Industrial Wastewater Treatment of Food Industry Using Best Techniques
Food processing industry wastewater poses pollution problems due to its high COD (Chemical Oxygen Demand) and BOD (Biochemical Oxygen Demand) Compared to other industrial sectors, food industry requires great amounts of water, since it is used throughout most of plant operations, such as production, cleaning, sanitizing, cooling and materials transport, among others. The wastewater streams with different levels of pollution load (low, medium and high contamination) are collected and treated in an on site installation or in a municipal sewage treatment plant. Increasing food production will increase the volume of sewage and the cost of disposal for food processing plants and present difficult challenges for municipal wastewater treatment plant operators. The production process includes five production lines were operating, chocolate cake line, three lines of different biscuits type, and ketchup line. The industry consumes about 141 m3/day for domestic water activitieswhile the overall total wastewater discharges equal 120 m3/day and 70 m3/day for domestic wastewater and industrial wastewater respectively. The main environmental problem of the industry is that the industrial wastewater resulting from the facility is not meeting the limits of the environmental regulations for the discharge of wastewater to the sewer network. Accordingly, the industry has to treat the wastewater prior to its discharge to the wastewater sanitary network.The main objectives of this study are management and control of liquid and solid wastes in the industry as well as selecting the different possible treatment trains for the wastewater prior to its discharge to the sewer system in order to protect the environment and to gain benefits as much as possible from the wasted materials and identify opportunities for introducing pollution prevention measures and best method for waste minimization as cleaner production system. A treatability study and analysis was conducted for investigating the feasibility of each of identifying the different possible treatment trains, selecting the most suitable treatment train, and developing the basic design for the selected treatment train for the wastewater streams that need to be treated prior to its discharge to the sewer system. As well as treatment procedure through a bench scale model and treatability study was developed for the industrial wastewater streams of the industry to study the analysis of waste discharges and investigate the most appropriate treatment techniques using two proposed streams of techniques; physical chemical treatment and physical chemical treatment followed by biological treatment technique (Coagulation followed by Sedimentation) or using biological treatment. Based on the analysis and treatability study of the alternative Physical Treatment by Gravity Settling, it is clear that the BOD and COD are still not complying with the regulatory limits for the discharge to the sewer system. Accordingly, equalization and gravity settling is not considered a feasible alternative for treatment of the industrial wastewater discharge. Moreover, based on the above calculations, mixing with industrial wastewater after equalization and gravity settling does not assist in complying with the regulatory limits. While through using Physicochemical Treatment by Coagulation and Sedimentation, it is resulted in reduction of COD and BOD by 81% and 85% respectively in the 24 hr composite sample. In the 48 hr sample, the reduction is 45% in the COD and 52% in BOD. Accordingly, the wastewater resulting after coagulation and sedimentation is complying with the discharge limits to the sewer system.As for the physical chemical treatment, through coagulation and sedimentation, it has resulted in reduction of the wastewater pollutants below the discharge limits. Accordingly, a Dissolved Air Floatation (DAF) Unit would be considered a feasible alternative as it is used to remove suspended solids and oil and grease from industrial wastewater. The previous results indicated that the best process alternative is the coagulation/flocculation followed by Dissolved Air Floatation (DAF) gives high treatment efficiency of the wastewater. So, the recommended treatment scheme would be carried out using aeration tank and DAF unit. Accordingly, basic engineering design is conducted for this alternative.