Purification and utilization of garlic processing wastewater in lotus pond wetlands

Based on the experiments of utilization of garlic processing wastewater in a lotus pond, this study demonstrates that lotus pond wetlands have a remarkable ability to remove organic pollutants and decrease chemical oxygen demand (COD_Cr), biochemical oxygen demand (BOD₅), and suspended substances (SS) in garlic processing wastewater. Results also show evident effects of lotus roots on absorption of NH₃-N. The pH value in a lotus pond with wastewater discharged was relatively stable. The water quality in the lotus pond reached the class II emission standard, according to the Integrated Wastewater Discharge Standard (GB8978-1996), seven days after pretreated garlic processing wastewater had been discharged into the lotus pond. Garlic processing wastewater irrigation does not produce pollution in the pond sediment and has no negative effect on the growth of lotus roots. Due to utilization of garlic processing wastewater, the output of lotus roots increased by 3.0% to 8.3%, and the quality of lotus roots was improved. Therefore, better purification and utilization results can be achieved.