene, ensuring they are removed before entering the biological treatment phase.