Combined Treatment Of Synthetic Flavor Wastewater Using A Coagulation,ASBR-SBR, And Fenton Process

Synthetic flavor is one of the most important raw materials in the field of light industry and food industry. Its wastewater is one kind of industry wastewater with the characteristics of high concentrations, complicated components, strong toxicity, and poor biodegradability. Its concentration of COD usually reaches up to104mg·L-1. These qualities make it one of the most hardly-treated industrial wastewater to be disposed of in certain single way. In this paper, the technological history, current situation and research development of synthetic flavor wastewater treatment were summarized, especially on the field of biochemical process, physical-chemistry process and the combination of different processes. To reach the equilibrium between relatively higher treatment effect and relatively lower cost, this study uses combined process of coagulation, anoxic sequencing batch reactor and sequencing batch reactor (ASBR-SBR), and Fenton together to treat synthetic flavor wastewater.The synthetic flavor wastewater was characterized by Gas Chromatography-Mass Spectrometry (GC-MS), and treated by a combined process of coagulation, ASBR-SBR, and Fenton. Optimum operating conditions for each process were investigated and fixed. The performance of the whole treatment was mainly evaluated by the COD removal ratio. First, the main components in the wastewater were detected by GC-MS. It is confirmed that the synthetic flavor wastewater treated here was composed of many bio-refractory matters, such as aromatic hydrocarbons (involving many PAHs), heterocyclic hydrocarbons and a little straight-chain hydrocarbon, including the current products of trimethyl pyrazine and2,3-dinethyl-pyrazine. Then, it has been confirmed that coagulation (at pH6.0and Alum dosage1000mg/L) effectively removed48%of the COD. The BOD5/COD ratio increased from0.09to0.21. The followed ASBR-SBR process, another69%of COD removal was obtained under the circle of ASBR10day and SBR1day. Finally, in order to eliminate the bio-refractory matters that failed to be degraded by the earlier processes, the Fenton process was carried out under its optimum conditions (pH3.0, FeSO4·7H2O5.0g/L, and H2O2(w/w30%)25.0mL/L), another COD removal of up to71%was achieved. The COD was reduced to890.0mg/L after the whole treatment and the total COD removal ratio was achieved up to95%. The combined processes were utilized successfully and pollutant loading of synthetic flavor wastewater was cut down very effectively.