EARLY REMEDIATION OF WASTEWATERS FROM ROMANIAN FOOD INDUSTRY: A CASE STUDY OF IMPROVING THE QUALITY OF DAIRY INDUSTRY WASTEWATER

Abstract

The purpose of this study was to demonstrate the role played by different wastewater treatment technologies in the dairy industry in the context of the challenges of sustainable development: water scarcity and conservation of water resources, the constant growth of the population and the costs of wastewater treatment in centralized systems, increasing constraints and stricter environmental protection regulations. In this sense, the efficiency of wastewater treatment plants belonging to a number of 8 factories was determined. The studied factories were divided into three groups according to the type of wastewater treatment technology, namely: the first group uses only the pretreatment stage; the second uses the mechanical-chemical and biological treatment stages with biogas production; the third group has an aerobic biological treatment coupled with a reverse osmosis module. Water samples were taken weekly from the influent and effluent of each wastewater treatment plant for 6 months (March-August 2022). A number of 8 quality parameters were analyzed for both waste water and treated water, in accordance with the national regulations. The results highlighted the fact that the values of chemical oxygen consumption (COD), five-days biochemical oxygen consumption (BOD5), total suspended solids (TSS), phosphorus (PTotal), respectively total nitrogen (NTotal), and ammonium nitrogen for all wastewater samples far exceeded the limits of admissibility provided by the national wastewater quality standards. Instead, the pH values and the chloride content were within acceptable limits. The apply of mechanical and biological wastewater treatments determined the decrease of COD, BOD5 and TSS concentrations by more than 95%, respectively by more than 85% in the case of PTotal. The efficiency of the reverse osmosis module was over 95% in the case of ammonium nitrogen elimination. As a result of the onsite implementation of these technologies for the treatment of wastewater from the dairy industry, the values of the quality indicators of the effluents were in accordance with the regulations regarding the discharge of treated water into natural receivers or into the urban sewage network without affecting the environment.