The Study On Treatment Of The Garlic-sliced Wastewater

The amount of garlic production in our country is very high, ranking first in the world, which is representing the world's total output of 1/4. Most of enterprises mainly processed on garlic slice. Sliced-garlic process produced a large amount of wastewater in the process of soaking, washing and centrifuging. The wastewater becomes a kind of refractory wastewater, because of the higher concentration of COD and allicin having a strong bactericidal effect. At domestic and abroad the research on treating the garlic-sliced wastewater is very little and there is not sophisticated technology to treat such wastewater, most of the wastewater is discharged directly after diluted, so as to have a greater impact on water environment.In this paper, the wastewater is studied with anaerobic and aerobic treatment process, the main contents are:1. Using Anaerobic Baffled Reactor (ABR) to treat garlic-sliced wastewater, and explore the best operation conditions.2. Aerobic process chooses BAF, activated sludge and trickling filter. First, studing the best operation conditions of the aerobic process to treat garlic-sliced wastewater. Second, choosing the best aerobic process as the following component process with ABR, and treating the wastewater.3. Exploring the feasibility and effectiveness of constructed wetland system treating ABR-BAF combined process water.In this paper, results showed that:1. The optimum HRT of ABR is 24 h, 6 kgCOD/m~3·d of the optimum organic load rate. The average removal rate of COD and BOD are 87% and 82%, respectively. ABR improves BOD/COD from 0.33～0.46 to 0.37～0.52, and increases the biodegradability of wastewater.2. The optimum running condition of the BAF was at the HRT 16 hours, the OLR 1.1～1.4 kgCOD/m~3·d and the gas/water rate of 10: 1, respectively, with the COD removal rate of 82.0%.3. The optimum running condition of Activated Sludge Process was at the HRT 12 hours and the OLR 1.0 kgCOD/m~3·d, respectively, with the COD removal rate of 88.0%.4. The best HRT of trickling filter is 16 h, OLR is 0.6 kgCOD/m~3·d, the removal rate is at 53%.5. After selection, BAF is selected as the following-up process of ABR. After treated by combined process of ABR-BAF, the COD removal rate could reach 98.4%～98.7%, and the effluent COD ranged from 79 mg/L to 94 mg/L, met I-class criteria specified in Integrated Wastewater Discharge Standard (GB8978-1996).6. The removal rate of COD of the wetland process reaches 52.1% in the optimum HRT (4.0d). After treated by constructed wetland, the concentration of COD is able to reduce 41 mg/L-49 mg/L, met I-class-A criteria specified in Discharge standard of pollutants for municipal wastewater treatment plant (GB18918-2002).