CO COMPOSTING OF FATS FROM THE DAIRY INDUSTRY SEPARATED BY DISSOLVED AIR FLOTATION EQUIPMENT (DAF)

LOVATO MARÍA; FIASCONARO, MARÍA LAURA; C.A: MARTÍN

Santa Margherita di Pula

Simposio; Sardinia 2017 - Sixteenth International Waste Management and Landfill Symposium.; 2017

IWWG - International Waste Working Group,

The State of Santa Fe produces almost 50 % of the milk of Argentina. Dairy industries are involved in the manufacturing of several products such as fluid milk, cheese, cream, etc. Dairy industries produce nearly thousands of liters of wastewater per day and represent an important pollution problem in the region. Dairy wastewater is characterized by high biological-oxygen demand (BOD) and chemical oxygen demand (COD) concentrations, and generally contains fats, nutrients, lactose, as well as detergents and sanitizing agents. Dairy wastewaters are generally treated using biological methods such as activated sludge processes, aerated lagoons, trickling filters, sequencing batch reactors (SBR), anaerobic sludge blanket (UASB) reactors, anaerobic filters, etc. (1). Common techniques for treating dairy industry wastewaters include grease traps, oil water separators for separation of floatable solids, equalization of flow, and clarifiers to remove SS. Over the last ten years, there has been an increasing interest on the use of dissolved air flotation equipments (DAF) for clarifying solids from biological systems in lieu of traditional gravity clarifiers (2). DAF is a relatively simple technology that uses fine air bubbles to separate liquid particles and light suspended solids (mostly fats) from wastewater. These particles and solids are floated via the bubbles to the surface of a flotation cell for removal from a wastewater stream. However, the bio solids that have been separated in the DAF equipment should be considered as a new problem. The management of these biosolids (DAFW) is complicated due to their high water content that makes them not suitable for incineration and deteriorates the landfills. This type of waste has similar properties that sludge from grease traps and was expected to be suitable for biological treatment in anaerobic reactors or aerobic composting using several co substrates as bulking agents and C-N sources (i.e., wood shavings and chips, green grass). Davidsson et al. (3) have studied the anaerobic co-digestion of grease trap sludge with sewage sludge at a wastewater treatment plant. However, the authors noted that single-substrate digestion of sludge from grease traps could be unwise since long-chain fatty acids are known to inhibit anaerobic microorganism?s activity.