Dairy wastewater treatment . Dairy production is the second largest sector in the food industry. Milk processing plants are spread across the country due to the widespread availability of feedstock. The technology of food production creates large amounts of waste with different contaminants and concentrations. This problem needs to be solved to make dairy industry environmentally clean. It will automatically improve the environmental conditions in the area, because in most cases dairy wastewater is discharged into the sewerage system without any treatment, which can lead to malfunctions of urban sewage treatment plants and reservoirs.
Dairy industry consumes water at approximately 5 m3 for 1 ton of feedstock. The water is used for various processes: for sanitary purposes, as a heating medium (steam), wet washing, etc.
The concentration of wastewater pollution at various dairy facilities varies considerably. The variation is due to a wide assortment of products and fluctuations in output and pollutant content in the wastewater during the day. Also, the pH of wastewater ranges from 5.5 to 8.5, at temperatures from 15 to 35 ° C.
The fat content in wastewater from butter, cream, sour cream factory cold rooms is 200-400 mg/l. Suspended particles are mainly fats and coagulated protein particles. Dissolved particles are organic acids and lactose.
Microbiological contamination of dairy wastewater is low and is represented mainly by microorganisms causing lactic, acidic and alcoholic fermentation.
Despite the significant fluctuations in concentration of pollutants, the wastewater should go through a bio-chemical treatment.
Dairy wastewater treatment should be implemented locally. The primary stage of treatment is biodegradation of organic substances by microorganisms. This method is extremely efficient because it does not leave any by-products, i.e. the compounds are oxidized to carbon dioxide and water.
This principle is traditionally used at urban (municipal) wastewater treatment plants. It can also be used for the treatment of industrial (dairy) wastewater with small amounts of pollutants.
The difficulty of using aerotanks for biological treatment of dairy wastewater is caused by slow metabolization of lactose. The solution to this problem could be an integrated anaerobic-aerobic purification process, which can remove a significant amount of pollutants.
Methane fermentation is used as a preliminary step of purifying concentrated wastewater, followed by a mandatory aerobic treatment. This produces large amounts of biogas (60-80% methane) that serves as an alternative energy source. In addition, methane fermentation of wastewater from food production (including milk) produces a substantial amount of B vitamins and other biologically active substances, which puts a high value on this sediment.