Treatment of the root vegetables wash water in Lithuania

Abstract

Increasing supply of the washed and „ready to eat“ vegetables to the market causes issues of the huge volumes of fresh water used and large quantities of wastewater generated in the processing that requires special treatment for the vegetable producers. In Lithuania, farmers, who engage in washing vegetables, face the problems of wastewater treatment, wastewater storage and utilization. Wastewater released to the environment from their farms would meet hygiene and environmental protection criteria. Four typical farms were chosen that represent different root vegetables, such as carrots and beetroots, and use different washing and wastewater treatment systems. Wash water of the carrots was more contaminated than that of beetroots, especially after polishing and processing. All farms transferred the wash water used to the settling ponds or settling tank. Settled water continuously was used for the first wash. Drinking water from well was used for the final wash of vegetables. As a certain amount of excess water consistently generate, it was stored in the ponds. Excess water and sediments were spread out on the fields periodically according to legislations. Wastewater of one carrots washing farm was treated in the system of surface flow constructed wetland and two biological ponds. As vegetables producing farms are located in rural areas, natural treatment methods are suitable for treatment of their wash water. Natural treatment systems are relatively inexpensive and need low-maintenance option compared with technical treatment systems. The results of research show that such natural wastewater treatment system is suitable for farms in Lithuania, that wash and produce root vegetables, but before releasing wastewater to the environment, it has to be settled.