Biological Anaerobic – Aerobic Treatment Of Dairy Wastewater In Poland
In 2014, farms across the EU-28 produced approximately 164.8 million tones of milk, of which 159.6 million tones (or 96.8 %) were cows’ milk. Cows’ milk production on farms was the highest in Bretagne (France), Southern and Eastern Ireland and Lombardia (Italy) and Masovia (Poland) (8,3%). Milk processing produces wastewater. In Poland 1 m 3 of processed milk accounts for 3.2 m 3 of wastewater. In 2013 the production of dairy products in Poland generated 26.5 hm 3 of sewage: 14.7 hm 3 of which was treated (9.3 hm 3 biologically and 5.4 hm 3 with increased nutrient removal). The dairy wastewater is primarily generated from the cleaning and washing operations. Its main contaminants are: high BOD and COD concentrations, and it contains fats, nutrients, lactose, as well as detergents and sanitizing agents. Biological treatment is the basic method used for wastewater from food processing. Dairy wastewater in Poland is treated using aerobic biological methods: circulated pond, activated sludge process, sequencing batch reactor, Moving Bed Biofilm Reactor and anaerobic reactors. The two steps anaerobic-aerobic reactors are used in two cases in Poland.
Critical review on biological treatment strategies of dairy wastewater
Dairy products are one of the richest sources of vital nutrients in the diet of human beings and it occupies an important place in satisfying their nutrient requirements. The dairy products possess a very short lifespan and during their decomposition create a huge nuisance to the environment. The dairy effluents discharged from the industries are mainly composed of complicated substances such as organic compounds, inorganic compounds, carbon, nitrogen, phosphorus, chlorides, sulphides, fats, oils, grease, etc. These organic loading present in the dairy effluent have a negative impact on the environment during its discharge to nearby water sources. The physical and chemical treatment of the dairy effluents is not as effective as the biological treatment. The biological treatment method is found to be the superior method for treating the dairy effluent. The biological wastewater treatment can be performed in two various conditions such as aerobic and anaerobic. The treatment methods such as aerobic lagoons, activated sludge, sequential batch reactor, trickling filter, completely stirred tank reactors, fluidized bed reactors, and anaerobic filters are some of the biological methods used in dairy effluent treatment. This review article has investigated in detail regarding the environmental impact of dairy effluents and their effective treatment using biological treatment technologies
Dissolved Oxygen Distribution in a Rectangular Airlift Bubble Column for Biological Nitrogen Removal
The rectangular airlift bubble column where anaerobic and aerobic regions coexisted was used, and the treatment of wastewater including nitrogen was performed. The effects of equipment and operation conditions on the gas holdup, liquid-phase volumetric mass transfer coefficient and liquid circulation flow rate were investigated in two different-size columns. On the basis of oxygen balance, the distribution of dissolved oxygen concentration in the column was calculated by using the experimental equations of flow characteristics. The results of wastewater treatment proved that the nitrogen removal was controlled by the volume fraction of anaerobic region.