Study On Dairy Wastewater Treatment With Hydrolytic Acidification-Biological Aerated Filter Process

At present, a severe problem comes to China. That is hard up in water resources. We have only a few water resources for each person. A large amount of water is used in industrial productions and the effluent is polluted so bad that lack of water resources has restricted Chinese economy development deeply. Dairy industries have made a great progress in these years. Accordingly, the amount of dairy production wastewater outflow is increased yearly and the wastewater is polluted severely. Dairy production wastewater is harmful to environment with a high concentration of COD, BOD, SS and it is well biodegradable without toxic substance. The dairy production wastewater is also fluctuant in quantity and characteristic. Since 1980s, the biological aerated filter (BAF) has got extensive researches and applications in the field of sewage treatment all over the world. It is approved in many researches that the biological aerated filter combines both biological treatment and solids removal in one submerged, aerated reactor so that the secondary sedimentation tank is not needed, accordingly the treatment process is simplified. Compared to activated sludge reactor, the BAF reactor has several advantages as below: higher organic loading rate, smaller acreage (1/3 of activated sludge reactor), lower in investment (save 30%), higher efficiency in oxygen transfer, better at water quality of effluent. In addition, sludge bulking will not come to BAF.The aim of this work is to identify the optimal technologic parameters of BAF and effective height of the fillings, and to review the effect and efficiency of BAF on dairy wastewater treatment.The dairy wastewater has a lower concentration of COD, BOD and SS after hydrolytic acidification, which is helpful to reduce the organic loading rate. At the same time, hydrolytic acidification degrades big molecules to small ones, and dairy production wastewater becomes more degradable. Otherwise organic nitrogen in wastewater is transformed to ammonia nitrogen, which is inorganic.The optimal technologic parameters are identified from the effect of GWR and the rate of the filtration on COD, SS and NH₄⁺-N removal efficiencies and the optimal GWR is 5 and the rate of filtration 0.1m³/(m²Â·h). In optimal...