Fragrance Manufacturing Wastewater: Pretreatment, Biological Treatment and CDOF
Fragrances are used widely in the food and personal care industries. The organic fraction of fragrance production wastewater contains large amounts of aromatic hydrocarbons, aromatic compounds and their derivatives — more than twenty species — including substances that inhibit microbial growth, such as phenol, toluene and benzaldehyde. Washing reactors and similar operations also introduce large quantities of surfactant. Fragrance wastewater is therefore high in concentration, variable in quality, rich in organic matter that suppresses microbial growth and complex in composition. It cannot be treated biologically without preparation, and it ranks among the more difficult industrial wastewaters.
Pretreatment Comes First
Because fragrance wastewater is poorly biodegradable, treatment normally begins with pretreatment. The options are micro-electrolysis, micro-electrolysis combined with catalytic oxidation, wet oxidation and ozone oxidation. Which one fits is decided by the results of a bench-scale process trial.
Once pretreatment has improved biodegradability, the wastewater passes to an equalisation tank for homogenisation and flow balancing, and then to the biological stage. The biological sequence runs anaerobic, denitrification, organic degradation, nitrification.
Applying CDOF to Fragrance Wastewater
For fragrance wastewater, SINOKLE combines its in-house CDOF (catalytic dissolved ozone flotation) technology with the biological train. CDOF lowers COD effectively and improves biodegradability, which prepares the water for the biological stage.
Process flow diagram of the CDOF catalytic ozone oxidation unit.
The diagram shows the working sequence of CDOF, which stands for Cyclonic Dissolved Ozone Flotation unit. It combines advanced ozone oxidation, cyclonic separation and dissolved gas flotation in a single unit, and removes a wide range of refractory pollutants efficiently in one pass.
Ozone catalytic oxidation has a short flow sheet and simple equipment. The treatment units are small and compact, the footprint is small, few electrical devices are needed, power consumption and operating cost are low, and operation is convenient and can be automated, which simplifies what is demanded of site staff. When flow or water quality changes, the process can be adjusted accordingly: it adapts well and tolerates shock loads. It can also be combined with other technologies such as biological treatment so that each contributes its strength and performance improves further.
Micro and nano bubble generation: high-efficiency gas dissolution, release and mixing.
The Micro and Nano Bubble Generator
The ultra-fine bubble generation technology centres on high-efficiency gas dissolution, release and mixing. Micro and nano bubbles are extremely fine bubbles below 50 microns in diameter. They rise slowly in water, stay in suspension for a long time and dissolve with high efficiency; they also self-oxygenate, carry a negative charge and are rich in strongly oxidising free radicals.
Pilot Test on a Fragrance Processing Wastewater
Pilot test data.
Pilot test conclusions.
With this process, at an ozone dose of 150 mg/L the effluent COD was 238.8 mg/L, the COD removed was 186.55 mg/L and the ozone dosage ratio was 0.80. The results show that part of the macromolecular COD was oxidised to smaller molecules, which improved the biodegradability of the wastewater; the process also carried part of the COD removal load. Both effects prepare the water for the biological stage that follows.
