Wastewater generated from food production and agricultural activities is a major source of environmental pollution. It is also among the most difficult and costly waste to manage because food processing wastewater can contain large quantities of nutrients, organic carbon, nitrogenous organics, inorganics, suspended and dissolved solids, and it has high biochemical and chemical oxygen demands. It must be treated to levels that will not damage receiving waters due to excessive nutrients or oxygen demand when directly discharged or will not disrupt the maximum allowable BOD, COD, pH and other parameters when discharged to sewers.
Each type of food processing wastewater will have special factors to consider, and in addition to the technology performance issues, seasonality of production adds to the complexities of the treatment choices and operations in several industries.
The range of food and agricultural wastes present different challenges. Industry examples include: meat and poultry products, dairy products, fruits and vegetables for canning and preserving, grain products, sugar and related confectionaries, fats and oils, beverages and brewing, etc. Biochemical oxygen demand (BOD) and chemical oxygen demand (COD) values for many wastes are in the thousands of milligrams per liter, and some like cheese production, winery and olive milling can be in the tens of thousands for COD. So, each waste type will have special factors to consider, and in addition to the technology performance issues, seasonality of production adds to the complexities of the treatment choices and operations in several industries.
Varieties of treatment technologies used for food processing wastewater are not unusual among wastewater treatment options and are included of typical arrays of biological and physical chemical treatments. Also, oxidative and anaerobic processes may be employed. The mentioned treatments are as follows: floatation, coagulation, sedimentation, filtration, adsorption, membranes, primary settling, secondary activated sludge, anaerobic digestion and even recovery of carbon dioxide or methane for subsequent uses.
Due to the water scarcity especially in the middle east region, most of the clients prefer to apply the treated wastewater in form of irrigation, surface cleaning and even recycling to the plant depending upon their requirement level. However, it must be noted that recycling treated wastewater to where it contacts with food is tricky, because various residual contaminants may penetrate into food.
Fruit and vegetable processing
Many of the aforementioned treatment processes are used in vegetable and food processing wastewater treatment. The production process produces waste streams from washing and rinsing, sorting, in-plant fluid transport methods, peeling, pureeing and juicing, blanching, canning, drying, cooking and cleanup. Most of the waste content is biodegradable carbohydrates, although salts may also be a contributor for some such as brining products.
There are many elements of production of fish products that generate solid and liquid wastes. Harvested product may be processed on shipboard or stored by icing or freezing for transport to the processing plant. Farmed product may be handled somewhat differently from wild-caught product. Wastes from eviscerating and butchering are collected, dried or screened and used as byproducts. The processing plant may further trim from the product and then cook, pack or freeze, generating other waste liquids and solids. Each type of product generates different levels of BOD, COD and often substantial amounts of fats, oils and grease and protein content.
Meat and poultry industries
Wastes from the meat and poultry industries include those generated by the animals during livestock holding as well as high-strength wastes produced during processing. These processes include: slaughtering, defeathering or hide removal, eviscerating and trimming, washing, disinfecting and cooling. Meat & poultry industries wastes are contained of nitrogenous organic (proteins), fats and inorganic (nitrates) components.
The two main elements are milk bottling and milk product production of whey, butter, cheese, ice cream, yogurts, cottage cheese and other milk derivatives. The latter post-milk processing is the largest contributor to wastewater production and to the strength of the wastewater. The COD levels at those stages, especially in cheese production, can be much more than 10 times the amount in milk bottling. Non-dairy ingredients such as flavors, sugars and fruits are also involved in production, and they can contribute to the waste stream. The waste products are mainly biodegradable, so aerobic and anaerobic processes are standard.
Oil and fat processing
Vegetable oil and animal fat production often involves solvent extraction or compression for olive and sesame oils. The oils must have further refining processes to remove some taste, free fatty acids and other residue components from the extracted oils and fats. Substantial amounts of solid residues are also generated from the vegetable oil production. In addition, extraction solvents must be removed. Olive oil production generates higher levels of COD and solid wastes compared to other food and agricultural wastes.
Food and agricultural wastes are ideal for biogas production due to the relatively high total organic carbon (TOC) loadings compared to many other wastes.
High-rate anaerobic digesters are attracting interest because of their higher loading capacities and lower sludge production. They can include: anaerobic filters, up flow anaerobic sludge blanket reactors, baffled fluidized beds, granular sludge beds. An important consideration is the presence of granular support media that provides an enlarged surface area, which enhances contact between the active microbial species on the surface and carbonaceous material and nutrients in the wastewater.
Discharges of food and agricultural wastes are a significant contributor to nutrient and carbonaceous and nitrogenous waste discharges. Treatment of agricultural and food processing wastewater is complex and costly because of the contaminant loadings and the variability of the different wastes encountered in a plant. Industries including poultry and meat processing, dairy products and oil production generate high-strength wastes. While common wastewater treatment processes are used, there are developments in anaerobic processes to produce methane gas for energy and electricity to offset process costs. In addition to reducing operating costs, they are environmentally friendly by reducing waste discharges and carbon footprints.
FARAN as an expert in wastewater treatment, offers its customers a broad scope of treatment methods to bring specific harmful substances in their wastewater within the range of permissible limit values. Our service portfolio not only comprises the planning and overseeing of a client’s project, but also encompasses repair and maintenance, and the operation of the wastewater treatment plant on the client’s behalf.
FARAN’s systems adapt to all situations whether it is newly constructed system for biological, chemical and physical processes, or expansion and optimization of an existing wastewater treatment system. We now invite you to convince yourself in person about our expertise and experience. In case of any changes in product baches, there will be no worries. In that, FARAN’s plants are perfectly designed to be flexible to any changes.